Programs & Examples On #Financial

Anything related to financial calculations and processing of financial data. For example, this tag can be used for questions about interest rates calculations, stock exchange data processing, market data analysis, etc.

Only numbers. Input number in React

one line of code

<input value={this.state.financialGoal} onChange={event => this.setState({financialGoal: event.target.value.replace(/\D/,'')})}/>

Remove all items from a FormArray in Angular

To keep the code clean I have created the following extension method for anyone using Angular 7 and below. This can also be used to extend any other functionality of Reactive Forms.

import { FormArray } from '@angular/forms';

declare module '@angular/forms/src/model' {
  interface FormArray {
    clearArray: () => FormArray;
  }
}

FormArray.prototype.clearArray = function () {
  const _self = this as FormArray;
  _self.controls = [];
  _self.setValue([]);
  _self.updateValueAndValidity();
  return _self;
}

Angular get object from array by Id

You can use .filter() or .find(). One difference that filter will iterate over all items and returns any which passes the condition as array while find will return the first matched item and break the iteration.

Example

_x000D_
_x000D_
var questions = [_x000D_
      {id: 1, question: "Do you feel a connection to a higher source and have a sense of comfort knowing that you are part of something greater than yourself?", category: "Spiritual", subs: []},_x000D_
      {id: 2, question: "Do you feel you are free of unhealthy behavior that impacts your overall well-being?", category: "Habits", subs: []},_x000D_
      {id: 3, question: "Do you feel you have healthy and fulfilling relationships?", category: "Relationships", subs: []},_x000D_
      {id: 4, question: "Do you feel you have a sense of purpose and that you have a positive outlook about yourself and life?", category: "Emotional Well-being", subs: []},_x000D_
      {id: 5, question: "Do you feel you have a healthy diet and that you are fueling your body for optimal health? ", category: "Eating Habits ", subs: []},_x000D_
      {id: 6, question: "Do you feel that you get enough rest and that your stress level is healthy?", category: "Relaxation ", subs: []},_x000D_
      {id: 7, question: "Do you feel you get enough physical activity for optimal health?", category: "Exercise ", subs: []},_x000D_
      {id: 8, question: "Do you feel you practice self-care and go to the doctor regularly?", category: "Medical Maintenance", subs: []},_x000D_
      {id: 9, question: "Do you feel satisfied with your income and economic stability?", category: "Financial", subs: []},_x000D_
      {id: 10, question: "Do you feel you do fun things and laugh enough in your life?", category: "Play", subs: []},_x000D_
      {id: 11, question: "Do you feel you have a healthy sense of balance in this area of your life?", category: "Work-life Balance", subs: []},_x000D_
      {id: 12, question: "Do you feel a sense of peace and contentment  in your home? ", category: "Home Environment", subs: []},_x000D_
      {id: 13, question: "Do you feel that you are challenged and growing as a person?", category: "Intellectual Wellbeing", subs: []},_x000D_
      {id: 14, question: "Do you feel content with what you see when you look in the mirror?", category: "Self-image", subs: []},_x000D_
      {id: 15, question: "Do you feel engaged at work and a sense of fulfillment with your job?", category: "Work Satisfaction", subs: []}_x000D_
];_x000D_
_x000D_
function getDimensionsByFilter(id){_x000D_
  return questions.filter(x => x.id === id);_x000D_
}_x000D_
_x000D_
function getDimensionsByFind(id){_x000D_
  return questions.find(x => x.id === id);_x000D_
}_x000D_
_x000D_
var test = getDimensionsByFilter(10);_x000D_
console.log(test);_x000D_
_x000D_
test = getDimensionsByFind(10);_x000D_
console.log(test);
_x000D_
_x000D_
_x000D_

Scraping data from website using vba

Other methods were mentioned so let us please acknowledge that, at the time of writing, we are in the 21st century. Let's park the local bus browser opening, and fly with an XMLHTTP GET request (XHR GET for short).

Wiki moment:

XHR is an API in the form of an object whose methods transfer data between a web browser and a web server. The object is provided by the browser's JavaScript environment

It's a fast method for retrieving data that doesn't require opening a browser. The server response can be read into an HTMLDocument and the process of grabbing the table continued from there.

Note that javascript rendered/dynamically added content will not be retrieved as there is no javascript engine running (which there is in a browser).

In the below code, the table is grabbed by its id cr1.

table

In the helper sub, WriteTable, we loop the columns (td tags) and then the table rows (tr tags), and finally traverse the length of each table row, table cell by table cell. As we only want data from columns 1 and 8, a Select Case statement is used specify what is written out to the sheet.


Sample webpage view:

Sample page view


Sample code output:

Code output


VBA:

Option Explicit
Public Sub GetRates()
    Dim html As HTMLDocument, hTable As HTMLTable '<== Tools > References > Microsoft HTML Object Library
    
    Set html = New HTMLDocument
      
    With CreateObject("MSXML2.XMLHTTP")
        .Open "GET", "https://uk.investing.com/rates-bonds/financial-futures", False
        .setRequestHeader "If-Modified-Since", "Sat, 1 Jan 2000 00:00:00 GMT" 'to deal with potential caching
        .send
        html.body.innerHTML = .responseText
    End With
    
    Application.ScreenUpdating = False
    
    Set hTable = html.getElementById("cr1")
    WriteTable hTable, 1, ThisWorkbook.Worksheets("Sheet1")
    
    Application.ScreenUpdating = True
End Sub

Public Sub WriteTable(ByVal hTable As HTMLTable, Optional ByVal startRow As Long = 1, Optional ByVal ws As Worksheet)
    Dim tSection As Object, tRow As Object, tCell As Object, tr As Object, td As Object, r As Long, C As Long, tBody As Object
    r = startRow: If ws Is Nothing Then Set ws = ActiveSheet
    With ws
        Dim headers As Object, header As Object, columnCounter As Long
        Set headers = hTable.getElementsByTagName("th")
        For Each header In headers
            columnCounter = columnCounter + 1
            Select Case columnCounter
            Case 2
                .Cells(startRow, 1) = header.innerText
            Case 8
                .Cells(startRow, 2) = header.innerText
            End Select
        Next header
        startRow = startRow + 1
        Set tBody = hTable.getElementsByTagName("tbody")
        For Each tSection In tBody
            Set tRow = tSection.getElementsByTagName("tr")
            For Each tr In tRow
                r = r + 1
                Set tCell = tr.getElementsByTagName("td")
                C = 1
                For Each td In tCell
                    Select Case C
                    Case 2
                        .Cells(r, 1).Value = td.innerText
                    Case 8
                        .Cells(r, 2).Value = td.innerText
                    End Select
                    C = C + 1
                Next td
            Next tr
        Next tSection
    End With
End Sub

Difference between no-cache and must-revalidate

max-age=0, must-revalidate and no-cache aren't exactly identical. With must-revalidate, if the server doesn't respond to a revalidation request, the browser/proxy is supposed to return a 504 error. With no-cache, it would just show the cached content, which would be probably preferred by the user (better to have something stale than nothing at all). This is why must-revalidate is intended for critical transactions only.

Python Pandas Error tokenizing data

I believe the solutions,

,engine='python'
, error_bad_lines = False

will be good if it is dummy columns and you want to delete it. In my case, the second row really had more columns and I wanted those columns to be integrated and to have the number of columns = MAX(columns).

Please refer to the solution below that I could not read anywhere:

try:
    df_data = pd.read_csv(PATH, header = bl_header, sep = str_sep)
except pd.errors.ParserError as err:
    str_find = 'saw '
    int_position = int(str(err).find(str_find)) + len(str_find)
    str_nbCol = str(err)[int_position:]
    l_col = range(int(str_nbCol))
    df_data = pd.read_csv(PATH, header = bl_header, sep = str_sep, names = l_col)

Rounding to two decimal places in Python 2.7?

A rather simple workaround is to convert the float into string first, the select the substring of the first four numbers, finally convert the substring back to float. For example:

>>> out1 = 1.2345
>>> out1 = float(str(out1)[0:4])
>>> out1

May not be super efficient but simple and works :)

"Unorderable types: int() < str()"

The issue here is that input() returns a string in Python 3.x, so when you do your comparison, you are comparing a string and an integer, which isn't well defined (what if the string is a word, how does one compare a string and a number?) - in this case Python doesn't guess, it throws an error.

To fix this, simply call int() to convert your string to an integer:

int(input(...))

As a note, if you want to deal with decimal numbers, you will want to use one of float() or decimal.Decimal() (depending on your accuracy and speed needs).

Note that the more pythonic way of looping over a series of numbers (as opposed to a while loop and counting) is to use range(). For example:

def main():
    print("Let me Retire Financial Calculator")
    deposit = float(input("Please input annual deposit in dollars: $"))
    rate = int(input ("Please input annual rate in percentage: %")) / 100
    time = int(input("How many years until retirement?"))
    value = 0
    for x in range(1, time+1):
        value = (value * rate) + deposit
        print("The value of your account after" + str(x) + "years will be $" + str(value))

javax.xml.bind.JAXBException: Class *** nor any of its super class is known to this context

I have the same problem and I solved it by adding package to explore to the Jaxb2marshaller. For spring will be define a bean like this:

@Bean
    public Jaxb2Marshaller marshaller() {
        Jaxb2Marshaller marshaller = new Jaxb2Marshaller();
        String[] packagesToScan= {"<packcge which contain the department class>"};
        marshaller.setPackagesToScan(packagesToScan);
        return marshaller;
    }

By this way if all your request and response classes are in the same package you do not need to specifically indicate the classes on the JAXBcontext

What are the differences between Pandas and NumPy+SciPy in Python?

pandas provides high level data manipulation tools built on top of NumPy. NumPy by itself is a fairly low-level tool, similar to MATLAB. pandas on the other hand provides rich time series functionality, data alignment, NA-friendly statistics, groupby, merge and join methods, and lots of other conveniences. It has become very popular in recent years in financial applications. I will have a chapter dedicated to financial data analysis using pandas in my upcoming book.

Uncaught ReferenceError: jQuery is not defined

For one, you don't seem to be including jQuery itself in the header but only a bunch of plugins. As for the '<' error, it's impossible to tell without seeing the generated HTML.

What is the most efficient way to loop through dataframes with pandas?

For sure, the fastest way to iterate over a dataframe is to access the underlying numpy ndarray either via df.values (as you do) or by accessing each column separately df.column_name.values. Since you want to have access to the index too, you can use df.index.values for that.

index = df.index.values
column_of_interest1 = df.column_name1.values
...
column_of_interestk = df.column_namek.values

for i in range(df.shape[0]):
   index_value = index[i]
   ...
   column_value_k = column_of_interest_k[i]

Not pythonic? Sure. But fast.

If you want to squeeze more juice out of the loop you will want to look into cython. Cython will let you gain huge speedups (think 10x-100x). For maximum performance check memory views for cython.

Server certificate verification failed: issuer is not trusted

from cmd run: SVN List URL you will be provided with 3 options (r)eject, (a)ccept, (p)ermanently. enter p. This resolved issue for me

Convert a string to a double - is this possible?

Use doubleval(). But be very careful about using decimals in financial transactions, and validate that user input very carefully.

How to add a Try/Catch to SQL Stored Procedure

Create Proc[usp_mquestions]  
( 
 @title  nvarchar(500),   --0
 @tags  nvarchar(max),   --1
 @category  nvarchar(200),   --2
 @ispoll  char(1),   --3
 @descriptions  nvarchar(max),   --4
)              
 AS  
 BEGIN TRY




BEGIN
DECLARE @message varchar(1000); 
DECLARE @tempid bigint; 

IF((SELECT count(id) from  [xyz] WHERE title=@title)>0)
BEGIN
SELECT 'record already existed.';
END
ELSE
BEGIN               


if @id=0 
begin 
select @tempid =id from [xyz] where id=@id;

if @tempid is null 
BEGIN 
        INSERT INTO xyz
        (entrydate,updatedate)
        VALUES
        (GETDATE(),GETDATE())

        SET @tempid=@@IDENTITY;
 END 
END 
ELSE 
BEGIN 
set @tempid=@id 
END 
if @tempid>0 
BEGIN 

    -- Updation of table begin--


UPDATE  tab_questions
set title=@title, --0 
 tags=@tags, --1 
 category=@category, --2 
 ispoll=@ispoll, --3 
 descriptions=@descriptions, --4 
 status=@status, --5

WHERE id=@tempid ; --9 ;


IF @id=0 
BEGIN 
SET @message= 'success:Record added successfully:'+ convert(varchar(10), @tempid)
END 
ELSE 
BEGIN 
SET @message= 'success:Record updated successfully.:'+ convert(varchar(10), @tempid)

END 
END 
ELSE 
BEGIN 
SET @message= 'failed:invalid request:'+convert(varchar(10), @tempid)
END 

END
END

END TRY
BEGIN CATCH
    SET @message='failed:'+ ERROR_MESSAGE();
END CATCH
SELECT @message;

Difference between numeric, float and decimal in SQL Server

Guidelines from MSDN: Using decimal, float, and real Data

The default maximum precision of numeric and decimal data types is 38. In Transact-SQL, numeric is functionally equivalent to the decimal data type. Use the decimal data type to store numbers with decimals when the data values must be stored exactly as specified.

The behavior of float and real follows the IEEE 754 specification on approximate numeric data types. Because of the approximate nature of the float and real data types, do not use these data types when exact numeric behavior is required, such as in financial applications, in operations involving rounding, or in equality checks. Instead, use the integer, decimal, money, or smallmoney data types. Avoid using float or real columns in WHERE clause search conditions, especially the = and <> operators. It is best to limit float and real columns to > or < comparisons.

What are the advantages of NumPy over regular Python lists?

All have highlighted almost all major differences between numpy array and python list, I will just brief them out here:

  1. Numpy arrays have a fixed size at creation, unlike python lists (which can grow dynamically). Changing the size of ndarray will create a new array and delete the original.

  2. The elements in a Numpy array are all required to be of the same data type (we can have the heterogeneous type as well but that will not gonna permit you mathematical operations) and thus will be the same size in memory

  3. Numpy arrays are facilitated advances mathematical and other types of operations on large numbers of data. Typically such operations are executed more efficiently and with less code than is possible using pythons build in sequences

Secure Web Services: REST over HTTPS vs SOAP + WS-Security. Which is better?

Technically, the way you have it worded, neither is correct, because the SOAP method's communication isn't secure, and the REST method didn't say anything about authenticating legitimate users.

HTTPS prevents attackers from eavesdropping on the communication between two systems. It also verifies that the host system (server) is actually the host system the user intends to access.

WS-Security prevents unauthorized applications (users) from accessing the system.

If a RESTful system has a way of authenticating users and a SOAP application with WS-Security is using HTTPS, then really both are secure. It's just a different way of presenting and accessing data.

How can I get stock quotes using Google Finance API?

The simplest way as you have explained is this link this is for 'Dow Jones Industrial Average'

Link 2 is for 'NASDAQ-100'

and for all related to NASDAQ link 3

I think this should be it, else you want same in JSON notations the same as Microsoft

Please refer this old post I think this will help,

Update:

To know the details of volume and other details, I have created a vbscript that is using IE object to fetch details from the link, and alerts the content in the particular id(Create a .vbs file and run it..

Set IE = CreateObject("InternetExplorer.Application")
while IE.readyState = 4: WScript.Sleep 10: wend
IE.Navigate "https://www.google.com/finance?q=INDEXNASDAQ%3ANDX&sq=NASDAQ&sp=2&ei=B3UoUsiIH5DIlgPEsQE"
IE.visible = true
while IE.readyState = 4: WScript.Sleep 10: wend
dim ht
ht= IE.document.getElementById("market-data-div").innerText
msgBox ht
IE.quit

this will alert the values from page like this

3,124.54 0.00 (0.00%)
Sep 4 - Close
INDEXNASDAQ real-time data - Disclaimer
Range       -
52 week 2,494.38 - 3,149.24
Open        -
Vol.    0.00

I am sure this will help..

Best/Most Comprehensive API for Stocks/Financial Data

Last I looked -- a couple of years ago -- there wasn't an easy option and the "solution" (which I did not agree with) was screen-scraping a number of websites. It may be easier now but I would still be surprised to see something, well, useful.

The problem here is that the data is immensely valuable (and very expensive), so while defining a method of retrieving it would be easy, getting the trading venues to part with their data would be next to impossible. Some of the MTFs (currently) provide their data for free but I'm not sure how you would get it without paying someone else, like Reuters, for it.

Disable browser 'Save Password' functionality

I tried above autocomplete="off" and yet anything successful. if you are using angular js my recommendation is to go with button and the ng-click.

<button type="button" class="" ng-click="vm.login()" />

This already have a accepted answer im adding this if someone cant solve the problem with the accepted answer he can go with my mechanism.

Thanks for the question and the answers.

JDBC connection failed, error: TCP/IP connection to host failed

Open %windir%\System32 folder and find SQLServerManagerXX.msc

For example:

C:\Windows\System32\SQLServerManager14.msc

Go to protocols settings then enable TCP/IP port is 1433 by default

enter image description here

enter image description here

How can I select an element by name with jQuery?

Any attribute can be selected using [attribute_name=value] way. See the sample here:

var value = $("[name='nameofobject']");

Haversine Formula in Python (Bearing and Distance between two GPS points)

There is also a vectorized implementation, which allows to use 4 numpy arrays instead of scalar values for coordinates:

def distance(s_lat, s_lng, e_lat, e_lng):

   # approximate radius of earth in km
   R = 6373.0

   s_lat = s_lat*np.pi/180.0                      
   s_lng = np.deg2rad(s_lng)     
   e_lat = np.deg2rad(e_lat)                       
   e_lng = np.deg2rad(e_lng)  

   d = np.sin((e_lat - s_lat)/2)**2 + np.cos(s_lat)*np.cos(e_lat) * np.sin((e_lng - s_lng)/2)**2

   return 2 * R * np.arcsin(np.sqrt(d))

Which Architecture patterns are used on Android?

Here is a great article on Common Design Patterns for Android:

Creational patterns:

  • Builder (e.g. AlertDialog.Builder)
  • Dependency Injection (e.g. Dagger 2)
  • Singleton

Structural patterns:

  • Adapter (e.g. RecyclerView.Adapter)
  • Facade (e.g. Retrofit)

Behavioral patterns:

  • Command (e.g. EventBus)
  • Observer (e.g. RxAndroid)
  • Model View Controller
  • Model View ViewModel (similar to the MVC pattern above)

What are the different types of indexes, what are the benefits of each?

Oracle has various combinations of b-tree, bitmap, partitioned and non-partitioned, reverse byte, bitmap join, and domain indexes.

Here's a link to the 11gR1 documentation on the subject: http://download.oracle.com/docs/cd/B28359_01/server.111/b28274/data_acc.htm#PFGRF004

How to open my files in data_folder with pandas using relative path?

With python or pandas when you use read_csv or pd.read_csv, both of them look into current working directory, by default where the python process have started. So you need to use os module to chdir() and take it from there.

import pandas as pd 
import os
print(os.getcwd())
os.chdir("D:/01Coding/Python/data_sets/myowndata")
print(os.getcwd())
df = pd.read_csv('data.csv',nrows=10)
print(df.head())

Sum a list of numbers in Python

So many solutions, but my favourite is still missing:

>>> import numpy as np
>>> arr = np.array([1,2,3,4,5])

a numpy array is not too different from a list (in this use case), except that you can treat arrays like numbers:

>>> ( arr[:-1] + arr[1:] ) / 2.0
[ 1.5  2.5  3.5  4.5]

Done!

explanation

The fancy indices mean this: [1:] includes all elements from 1 to the end (thus omitting element 0), and [:-1] are all elements except the last one:

>>> arr[:-1]
array([1, 2, 3, 4])
>>> arr[1:]
array([2, 3, 4, 5])

So adding those two gives you an array consisting of elements (1+2), (2+3) and so on. Note that I'm dividing by 2.0, not 2 because otherwise Python believes that you're only using integers and produces rounded integer results.

advantage of using numpy

Numpy can be much faster than loops around lists of numbers. Depending on how big your list is, several orders of magnitude faster. Also, it's a lot less code, and at least to me, it's easier to read. I'm trying to make a habit out of using numpy for all groups of numbers, and it is a huge improvement to all the loops and loops-within-loops I would otherwise have had to write.

How to draw a line with matplotlib?

This will draw a line that passes through the points (-1, 1) and (12, 4), and another one that passes through the points (1, 3) et (10, 2)

x1 are the x coordinates of the points for the first line, y1 are the y coordinates for the same -- the elements in x1 and y1 must be in sequence.

x2 and y2 are the same for the other line.

import matplotlib.pyplot as plt
x1, y1 = [-1, 12], [1, 4]
x2, y2 = [1, 10], [3, 2]
plt.plot(x1, y1, x2, y2, marker = 'o')
plt.show()

enter image description here

I suggest you spend some time reading / studying the basic tutorials found on the very rich matplotlib website to familiarize yourself with the library.

What if I don't want line segments?

There are no direct ways to have lines extend to infinity... matplotlib will either resize/rescale the plot so that the furthest point will be on the boundary and the other inside, drawing line segments in effect; or you must choose points outside of the boundary of the surface you want to set visible, and set limits for the x and y axis.

As follows:

import matplotlib.pyplot as plt
x1, y1 = [-1, 12], [1, 10]
x2, y2 = [-1, 10], [3, -1]
plt.xlim(0, 8), plt.ylim(-2, 8)
plt.plot(x1, y1, x2, y2, marker = 'o')
plt.show()

enter image description here

LINQ: Distinct values

Are you trying to be distinct by more than one field? If so, just use an anonymous type and the Distinct operator and it should be okay:

var query = doc.Elements("whatever")
               .Select(element => new {
                             id = (int) element.Attribute("id"),
                             category = (int) element.Attribute("cat") })
               .Distinct();

If you're trying to get a distinct set of values of a "larger" type, but only looking at some subset of properties for the distinctness aspect, you probably want DistinctBy as implemented in MoreLINQ in DistinctBy.cs:

 public static IEnumerable<TSource> DistinctBy<TSource, TKey>(
     this IEnumerable<TSource> source,
     Func<TSource, TKey> keySelector,
     IEqualityComparer<TKey> comparer)
 {
     HashSet<TKey> knownKeys = new HashSet<TKey>(comparer);
     foreach (TSource element in source)
     {
         if (knownKeys.Add(keySelector(element)))
         {
             yield return element;
         }
     }
 }

(If you pass in null as the comparer, it will use the default comparer for the key type.)

How can I mock an ES6 module import using Jest?

The claims that you have to mock it at the top of your file are false.

Mock a named ES Import:

// import the named module
import { useWalkthroughAnimations } from '../hooks/useWalkthroughAnimations';

// mock the file and its named export
jest.mock('../hooks/useWalkthroughAnimations', () => ({
  useWalkthroughAnimations: jest.fn()
}));

// do whatever you need to do with your mocked function
useWalkthroughAnimations.mockReturnValue({ pageStyles, goToNextPage, page });

Authentication failed to bitbucket

I got this error using Azure DevOps even though I had added a Personal Access Tokens as the example shown.

enter image description here

Solved it by running git pull -v from Sourcetree terminal and adding the Personal Access Tokens again through there.

enter image description here

Javascript - get array of dates between 2 dates

I have been using @Mohammed Safeer solution for a while and I made a few improvements. Using formated dates is a bad practice while working in your controllers. moment().format() should be used only for display purposes in views. Also remember that moment().clone() ensures separation from input parameters, meaning that the input dates are not altered. I strongly encourage you to use moment.js when working with dates.

Usage:

  • Provide moment.js dates as values for startDate, endDate parameters
  • interval parameter is optional and defaults to 'days'. Use intervals suported by .add() method (moment.js). More details here
  • total parameter is useful when specifying intervals in minutes. It defaults to 1.

Invoke:

var startDate = moment(),
    endDate = moment().add(1, 'days');

getDatesRangeArray(startDate, endDate, 'minutes', 30);

Function:

var getDatesRangeArray = function (startDate, endDate, interval, total) {
    var config = {
            interval: interval || 'days',
            total: total || 1
        },
        dateArray = [],
        currentDate = startDate.clone();

    while (currentDate < endDate) {
        dateArray.push(currentDate);
        currentDate = currentDate.clone().add(config.total, config.interval);
    }

    return dateArray;
};

In c# what does 'where T : class' mean?

'T' represents a generic type. It means it can accept any type of class. The following article might help:

http://www.15seconds.com/issue/031024.htm

How to make my font bold using css?

Selector name{
font-weight:bold;
}

Suppose you want to make bold for p element

p{
font-weight:bold;
}

You can use other alternative value instead of bold like

p{
 font-weight:bolder;
 font-weight:600;
}

File path to resource in our war/WEB-INF folder?

Now with Java EE 7 you can find the resource more easily with

InputStream resource = getServletContext().getResourceAsStream("/WEB-INF/my.json");

https://docs.oracle.com/javaee/7/api/javax/servlet/GenericServlet.html#getServletContext--

C# - How to add an Excel Worksheet programmatically - Office XP / 2003

You need to add a COM reference in your project to the "Microsoft Excel 11.0 Object Library" - or whatever version is appropriate.

This code works for me:

private void AddWorksheetToExcelWorkbook(string fullFilename,string worksheetName)
{
    Microsoft.Office.Interop.Excel.Application xlApp = null;
    Workbook xlWorkbook = null;
    Sheets xlSheets = null;
    Worksheet xlNewSheet = null;

    try {
        xlApp = new Microsoft.Office.Interop.Excel.Application();

        if (xlApp == null)
            return;

        // Uncomment the line below if you want to see what's happening in Excel
        // xlApp.Visible = true;

        xlWorkbook = xlApp.Workbooks.Open(fullFilename, 0, false, 5, "", "",
                false, XlPlatform.xlWindows, "",
                true, false, 0, true, false, false);

        xlSheets = xlWorkbook.Sheets as Sheets;

        // The first argument below inserts the new worksheet as the first one
        xlNewSheet = (Worksheet)xlSheets.Add(xlSheets[1], Type.Missing, Type.Missing, Type.Missing);
        xlNewSheet.Name = worksheetName;

        xlWorkbook.Save();
        xlWorkbook.Close(Type.Missing,Type.Missing,Type.Missing);
        xlApp.Quit();
    }
    finally {
        Marshal.ReleaseComObject(xlNewSheet);
        Marshal.ReleaseComObject(xlSheets);
        Marshal.ReleaseComObject(xlWorkbook);
        Marshal.ReleaseComObject(xlApp);
        xlApp = null;
    }
}

Note that you want to be very careful about properly cleaning up and releasing your COM object references. Included in that StackOverflow question is a useful rule of thumb: "Never use 2 dots with COM objects". In your code; you're going to have real trouble with that. My demo code above does NOT properly clean up the Excel app, but it's a start!

Some other links that I found useful when looking into this question:

According to MSDN

To use COM interop, you must have administrator or Power User security permissions.

Hope that helps.

Using SELECT result in another SELECT

NewScores is an alias to Scores table - it looks like you can combine the queries as follows:

SELECT 
    ROW_NUMBER() OVER( ORDER BY NETT) AS Rank, 
    Name, 
    FlagImg, 
    Nett, 
    Rounds 
FROM (
    SELECT 
        Members.FirstName + ' ' + Members.LastName AS Name, 
        CASE 
            WHEN MenuCountry.ImgURL IS NULL THEN 
                '~/images/flags/ismygolf.png' 
            ELSE 
                MenuCountry.ImgURL 
        END AS FlagImg, 
        AVG(CAST(NewScores.NetScore AS DECIMAL(18, 4))) AS Nett, 
        COUNT(Score.ScoreID) AS Rounds 
    FROM 
        Members 
        INNER JOIN 
        Score NewScores
            ON Members.MemberID = NewScores.MemberID 
        LEFT OUTER JOIN MenuCountry 
            ON Members.Country = MenuCountry.ID 
    WHERE 
        Members.Status = 1 
        AND NewScores.InsertedDate >= DATEADD(mm, -3, GETDATE())
    GROUP BY 
        Members.FirstName + ' ' + Members.LastName, 
        MenuCountry.ImgURL
    ) AS Dertbl 
ORDER BY;

How can I change the default width of a Twitter Bootstrap modal box?

you can use any prefix or postfix name for modal. but you need to make sure that's should use everywhere with same prefix/postfix name.    

body .modal-nk {
        /* new custom width */
        width: 560px;
        /* must be half of the width, minus scrollbar on the left (30px) */
        margin-left: -280px;
    }

or

body .nk-modal {
            /* new custom width */
            width: 560px;
            /* must be half of the width, minus scrollbar on the left (30px) */
            margin-left: -280px;
        }

JQuery Calculate Day Difference in 2 date textboxes

   **This is a simple way of getting the DAYS between two dates** 
    var d1 = moment($("#StartDate").data("DateTimePicker").date());
    var d2 = moment($("#EndDate").data("DateTimePicker").date());

    var diffInDays = d2.diff(d1, 'days');

    if (diffInDays > 0)
    {
        $("#Total").val(diffInDays);
    }
    else
    {
        $("#Total").val(0);
    }

A failure occurred while executing com.android.build.gradle.internal.tasks

In my case the issue was related to View Binding. It couldn't generate binding classes due to an invalid xml layout file. In the file I had a Switch with an id switch, which is a Java keyword. Renaming the Switch id resolved the issue.enter image description here

Load image from resources

    this.toolStrip1 = new System.Windows.Forms.ToolStrip();
    this.toolStrip1.Location = new System.Drawing.Point(0, 0);
    this.toolStrip1.Name = "toolStrip1";
    this.toolStrip1.Size = new System.Drawing.Size(444, 25);
    this.toolStrip1.TabIndex = 0;
    this.toolStrip1.Text = "toolStrip1";
    object O = global::WindowsFormsApplication1.Properties.Resources.ResourceManager.GetObject("best_robust_ghost");

    ToolStripButton btn = new ToolStripButton("m1");
    btn.DisplayStyle = ToolStripItemDisplayStyle.Image;
    btn.Image = (Image)O;
    this.toolStrip1.Items.Add(btn);

    this.Controls.Add(this.toolStrip1);

Access-Control-Allow-Origin Multiple Origin Domains?

Sounds like the recommended way to do it is to have your server read the Origin header from the client, compare that to the list of domains you would like to allow, and if it matches, echo the value of the Origin header back to the client as the Access-Control-Allow-Origin header in the response.

With .htaccess you can do it like this:

# ----------------------------------------------------------------------
# Allow loading of external fonts
# ----------------------------------------------------------------------
<FilesMatch "\.(ttf|otf|eot|woff|woff2)$">
    <IfModule mod_headers.c>
        SetEnvIf Origin "http(s)?://(www\.)?(google.com|staging.google.com|development.google.com|otherdomain.example|dev02.otherdomain.example)$" AccessControlAllowOrigin=$0
        Header add Access-Control-Allow-Origin %{AccessControlAllowOrigin}e env=AccessControlAllowOrigin
        Header merge Vary Origin
    </IfModule>
</FilesMatch>

How to make a GUI for bash scripts?

Before actually using GUI dialogues, consider using console prompts. Quite often you can get away with simple "y/n?" prompts, which in bash you achieve via the read command..

read -p "Do something? ";
if [ $REPLY == "y" ]; then
    echo yay;
fi

If console prompt's just won't cut it, Zenity is really easy to use, for example:

      zenity --error --text="Testing..."
      zenity --question --text="Continue?"

This only works on Linux/Gnome (or rather, it'll only be installed by default on such systems). The read method will work on pretty much any platform (including headless machines, or via SSH)

If you need anything more complex than what read or Zenity provides, "change to C++" is really the best method (although I'd recommend Python/Ruby over C++ for such shell-script-replacement tasks)

I want to do simple interface for some strange game, the progress bar for health or something is the example for what I want. Variable "HEALTH" is 34, so make progress bar filled in 34/100

As a command-line script, it'd use Python:

$ export HEALTH=34
$ python -c "import os; print '*' * int(os.environ.get('HEALTH', 0))"
**********************************

Or to normalise the values between 1 and 78 (so you don't get line-wrapping on a standard terminal size):

$ python -c "import os; print '*' * int((int(os.environ.get('HEALTH', 0)) / 100.0) * 78)"

Zenity also has a Progress Dialog,

#!/bin/sh
(
echo "10" ; sleep 1
echo "# Updating mail logs" ; sleep 1
echo "20" ; sleep 1
echo "# Resetting cron jobs" ; sleep 1
echo "50" ; sleep 1
echo "This line will just be ignored" ; sleep 1
echo "75" ; sleep 1
echo "# Rebooting system" ; sleep 1
echo "100" ; sleep 1
) |
zenity --progress \
  --title="Update System Logs" \
  --text="Scanning mail logs..." \
  --percentage=0

if [ "$?" = -1 ] ; then
        zenity --error \
          --text="Update canceled."
fi

As I said before, if Zenity cannot do what you need, look into writing your game-thing as a "proper" script in Python/Ruby/Perl/C++/etc as it sounds like you're pushing the bounds of what a shell-script can do..

SQL MAX of multiple columns?

For T-SQL (MSSQL 2008+)

SELECT
  (SELECT
     MAX(MyMaxName) 
   FROM ( VALUES 
            (MAX(Field1)), 
            (MAX(Field2)) 
        ) MyAlias(MyMaxName)
  ) 
FROM MyTable1

Javascript add method to object

You can make bar a function making it a method.

Foo.bar = function(passvariable){  };

As a property it would just be assigned a string, data type or boolean

Foo.bar = "a place";

'module' object is not callable - calling method in another file

The problem is in the import line. You are importing a module, not a class. Assuming your file is named other_file.py (unlike java, again, there is no such rule as "one class, one file"):

from other_file import findTheRange

if your file is named findTheRange too, following java's convenions, then you should write

from findTheRange import findTheRange

you can also import it just like you did with random:

import findTheRange
operator = findTheRange.findTheRange()

Some other comments:

a) @Daniel Roseman is right. You do not need classes here at all. Python encourages procedural programming (when it fits, of course)

b) You can build the list directly:

  randomList = [random.randint(0, 100) for i in range(5)]

c) You can call methods in the same way you do in java:

largestInList = operator.findLargest(randomList)
smallestInList = operator.findSmallest(randomList)

d) You can use built in function, and the huge python library:

largestInList = max(randomList)
smallestInList = min(randomList)

e) If you still want to use a class, and you don't need self, you can use @staticmethod:

class findTheRange():
    @staticmethod
    def findLargest(_list):
        #stuff...

Change image source in code behind - Wpf

You are all wrong! Why? Because all you need is this code to work:

(image View) / C# Img is : your Image box

Keep this as is, without change ("ms-appx:///) this is code not your app name Images is your folder in your project you can change it. dog.png is your file in your folder, as well as i do my folder 'Images' and file 'dog.png' So the uri is :"ms-appx:///Images/dog.png" and my code :


private void Button_Click(object sender, RoutedEventArgs e)
    {
         img.Source = new BitmapImage(new Uri("ms-appx:///Images/dog.png"));
    }

How to print current date on python3?

This function allows you to get the date and time in lots of formats (see the bottom of this post).

# Get the current date or time
def getdatetime(timedateformat='complete'):
    from datetime import datetime
    timedateformat = timedateformat.lower()
    if timedateformat == 'day':
        return ((str(datetime.now())).split(' ')[0]).split('-')[2]
    elif timedateformat == 'month':
        return ((str(datetime.now())).split(' ')[0]).split('-')[1]
    elif timedateformat == 'year':
        return ((str(datetime.now())).split(' ')[0]).split('-')[0]
    elif timedateformat == 'hour':
        return (((str(datetime.now())).split(' ')[1]).split('.')[0]).split(':')[0]
    elif timedateformat == 'minute':
        return (((str(datetime.now())).split(' ')[1]).split('.')[0]).split(':')[1]
    elif timedateformat == 'second':
        return (((str(datetime.now())).split(' ')[1]).split('.')[0]).split(':')[2]
    elif timedateformat == 'millisecond':
        return (str(datetime.now())).split('.')[1]
    elif timedateformat == 'yearmonthday':
        return (str(datetime.now())).split(' ')[0]
    elif timedateformat == 'daymonthyear':
        return ((str(datetime.now())).split(' ')[0]).split('-')[2] + '-' + ((str(datetime.now())).split(' ')[0]).split('-')[1] + '-' + ((str(datetime.now())).split(' ')[0]).split('-')[0]
    elif timedateformat == 'hourminutesecond':
        return ((str(datetime.now())).split(' ')[1]).split('.')[0]
    elif timedateformat == 'secondminutehour':
        return (((str(datetime.now())).split(' ')[1]).split('.')[0]).split(':')[2] + ':' + (((str(datetime.now())).split(' ')[1]).split('.')[0]).split(':')[1] + ':' + (((str(datetime.now())).split(' ')[1]).split('.')[0]).split(':')[0]
    elif timedateformat == 'complete':
        return str(datetime.now())
    elif timedateformat == 'datetime':
        return (str(datetime.now())).split('.')[0]
    elif timedateformat == 'timedate':
        return ((str(datetime.now())).split('.')[0]).split(' ')[1] + ' ' + ((str(datetime.now())).split('.')[0]).split(' ')[0]

To obtain the time or date, just use getdatetime("<TYPE>"), replacing <TYPE> with one of the following arguments:

All example outputs use this model information: 25-11-2017 03:23:56.477017

Argument Meaning Example output
day Get the current day 25
month Get the current month 11
year Get the current year 2017
hour Get the current hour 03
minute Get the current minute 23
second Get the current second 56
millisecond Get the current millisecond 477017
yearmonthday Get the year, month and day 2017-11-25
daymonthyear Get the day, month and year 25-11-2017
hourminutesecond Get the hour, minute and second 03:23:56
secondminutehour Get the second, minute and hour 56:23:03
complete Get the complete date and time 2017-11-25 03:23:56.477017
datetime Get the date and time 2017-11-25 03:23:56
timedate Get the time and date 03:23:56 2017-11-25

Run ScrollTop with offset of element by ID

No magic involved, just subtract from the offset top of the element

$('html, body').animate({scrollTop: $('#contact').offset().top -100 }, 'slow');

How do I join two lists in Java?

public static <T> List<T> merge(@Nonnull final List<T>... list) {
    // calculate length first
    int mergedLength = 0;
    for (List<T> ts : list) {
      mergedLength += ts.size();
    }

    final List<T> mergedList = new ArrayList<>(mergedLength);

    for (List<T> ts : list) {
      mergedList.addAll(ts);
    }

    return mergedList;
  }

Android: Tabs at the BOTTOM

For all those of you that try to remove the separating line of the tabWidget, here is an example project (and its respective tutorial), that work great for customizing the tabs and thus removing problems when tabs are at bottom. Eclipse Project: android-custom-tabs ; Original explanation: blog; Hope this helped.

Incomplete type is not allowed: stringstream

Some of the system headers provide a forward declaration of std::stringstream without the definition. This makes it an 'incomplete type'. To fix that you need to include the definition, which is provided in the <sstream> header:

#include <sstream>

Split (explode) pandas dataframe string entry to separate rows

After painful experimentation to find something faster than the accepted answer, I got this to work. It ran around 100x faster on the dataset I tried it on.

If someone knows a way to make this more elegant, by all means please modify my code. I couldn't find a way that works without setting the other columns you want to keep as the index and then resetting the index and re-naming the columns, but I'd imagine there's something else that works.

b = DataFrame(a.var1.str.split(',').tolist(), index=a.var2).stack()
b = b.reset_index()[[0, 'var2']] # var1 variable is currently labeled 0
b.columns = ['var1', 'var2'] # renaming var1

How to listen for a WebView finishing loading a URL?

If you want show a progress bar you need to listen for a progress change event, not just for the completion of page:

mWebView.setWebChromeClient(new WebChromeClient(){

            @Override
            public void onProgressChanged(WebView view, int newProgress) {

                //change your progress bar
            }


        });

BTW if you want display just an Indeterminate ProgressBar overriding the method onPageFinished is enough

How to compare two dates?

Use time

Let's say you have the initial dates as strings like these:
date1 = "31/12/2015"
date2 = "01/01/2016"

You can do the following:
newdate1 = time.strptime(date1, "%d/%m/%Y") and newdate2 = time.strptime(date2, "%d/%m/%Y") to convert them to python's date format. Then, the comparison is obvious:

newdate1 > newdate2 will return False
newdate1 < newdate2 will return True

Tomcat starts but home page cannot open with url http://localhost:8080

If you are using eclipse to start the server then check for the server location being used and the deployment path:

tomcat server location and deploy path

In my case changing this to Tomcat installation instead of workspace metadata worked for me.

How do I sort a two-dimensional (rectangular) array in C#?

Can I check - do you mean a rectangular array ([,])or a jagged array ([][])?

It is quite easy to sort a jagged array; I have a discussion on that here. Obviously in this case the Comparison<T> would involve a column instead of sorting by ordinal - but very similar.

Sorting a rectangular array is trickier... I'd probably be tempted to copy the data out into either a rectangular array or a List<T[]>, and sort there, then copy back.

Here's an example using a jagged array:

static void Main()
{  // could just as easily be string...
    int[][] data = new int[][] { 
        new int[] {1,2,3}, 
        new int[] {2,3,4}, 
        new int[] {2,4,1} 
    }; 
    Sort<int>(data, 2); 
} 
private static void Sort<T>(T[][] data, int col) 
{ 
    Comparer<T> comparer = Comparer<T>.Default;
    Array.Sort<T[]>(data, (x,y) => comparer.Compare(x[col],y[col])); 
} 

For working with a rectangular array... well, here is some code to swap between the two on the fly...

static T[][] ToJagged<T>(this T[,] array) {
    int height = array.GetLength(0), width = array.GetLength(1);
    T[][] jagged = new T[height][];

    for (int i = 0; i < height; i++)
    {
        T[] row = new T[width];
        for (int j = 0; j < width; j++)
        {
            row[j] = array[i, j];
        }
        jagged[i] = row;
    }
    return jagged;
}
static T[,] ToRectangular<T>(this T[][] array)
{
    int height = array.Length, width = array[0].Length;
    T[,] rect = new T[height, width];
    for (int i = 0; i < height; i++)
    {
        T[] row = array[i];
        for (int j = 0; j < width; j++)
        {
            rect[i, j] = row[j];
        }
    }
    return rect;
}
// fill an existing rectangular array from a jagged array
static void WriteRows<T>(this T[,] array, params T[][] rows)
{
    for (int i = 0; i < rows.Length; i++)
    {
        T[] row = rows[i];
        for (int j = 0; j < row.Length; j++)
        {
            array[i, j] = row[j];
        }
    }
}

Setting background-image using jQuery CSS property

For those using an actual URL and not a variable:

$('myObject').css('background-image', 'url(../../example/url.html)');

Styling input radio with css

See this Fiddle

<input type="radio" id="radio-2-1" name="radio-2-set" class="regular-radio" /><label for="radio-2-1"></label>
<input type="radio" id="radio-2-2" name="radio-2-set" class="regular-radio" /><label for="radio-2-2"></label>
<input type="radio" id="radio-2-3" name="radio-2-set" class="regular-radio" /><label for="radio-2-3"></label>

.regular-radio {
    display: none;
}

.regular-radio + label {
    -webkit-appearance: none;
    background-color: #e1e1e1;
    border: 4px solid #e1e1e1;
    border-radius: 10px;
    width: 100%;
    display: inline-block;
    position: relative;
    width: 10px;
    height: 10px;
}

.regular-radio:checked + label {
    background: grey;
    border: 4px solid #e1e1e1;
}

How can I compare two lists in python and return matches

A quick performance test showing Lutz's solution is the best:

import time

def speed_test(func):
    def wrapper(*args, **kwargs):
        t1 = time.time()
        for x in xrange(5000):
            results = func(*args, **kwargs)
        t2 = time.time()
        print '%s took %0.3f ms' % (func.func_name, (t2-t1)*1000.0)
        return results
    return wrapper

@speed_test
def compare_bitwise(x, y):
    set_x = frozenset(x)
    set_y = frozenset(y)
    return set_x & set_y

@speed_test
def compare_listcomp(x, y):
    return [i for i, j in zip(x, y) if i == j]

@speed_test
def compare_intersect(x, y):
    return frozenset(x).intersection(y)

# Comparing short lists
a = [1, 2, 3, 4, 5]
b = [9, 8, 7, 6, 5]
compare_bitwise(a, b)
compare_listcomp(a, b)
compare_intersect(a, b)

# Comparing longer lists
import random
a = random.sample(xrange(100000), 10000)
b = random.sample(xrange(100000), 10000)
compare_bitwise(a, b)
compare_listcomp(a, b)
compare_intersect(a, b)

These are the results on my machine:

# Short list:
compare_bitwise took 10.145 ms
compare_listcomp took 11.157 ms
compare_intersect took 7.461 ms

# Long list:
compare_bitwise took 11203.709 ms
compare_listcomp took 17361.736 ms
compare_intersect took 6833.768 ms

Obviously, any artificial performance test should be taken with a grain of salt, but since the set().intersection() answer is at least as fast as the other solutions, and also the most readable, it should be the standard solution for this common problem.

SQL ON DELETE CASCADE, Which Way Does the Deletion Occur?

Here is a simple example for others visiting this old post, but is confused by the example in the question and the other answer:

Delivery -> Package (One -> Many)

CREATE TABLE Delivery(
    Id INT IDENTITY PRIMARY KEY,
    NoteNumber NVARCHAR(255) NOT NULL
)

CREATE TABLE Package(
    Id INT IDENTITY PRIMARY KEY,
    Status INT NOT NULL DEFAULT 0,
    Delivery_Id INT NOT NULL,
    CONSTRAINT FK_Package_Delivery_Id FOREIGN KEY (Delivery_Id) REFERENCES Delivery (Id) ON DELETE CASCADE
)

The entry with the foreign key Delivery_Id (Package) is deleted with the referenced entity in the FK relationship (Delivery).

So when a Delivery is deleted the Packages referencing it will also be deleted. If a Package is deleted nothing happens to any deliveries.

Is there a way to create interfaces in ES6 / Node 4?

Interfaces are not part of the ES6 but classes are.

If you really need them, you should look at TypeScript which support them.

Pandas: Creating DataFrame from Series

I guess anther way, possibly faster, to achieve this is 1) Use dict comprehension to get desired dict (i.e., taking 2nd col of each array) 2) Then use pd.DataFrame to create an instance directly from the dict without loop over each col and concat.

Assuming your mat looks like this (you can ignore this since your mat is loaded from file):

In [135]: mat = {'a': np.random.randint(5, size=(4,2)),
   .....: 'b': np.random.randint(5, size=(4,2))}

In [136]: mat
Out[136]: 
{'a': array([[2, 0],
        [3, 4],
        [0, 1],
        [4, 2]]), 'b': array([[1, 0],
        [1, 1],
        [1, 0],
        [2, 1]])}

Then you can do:

In [137]: df = pd.DataFrame ({name:mat[name][:,1] for name in mat})

In [138]: df
Out[138]: 
   a  b
0  0  0
1  4  1
2  1  0
3  2  1

[4 rows x 2 columns]

Convert spark DataFrame column to python list

I ran a benchmarking analysis and list(mvv_count_df.select('mvv').toPandas()['mvv']) is the fastest method. I'm very surprised.

I ran the different approaches on 100 thousand / 100 million row datasets using a 5 node i3.xlarge cluster (each node has 30.5 GBs of RAM and 4 cores) with Spark 2.4.5. Data was evenly distributed on 20 snappy compressed Parquet files with a single column.

Here's the benchmarking results (runtimes in seconds):

+-------------------------------------------------------------+---------+-------------+
|                          Code                               | 100,000 | 100,000,000 |
+-------------------------------------------------------------+---------+-------------+
| df.select("col_name").rdd.flatMap(lambda x: x).collect()    |     0.4 | 55.3        |
| list(df.select('col_name').toPandas()['col_name'])          |     0.4 | 17.5        |
| df.select('col_name').rdd.map(lambda row : row[0]).collect()|     0.9 | 69          |
| [row[0] for row in df.select('col_name').collect()]         |     1.0 | OOM         |
| [r[0] for r in mid_df.select('col_name').toLocalIterator()] |     1.2 | *           |
+-------------------------------------------------------------+---------+-------------+

* cancelled after 800 seconds

Golden rules to follow when collecting data on the driver node:

  • Try to solve the problem with other approaches. Collecting data to the driver node is expensive, doesn't harness the power of the Spark cluster, and should be avoided whenever possible.
  • Collect as few rows as possible. Aggregate, deduplicate, filter, and prune columns before collecting the data. Send as little data to the driver node as you can.

toPandas was significantly improved in Spark 2.3. It's probably not the best approach if you're using a Spark version earlier than 2.3.

See here for more details / benchmarking results.

Background images: how to fill whole div if image is small and vice versa

Try below code segment, I've tried it myself before :

#your-div {
    background: url("your-image-link") no-repeat;
    background-size: cover;
    background-clip: border-box;
}

how to use "tab space" while writing in text file

use \t instead of space.

bw.write("\t"); 

How to preserve insertion order in HashMap?

HashMap is unordered per the second line of the documentation:

This class makes no guarantees as to the order of the map; in particular, it does not guarantee that the order will remain constant over time.

Perhaps you can do as aix suggests and use a LinkedHashMap, or another ordered collection. This link can help you find the most appropriate collection to use.

Encoding conversion in java

It is a whole lot easier if you think of unicode as a character set (which it actually is - it is very basically the numbered set of all known characters). You can encode it as UTF-8 (1-3 bytes per character depending) or maybe UTF-16 (2 bytes per character or 4 bytes using surrogate pairs).

Back in the mist of time Java used to use UCS-2 to encode the unicode character set. This could only handle 2 bytes per character and is now obsolete. It was a fairly obvious hack to add surrogate pairs and move up to UTF-16.

A lot of people think they should have used UTF-8 in the first place. When Java was originally written unicode had far more than 65535 characters anyway...

What are the advantages of NumPy over regular Python lists?

All have highlighted almost all major differences between numpy array and python list, I will just brief them out here:

  1. Numpy arrays have a fixed size at creation, unlike python lists (which can grow dynamically). Changing the size of ndarray will create a new array and delete the original.

  2. The elements in a Numpy array are all required to be of the same data type (we can have the heterogeneous type as well but that will not gonna permit you mathematical operations) and thus will be the same size in memory

  3. Numpy arrays are facilitated advances mathematical and other types of operations on large numbers of data. Typically such operations are executed more efficiently and with less code than is possible using pythons build in sequences

Centering a div block without the width

<div class="product_container">
<div class="outer-center">
<div class="product inner-center">
    </div>
</div>
<div class="clear"></div>
</div>

.outer-center
{
float: right;
right: 50%;
position: relative;
}
.inner-center 
{
float: right;
right: -50%;
position: relative;
}
.clear 
{
clear: both;
}

.product_container
{
overflow:hidden;
}

If you dont provide "overflow:hidden" for ".product_container" the "outer-center" div will overlap other nearby contents to the right of it. Any links or buttons to the right of "outer-center" wont work. Try background color for "outer-center" to understand the need of "overflow :hidden"

How to calculate the median of an array?

Use Arrays.sort and then take the middle element (in case the number n of elements in the array is odd) or take the average of the two middle elements (in case n is even).

  public static long median(long[] l)
  {
    Arrays.sort(l);
    int middle = l.length / 2;
    if (l.length % 2 == 0)
    {
      long left = l[middle - 1];
      long right = l[middle];
      return (left + right) / 2;
    }
    else
    {
      return l[middle];
    }
  }

Here are some examples:

  @Test
  public void evenTest()
  {
    long[] l = {
        5, 6, 1, 3, 2
    };
    Assert.assertEquals((3 + 4) / 2, median(l));
  }

  @Test
  public oddTest()
  {
    long[] l = {
        5, 1, 3, 2, 4
    };
    Assert.assertEquals(3, median(l));
  }

And in case your input is a Collection, you might use Google Guava to do something like this:

public static long median(Collection<Long> numbers)
{
  return median(Longs.toArray(numbers)); // requires import com.google.common.primitives.Longs;
}

JavaScript Regular Expression Email Validation

You can also try this expression, I have tested it against many email addresses.

var pattern = /^[A-Za-z0-9._%+-]+@([A-Za-z0-9-]+\.)+([A-Za-z0-9]{2,4}|museum)$/;

How to change already compiled .class file without decompile?

You can follow these steps to modify your java class:

  1. Decompile the .class file as you have done and save it as .java
  2. Create a project in Eclipse with that java file, the original JAR as library, and all its dependencies
  3. Change the .java and compile
  4. Get the modified .class file and put it again inside the original JAR.

javascript check for not null

There are 3 ways to check for "not null". My recommendation is to use the Strict Not Version.

1. Strict Not Version

if (val !== null) { ... }

The Strict Not Version uses the "Strict Equality Comparison Algorithm" http://www.ecma-international.org/ecma-262/5.1/#sec-11.9.6. The !== has faster performance, than the != operator because the Strict Equality Comparison Algorithm doesn't typecast values.

2. Non-strict Not Version

if (val != 'null') { ... }

The Non-strict version uses the "Abstract Equality Comparison Algorithm" http://www.ecma-international.org/ecma-262/5.1/#sec-11.9.3. The != has slower performance, than the !== operator because the Abstract Equality Comparison Algorithm typecasts values.

3. Double Not Version

if (!!val) { ... }

The Double Not Version !! has faster performance, than both the Strict Not Version !== and the Non-Strict Not Version != (https://jsperf.com/tfm-not-null/6). However, it will typecast "Falsey" values like undefined and NaN into False (http://www.ecma-international.org/ecma-262/5.1/#sec-9.2) which may lead to unexpected results, and it has worse readability because null isn't explicitly stated.

What are the differences among grep, awk & sed?

Grep is useful if you want to quickly search for lines that match in a file. It can also return some other simple information like matching line numbers, match count, and file name lists.

Awk is an entire programming language built around reading CSV-style files, processing the records, and optionally printing out a result data set. It can do many things but it is not the easiest tool to use for simple tasks.

Sed is useful when you want to make changes to a file based on regular expressions. It allows you to easily match parts of lines, make modifications, and print out results. It's less expressive than awk but that lends it to somewhat easier use for simple tasks. It has many more complicated operators you can use (I think it's even turing complete), but in general you won't use those features.

HTML5 Audio Looping

Try using jQuery for the event listener, it will then work in Firefox.

myAudio = new Audio('someSound.ogg');

$(myAudio).bind('ended', function()  {
    myAudio.currentTime = 0;
    myAudio.play();
});

myAudio.play();

Something like that.

What is the point of "Initial Catalog" in a SQL Server connection string?

This is the initial database of the data source when you connect.

Edited for clarity:

If you have multiple databases in your SQL Server instance and you don't want to use the default database, you need some way to specify which one you are going to use.

Angular - res.json() is not a function

HttpClient.get() applies res.json() automatically and returns Observable<HttpResponse<string>>. You no longer need to call this function yourself.

See Difference between HTTP and HTTPClient in angular 4?

How to silence output in a Bash script?

Useful in scripts:


Get only the STDERR in a file, while hiding any STDOUT even if the program to hide isn't existing at all (does not ever hang parent script), this alone was working:

stty -echo && ./programMightNotExist 2> errors.log && stty echo

Detach completely and silence everything, even killing the parent script won't abort ./prog :

 ./prog </dev/null >/dev/null 2>&1 &

How to get the mobile number of current sim card in real device?

Hi Actually this is my same question but I didn't get anything.Now I got mobile number and his email-Id from particular Android real device(Android Mobile).Now a days 90% people using what's App application on Android Mobile.And now I am getting Mobile no and email-ID Through this What's app API.Its very simple to use see this below code.

            AccountManager am = AccountManager.get(this);
            Account[] accounts = am.getAccounts();
      for (Account ac : accounts) 
       {
        acname = ac.name;

        if (acname.startsWith("91")) {
            mobile_no = acname;
        }else if(acname.endsWith("@gmail.com")||acname.endsWith("@yahoo.com")||acname.endsWith("@hotmail.com")){
            email = acname;
        }

        // Take your time to look at all available accounts
        Log.i("Accounts : ", "Accounts : " + acname);
    }

and import this API

    import android.accounts.Account;
    import android.accounts.AccountManager;

Programmatically add new column to DataGridView

Here's a sample method that adds two extra columns programmatically to the grid view:

    private void AddColumnsProgrammatically()
    {
        // I created these columns at function scope but if you want to access 
        // easily from other parts of your class, just move them to class scope.
        // E.g. Declare them outside of the function...
        var col3 = new DataGridViewTextBoxColumn();
        var col4 = new DataGridViewCheckBoxColumn();

        col3.HeaderText = "Column3";
        col3.Name = "Column3";

        col4.HeaderText = "Column4";
        col4.Name = "Column4";

        dataGridView1.Columns.AddRange(new DataGridViewColumn[] {col3,col4});
    }

A great way to figure out how to do this kind of process is to create a form, add a grid view control and add some columns. (This process will actually work for ANY kind of form control. All instantiation and initialization happens in the Designer.) Then examine the form's Designer.cs file to see how the construction takes place. (Visual Studio does everything programmatically but hides it in the Form Designer.)

For this example I created two columns for the view named Column1 and Column2 and then searched Form1.Designer.cs for Column1 to see everywhere it was referenced. The following information is what I gleaned and, copied and modified to create two more columns dynamically:

// Note that this info scattered throughout the designer but can easily collected.

        System.Windows.Forms.DataGridViewTextBoxColumn Column1;
        System.Windows.Forms.DataGridViewCheckBoxColumn Column2;

        this.Column1 = new System.Windows.Forms.DataGridViewTextBoxColumn();
        this.Column2 = new System.Windows.Forms.DataGridViewCheckBoxColumn();

        this.dataGridView1.Columns.AddRange(new System.Windows.Forms.DataGridViewColumn[] {
        this.Column1,
        this.Column2});

        this.Column1.HeaderText = "Column1";
        this.Column1.Name = "Column1";

        this.Column2.HeaderText = "Column2";
        this.Column2.Name = "Column2";

How long do browsers cache HTTP 301s?

In the absense of cache control directives that specify otherwise, a 301 redirect defaults to being cached without any expiry date.

That is, it will remain cached for as long as the browser's cache can accommodate it. It will be removed from the cache if you manually clear the cache, or if the cache entries are purged to make room for new ones.

You can verify this at least in Firefox by going to about:cache and finding it under disk cache. It works this way in other browsers including Chrome and the Chromium based Edge, though they don't have an about:cache for inspecting the cache.

In all browsers it is still possible to override this default behavior using caching directives, as described below:

If you don't want the redirect to be cached

This indefinite caching is only the default caching by these browsers in the absence of headers that specify otherwise. The logic is that you are specifying a "permanent" redirect and not giving them any other caching instructions, so they'll treat it as if you wanted it indefinitely cached.

The browsers still honor the Cache-Control and Expires headers like with any other response, if they are specified.

You can add headers such as Cache-Control: max-age=3600 or Expires: Thu, 01 Dec 2014 16:00:00 GMT to your 301 redirects. You could even add Cache-Control: no-cache so it won't be cached permanently by the browser or Cache-Control: no-store so it can't even be stored in temporary storage by the browser.

Though, if you don't want your redirect to be permanent, it may be a better option to use a 302 or 307 redirect. Issuing a 301 redirect but marking it as non-cacheable is going against the spirit of what a 301 redirect is for, even though it is technically valid. YMMV, and you may find edge cases where it makes sense for a "permanent" redirect to have a time limit. Note that 302 and 307 redirects aren't cached by default by browsers.

If you previously issued a 301 redirect but want to un-do that

If people still have the cached 301 redirect in their browser they will continue to be taken to the target page regardless of whether the source page still has the redirect in place. Your options for fixing this include:

  • A simple solution is to issue another redirect back again.

    If the browser is directed back to a same URL a second time during a redirect, it should fetch it from the origin again instead of redirecting again from cache, in an attempt to avoid a redirect loop. Comments on this answer indicate this now works in all major browsers - but there may be some minor browsers where it doesn't.

  • If you don't have control over the site where the previous redirect target went to, then you are out of luck. Try and beg the site owner to redirect back to you.

Prevention is better than cure - avoid a 301 redirect if you are not sure you want to permanently de-commission the old URL.

Saving results with headers in Sql Server Management Studio

The same problem exists in Visual Studio, here's how to fix it there:

Go to:

Tools > Options > SQL Server Tools > Transact-SQL Editor > Query Results > Results To Grid

Now click the check box to true: "Include column headers when copying or saving the results"

Recover sa password

best answer written by Dmitri Korotkevitch:

Speaking of the installation, SQL Server 2008 allows you to set authentication mode (Windows or SQL Server) during the installation process. You will be forced to choose the strong password for sa user in the case if you choose sql server authentication mode during setup.

If you install SQL Server with Windows Authentication mode and want to change it, you need to do 2 different things:

  1. Go to SQL Server Properties/Security tab and change the mode to SQL Server authentication mode

  2. Go to security/logins, open SA login properties

a. Uncheck "Enforce password policy" and "Enforce password expiration" check box there if you decide to use weak password

b. Assign password to SA user

c. Open "Status" tab and enable login.

I don't need to mention that every action from above would violate security best practices that recommend to use windows authentication mode, have sa login disabled and use strong passwords especially for sa login.

Trying to SSH into an Amazon Ec2 instance - permission error

You can find the answer from the ASW guide. 400 protects it by making it read only and only for the owner.

chmod 400 mykey.pem

Regex to replace multiple spaces with a single space

Try this to replace multiple spaces with a single space.

<script type="text/javascript">
    var myStr = "The dog      has a long   tail, and it     is RED!";
    alert(myStr);  // Output 'The dog      has a long   tail, and it     is RED!'

    var newStr = myStr.replace(/  +/g, ' ');
    alert(newStr);  // Output 'The dog has a long tail, and it is RED!'
</script>

Read more @ Replacing Multiple Spaces with Single Space

Unique constraint on multiple columns

USE [TSQL2012]
GO

/****** Object:  Table [dbo].[Table_1]    Script Date: 11/22/2015 12:45:47 PM ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[Table_1](
    [seq] [bigint] IDENTITY(1,1) NOT NULL,
    [ID] [int] NOT NULL,
    [name] [nvarchar](50) NULL,
    [cat] [nvarchar](50) NULL,
 CONSTRAINT [PK_Table_1] PRIMARY KEY CLUSTERED 
(
    [ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY],
 CONSTRAINT [IX_Table_1] UNIQUE NONCLUSTERED 
(
    [name] ASC,
    [cat] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

Cannot deserialize the JSON array (e.g. [1,2,3]) into type ' ' because type requires JSON object (e.g. {"name":"value"}) to deserialize correctly

If one wants to support Generics (in an extension method) this is the pattern...

public  static List<T> Deserialize<T>(this string SerializedJSONString)
{
    var stuff = JsonConvert.DeserializeObject<List<T>>(SerializedJSONString);
    return stuff;
}

It is used like this:

var rc = new MyHttpClient(URL);
//This response is the JSON Array (see posts above)
var response = rc.SendRequest();
var data = response.Deserialize<MyClassType>();

MyClassType looks like this (must match name value pairs of JSON array)

[JsonObject(MemberSerialization = MemberSerialization.OptIn)]
 public class MyClassType
 {
    [JsonProperty(PropertyName = "Id")]
    public string Id { get; set; }

    [JsonProperty(PropertyName = "Name")]
    public string Name { get; set; }

    [JsonProperty(PropertyName = "Description")]
    public string Description { get; set; }

    [JsonProperty(PropertyName = "Manager")]
    public string Manager { get; set; }

    [JsonProperty(PropertyName = "LastUpdate")]
    public DateTime LastUpdate { get; set; }
 }

Use NUGET to download Newtonsoft.Json add a reference where needed...

using Newtonsoft.Json;

How to Flatten a Multidimensional Array?

If you have an array of objects and want to flatten it with a node, just use this function:

function objectArray_flatten($array,$childField) {
    $result = array();
    foreach ($array as $node)
    {
        $result[] = $node;
        if(isset($node->$childField))
        {
            $result = array_merge(
                $result, 
                objectArray_flatten($node->$childField,$childField)
            );
            unset($node->$childField);
        }

    }
    return $result;
}

How to open this .DB file?

I don't think there is a way to tell which program to use from just the .db extension. It could even be an encrypted database which can't be opened. You can MS Access, or a sqlite manager.

Edit: Try to rename the file to .txt and open it with a text editor. The first couple of words in the file could tell you the DB Type.

If it is a SQLite database, it will start with "SQLite format 3"

DataTables fixed headers misaligned with columns in wide tables

Faced the same issue recently and was still searching for the solution when I tried something on my css, check if adding to your cells (th and td)

-webkit-box-sizing: content-box; 
-moz-box-sizing: content-box;  
-sizing: content-box;

will resolve this issue; for me, I was using some html/css framework that was adding a the value border-box in every element.

Are multiple `.gitignore`s frowned on?

I can think of at least two situations where you would want to have multiple .gitignore files in different (sub)directories.

  • Different directories have different types of file to ignore. For example the .gitignore in the top directory of your project ignores generated programs, while Documentation/.gitignore ignores generated documentation.

  • Ignore given files only in given (sub)directory (you can use /sub/foo in .gitignore, though).

Please remember that patterns in .gitignore file apply recursively to the (sub)directory the file is in and all its subdirectories, unless pattern contains '/' (so e.g. pattern name applies to any file named name in given directory and all its subdirectories, while /name applies to file with this name only in given directory).

How to select Multiple images from UIImagePickerController

You can't use UIImagePickerController, but you can use a custom image picker. I think ELCImagePickerController is the best option, but here are some other libraries you could use:

Objective-C
1. ELCImagePickerController
2. WSAssetPickerController
3. QBImagePickerController
4. ZCImagePickerController
5. CTAssetsPickerController
6. AGImagePickerController
7. UzysAssetsPickerController
8. MWPhotoBrowser
9. TSAssetsPickerController
10. CustomImagePicker
11. InstagramPhotoPicker
12. GMImagePicker
13. DLFPhotosPicker
14. CombinationPickerController
15. AssetPicker
16. BSImagePicker
17. SNImagePicker
18. DoImagePickerController
19. grabKit
20. IQMediaPickerController
21. HySideScrollingImagePicker
22. MultiImageSelector
23. TTImagePicker
24. SelectImages
25. ImageSelectAndSave
26. imagepicker-multi-select
27. MultiSelectImagePickerController
28. YangMingShan(Yahoo like image selector)
29. DBAttachmentPickerController
30. BRImagePicker
31. GLAssetGridViewController
32. CreolePhotoSelection

Swift
1. LimPicker (Similar to WhatsApp's image picker)
2. RMImagePicker
3. DKImagePickerController
4. BSImagePicker
5. Fusuma(Instagram like image selector)
6. YangMingShan(Yahoo like image selector)
7. NohanaImagePicker
8. ImagePicker
9. OpalImagePicker
10. TLPhotoPicker
11. AssetsPickerViewController
12. Alerts-and-pickers/Telegram Picker

Thanx to @androidbloke,
I have added some library that I know for multiple image picker in swift.
Will update list as I find new ones.
Thank You.

Android - Get value from HashMap

for (Object key : meMap.keySet()) {
        String value=(String)meMap.get(key);
        Toast.makeText(ctx, "Key: "+key+" Value: "+value, Toast.LENGTH_LONG).show();
    }

CSS text-transform capitalize on all caps

all wrong it does exist --> font-variant: small-caps;

text-transform:capitalize; just the first letter cap

How to round a number to n decimal places in Java

@Milhous: the decimal format for rounding is excellent:

You can also use the

DecimalFormat df = new DecimalFormat("#.00000");
df.format(0.912385);

to make sure you have the trailing 0's.

I would add that this method is very good at providing an actual numeric, rounding mechanism - not only visually, but also when processing.

Hypothetical: you have to implement a rounding mechanism into a GUI program. To alter the accuracy / precision of a result output simply change the caret format (i.e. within the brackets). So that:

DecimalFormat df = new DecimalFormat("#0.######");
df.format(0.912385);

would return as output: 0.912385

DecimalFormat df = new DecimalFormat("#0.#####");
df.format(0.912385);

would return as output: 0.91239

DecimalFormat df = new DecimalFormat("#0.####");
df.format(0.912385);

would return as output: 0.9124

[EDIT: also if the caret format is like so ("#0.############") and you enter a decimal, e.g. 3.1415926, for argument's sake, DecimalFormat does not produce any garbage (e.g. trailing zeroes) and will return: 3.1415926 .. if you're that way inclined. Granted, it's a little verbose for the liking of some dev's - but hey, it's got a low memory footprint during processing and is very easy to implement.]

So essentially, the beauty of DecimalFormat is that it simultaneously handles the string appearance - as well as the level of rounding precision set. Ergo: you get two benefits for the price of one code implementation. ;)

HTML5 and frameborder

As per the other posting here, the best solution is to use the CSS entry of

style="border:0;"

Apache SSL Configuration Error (SSL Connection Error)

I had this error when I first followed instructions to set up the default apache2 ssl configuration, by putting a symlink for /etc/apache2/sites-available/default-ssl in /etc/apache2/sites-enabled. I then subsequently tried to add another NameVirtualHost on port 443 in another configuration file, and started getting this error.

I fixed it by deleting the /etc/apache2/sites-enabled/default-ssl symlink, and then just having these lines in another config file (httpd.conf, which probably isn't good form, but worked):

NameVirtualHost *:443

<VirtualHost *:443>
  SSLEngine on
  SSLCertificateChainFile    /etc/apache2/ssl/chain_file.crt
  SSLCertificateFile    /etc/apache2/ssl/site_certificate.crt
  SSLCertificateKeyFile /etc/apache2/ssl/site_key.key
  ServerName www.mywebsite.com
  ServerAlias www.mywebsite.com
  DocumentRoot /var/www/mywebsite_root/


</VirtualHost>

ImageView in circular through xml

if you'd rather cut the image to display in circular, here you go

public static Bitmap getCircularBitmap(Bitmap bitmap) {
        Bitmap output;

        if (bitmap.getWidth() > bitmap.getHeight()) {
            output = Bitmap.createBitmap(bitmap.getHeight(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);
        } else {
            output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getWidth(), Bitmap.Config.ARGB_8888);
        }

        Canvas canvas = new Canvas(output);

        final int color = 0xff424242;
        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());

        float r = 0;

        if (bitmap.getWidth() > bitmap.getHeight()) {
            r = bitmap.getHeight() / 2;
        } else {
            r = bitmap.getWidth() / 2;
        }

        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        canvas.drawCircle(r, r, r, paint);
        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);
        return output;
    }

Unresolved external symbol on static class members

Since this is the first SO thread that seemed to come up for me when searching for "unresolved externals with static const members" in general, I'll leave another hint to solve one problem with unresolved externals here:

For me, the thing that I forgot was to mark my class definition __declspec(dllexport), and when called from another class (outside that class's dll's boundaries), I of course got the my unresolved external error.
Still, easy to forget when you're changing an internal helper class to a one accessible from elsewhere, so if you're working in a dynamically linked project, you might as well check that, too.

Visual Studio error "Object reference not set to an instance of an object" after install of ASP.NET and Web Tools 2015

Restarting Visual Studio did it for me. On the next run, it displayed a "Scanning new and updated MEF components ..." and then it executed normally.

It seems to be related to Windows update somehow, although I don't have proof.

Dynamic constant assignment

In Ruby, any variable whose name starts with a capital letter is a constant and you can only assign to it once. Choose one of these alternatives:

class MyClass
  MYCONSTANT = "blah"

  def mymethod
    MYCONSTANT
  end
end

class MyClass
  def mymethod
    my_constant = "blah"
  end
end

In-memory size of a Python structure

Also you can use guppy module.

>>> from guppy import hpy; hp=hpy()
>>> hp.heap()
Partition of a set of 25853 objects. Total size = 3320992 bytes.
 Index  Count   %     Size   % Cumulative  % Kind (class / dict of class)
     0  11731  45   929072  28    929072  28 str
     1   5832  23   469760  14   1398832  42 tuple
     2    324   1   277728   8   1676560  50 dict (no owner)
     3     70   0   216976   7   1893536  57 dict of module
     4    199   1   210856   6   2104392  63 dict of type
     5   1627   6   208256   6   2312648  70 types.CodeType
     6   1592   6   191040   6   2503688  75 function
     7    199   1   177008   5   2680696  81 type
     8    124   0   135328   4   2816024  85 dict of class
     9   1045   4    83600   3   2899624  87 __builtin__.wrapper_descriptor
<90 more rows. Type e.g. '_.more' to view.>

And:

>>> hp.iso(1, [1], "1", (1,), {1:1}, None)
Partition of a set of 6 objects. Total size = 560 bytes.
 Index  Count   %     Size   % Cumulative  % Kind (class / dict of class)
     0      1  17      280  50       280  50 dict (no owner)
     1      1  17      136  24       416  74 list
     2      1  17       64  11       480  86 tuple
     3      1  17       40   7       520  93 str
     4      1  17       24   4       544  97 int
     5      1  17       16   3       560 100 types.NoneType

Open popup and refresh parent page on close popup

window.open will return a reference to the newly created window, provided the URL opened complies with Same Origin Policy.

This should work:

function windowClose() {
    window.location.reload();
}

var foo = window.open("foo.html","windowName", "width=200,height=200,scrollbars=no");
foo.onbeforeunload= windowClose;?

Get type of all variables

> mtcars %>% 
+     summarise_all(typeof) %>% 
+     gather
    key  value
1   mpg double
2   cyl double
3  disp double
4    hp double
5  drat double
6    wt double
7  qsec double
8    vs double
9    am double
10 gear double
11 carb double

I try class and typeof functions, but all fails.

How to check variable type at runtime in Go language

The answer by @Darius is the most idiomatic (and probably more performant) method. One limitation is that the type you are checking has to be of type interface{}. If you use a concrete type it will fail.

An alternative way to determine the type of something at run-time, including concrete types, is to use the Go reflect package. Chaining TypeOf(x).Kind() together you can get a reflect.Kind value which is a uint type: http://golang.org/pkg/reflect/#Kind

You can then do checks for types outside of a switch block, like so:

import (
    "fmt"
    "reflect"
)

// ....

x := 42
y := float32(43.3)
z := "hello"

xt := reflect.TypeOf(x).Kind()
yt := reflect.TypeOf(y).Kind()
zt := reflect.TypeOf(z).Kind()

fmt.Printf("%T: %s\n", xt, xt)
fmt.Printf("%T: %s\n", yt, yt)
fmt.Printf("%T: %s\n", zt, zt)

if xt == reflect.Int {
    println(">> x is int")
}
if yt == reflect.Float32 {
    println(">> y is float32")
}
if zt == reflect.String {
    println(">> z is string")
}

Which prints outs:

reflect.Kind: int
reflect.Kind: float32
reflect.Kind: string
>> x is int
>> y is float32
>> z is string

Again, this is probably not the preferred way to do it, but it's good to know alternative options.

Send password when using scp to copy files from one server to another

Here is how I resolved it.

It is not the most secure way however it solved my problem as security was not an issue on internal servers.

Create a new file say password.txt and store the password for the server where the file will be pasted. Save this to a location on the host server.

scp -W location/password.txt copy_file_location paste_file_location

Cheers!

How to efficiently build a tree from a flat structure?

Here is java solution of the answer by Mehrdad Afshari.

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

public class Tree {

    Iterator<Node> buildTreeAndGetRoots(List<MyObject> actualObjects) {
        Map<Integer, Node> lookup = new HashMap<>();
        actualObjects.forEach(x -> lookup.put(x.id, new Node(x)));
        //foreach (var item in lookup.Values)
        lookup.values().forEach(item ->
                {
                    Node proposedParent;
                    if (lookup.containsKey(item.associatedObject.parentId)) {
                        proposedParent = lookup.get(item.associatedObject.parentId);
                        item.parent = proposedParent;
                        proposedParent.children.add(item);
                    }
                }
        );
        //return lookup.values.Where(x =>x.Parent ==null);
        return lookup.values().stream().filter(x -> x.parent == null).iterator();
    }

}

class MyObject { // The actual object
    public int parentId;
    public int id;
}

class Node {
    public List<Node> children = new ArrayList<Node>();
    public Node parent;
    public MyObject associatedObject;

    public Node(MyObject associatedObject) {
        this.associatedObject = associatedObject;
    }
}

Expand/collapse section in UITableView in iOS

I found another relatively simple way to solve that problem. By using this method we will not required to alter our cell which is almost always related to data array index, potentially causing mess in our view controller.

First, we add this following properties to our controller class:

@property (strong, nonatomic) NSMutableArray* collapsedSections;
@property (strong, nonatomic) NSMutableArray* sectionViews;

collapsedSections will save collapsed section numbers. sectionViews will store our custom section view.

Synthesize it:

@synthesize collapsedSections;
@synthesize sectionViews;

Initialize it:

- (void) viewDidLoad
{
    [super viewDidLoad];

    self.collapsedSections = [NSMutableArray array];
    self.sectionViews      = [NSMutableArray array];
}

After that, we must connect our UITableView so it can be accessed from within our view controller class:

@property (strong, nonatomic) IBOutlet UITableView *tblMain;

Connect it from XIB to view controller using ctrl + drag like usually.

Then we create view as custom section header for our table view by implementing this UITableView delegate:

- (UIView*) tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
    // Create View
    CGRect frame = CGRectZero;

    frame.origin = CGPointZero;

    frame.size.height = 30.f;
    frame.size.width  = tableView.bounds.size.width;

    UIView* view = [[UIView alloc] initWithFrame:frame];

    [view setBackgroundColor:[UIColor blueColor]];

    // Add label for title
    NSArray* titles = @[@"Title 1", @"Title 2", @"Title 3"];

    NSString* selectedTitle = [titles objectAtIndex:section];

    CGRect labelFrame = frame;

    labelFrame.size.height = 30.f;
    labelFrame.size.width -= 20.f;
    labelFrame.origin.x += 10.f;

    UILabel* titleLabel = [[UILabel alloc] initWithFrame:labelFrame];

    [titleLabel setText:selectedTitle];
    [titleLabel setTextColor:[UIColor whiteColor]];

    [view addSubview:titleLabel];

    // Add touch gesture
    [self attachTapGestureToView:view];

    // Save created view to our class property array
    [self saveSectionView:view inSection:section];

    return view;
}

Next, we implement method to save our previously created custom section header in class property:

- (void) saveSectionView:(UIView*) view inSection:(NSInteger) section
{
    NSInteger sectionCount = [self numberOfSectionsInTableView:[self tblMain]];

    if(section < sectionCount)
    {
        if([[self sectionViews] indexOfObject:view] == NSNotFound)
        {
            [[self sectionViews] addObject:view];
        }
    }
}

Add UIGestureRecognizerDelegate to our view controller .h file:

@interface MyViewController : UIViewController<UITableViewDelegate, UITableViewDataSource, UIGestureRecognizerDelegate>

Then we create method attachTapGestureToView:

- (void) attachTapGestureToView:(UIView*) view
{
    UITapGestureRecognizer* tapAction = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(onTap:)];

    [tapAction setDelegate:self];

    [view addGestureRecognizer:tapAction];
}

Above method will add tap gesture recognizer to all of section view we created before. Next we should implement onTap: selector

- (void) onTap:(UITapGestureRecognizer*) gestureRecognizer
{
    // Take view who attach current recognizer
    UIView* sectionView = [gestureRecognizer view]; 

    // [self sectionViews] is Array containing our custom section views
    NSInteger section = [self sectionNumberOfView:sectionView];

    // [self tblMain] is our connected IBOutlet table view
    NSInteger sectionCount = [self numberOfSectionsInTableView:[self tblMain]];

    // If section more than section count minus one set at last
    section = section > (sectionCount - 1) ? 2 : section;

    [self toggleCollapseSection:section];
}

Above method will invoked when user tap any of our table view section. This method search correct section number based on our sectionViews array we created before.

Also, we implement method to get wihch section of header view belongs to.

- (NSInteger) sectionNumberOfView:(UIView*) view
{
    UILabel* label = [[view subviews] objectAtIndex:0];

    NSInteger sectionNum = 0;

    for(UIView* sectionView in [self sectionViews])
    {
        UILabel* sectionLabel = [[sectionView subviews] objectAtIndex:0];

        //NSLog(@"Section: %d -> %@ vs %@", sectionNum, [label text], [sectionLabel text]);

        if([[label text] isEqualToString:[sectionLabel text]])
        {
            return sectionNum;
        }

        sectionNum++;
    }

    return NSNotFound;
}

Next, we must implement method toggleCollapseSection:

- (void) toggleCollapseSection:(NSInteger) section
{
    if([self isCollapsedSection:section])
    {
        [self removeCollapsedSection:section];
    }
    else
    {
        [self addCollapsedSection:section];
    }

    [[self tblMain] reloadSections:[NSIndexSet indexSetWithIndex:section] withRowAnimation:UITableViewRowAnimationFade];
}

This method will insert/remove section number to our collapsedSections array we created before. When a section number inserted to that array, it means that the section should be collapsed and expanded if otherwise.

Next we implement removeCollapsedSection:, addCollapsedSection:section and isCollapsedSection:section

- (BOOL)isCollapsedSection:(NSInteger) section
{
    for(NSNumber* existing in [self collapsedSections])
    {
        NSInteger current = [existing integerValue];

        if(current == section)
        {
            return YES;
        }
    }

    return NO;
}

- (void)removeCollapsedSection:(NSInteger) section
{
    [[self collapsedSections] removeObjectIdenticalTo:[NSNumber numberWithInteger:section]];
}

- (void)addCollapsedSection:(NSInteger) section
{
    [[self collapsedSections] addObject:[NSNumber numberWithInteger:section]];
}

This three method is just helpers to make us easier in accessing collapsedSections array.

Finally, implement this table view delegate so our custom section views looks nice.

- (CGFloat) tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
    return 30.f; // Same as each custom section view height
}

Hope it helps.

Function to Calculate Median in SQL Server

For a continuous variable/measure 'col1' from 'table1'

select col1  
from
    (select top 50 percent col1, 
    ROW_NUMBER() OVER(ORDER BY col1 ASC) AS Rowa,
    ROW_NUMBER() OVER(ORDER BY col1 DESC) AS Rowd
    from table1 ) tmp
where tmp.Rowa = tmp.Rowd

How to add certificate chain to keystore?

From the keytool man - it imports certificate chain, if input is given in PKCS#7 format, otherwise only the single certificate is imported. You should be able to convert certificates to PKCS#7 format with openssl, via openssl crl2pkcs7 command.

How can I use a carriage return in a HTML tooltip?

We had a requirement where we needed to test all of these, here is what I wish to share

_x000D_
_x000D_
document.getElementById("tooltip").setAttribute("title", "Tool\x0ATip\x0AOn\x0ANew\x0ALine")
_x000D_
<p title='Tool_x000D_
Tip_x000D_
On_x000D_
New_x000D_
Line'>Tooltip with <pre>_x000D_
  new _x000D_
  line</pre> Works in all browsers</p>_x000D_
<hr/>_x000D_
_x000D_
<p title="Tool&#13;Tip&#13;On&#13;New&#13;Line">Tooltip with <code>&amp;#13;</code> Not works Firefox browsers</p>_x000D_
<hr/>_x000D_
_x000D_
<p title='Tool&#10;Tip&#10;On&#10;New&#10;Line'>Tooltip with <code>&amp;#10;</code> Works in some browsers</p>_x000D_
<hr/>_x000D_
_x000D_
<p title='Tool&#x0aTip&#x0aOn&#x0aNew&#x0aLine'>Tooltip with <code>&amp;#xD;</code> May work in some browsers</p>_x000D_
<hr/>_x000D_
_x000D_
<p id='tooltip'>Tooltip with <code>document.getElementById("tooltip").setAttribute("title", "Tool\x0ATip\x0AOn\x0ANew\x0ALine")</code> May work in some browsers</p>_x000D_
<hr/>_x000D_
_x000D_
_x000D_
<p title="List:_x000D_
  • List item here_x000D_
  • Another list item here_x000D_
  • Aaaand another list item, lol">Tooltip with <code>• </code>Unordered list tooltip</p>_x000D_
<hr/>_x000D_
_x000D_
_x000D_
<p title='Tool\nTip\nOn\nNew\nLine'>Tooltip with <code>\n</code> May not work in modern browsers</p>_x000D_
<hr/>_x000D_
_x000D_
<p title='Tool\tTip\tOn\tNew\tLine'>Tooltip with <code>\t</code> May not work in modern browsers</p>_x000D_
<hr/>_x000D_
_x000D_
<p title='Tool&#013;Tip&#013;On&#013;New&#013;Line'>Tooltip with <code>&amp;#013;</code> Works in most browsers</p>_x000D_
<hr/>
_x000D_
_x000D_
_x000D_

Fiddle

Min / Max Validator in Angular 2 Final

I've added a max validation to amd's great answer.

import { Directive, Input, forwardRef } from '@angular/core'
import { NG_VALIDATORS, Validator, AbstractControl, Validators } from '@angular/forms'

/*
 * This is a wrapper for [min] and [max], used to work with template driven forms
 */

@Directive({
  selector: '[min]',
  providers: [{ provide: NG_VALIDATORS, useExisting: MinNumberValidator, multi: true }]
})
export class MinNumberValidator implements Validator {

  @Input() min: number;

  validate(control: AbstractControl): { [key: string]: any } {
    return Validators.min(this.min)(control)
  }
}

@Directive({
  selector: '[max]',
  providers: [{ provide: NG_VALIDATORS, useExisting: MaxNumberValidator, multi: true }]
})
export class MaxNumberValidator implements Validator {

  @Input() max: number;

  validate(control: AbstractControl): { [key: string]: any } {
    return Validators.max(this.max)(control)
  }
}

Rounding Bigdecimal values with 2 Decimal Places

You may try this:

public static void main(String[] args) {
    BigDecimal a = new BigDecimal("10.12345");
    System.out.println(toPrecision(a, 2));
}

private static BigDecimal toPrecision(BigDecimal dec, int precision) {
    String plain = dec.movePointRight(precision).toPlainString();
    return new BigDecimal(plain.substring(0, plain.indexOf("."))).movePointLeft(precision);
}

OUTPUT:

10.12

Running multiple AsyncTasks at the same time -- not possible?

AsyncTask uses a thread pool pattern for running the stuff from doInBackground(). The issue is initially (in early Android OS versions) the pool size was just 1, meaning no parallel computations for a bunch of AsyncTasks. But later they fixed that and now the size is 5, so at most 5 AsyncTasks can run simultaneously. Unfortunately I don't remember in what version exactly they changed that.

UPDATE:

Here is what current (2012-01-27) API says on this:

When first introduced, AsyncTasks were executed serially on a single background thread. Starting with DONUT, this was changed to a pool of threads allowing multiple tasks to operate in parallel. After HONEYCOMB, it is planned to change this back to a single thread to avoid common application errors caused by parallel execution. If you truly want parallel execution, you can use the executeOnExecutor(Executor, Params...) version of this method with THREAD_POOL_EXECUTOR; however, see commentary there for warnings on its use.

DONUT is Android 1.6, HONEYCOMB is Android 3.0.

UPDATE: 2

See the comment by kabuko from Mar 7 2012 at 1:27.

It turns out that for APIs where "a pool of threads allowing multiple tasks to operate in parallel" is used (starting from 1.6 and ending on 3.0) the number of simultaneously running AsyncTasks depends on how many tasks have been passed for execution already, but have not finished their doInBackground() yet.

This is tested/confirmed by me on 2.2. Suppose you have a custom AsyncTask that just sleeps a second in doInBackground(). AsyncTasks use a fixed size queue internally for storing delayed tasks. Queue size is 10 by default. If you start 15 your custom tasks in a row, then first 5 will enter their doInBackground(), but the rest will wait in a queue for a free worker thread. As soon as any of the first 5 finishes, and thus releases a worker thread, a task from the queue will start execution. So in this case at most 5 tasks will run simultaneously. However if you start 16 your custom tasks in a row, then first 5 will enter their doInBackground(), the rest 10 will get into the queue, but for the 16th a new worker thread will be created so it'll start execution immediately. So in this case at most 6 tasks will run simultaneously.

There is a limit of how many tasks can be run simultaneously. Since AsyncTask uses a thread pool executor with limited max number of worker threads (128) and the delayed tasks queue has fixed size 10, if you try to execute more than 138 your custom tasks the app will crash with java.util.concurrent.RejectedExecutionException.

Starting from 3.0 the API allows to use your custom thread pool executor via AsyncTask.executeOnExecutor(Executor exec, Params... params) method. This allows, for instance, to configure the size of the delayed tasks queue if default 10 is not what you need.

As @Knossos mentions, there is an option to use AsyncTaskCompat.executeParallel(task, params); from support v.4 library to run tasks in parallel without bothering with API level. This method became deprecated in API level 26.0.0.

UPDATE: 3

Here is a simple test app to play with number of tasks, serial vs. parallel execution: https://github.com/vitkhudenko/test_asynctask

UPDATE: 4 (thanks @penkzhou for pointing this out)

Starting from Android 4.4 AsyncTask behaves differently from what was described in UPDATE: 2 section. There is a fix to prevent AsyncTask from creating too many threads.

Before Android 4.4 (API 19) AsyncTask had the following fields:

private static final int CORE_POOL_SIZE = 5;
private static final int MAXIMUM_POOL_SIZE = 128;
private static final BlockingQueue<Runnable> sPoolWorkQueue =
        new LinkedBlockingQueue<Runnable>(10);

In Android 4.4 (API 19) the above fields are changed to this:

private static final int CPU_COUNT = Runtime.getRuntime().availableProcessors();
private static final int CORE_POOL_SIZE = CPU_COUNT + 1;
private static final int MAXIMUM_POOL_SIZE = CPU_COUNT * 2 + 1;
private static final BlockingQueue<Runnable> sPoolWorkQueue =
        new LinkedBlockingQueue<Runnable>(128);

This change increases the size of the queue to 128 items and reduces the maximum number of threads to the number of CPU cores * 2 + 1. Apps can still submit the same number of tasks.

How to convert an array into an object using stdClass()

To convert array to object using stdClass just add (object) to array u declare.

EX:

echo $array['value'];
echo $object->value;

to convert object to array

$obj = (object)$array;

to convert array to object

$arr = (array)$object

with these methods you can swap between array and object very easily.


Another method is to use json

$object = json_decode(json_encode($array), FALSE);

But this is a much more memory intensive way to do and is not supported by versions of PHP <= 5.1

read file in classpath

Change . to / as the path separator and use getResourceAsStream:

reader = new BufferedReader(new InputStreamReader(
    getClass().getClassLoader().getResourceAsStream(
        "com/company/app/dao/sql/SqlQueryFile.sql")));

or

reader = new BufferedReader(new InputStreamReader(
    getClass().getResourceAsStream(
        "/com/company/app/dao/sql/SqlQueryFile.sql")));

Note the leading slash when using Class.getResourceAsStream() vs ClassLoader.getResourceAsStream. getSystemResourceAsStream uses the system classloader which isn't what you want.

I suspect that using slashes instead of dots would work for ClassPathResource too.

Assert equals between 2 Lists in Junit

Don't reinvent the wheel!

There's a Google Code library that does this for you: Hamcrest

[Hamcrest] Provides a library of matcher objects (also known as constraints or predicates) allowing 'match' rules to be defined declaratively, to be used in other frameworks. Typical scenarios include testing frameworks, mocking libraries and UI validation rules.

load Js file in HTML

I had the same problem, and found the answer. If you use node.js with express, you need to give it its own function in order for the js file to be reached. For example:

const script = path.join(__dirname, 'script.js');
const server = express().get('/', (req, res) => res.sendFile(script))

what is the use of annotations @Id and @GeneratedValue(strategy = GenerationType.IDENTITY)? Why the generationtype is identity?

Let me answer this question:
First of all, using annotations as our configure method is just a convenient method instead of coping the endless XML configuration file.

The @Idannotation is inherited from javax.persistence.Id, indicating the member field below is the primary key of current entity. Hence your Hibernate and spring framework as well as you can do some reflect works based on this annotation. for details please check javadoc for Id

The @GeneratedValue annotation is to configure the way of increment of the specified column(field). For example when using Mysql, you may specify auto_increment in the definition of table to make it self-incremental, and then use

@GeneratedValue(strategy = GenerationType.IDENTITY)

in the Java code to denote that you also acknowledged to use this database server side strategy. Also, you may change the value in this annotation to fit different requirements.

1. Define Sequence in database

For instance, Oracle has to use sequence as increment method, say we create a sequence in Oracle:

create sequence oracle_seq;

2. Refer the database sequence

Now that we have the sequence in database, but we need to establish the relation between Java and DB, by using @SequenceGenerator:

@SequenceGenerator(name="seq",sequenceName="oracle_seq")

sequenceName is the real name of a sequence in Oracle, name is what you want to call it in Java. You need to specify sequenceName if it is different from name, otherwise just use name. I usually ignore sequenceName to save my time.

3. Use sequence in Java

Finally, it is time to make use this sequence in Java. Just add @GeneratedValue:

@GeneratedValue(strategy=GenerationType.SEQUENCE, generator="seq")

The generator field refers to which sequence generator you want to use. Notice it is not the real sequence name in DB, but the name you specified in name field of SequenceGenerator.

4. Complete

So the complete version should be like this:

public class MyTable
{
    @Id
    @SequenceGenerator(name="seq",sequenceName="oracle_seq")        
    @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="seq")               
    private Integer pid;
}

Now start using these annotations to make your JavaWeb development easier.

Specify an SSH key for git push for a given domain

To use a specific key on the fly:

GIT_SSH_COMMAND='ssh -i $HOME/.ssh/id_ed25519 -o IdentitiesOnly=yes -F /dev/null' git push origin c13_training_network

Explanation:

  • local ENV var before doing the push
  • -i specifies key
  • -F forces an empty config so your global one doesn't overwrite this temporary command

How Do I Uninstall Yarn

If you are still getting errors after deleting ~/.yarn about files not being found, don't forget to delete the yarn rc file:

rm ~/.yarnrc.yml 

How to use BigInteger?

Actually you can use,

BigInteger sum= new BigInteger("12345");

for creating object for BigInteger class.But the problem here is,you cannot give a variable in the double quotes.So we have to use the valueOf() method and we have to store the answer in that sum again.So we will write,

sum= sum.add(BigInteger.valueOf(i));

Go to particular revision

To go to a particular version/commit run following commands. HASH-CODE you can get from git log --oneline -n 10

git reset --hard HASH-CODE

Note - After reset to particular version/commit you can run git pull --rebase, if you want to bring back all the commits which are discarded.

How to fix Hibernate LazyInitializationException: failed to lazily initialize a collection of roles, could not initialize proxy - no Session

The best way to handle the LazyInitializationException is to use the JOIN FETCH directive for all the entities that you need to fetch along.

Anyway, DO NOT use the following Anti-Patterns as suggested by some of the answers:

Sometimes, a DTO projection is a better choice than fetching entities, and this way, you won't get any LazyInitializationException.

SQL 'like' vs '=' performance

First things first ,

they are not always equal

    select 'Hello' from dual where 'Hello  ' like 'Hello';

    select 'Hello' from dual where 'Hello  ' =  'Hello';

when things are not always equal , talking about their performance isn't that relevant.

If you are working on strings and only char variables , then you can talk about performance . But don't use like and "=" as being generally interchangeable .

As you would have seen in many posts ( above and other questions) , in cases when they are equal the performance of like is slower owing to pattern matching (collation)

'names' attribute must be the same length as the vector

I have seen such error and i solved it. You may have missing values in your data set. Number of observations in every column must also be the same.

HTML input file selection event not firing upon selecting the same file

Set the value of the input to null on each onclick event. This will reset the input's value and trigger the onchange event even if the same path is selected.

input.onclick = function () {
    this.value = null;
};

input.onchange = function () {
    alert(this.value);
};?

Here's a DEMO.

Note: It's normal if your file is prefixed with 'C:\fakepath\'. That's a security feature preventing JavaScript from knowing the file's absolute path. The browser still knows it internally.

PHP refresh window? equivalent to F5 page reload?

PHP cannot force the client to do anything. It cannot refresh the page, let alone refresh the parent of a frame.

EDIT: You can of course, make PHP write JavaScript, but this is not PHP doing, it's actually JavaScript, and it will fail if JavaScript is disabled.

<?php
    echo '<script>parent.window.location.reload(true);</script>';
?>

Delete dynamically-generated table row using jQuery

You should use Event Delegation, because of the fact that you are creating dynamic rows.

$(document).on('click','button.removebutton', function() {
    alert("aa");
  $(this).closest('tr').remove();
  return false;
});

Live Demo

Maven: How do I activate a profile from command line?

I have encountered this problem and i solved mentioned problem by adding -DprofileIdEnabled=true parameter while running mvn cli command.

Please run your mvn cli command as : mvn clean install -Pdev1 -DprofileIdEnabled=true.

In addition to this solution, you don't need to remove activeByDefault settings in your POM mentioned as previouses answer.

I hope this answer solve your problem.

How to break/exit from a each() function in JQuery?

Return false from the anonymous function:

$(xml).find("strengths").each(function() {
  // Code
  // To escape from this block based on a condition:
  if (something) return false;
});

From the documentation of the each method:

Returning 'false' from within the each function completely stops the loop through all of the elements (this is like using a 'break' with a normal loop). Returning 'true' from within the loop skips to the next iteration (this is like using a 'continue' with a normal loop).

How to prevent robots from automatically filling up a form?

With the emergence of headless browsers (like phantomjs) which can emulate anything, you can't suppose that :

  • spam bots do not use javascript,
  • you can track mouse events to detect bot,
  • they won't see that a field is visually hidden,
  • they won't wait a given time before submitting.

If that used to be true, it is no longer true.

If you wan't an user friendly solution, just give them a beautiful "i am a spammer" submit button:

 <input type="submit" name="ignore" value="I am a spammer!" />
 <input type="image" name="accept" value="submit.png" alt="I am not a spammer" />

Of course you can play with two image input[type=image] buttons, changing the order after each load, the text alternatives, the content of the images (and their size) or the name of the buttons; which will require some server work.

 <input type="image" name="random125454548" value="random125454548.png"
      alt="I perfectly understand that clicking on this link will send the
      e-mail to the expected person" />
 <input type="image" name="random125452548" value="random125452548.png"
      alt="I really want to cancel the submission of this form" />

For accessibility reasons, you have to put a correct textual alternative, but I think that a long sentence is better for screenreaders users than being considered as a bot.

Additional note: those examples illustrate that understanding english (or any language), and having to make a simple choice, is harder for a spambot than : waiting 10 seconds, handling CSS or javascript, knowing that a field is hidden, emulating mouse move or emulating keyboard typing, ...

Compare two date formats in javascript/jquery

To comapre dates of string format (mm-dd-yyyy).

    var job_start_date = "10-1-2014"; // Oct 1, 2014
    var job_end_date = "11-1-2014"; // Nov 1, 2014
    job_start_date = job_start_date.split('-');
    job_end_date = job_end_date.split('-');

    var new_start_date = new Date(job_start_date[2],job_start_date[0],job_start_date[1]);
    var new_end_date = new Date(job_end_date[2],job_end_date[0],job_end_date[1]);

    if(new_end_date <= new_start_date) {
      // your code
    }

How to write a:hover in inline CSS?

My problem was that I'm building a website which uses a lot of image-icons that have to be swapped by a different image on hover (e.g. blue-ish images turn red-ish on hover). I produced the following solution for this:

_x000D_
_x000D_
.container div {_x000D_
  width: 100px;_x000D_
  height: 100px;_x000D_
  background-size: 100px 100px;_x000D_
}_x000D_
.container:hover .withoutHover {_x000D_
  display: none;_x000D_
}_x000D_
.container .withHover {_x000D_
  display: none;_x000D_
}_x000D_
.container:hover .withHover {_x000D_
  display: block;_x000D_
}
_x000D_
<p>Hover the image to see it switch with the other. Note that I deliberately used inline CSS because I decided it was the easiest and clearest solution for my problem that uses more of these image pairs (with different URL's)._x000D_
</p>_x000D_
<div class=container>_x000D_
<div class=withHover style="background-image: url('https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQrqRsWFJ3492s0t0NmPEcpTQYTqNnH188R606cLOHm8H2pUGlH')"></div>_x000D_
<div class=withoutHover style="background-image: url('http://i.telegraph.co.uk/multimedia/archive/03523/Cat-Photo-Bombs-fa_3523609b.jpg')"></div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

I introduced a container containing the pair of images. The first is visible and the other is hidden (display:none). When hovering the container, the first becomes hidden (display:none) and the second shows up again (display:block).

How to do a deep comparison between 2 objects with lodash?

We had this requirement on getting the delta between two json updates for tracking database updates. Maybe someone else can find this helpful.

https://gist.github.com/jp6rt/7fcb6907e159d7851c8d59840b669e3d

const {
  isObject,
  isEqual,
  transform,
  has,
  merge,
} = require('lodash');
const assert = require('assert');

/**
 * Perform a symmetric comparison on JSON object.
 * @param {*} baseObj - The base object to be used for comparison against the withObj.
 * @param {*} withObj - The withObject parameter is used as the comparison on the base object.
 * @param {*} invert  - Because this is a symmetric comparison. Some values in the with object
 *                      that doesn't exist on the base will be lost in translation.
 *                      You can execute again the function again with the parameters interchanged.
 *                      However you will lose the reference if the value is from the base or with
 *                      object if you intended to do an assymetric comparison.
 *                      Setting this to true will do make sure the reference is not lost.
 * @returns           - The returned object will label the result of the comparison with the
 *                      value from base and with object.
 */
const diffSym = (baseObj, withObj, invert = false) => transform(baseObj, (result, value, key) => {
  if (isEqual(value, withObj[key])
    && has(withObj, key)) {
    return;
  }

  if (isObject(value)
    && isObject(withObj[key])
    && !Array.isArray(value)) {
    result[key] = diffSym(value, withObj[key], invert);
    return;
  }

  if (!invert) {
    result[key] = {
      base: value,
      with: withObj[key],
    };
    return;
  }

  if (invert) {
    result[key] = {
      base: withObj[key],
      with: value,
    };
  }
});

/**
 * Perform a assymmetric comparison on JSON object.
 * @param {*} baseObj - The base object to be used for comparison against the withObj.
 * @param {*} withObj - The withObject parameter is used as the comparison on the base object.
 * @returns           - The returned object will label the values with
 *                      reference to the base and with object.
 */
const diffJSON = (baseObj, withObj) => {
  // Deep clone the objects so we don't update the reference objects.
  const baseObjClone = JSON.parse(JSON.stringify(baseObj));
  const withObjClone = JSON.parse(JSON.stringify(withObj));

  const beforeDelta = diffSym(baseObjClone, withObjClone);
  const afterDelta = diffSym(withObjClone, baseObjClone, true);

  return merge(afterDelta, beforeDelta);
};

// By Example:

const beforeDataObj = {
  a: 1,
  c: { d: 2, f: 3 },
  g: 4,
  h: 5,
};
const afterDataObj = {
  a: 2,
  b: 3,
  c: { d: 1, e: 1 },
  h: 5,
};

const delta = diffJSON(beforeDataObj, afterDataObj);

// Assert expected result.
assert(isEqual(delta, {
  a: { base: 1, with: 2 },
  b: { base: undefined, with: 3 },
  c: {
    d: { base: 2, with: 1 },
    e: { base: undefined, with: 1 },
    f: { base: 3, with: undefined },
  },
  g: { base: 4, with: undefined },
}));

How to edit binary file on Unix systems

For small changes, I have used hexedit:

http://rigaux.org/hexedit.html

Simple but fast and useful.

how to install tensorflow on anaconda python 3.6

I use this method as told by one of the user: This is what I did for Installing Anaconda Python 3.6 version and Tensorflow on Window 10 64bit.And It was success!

Go to https://www.continuum.io/downloads to download Anaconda Python 3.6 version for Window 64bit. Create a conda environment named tensorflow by invoking the following command:

C:> conda create -n tensorflow Activate the conda environment by issuing the following command:

C:> activate tensorflow (tensorflow)C:> # Your prompt should change Go to http://www.lfd.uci.edu/~gohlke/pythonlibs/enter code here download “tensorflow-1.0.1-cp36-cp36m-win_amd64.whl”. (For my case, the file will be located in “C:\Users\Joshua\Downloads” once after downloaded) Install the Tensorflow by using following command:

(tensorflow)C:>pip install C:\Users\Joshua\Downloads\ tensorflow-1.0.1-cp36-cp36m-win_amd64.whl

but nothing happens in the prompt. It starts from the new line with the tensorflow as if nothing was written. Whats the problem?

How to run a function in jquery

Alternatively (I'd say preferably), you can do it like this:

$(function () {
  $("div.class, div.secondclass").click(function(){
    //Doo something
  });
});

How do I combine 2 javascript variables into a string

You can use the JavaScript String concat() Method,

var str1 = "Hello ";
var str2 = "world!";
var res = str1.concat(str2); //will return "Hello world!"

Its syntax is:

string.concat(string1, string2, ..., stringX)

How can I change text color via keyboard shortcut in MS word 2010

You could use a macro, but it’s simpler to use styles. Define a character style that has the desired text color and assign a shortcut key to it, say Alt+R. In order to be able to switch color using just the keyboard, define another character style, say “normal”, that has no special feature—just for use to get normal text after switching to your colored style, and assign another shortcut to it, say Alt+N. Then you would just type text, press Alt+R to switch to colored text, type that text, press Alt+N to resume normal text color, etc.

Descending order by date filter in AngularJs

According to documentation you can use the reverse argument.

filter:orderBy(array, expression[, reverse]);

Change your filter to:

orderBy: 'created_at':true

What is the difference between ApplicationContext and WebApplicationContext in Spring MVC?

Web application context, specified by the WebApplicationContext interface, is a Spring application context for a web applications. It has all the properties of a regular Spring application context, given that the WebApplicationContext interface extends the ApplicationContext interface, and add a method for retrieving the standard Servlet API ServletContext for the web application.

In addition to the standard Spring bean scopes singleton and prototype, there are three additional scopes available in a web application context:

  • request - scopes a single bean definition to the lifecycle of a single HTTP request; that is, each HTTP request has its own instance of a bean created off the back of a single bean definition
  • session - scopes a single bean definition to the lifecycle of an HTTP Session
  • application - scopes a single bean definition to the lifecycle of a ServletContext

Socket.io + Node.js Cross-Origin Request Blocked

I tried above and nothing worked for me. Following code is from socket.io documentation and it worked.

io.origins((origin, callback) => {
  if (origin !== 'https://foo.example.com') {
      return callback('origin not allowed', false);
  }
  callback(null, true);
});

Where is the Docker daemon log?

Using CentOS7, logs are available using the command journalctl -u docker. Answering distinctly, because @sabin's answer might be accurate for older versions of CentOS but was not true for me.

systemd has its own logging system called the journal. The logs for the docker daemon can be viewed using journalctl -u docker

Ref: https://docs.docker.com/engine/admin/configuring/

Python: download a file from an FTP server

urllib2.urlopen handles ftp links.

python .replace() regex

In order to replace text using regular expression use the re.sub function:

sub(pattern, repl, string[, count, flags])

It will replace non-everlaping instances of pattern by the text passed as string. If you need to analyze the match to extract information about specific group captures, for instance, you can pass a function to the string argument. more info here.

Examples

>>> import re
>>> re.sub(r'a', 'b', 'banana')
'bbnbnb'

>>> re.sub(r'/\d+', '/{id}', '/andre/23/abobora/43435')
'/andre/{id}/abobora/{id}'

Split files using tar, gz, zip, or bzip2

You can use the split command with the -b option:

split -b 1024m file.tar.gz

It can be reassembled on a Windows machine using @Joshua's answer.

copy /b file1 + file2 + file3 + file4 filetogether

Edit: As @Charlie stated in the comment below, you might want to set a prefix explicitly because it will use x otherwise, which can be confusing.

split -b 1024m "file.tar.gz" "file.tar.gz.part-"

// Creates files: file.tar.gz.part-aa, file.tar.gz.part-ab, file.tar.gz.part-ac, ...

Edit: Editing the post because question is closed and the most effective solution is very close to the content of this answer:

# create archives
$ tar cz my_large_file_1 my_large_file_2 | split -b 1024MiB - myfiles_split.tgz_
# uncompress
$ cat myfiles_split.tgz_* | tar xz

This solution avoids the need to use an intermediate large file when (de)compressing. Use the tar -C option to use a different directory for the resulting files. btw if the archive consists from only a single file, tar could be avoided and only gzip used:

# create archives
$ gzip -c my_large_file | split -b 1024MiB - myfile_split.gz_
# uncompress
$ cat myfile_split.gz_* | gunzip -c > my_large_file

For windows you can download ported versions of the same commands or use cygwin.

C++: Converting Hexadecimal to Decimal

only use:

cout << dec << 0x;

How do I make an asynchronous GET request in PHP?

For me the question about asynchronous GET request is appeared because of I met with situation when I need to do hundreds of requests, get and deal with result data on every request and every request takes significant milliseconds of executing that leads to minutes(!) of total executing with simple file_get_contents.

In this case it was very helpful comment of w_haigh at php.net on function http://php.net/manual/en/function.curl-multi-init.php

So, here is my upgraded and cleaned version of making lot of requests simultaneously. For my case it's equivalent to "asynchronous" way. May be it helps for someone!

// Build the multi-curl handle, adding both $ch
$mh = curl_multi_init();

// Build the individual requests, but do not execute them
$chs = [];
$chs['ID0001'] = curl_init('http://webservice.example.com/?method=say&word=Hello');
$chs['ID0002'] = curl_init('http://webservice.example.com/?method=say&word=World');
// $chs[] = ...
foreach ($chs as $ch) {
    curl_setopt_array($ch, [
        CURLOPT_RETURNTRANSFER => true,  // Return requested content as string
        CURLOPT_HEADER => false,         // Don't save returned headers to result
        CURLOPT_CONNECTTIMEOUT => 10,    // Max seconds wait for connect
        CURLOPT_TIMEOUT => 20,           // Max seconds on all of request
        CURLOPT_USERAGENT => 'Robot YetAnotherRobo 1.0',
    ]);

    // Well, with a little more of code you can use POST queries too
    // Also, useful options above can be  CURLOPT_SSL_VERIFYHOST => 0  
    // and  CURLOPT_SSL_VERIFYPEER => false ...

    // Add every $ch to the multi-curl handle
    curl_multi_add_handle($mh, $ch);
}

// Execute all of queries simultaneously, and continue when ALL OF THEM are complete
$running = null;
do {
    curl_multi_exec($mh, $running);
} while ($running);

// Close the handles
foreach ($chs as $ch) {
    curl_multi_remove_handle($mh, $ch);
}
curl_multi_close($mh);

// All of our requests are done, we can now access the results
// With a help of ids we can understand what response was given
// on every concrete our request
$responses = [];
foreach ($chs as $id => $ch) {
    $responses[$id] = curl_multi_getcontent($ch);
    curl_close($ch);
}
unset($chs); // Finita, no more need any curls :-)

print_r($responses); // output results

It's easy to rewrite this to handle POST or other types of HTTP(S) requests or any combinations of them. And Cookie support, redirects, http-auth, etc.

How do negative margins in CSS work and why is (margin-top:-5 != margin-bottom:5)?

I'll try to explain it visually:

_x000D_
_x000D_
/**_x000D_
 * explaining margins_x000D_
 */_x000D_
_x000D_
body {_x000D_
  padding: 3em 15%_x000D_
}_x000D_
_x000D_
.parent {_x000D_
  width: 50%;_x000D_
  width: 400px;_x000D_
  height: 400px;_x000D_
  position: relative;_x000D_
  background: lemonchiffon;_x000D_
}_x000D_
_x000D_
.parent:before,_x000D_
.parent:after {_x000D_
  position: absolute;_x000D_
  content: "";_x000D_
}_x000D_
_x000D_
.parent:before {_x000D_
  top: 0;_x000D_
  bottom: 0;_x000D_
  left: 50%;_x000D_
  border-left: dashed 1px #ccc;_x000D_
}_x000D_
_x000D_
.parent:after {_x000D_
  left: 0;_x000D_
  right: 0;_x000D_
  top: 50%;_x000D_
  border-top: dashed 1px #ccc;_x000D_
}_x000D_
_x000D_
.child {_x000D_
  width: 200px;_x000D_
  height: 200px;_x000D_
  background: rgba(200, 198, 133, .5);_x000D_
}_x000D_
_x000D_
ul {_x000D_
  padding: 5% 20px;_x000D_
}_x000D_
_x000D_
.set1 .child {_x000D_
  margin: 0;_x000D_
  position: relative;_x000D_
}_x000D_
_x000D_
.set2 .child {_x000D_
  margin-left: 75px;_x000D_
  position: relative;_x000D_
}_x000D_
_x000D_
.set3 .child {_x000D_
  margin-left: -75px;_x000D_
  position: relative;_x000D_
}_x000D_
_x000D_
_x000D_
/* position absolute */_x000D_
_x000D_
.set4 .child {_x000D_
  top: 50%;_x000D_
  left: 50%;_x000D_
  margin: 0;_x000D_
  position: absolute;_x000D_
}_x000D_
_x000D_
.set5 .child {_x000D_
  top: 50%;_x000D_
  left: 50%;_x000D_
  margin-left: 75px;_x000D_
  position: absolute;_x000D_
}_x000D_
_x000D_
.set6 .child {_x000D_
  top: 50%; /* level from which margin-top starts _x000D_
 - downwards, in the case of a positive margin_x000D_
 - upwards, in the case of a negative margin _x000D_
 */_x000D_
  left: 50%; /* level from which margin-left starts _x000D_
 - towards right, in the case of a positive margin_x000D_
 - towards left, in the case of a negative margin _x000D_
 */_x000D_
  margin: -75px;_x000D_
  position: absolute;_x000D_
}
_x000D_
<!-- content to be placed inside <body>…</body> -->_x000D_
<h2><code>position: relative;</code></h2>_x000D_
<h3>Set 1</h3>_x000D_
<div class="parent set 1">_x000D_
  <div class="child">_x000D_
    <pre>_x000D_
.set1 .child {_x000D_
  margin: 0;_x000D_
  position: relative;_x000D_
}_x000D_
  </pre>_x000D_
  </div>_x000D_
</div>_x000D_
_x000D_
<h3>Set 2</h3>_x000D_
<div class="parent set2">_x000D_
  <div class="child">_x000D_
    <pre>_x000D_
.set2 .child {_x000D_
  margin-left: 75px;_x000D_
  position: relative;_x000D_
}_x000D_
  </pre>_x000D_
  </div>_x000D_
</div>_x000D_
_x000D_
<h3>Set 3</h3>_x000D_
<div class="parent set3">_x000D_
  <div class="child">_x000D_
    <pre>_x000D_
.set3 .child {_x000D_
  margin-left: -75px;_x000D_
  position: relative;_x000D_
}_x000D_
  </pre>_x000D_
  </div>_x000D_
</div>_x000D_
_x000D_
<h2><code>position: absolute;</code></h2>_x000D_
_x000D_
<h3>Set 4</h3>_x000D_
<div class="parent set4">_x000D_
  <div class="child">_x000D_
    <pre>_x000D_
.set4 .child {_x000D_
  top: 50%;_x000D_
  left: 50%;_x000D_
  margin: 0;_x000D_
  position: absolute;_x000D_
}_x000D_
  </pre>_x000D_
  </div>_x000D_
</div>_x000D_
_x000D_
<h3>Set 5</h3>_x000D_
<div class="parent set5">_x000D_
  <div class="child">_x000D_
    <pre>_x000D_
.set5 .child {_x000D_
  top: 50%;_x000D_
  left: 50%;_x000D_
  margin-left: 75px;_x000D_
  position: absolute;_x000D_
}_x000D_
  </pre>_x000D_
  </div>_x000D_
</div>_x000D_
_x000D_
<h3>Set 6</h3>_x000D_
<div class="parent set6">_x000D_
  <div class="child">_x000D_
    <pre>_x000D_
.set6 .child {_x000D_
  top: 50%;_x000D_
  left: 50%;_x000D_
  margin: -75px;_x000D_
  position: absolute;_x000D_
}_x000D_
  </pre>_x000D_
  </div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

How to skip the first n rows in sql query

I know it's quite late now to answer the query. But I have a little different solution than the others which I believe has better performance because no comparisons are performed in the SQL query only sorting is done. You can see its considerable performance improvement basically when value of SKIP is LARGE enough.

  1. Best performance but only for SQL Server 2012 and above. Originally from @Majid Basirati's answer which is worth mentioning again.

    DECLARE @Skip INT = 2, @Take INT = 2
    
    SELECT * FROM TABLE_NAME
    ORDER BY ID ASC
    OFFSET (@Skip) ROWS FETCH NEXT (@Take) ROWS ONLY
    
  2. Not as Good as the first one but compatible with SQL Server 2005 and above.

    DECLARE @Skip INT = 2, @Take INT = 2
    
    SELECT * FROM 
    (
        SELECT TOP (@Take) * FROM 
        (
            SELECT TOP (@Take + @Skip) * FROM TABLE_NAME
            ORDER BY ID ASC
        ) T1
        ORDER BY ID DESC
    ) T2
    ORDER BY ID ASC
    

Getting "The remote certificate is invalid according to the validation procedure" when SMTP server has a valid certificate

Old post, but I thought I would share my solution because there aren't many solutions out there for this issue.

If you're running an old Windows Server 2003 machine, you likely need to install a hotfix (KB938397).

This problem occurs because the Cryptography API 2 (CAPI2) in Windows Server 2003 does not support the SHA2 family of hashing algorithms. CAPI2 is the part of the Cryptography API that handles certificates.

https://support.microsoft.com/en-us/kb/938397

For whatever reason, Microsoft wants to email you this hotfix instead of allowing you to download directly. Here's a direct link to the hotfix from the email:

http://hotfixv4.microsoft.com/Windows Server 2003/sp3/Fix200653/3790/free/315159_ENU_x64_zip.exe

How to do encryption using AES in Openssl

My suggestion is to run

openssl enc -aes-256-cbc -in plain.txt -out encrypted.bin

under debugger and see what exactly what it is doing. openssl.c is the only real tutorial/getting started/reference guide OpenSSL has. All other documentation is just an API reference.

U1: My guess is that you are not setting some other required options, like mode of operation (padding).

U2: this is probably a duplicate of this question: AES CTR 256 Encryption Mode of operation on OpenSSL and answers there will likely help.

PersistenceContext EntityManager injection NullPointerException

An entity manager can only be injected in classes running inside a transaction. In other words, it can only be injected in a EJB. Other classe must use an EntityManagerFactory to create and destroy an EntityManager.

Since your TestService is not an EJB, the annotation @PersistenceContext is simply ignored. Not only that, in JavaEE 5, it's not possible to inject an EntityManager nor an EntityManagerFactory in a JAX-RS Service. You have to go with a JavaEE 6 server (JBoss 6, Glassfish 3, etc).

Here's an example of injecting an EntityManagerFactory:

package com.test.service;

import java.util.*;
import javax.persistence.*;
import javax.ws.rs.*;

@Path("/service")
public class TestService {

    @PersistenceUnit(unitName = "test")
    private EntityManagerFactory entityManagerFactory;

    @GET
    @Path("/get")
    @Produces("application/json")
    public List get() {
        EntityManager entityManager = entityManagerFactory.createEntityManager();
        try {
            return entityManager.createQuery("from TestEntity").getResultList();
        } finally {
            entityManager.close();
        }
    }
}

The easiest way to go here is to declare your service as a EJB 3.1, assuming you're using a JavaEE 6 server.

Related question: Inject an EJB into JAX-RS (RESTful service)

UIAlertView first deprecated IOS 9

Check this:

UIAlertController *alertctrl =[UIAlertController alertControllerWithTitle:@"choose Image" message:nil preferredStyle:UIAlertControllerStyleActionSheet];
    UIAlertAction *camera =[UIAlertAction actionWithTitle:@"camera" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        [self Action];  //call Action need to perform 
    }];

[alertctrl addAction:camera];
-(void)Action 

{

}

How to remove an iOS app from the App Store

Steps to Remove app from App Store

  1. Click the My Apps section.
  2. Select the app you'd like to remove.
  3. Click the Pricing tab from the app listing page.
  4. Click the "specific territories" link.
  5. In the drop-down section that appears below, click "Deselect All' at the top right. This will uncheck every territory below.
  6. A confirmation message will appear at the top of the screen.
  7. Return to the My Apps section by clicking the navigation button at the top left.
  8. The application status has changed to "Developer Removed From Sale."
  9. Within 24 hours (though usually less) your app will no longer appear in the App Store.

enter image description here

Rails where condition using NOT NIL

For Rails4:

So, what you're wanting is an inner join, so you really should just use the joins predicate:

  Foo.joins(:bar)

  Select * from Foo Inner Join Bars ...

But, for the record, if you want a "NOT NULL" condition simply use the not predicate:

Foo.includes(:bar).where.not(bars: {id: nil})

Select * from Foo Left Outer Join Bars on .. WHERE bars.id IS NOT NULL

Note that this syntax reports a deprecation (it talks about a string SQL snippet, but I guess the hash condition is changed to string in the parser?), so be sure to add the references to the end:

Foo.includes(:bar).where.not(bars: {id: nil}).references(:bar)

DEPRECATION WARNING: It looks like you are eager loading table(s) (one of: ....) that are referenced in a string SQL snippet. For example:

Post.includes(:comments).where("comments.title = 'foo'")

Currently, Active Record recognizes the table in the string, and knows to JOIN the comments table to the query, rather than loading comments in a separate query. However, doing this without writing a full-blown SQL parser is inherently flawed. Since we don't want to write an SQL parser, we are removing this functionality. From now on, you must explicitly tell Active Record when you are referencing a table from a string:

Post.includes(:comments).where("comments.title = 'foo'").references(:comments)

WampServer orange icon

I ran into this same problem this morning but none of the answers above provided me with the solution.

I realised eventually that my issue was because I had changed the DocumentRoot to a subfolder of the www directory, as I had previously been running a Symfony2 project inside www.

With the new project I am working on inside www, that old DocumentRoot dir did not exist any more so Apache failed to start.

wampserver -> Apache -> httpd.conf, then look for "DocumentRoot" and make sure the directory it points to exists or else change it to one that does.

Thank you to RiggsFolly, it was because of your hint about the Event Viewer above that I found the issue.

Get query string parameters url values with jQuery / Javascript (querystring)

I wrote a little function where you only have to parse the name of the query parameter. So if you have: ?Project=12&Mode=200&date=2013-05-27 and you want the 'Mode' parameter you only have to parse the 'Mode' name into the function:

function getParameterByName( name ){
    var regexS = "[\\?&]"+name+"=([^&#]*)", 
  regex = new RegExp( regexS ),
  results = regex.exec( window.location.search );
  if( results == null ){
    return "";
  } else{
    return decodeURIComponent(results[1].replace(/\+/g, " "));
  }
}

// example caller:
var result =  getParameterByName('Mode');

How do I deploy Node.js applications as a single executable file?

There are a number of steps you have to go through to create an installer and it varies for each Operating System. For Example:

How to run shell script on host from docker container?

You can use the pipe concept, but use a file on the host and fswatch to accomplish the goal to execute a script on the host machine from a docker container. Like so (Use at your own risk):

#! /bin/bash

touch .command_pipe
chmod +x .command_pipe

# Use fswatch to execute a command on the host machine and log result
fswatch -o --event Updated .command_pipe | \
            xargs -n1 -I "{}"  .command_pipe >> .command_pipe_log  &

 docker run -it --rm  \
   --name alpine  \
   -w /home/test \
   -v $PWD/.command_pipe:/dev/command_pipe \
   alpine:3.7 sh

rm -rf .command_pipe
kill %1

In this example, inside the container send commands to /dev/command_pipe, like so:

/home/test # echo 'docker network create test2.network.com' > /dev/command_pipe

On the host, you can check if the network was created:

$ docker network ls | grep test2
8e029ec83afe        test2.network.com                            bridge              local

Android : difference between invisible and gone?

INVISIBLE:

This view is invisible, but it still takes up space for layout purposes.

GONE:

This view is invisible, and it doesn't take any space for layout purposes.

Python socket.error: [Errno 111] Connection refused

The problem obviously was (as you figured it out) that port 36250 wasn't open on the server side at the time you tried to connect (hence connection refused). I can see the server was supposed to open this socket after receiving SEND command on another connection, but it apparently was "not opening [it] up in sync with the client side".

Well, the main reason would be there was no synchronisation whatsoever. Calling:

cs.send("SEND " + FILE)
cs.close()

would just place the data into a OS buffer; close would probably flush the data and push into the network, but it would almost certainly return before the data would reach the server. Adding sleep after close might mitigate the problem, but this is not synchronisation.

The correct solution would be to make sure the server has opened the connection. This would require server sending you some message back (for example OK, or better PORT 36250 to indicate where to connect). This would make sure the server is already listening.

The other thing is you must check the return values of send to make sure how many bytes was taken from your buffer. Or use sendall.

(Sorry for disturbing with this late answer, but I found this to be a high traffic question and I really didn't like the sleep idea in the comments section.)

Why GDB jumps unpredictably between lines and prints variables as "<value optimized out>"?

You pretty much can't set the value of found. Debugging optimized programs is rarely worth the trouble, the compiler can rearrange the code in ways that it'll in no way correspond to the source code (other than producing the same result), thus confusing debuggers to no end.

How to filter Android logcat by application?

to filter the logs on command line use the below script

adb logcat com.yourpackage:v

How can I repeat a character in Bash?

function repeatString()
{
    local -r string="${1}"
    local -r numberToRepeat="${2}"

    if [[ "${string}" != '' && "${numberToRepeat}" =~ ^[1-9][0-9]*$ ]]
    then
        local -r result="$(printf "%${numberToRepeat}s")"
        echo -e "${result// /${string}}"
    fi
}

Sample runs

$ repeatString 'a1' 10 
a1a1a1a1a1a1a1a1a1a1

$ repeatString 'a1' 0 

$ repeatString '' 10 

Reference lib at: https://github.com/gdbtek/linux-cookbooks/blob/master/libraries/util.bash

Why doesn't Python have multiline comments?

Assume that they were just considered unnecessary. Since it's so easy to just type #a comment, multiline comments can just consist of many single line comments.

For HTML, on the other hand, there's more of a need for multiliners. It's harder to keep typing <!--comments like this-->.

Best way to generate a random float in C#

I prefer using the following code to generate a decimal number up to fist decimal point. you can copy paste the 3rd line to add more numbers after decimal point by appending that number in string "combined". You can set the minimum and maximum value by changing the 0 and 9 to your preferred value.

Random r = new Random();
string beforePoint = r.Next(0, 9).ToString();//number before decimal point
string afterPoint = r.Next(0,9).ToString();//1st decimal point
//string secondDP = r.Next(0, 9).ToString();//2nd decimal point
string combined = beforePoint+"."+afterPoint;
decimalNumber= float.Parse(combined);
Console.WriteLine(decimalNumber);

I hope that it helped you.

How do I validate a date in rails?

Since you need to handle the date string before it is converted to a date in your model, I'd override the accessor for that field

Let's say your date field is published_date. Add this to your model object:

def published_date=(value)
    # do sanity checking here
    # then hand it back to rails to convert and store
    self.write_attribute(:published_date, value) 
end

How to split CSV files as per number of rows specified?

This should do it for you - all your files will end up called Part1-Part500.

#!/bin/bash
FILENAME=10000.csv
HDR=$(head -1 $FILENAME)   # Pick up CSV header line to apply to each file
split -l 20 $FILENAME xyz  # Split the file into chunks of 20 lines each
n=1
for f in xyz*              # Go through all newly created chunks
do
   echo $HDR > Part${n}    # Write out header to new file called "Part(n)"
   cat $f >> Part${n}      # Add in the 20 lines from the "split" command
   rm $f                   # Remove temporary file
   ((n++))                 # Increment name of output part
done

What does ENABLE_BITCODE do in xcode 7?

Bitcode (iOS, watchOS)

Bitcode is an intermediate representation of a compiled program. Apps you upload to iTunes Connect that contain bitcode will be compiled and linked on the App Store. Including bitcode will allow Apple to re-optimize your app binary in the future without the need to submit a new version of your app to the store.


Basically this concept is somewhat similar to java where byte code is run on different JVM's and in this case the bitcode is placed on iTune store and instead of giving the intermediate code to different platforms(devices) it provides the compiled code which don't need any virtual machine to run.

Thus we need to create the bitcode once and it will be available for existing or coming devices. It's the Apple's headache to compile an make it compatible with each platform they have.

Devs don't have to make changes and submit the app again to support new platforms.

Let's take the example of iPhone 5s when apple introduced x64 chip in it. Although x86 apps were totally compatible with x64 architecture but to fully utilise the x64 platform the developer has to change the architecture or some code. Once s/he's done the app is submitted to the app store for the review.

If this bitcode concept was launched earlier then we the developers doesn't have to make any changes to support the x64 bit architecture.

REST API error return good practices

Please stick to the semantics of protocol. Use 2xx for successful responses and 4xx , 5xx for error responses - be it your business exceptions or other. Had using 2xx for any response been the intended use case in the protocol, they would not have other status codes in the first place.

How to use Git and Dropbox together?

Without using third-party integration tools, I could enhance the condition a bit and use DropBox and other similar cloud disk services such as SpiderOak with Git.

The goal is to avoid the synchronization in the middle of these files modifications, as it can upload a partial state and will then download it back, completely corrupting your git state.

To avoid this issue, I did:

  1. Bundle my git index in one file using git bundle create my_repo.git --all.
  2. Set a delay for the file monitoring, eg 5 minutes, instead of instantaneous. This reduces the chances DropBox synchronizes a partial state in the middle of a change. It also helps greatly when modifying files on the cloud disk on-the-fly (such as with instantaneous saving note-taking apps).

It's not perfect as there is no guarantee it won't mess up the git state again, but it helps and for the moment I did not get any issue.

Force youtube embed to start in 720p

I've managed to get this working by the following fix:

//www.youtube.com/embed/_YOUR_VIDEO_CODE_/?vq=hd720

You video should have the hd720 resolution to do so.

I was using the embedding via iframe, BTW. Hope someone will find this helpful.

Jenkins restrict view of jobs per user

Think this is, what you are searching for: Allow access to specific projects for Users

Short description without screenshots:
Use Jenkins "Project-based Matrix Authorization Strategy" under "Manage Jenkins" => "Configure System". On the configuration page of each project, you now have "Enable project-based security". Now add each user you want to authorize.

VB.NET - How to move to next item a For Each Loop?

What about:

If Not I = x Then

  ' Do something '

End If

' Move to next item '

JS jQuery - check if value is in array

The Array.prototype property represents the prototype for the Array constructor and allows you to add new properties and methods to all Array objects. we can create a prototype for this purpose

Array.prototype.has_element = function(element) {
    return $.inArray( element, this) !== -1;
};

And then use it like this

var numbers= [1, 2, 3, 4];
numbers.has_element(3) => true
numbers.has_element(10) => false

See the Demo below

_x000D_
_x000D_
Array.prototype.has_element = function(element) {_x000D_
  return $.inArray(element, this) !== -1;_x000D_
};_x000D_
_x000D_
_x000D_
_x000D_
var numbers = [1, 2, 3, 4];_x000D_
console.log(numbers.has_element(3));_x000D_
console.log(numbers.has_element(10));
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
_x000D_
_x000D_
_x000D_

How to send a html email with the bash command "sendmail"?

Found solution in http://senthilkl.blogspot.lu/2012/11/how-to-send-html-emails-using-sendemail.html

sendEmail -f "oracle@server" -t "[email protected]" -u "Alert: Backup complete" -o message-content-type=html -o message-file=$LOG_FILE  -a $LOG_FILE_ATTACH 

Return Boolean Value on SQL Select Statement

For those of you who are interested in getting the value adding a custom column name, this worked for me:

CAST(
    CASE WHEN EXISTS ( 
           SELECT * 
           FROM mytable 
           WHERE mytable.id = 1
    ) 
    THEN TRUE 
    ELSE FALSE 
    END AS bool) 
AS "nameOfMyColumn"

You can skip the double quotes from the column name in case you're not interested in keeping the case sensitivity of the name (in some clients).

I slightly tweaked @Chad's answer for this.

How can I generate a list of consecutive numbers?

You can use itertools.count() to generate unbounded sequences. (itertools is in the Python standard library). Docs here:
https://docs.python.org/3/library/itertools.html#itertools.count

getContext is not a function

Actually we get this error also when we create canvas in javascript as below.

document.createElement('canvas');

Here point to be noted we have to provide argument name correctly as 'canvas' not anything else.

Thanks

Setting up Vim for Python

There is a bundled collection of Vim plugins for Python development: http://www.vim.org/scripts/script.php?script_id=3770

How to fix "'System.AggregateException' occurred in mscorlib.dll"

As the message says, you have a task which threw an unhandled exception.

Turn on Break on All Exceptions (Debug, Exceptions) and rerun the program.
This will show you the original exception when it was thrown in the first place.


(comment appended): In VS2015 (or above). Select Debug > Options > Debugging > General and unselect the "Enable Just My Code" option.

How to get GET (query string) variables in Express.js on Node.js?

For Express.js you want to do req.params:

app.get('/user/:id', function(req, res) {
  res.send('user' + req.params.id);    
});

jQuery count number of divs with a certain class?

I just created this js function using the jQuery size function http://api.jquery.com/size/

function classCount(name){
  alert($('.'+name).size())
}

It alerts out the number of times the class name occurs in the document.

Select query to remove non-numeric characters

In case if there are some characters possible between digits (e.g. thousands separators), you may try following:

declare @table table (DirtyCol varchar(100))
insert into @table values
    ('AB ABCDE # 123')
    ,('ABCDE# 123')
    ,('AB: ABC# 123')
    ,('AB#')
    ,('AB # 1 000 000')
    ,('AB # 1`234`567')
    ,('AB # (9)(876)(543)')

;with tally as (select top (100) N=row_number() over (order by @@spid) from sys.all_columns),
data as (
    select DirtyCol, Col
    from @table
        cross apply (
            select (select C + ''
            from (select N, substring(DirtyCol, N, 1) C from tally where N<=datalength(DirtyCol)) [1]
            where C between '0' and '9'
            order by N
            for xml path(''))
        ) p (Col)
    where p.Col is not NULL
)
select DirtyCol, cast(Col as int) IntCol
from data

Output is:

DirtyCol              IntCol
--------------------- -------
AB ABCDE # 123        123
ABCDE# 123            123
AB: ABC# 123          123
AB # 1 000 000        1000000
AB # 1`234`567        1234567
AB # (9)(876)(543)    9876543

For update, add ColToUpdate to select list of the data cte:

;with num as (...),
data as (
    select ColToUpdate, /*DirtyCol, */Col
    from ...
)
update data
set ColToUpdate = cast(Col as int)

Absolute and Flexbox in React Native

Ok, solved my problem, if anyone is passing by here is the answer:

Just had to add left: 0, and top: 0, to the styles, and yes, I'm tired.

position: 'absolute',
left:     0,
top:      0,

How to access a RowDataPacket object

Simpler way:

.then( resp=> {
  let resultFromDb= Object.values(resp)[0]
  console.log(resultFromDb)
}

In my example I received an object in response. When I use Object.values I have the value of the property as a response, however it comes inside an array, using [0] access the first index of this array, now i have the value to use it where I need it.

Git copy changes from one branch to another

Merge the changes from BranchA to BranchB. When you are on BranchB execute git merge BranchA

Set value of hidden input with jquery

You don't need to set name , just giving an id is enough.

<input type="hidden" id="testId" />

and than with jquery you can use 'val()' method like below:

 $('#testId').val("work");

Pass path with spaces as parameter to bat file

If you have a path with spaces you must surround it with quotation marks (").

Not sure if that's exactly what you're asking though?

How do you split a list into evenly sized chunks?

a = [1, 2, 3, 4, 5, 6, 7, 8, 9]
CHUNK = 4
[a[i*CHUNK:(i+1)*CHUNK] for i in xrange((len(a) + CHUNK - 1) / CHUNK )]

How do you get assembler output from C/C++ source in gcc?

If what you want to see depends on the linking of the output, then objdump on the output object file/executable may also be useful in addition to the aforementioned gcc -S. Here's a very useful script by Loren Merritt that converts the default objdump syntax into the more readable nasm syntax:

#!/usr/bin/perl -w
$ptr='(BYTE|WORD|DWORD|QWORD|XMMWORD) PTR ';
$reg='(?:[er]?(?:[abcd]x|[sd]i|[sb]p)|[abcd][hl]|r1?[0-589][dwb]?|mm[0-7]|xmm1?[0-9])';
open FH, '-|', '/usr/bin/objdump', '-w', '-M', 'intel', @ARGV or die;
$prev = "";
while(<FH>){
    if(/$ptr/o) {
        s/$ptr(\[[^\[\]]+\],$reg)/$2/o or
        s/($reg,)$ptr(\[[^\[\]]+\])/$1$3/o or
        s/$ptr/lc $1/oe;
    }
    if($prev =~ /\t(repz )?ret / and
       $_ =~ /\tnop |\txchg *ax,ax$/) {
       # drop this line
    } else {
       print $prev;
       $prev = $_;
    }
}
print $prev;
close FH;

I suspect this can also be used on the output of gcc -S.

Django return redirect() with parameters

Firstly, your URL definition does not accept any parameters at all. If you want parameters to be passed from the URL into the view, you need to define them in the urlconf.

Secondly, it's not at all clear what you are expecting to happen to the cleaned_data dictionary. Don't forget you can't redirect to a POST - this is a limitation of HTTP, not Django - so your cleaned_data either needs to be a URL parameter (horrible) or, slightly better, a series of GET parameters - so the URL would be in the form:

/link/mybackend/?field1=value1&field2=value2&field3=value3

and so on. In this case, field1, field2 and field3 are not included in the URLconf definition - they are available in the view via request.GET.

So your urlconf would be:

url(r'^link/(?P<backend>\w+?)/$', my_function)

and the view would look like:

def my_function(request, backend):
   data = request.GET

and the reverse would be (after importing urllib):

return "%s?%s" % (redirect('my_function', args=(backend,)),
                  urllib.urlencode(form.cleaned_data))

Edited after comment

The whole point of using redirect and reverse, as you have been doing, is that you go to the URL - it returns an Http code that causes the browser to redirect to the new URL, and call that.

If you simply want to call the view from within your code, just do it directly - no need to use reverse at all.

That said, if all you want to do is store the data, then just put it in the session:

request.session['temp_data'] = form.cleaned_data

Is there a job scheduler library for node.js?

This won't be suitable for everyone, but if your application is already setup to take commands via a socket, you can use netcat to issue a commands via cron proper.

echo 'mycommand' | nc -U /tmp/myapp.sock

AngularJS dynamic routing

Here is another solution that works good.

(function() {
    'use strict';

    angular.module('cms').config(route);
    route.$inject = ['$routeProvider'];

    function route($routeProvider) {

        $routeProvider
            .when('/:section', {
                templateUrl: buildPath
            })
            .when('/:section/:page', {
                templateUrl: buildPath
            })
            .when('/:section/:page/:task', {
                templateUrl: buildPath
            });



    }

    function buildPath(path) {

        var layout = 'layout';

        angular.forEach(path, function(value) {

            value = value.charAt(0).toUpperCase() + value.substring(1);
            layout += value;

        });

        layout += '.tpl';

        return 'client/app/layouts/' + layout;

    }

})();

How to export MySQL database with triggers and procedures?

mysqldump will backup by default all the triggers but NOT the stored procedures/functions. There are 2 mysqldump parameters that control this behavior:

  • --routines – FALSE by default
  • --triggers – TRUE by default

so in mysqldump command , add --routines like :

mysqldump <other mysqldump options> --routines > outputfile.sql

See the MySQL documentation about mysqldump arguments.

Enable binary mode while restoring a Database from an SQL dump

I had this error once, after running mysqldump on Windows PowerShell like so:

mysqldump -u root p my_db --no-data --no-create-db --no-create-info --routines --triggers --skip-opt --set-gtid-purged=OFF > db_objects.sql

What I did was change it to this (pipe instead to Set-Content):

mysqldump -u root p my_db --no-data --no-create-db --no-create-info --routines --triggers --skip-opt --set-gtid-purged=OFF | Set-Content db_objects.sql

And the problem went away!

Removing padding gutter from grid columns in Bootstrap 4

Bootstrap4: Comes with .no-gutters out of the box. source: https://github.com/twbs/bootstrap/pull/21211/files

Bootstrap3:

Requires custom CSS.

Stylesheet:

.row.no-gutters {
  margin-right: 0;
  margin-left: 0;

  & > [class^="col-"],
  & > [class*=" col-"] {
    padding-right: 0;
    padding-left: 0;
  }
}

Then to use:

<div class="row no-gutters">
  <div class="col-xs-4">...</div>
  <div class="col-xs-4">...</div>
  <div class="col-xs-4">...</div>
</div>

It will:

  • Remove margin from the row
  • Remove padding from all columns directly beneath the row

Gridview row editing - dynamic binding to a DropDownList

Quite easy... You're doing it wrong, because by that event the control is not there:

protected void gv_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow && 
        (e.Row.RowState & DataControlRowState.Edit) == DataControlRowState.Edit)
    { 
        // Here you will get the Control you need like:
        DropDownList dl = (DropDownList)e.Row.FindControl("ddlPBXTypeNS");
    }
}

That is, it will only be valid for a DataRow (the actually row with data), and if it's in Edit mode... because you only edit one row at a time. The e.Row.FindControl("ddlPBXTypeNS") will only find the control that you want.

535-5.7.8 Username and Password not accepted

Goto config/initializers/setup_mail.rb Check whether the configuration there matches the configuration written in the development.rb file.It should look like the following in both files:

config.action_mailer.smtp_settings = {
     :address =>"[email protected]",
     :port => 587,
     :domain => "gmail.com",
     :user_name => "[email protected]",
     :password => "********",
     :authentication => 'plain',
     :enable_starttls_auto => true,
     :openssl_verify_mode => 'none' 
     } 

This will most certainly solve your problem.

How can I format decimal property to currency?

You can use String.Format, see the code [via How-to Geek]:

decimal moneyvalue = 1921.39m;
string html = String.Format("Order Total: {0:C}", moneyvalue);
Console.WriteLine(html);
// Output: $1,921.39

See also:

LINQ-to-SQL vs stored procedures?

IMHO, RAD = LINQ, RUP = Stored Procs. I worked for a large Fortune 500 company for many years, at many levels including management, and frankly, I would never hire RUP developers to do RAD development. They are so siloed that they very limited knowledge of what to do at other levels of the process. With a siloed environment, it makes sense to give DBAs control over the data through very specific entry points, because others frankly don't know the best ways to accomplish data management.

But large enterprises move painfully slow in the development arena, and this is extremely costly. There are times when you need to move faster to save both time and money, and LINQ provides that and more in spades.

Sometimes I think that DBAs are biased against LINQ because they feel it threatens their job security. But that's the nature of the beast, ladies and gentlemen.

Difference between | and || or & and && for comparison

(Assuming C, C++, Java, JavaScript)

| and & are bitwise operators while || and && are logical operators. Usually you'd want to use || and && for if statements and loops and such (i.e. for your examples above). The bitwise operators are for setting and checking bits within bitmasks.

What does it mean to "call" a function in Python?

when you invoke a function , it is termed 'calling' a function . For eg , suppose you've defined a function that finds the average of two numbers like this-

def avgg(a,b) :
        return (a+b)/2;

now, to call the function , you do like this .

x=avgg(4,6)
print x

value of x will be 5 .

How can I disable all views inside the layout?

Another way is to call setEnabled() on each child (for example if you want to do some extra check on child before disabling)

LinearLayout layout = (LinearLayout) findViewById(R.id.my_layout);
for (int i = 0; i < layout.getChildCount(); i++) {
    View child = layout.getChildAt(i);
    child.setEnabled(false);
}

Python "\n" tag extra line

This:

    print "\n"

is printing out two \n characters -- the one you tell it to, and the one that Python prints out at the end of any line which doesn't end with a , like you use in print a,. Simply use

    print

instead.

What is the equivalent of Select Case in Access SQL?

Consider the Switch Function as an alternative to multiple IIf() expressions. It will return the value from the first expression/value pair where the expression evaluates as True, and ignore any remaining pairs. The concept is similar to the SELECT ... CASE approach you referenced but which is not available in Access SQL.

If you want to display a calculated field as commission:

SELECT
    Switch(
        OpeningBalance < 5001, 20,
        OpeningBalance < 10001, 30,
        OpeningBalance < 20001, 40,
        OpeningBalance >= 20001, 50
        ) AS commission
FROM YourTable;

If you want to store that calculated value to a field named commission:

UPDATE YourTable
SET commission =
    Switch(
        OpeningBalance < 5001, 20,
        OpeningBalance < 10001, 30,
        OpeningBalance < 20001, 40,
        OpeningBalance >= 20001, 50
        );

Either way, see whether you find Switch() easier to understand and manage. Multiple IIf()s can become mind-boggling as the number of conditions grows.

Detecting superfluous #includes in C/C++?

This article explains a technique of #include removing by using the parsing of Doxygen. That's just a perl script, so it's quite easy to use.

Two versions of python on linux. how to make 2.7 the default

Add /usr/local/bin to your PATH environment variable, earlier in the list than /usr/bin.

Generally this is done in your shell's rc file, e.g. for bash, you'd put this in .bashrc:

export PATH="/usr/local/bin:$PATH"

This will cause your shell to look first for a python in /usr/local/bin, before it goes with the one in /usr/bin.

(Of course, this means you also need to have /usr/local/bin/python point to python2.7 - if it doesn't already, you'll need to symlink it.)

What is Hive: Return Code 2 from org.apache.hadoop.hive.ql.exec.MapRedTask

I was also facing same error when I was inserting the data into HIVE external table which was pointing to Elastic search cluster.

I replaced the older JAR elasticsearch-hadoop-2.0.0.RC1.jar to elasticsearch-hadoop-5.6.0.jar, and everything worked fine.

My Suggestion is please use the specific JAR as per the elastic search version. Don't use older JARs if you are using newer version of elastic search.

Thanks to this post Hive- Elasticsearch Write Operation #409

Easiest way to make lua script wait/pause/sleep/block for a few seconds?

You can do this:

function Sleep(seconds)
    local endTime = os.time() + seconds
    while os.time() < endTime do
    end
end
print("This is printed first!")
Sleep(5)
print("This is printed 5 seconds later!")

Appropriate datatype for holding percent values?

  • Hold as a decimal.
  • Add check constraints if you want to limit the range (e.g. between 0 to 100%; in some cases there may be valid reasons to go beyond 100% or potentially even into the negatives).
  • Treat value 1 as 100%, 0.5 as 50%, etc. This will allow any math operations to function as expected (i.e. as opposed to using value 100 as 100%).
  • Amend precision and scale as required (these are the two values in brackets columnName decimal(precision, scale). Precision says the total number of digits that can be held in the number, scale says how many of those are after the decimal place, so decimal(3,2) is a number which can be represented as #.##; decimal(5,3) would be ##.###.
  • decimal and numeric are essentially the same thing. However decimal is ANSI compliant, so always use that unless told otherwise (e.g. by your company's coding standards).

Example Scenarios

  • For your case (0.00% to 100.00%) you'd want decimal(5,4).
  • For the most common case (0% to 100%) you'd want decimal(3,2).
  • In both of the above, the check constraints would be the same

Example:

if object_id('Demo') is null
create table Demo
    (
        Id bigint not null identity(1,1) constraint pk_Demo primary key
        , Name nvarchar(256) not null constraint uk_Demo unique 
        , SomePercentValue decimal(3,2) constraint chk_Demo_SomePercentValue check (SomePercentValue between 0 and 1)
        , SomePrecisionPercentValue decimal(5,2) constraint chk_Demo_SomePrecisionPercentValue check (SomePrecisionPercentValue between 0 and 1)
    )

Further Reading:

Run JavaScript in Visual Studio Code

I am surprised this has not been mentioned yet:

Simply open the .js file in question in VS Code, switch to the 'Debug Console' tab, hit the debug button in the left nav bar, and click the run icon (play button)!

Requires nodejs to be installed!

What does [STAThread] do?

The STAThreadAttribute is essentially a requirement for the Windows message pump to communicate with COM components. Although core Windows Forms does not use COM, many components of the OS such as system dialogs do use this technology.

MSDN explains the reason in slightly more detail:

STAThreadAttribute indicates that the COM threading model for the application is single-threaded apartment. This attribute must be present on the entry point of any application that uses Windows Forms; if it is omitted, the Windows components might not work correctly. If the attribute is not present, the application uses the multithreaded apartment model, which is not supported for Windows Forms.

This blog post (Why is STAThread required?) also explains the requirement quite well. If you want a more in-depth view as to how the threading model works at the CLR level, see this MSDN Magazine article from June 2004 (Archived, Apr. 2009).

How to make a list of n numbers in Python and randomly select any number?

You can create the enumeration of the elements by something like this:

mylist = list(xrange(10))

Then you can use the random.choice function to select your items:

import random
...
random.choice(mylist)

As Asim Ihsan correctly stated, my answer did not address the full problem of the OP. To remove the values from the list, simply list.remove() can be called:

import random
...
value = random.choice(mylist)
mylist.remove(value)

As takataka pointed out, the xrange builtin function was renamed to range in Python 3.

How to change color of ListView items on focus and on click

Very old but I have just struggled with this, this is how I solved it in pure xml. In res/values/colors.xml I added three colours (the colour_...);

<resources>

    <color name="black_overlay">#66000000</color>

    <color name="colour_highlight_grey">#ff666666</color>
    <color name="colour_dark_blue">#ff000066</color>
    <color name="colour_dark_green">#ff006600</color>

</resources>

In the res/drawable folder I created listview_colours.xml which contained;

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@color/colour_highlight_grey" android:state_pressed="true"/>
    <item android:drawable="@color/colour_dark_blue" android:state_selected="true"/>
    <item android:drawable="@color/colour_dark_green" android:state_activated="true"/>
    <item android:drawable="@color/colour_dark_blue" android:state_focused="true"/>
</selector>

In the main_activity.xml find the List View and add the drawable to listSelector;

<ListView
    android:id="@+id/menuList"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:listSelector="@drawable/listview_colours"
    android:background="#ff222222"/>
</LinearLayout>

Play with the state_... items in the listview_colours.xml to get the effect you want.

There is also a method where you can set the style of the List View but I never managed to get it to work