Programs & Examples On #Mysql error 1292

MySQL error when trying to compare numeric and non-numeric data

Error Code 1292 - Truncated incorrect DOUBLE value - Mysql

This message means you're trying to compare a number and a string in a WHERE or ON clause. In your query, the only potential place where that could be occurring is ON ac.company_code = ta.company_code; either make sure they have similar declarations, or use an explicit CAST to convert the number to a string.

If you turn off strict mode, the error should turn into a warning.

error code 1292 incorrect date value mysql

I happened to be working in localhost , in windows 10, using WAMP, as it turns out, Wamp has a really accessible configuration interface to change the MySQL configuration. You just need to go to the Wamp panel, then to MySQL, then to settings and change the mode to sql-mode: none.(essentially disabling the strict mode) The following picture illustrates this.

enter image description here

How to pass a parameter to Vue @click event handler

Just use a normal Javascript expression, no {} or anything necessary:

@click="addToCount(item.contactID)"

if you also need the event object:

@click="addToCount(item.contactID, $event)"

Angular: conditional class with *ngClass

to extend MostafaMashayekhi his answer for option two> you can also chain multiple options with a ','

[ngClass]="{'my-class': step=='step1', 'my-class2':step=='step2' }"

Also *ngIf can be used in some of these situations usually combined with a *ngFor

class="mats p" *ngIf="mat=='painted'"

Is there an easy way to add a border to the top and bottom of an Android View?

Simplest way to add borders to inset the borders using InsetDrawable,following will show top border only :

<?xml version="1.0" encoding="utf-8"?>
<inset xmlns:android="http://schemas.android.com/apk/res/android"
    android:insetBottom="-2dp"
    android:insetLeft="-2dp"
    android:insetRight="-2dp">
    <shape android:shape="rectangle">

        <solid android:color="@color/light_gray" />
        <stroke
            android:width=".5dp"
            android:color="@color/dark_gray" />
    </shape>
</inset>

Vertically aligning text next to a radio button

HTML:

<label><input type="radio" id="opt1" name="opt1" value="1"> A label</label>

CSS:

label input[type="radio"] { vertical-align: text-bottom; }

What is the benefit of using "SET XACT_ABORT ON" in a stored procedure?

SET XACT_ABORT ON instructs SQL Server to rollback the entire transaction and abort the batch when a run-time error occurs. It covers you in cases like a command timeout occurring on the client application rather than within SQL Server itself (which isn't covered by the default XACT_ABORT OFF setting.)

Since a query timeout will leave the transaction open, SET XACT_ABORT ON is recommended in all stored procedures with explicit transactions (unless you have a specific reason to do otherwise) as the consequences of an application performing work on a connection with an open transaction are disastrous.

There's a really great overview on Dan Guzman's Blog,

Correlation between two vectors?

Given:

A_1 = [10 200 7 150]';
A_2 = [0.001 0.450 0.007 0.200]';

(As others have already pointed out) There are tools to simply compute correlation, most obviously corr:

corr(A_1, A_2);  %Returns 0.956766573975184  (Requires stats toolbox)

You can also use base Matlab's corrcoef function, like this:

M = corrcoef([A_1 A_2]):  %Returns [1 0.956766573975185; 0.956766573975185 1];
M(2,1);  %Returns 0.956766573975184 

Which is closely related to the cov function:

cov([condition(A_1) condition(A_2)]);

As you almost get to in your original question, you can scale and adjust the vectors yourself if you want, which gives a slightly better understanding of what is going on. First create a condition function which subtracts the mean, and divides by the standard deviation:

condition = @(x) (x-mean(x))./std(x);  %Function to subtract mean AND normalize standard deviation

Then the correlation appears to be (A_1 * A_2)/(A_1^2), like this:

(condition(A_1)' * condition(A_2)) / sum(condition(A_1).^2);  %Returns 0.956766573975185

By symmetry, this should also work

(condition(A_1)' * condition(A_2)) / sum(condition(A_2).^2); %Returns 0.956766573975185

And it does.

I believe, but don't have the energy to confirm right now, that the same math can be used to compute correlation and cross correlation terms when dealing with multi-dimensiotnal inputs, so long as care is taken when handling the dimensions and orientations of the input arrays.

Laravel 5.4 ‘cross-env’ Is Not Recognized as an Internal or External Command

I think this log entry Local package.json exists, but node_modules missing, did you mean to install? has gave me the solution.

npm install && npm run dev

Code not running in IE 11, works fine in Chrome

If this is happening in Angular 2+ application, you can just uncomment string polyfills in polyfills.ts:

import 'core-js/es6/string';

Null vs. False vs. 0 in PHP

False, Null, Nothing, 0, Undefined, etc., etc.

Each of these has specific meanings that correlate with actual concepts. Sometimes multiple meanings are overloaded into a single keyword or value.

In C and C++, NULL, False and 0 are overloaded to the same value. In C# they're 3 distinct concepts.

null or NULL usually indicates a lack of value, but usually doesn't specify why. 0 indicates the natural number zero and has type-equivalence to 1, 2, 3, etc. and in languages that support separate concepts of NULL should be treated only a number.

False indicates non-truth. And it used in binary values. It doesn't mean unset, nor does it mean 0. It simply indicates one of two binary values.

Nothing can indicate that the value is specifically set to be nothing which indicates the same thing as null, but with intent.

Undefined in some languages indicates that the value has yet to be set because no code has specified an actual value.

How to get selected path and name of the file opened with file dialog?

You can get any part of the file path using the FileSystemObject. GetFileName(filepath) gives you what you want.

Modified code below:

Sub GetFilePath()
Dim objFSO as New FileSystemObject

Set myFile = Application.FileDialog(msoFileDialogOpen)
With myFile
.Title = "Choose File"
.AllowMultiSelect = False
If .Show <> -1 Then
Exit Sub
End If
FileSelected = .SelectedItems(1)
End With

ActiveSheet.Range("A1") = FileSelected 'The file path
ActiveSheet.Range("A2") = objFSO.GetFileName(FileSelected) 'The file name
End Sub

How to set a binding in Code?

Replace:

myBinding.Source = ViewModel.SomeString;

with:

myBinding.Source = ViewModel;

Example:

Binding myBinding = new Binding();
myBinding.Source = ViewModel;
myBinding.Path = new PropertyPath("SomeString");
myBinding.Mode = BindingMode.TwoWay;
myBinding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
BindingOperations.SetBinding(txtText, TextBox.TextProperty, myBinding);

Your source should be just ViewModel, the .SomeString part is evaluated from the Path (the Path can be set by the constructor or by the Path property).

PHP: Convert any string to UTF-8 without knowing the original character set, or at least try

The main problem for me is that I don't know what encoding the source of any string is going to be - it could be from a text box (using is only useful if the user is actually submitted the form), or it could be from an uploaded text file, so I really have no control over the input.

I don't think it's a problem. An application knows the source of the input. If it's from a form, use UTF-8 encoding in your case. That works. Just verify the data provided is correctly encoded (validation). Keep in mind that not all databases support UTF-8 in it's full range.

If it's a file you won't save it UTF-8 encoded into the database but in binary form. When you output the file again, use binary output as well, then this is totally transparent.

Your idea is nice that a user can tell the encoding, be he/she can tell anyway after downloading the file, as it's binary.

So I must admit I don't see a specific issue you raise with your question. But maybe you can add some more details what your problem is.

.do extension in web pages?

.do comes from the Struts framework. See this question: Why do Java webapps use .do extension? Where did it come from? Also you can change what your urls look like using mod_rewrite (on Apache).

Failing to run jar file from command line: “no main manifest attribute”

First run your application from eclipse to create launch configuration. Then just follow the steps:

  1. From the menu bar's File menu, select Export.
  2. Expand the Java node and select Runnable JAR file. Click Next.
  3. In the Runnable JAR File Specification page, select a 'Java Application' launch configuration to use to create a runnable JAR.
  4. In the Export destination field, either type or click Browse to select a location for the JAR file.
  5. Select an appropriate library handling strategy.
  6. Optionally, you can also create an ANT script to quickly regenerate a previously created runnable JAR file.

Source: Creating a New Runnable JAR File at Eclipse.org

What's the difference between faking, mocking, and stubbing?

You can get some information :

From Martin Fowler about Mock and Stub

Fake objects actually have working implementations, but usually take some shortcut which makes them not suitable for production

Stubs provide canned answers to calls made during the test, usually not responding at all to anything outside what's programmed in for the test. Stubs may also record information about calls, such as an email gateway stub that remembers the messages it 'sent', or maybe only how many messages it 'sent'.

Mocks are what we are talking about here: objects pre-programmed with expectations which form a specification of the calls they are expected to receive.

From xunitpattern:

Fake: We acquire or build a very lightweight implementation of the same functionality as provided by a component that the SUT depends on and instruct the SUT to use it instead of the real.

Stub : This implementation is configured to respond to calls from the SUT with the values (or exceptions) that will exercise the Untested Code (see Production Bugs on page X) within the SUT. A key indication for using a Test Stub is having Untested Code caused by the inability to control the indirect inputs of the SUT

Mock Object that implements the same interface as an object on which the SUT (System Under Test) depends. We can use a Mock Object as an observation point when we need to do Behavior Verification to avoid having an Untested Requirement (see Production Bugs on page X) caused by an inability to observe side-effects of invoking methods on the SUT.

Personally

I try to simplify by using : Mock and Stub. I use Mock when it's an object that returns a value that is set to the tested class. I use Stub to mimic an Interface or Abstract class to be tested. In fact, it doesn't really matter what you call it, they are all classes that aren't used in production, and are used as utility classes for testing.

Errors: Data path ".builders['app-shell']" should have required property 'class'

I changed @angular-devkit/build-angular": "0.9.0.1" to @angular-devkit/build-angular": "0.13.4" and it worked.

Laravel - Session store not set on request

A problem can be that you try to access you session inside of your controller's __constructor() function.

From Laravel 5.3+ this is not possible anymore because it is not intended to work anyway, as stated in the upgrade guide.

In previous versions of Laravel, you could access session variables or the authenticated user in your controller's constructor. This was never intended to be an explicit feature of the framework. In Laravel 5.3, you can't access the session or authenticated user in your controller's constructor because the middleware has not run yet.

For more background information also read Taylor his response.

Workaround

If you still want to use this, you can dynamically create a middleware and run it in the constructor, as described in the upgrade guide:

As an alternative, you may define a Closure based middleware directly in your controller's constructor. Before using this feature, make sure that your application is running Laravel 5.3.4 or above:

<?php

namespace App\Http\Controllers;

use App\User;
use Illuminate\Support\Facades\Auth;
use App\Http\Controllers\Controller;

class ProjectController extends Controller
{
    /**
     * All of the current user's projects.
     */
    protected $projects;

    /**
     * Create a new controller instance.
     *
     * @return void
     */
    public function __construct()
    {
        $this->middleware(function ($request, $next) {
            $this->projects = Auth::user()->projects;

            return $next($request);
        });
    }
}

How to calculate the inverse of the normal cumulative distribution function in python?

NORMSINV (mentioned in a comment) is the inverse of the CDF of the standard normal distribution. Using scipy, you can compute this with the ppf method of the scipy.stats.norm object. The acronym ppf stands for percent point function, which is another name for the quantile function.

In [20]: from scipy.stats import norm

In [21]: norm.ppf(0.95)
Out[21]: 1.6448536269514722

Check that it is the inverse of the CDF:

In [34]: norm.cdf(norm.ppf(0.95))
Out[34]: 0.94999999999999996

By default, norm.ppf uses mean=0 and stddev=1, which is the "standard" normal distribution. You can use a different mean and standard deviation by specifying the loc and scale arguments, respectively.

In [35]: norm.ppf(0.95, loc=10, scale=2)
Out[35]: 13.289707253902945

If you look at the source code for scipy.stats.norm, you'll find that the ppf method ultimately calls scipy.special.ndtri. So to compute the inverse of the CDF of the standard normal distribution, you could use that function directly:

In [43]: from scipy.special import ndtri

In [44]: ndtri(0.95)
Out[44]: 1.6448536269514722

Access denied for user 'root'@'localhost' (using password: Yes) after password reset LINUX

On mac os, please follow below steps:

Stop MySQL

$ sudo /usr/local/mysql/support-files/mysql.server stop Start it in safe mode:

$ sudo mysqld_safe --skip-grant-tables (above line is the whole command)

This will be an ongoing command until the process is finished so open another shell/terminal window, log in without a password:

$ mysql -u root

mysql> UPDATE mysql.user SET Password=PASSWORD('password') WHERE User='root'; Start MySQL

sudo /usr/local/mysql/support-files/mysql.server start your new password is 'password'.

Neatest way to remove linebreaks in Perl

In your example, you can just go:

chomp(@lines);

Or:

$_=join("", @lines);
s/[\r\n]+//g;

Or:

@lines = split /[\r\n]+/, join("", @lines);

Using these directly on a file:

perl -e '$_=join("",<>); s/[\r\n]+//g; print' <a.txt |less

perl -e 'chomp(@a=<>);print @a' <a.txt |less

How to convert a hex string to hex number

Use int function with second parameter 16, to convert a hex string to an integer. Finally, use hex function to convert it back to a hexadecimal number.

print hex(int("0xAD4", 16) + int("0x200", 16)) # 0xcd4

Instead you could directly do

print hex(int("0xAD4", 16) + 0x200) # 0xcd4

How do I find duplicates across multiple columns?

Given a staging table with 70 columns and only 4 representing duplicates, this code will return the offending columns:

SELECT 
    COUNT(*)
    ,LTRIM(RTRIM(S.TransactionDate)) 
    ,LTRIM(RTRIM(S.TransactionTime))
    ,LTRIM(RTRIM(S.TransactionTicketNumber)) 
    ,LTRIM(RTRIM(GrossCost)) 
FROM Staging.dbo.Stage S
GROUP BY 
    LTRIM(RTRIM(S.TransactionDate)) 
    ,LTRIM(RTRIM(S.TransactionTime))
    ,LTRIM(RTRIM(S.TransactionTicketNumber)) 
    ,LTRIM(RTRIM(GrossCost)) 
HAVING COUNT(*) > 1

.

RestTemplate: How to send URL and query parameters together

One simple way to do that is:

String url = "http://test.com/Services/rest/{id}/Identifier"

UriComponents uriComponents = UriComponentsBuilder.fromUriString(url).build();
uriComponents = uriComponents.expand(Collections.singletonMap("id", "1234"));

and then adds the query params.

How to calculate the running time of my program?

Use System.currentTimeMillis() or System.nanoTime() if you want even more precise reading. Usually, milliseconds is precise enough if you need to output the value to the user. Moreover, System.nanoTime() may return negative values, thus it may be possible that, if you're using that method, the return value is not correct.

A general and wide use would be to use milliseconds :

long start = System.currentTimeMillis();

... 


long end = System.currentTimeMillis();

NumberFormat formatter = new DecimalFormat("#0.00000");
System.out.print("Execution time is " + formatter.format((end - start) / 1000d) + " seconds");

Note that nanoseconds are usually used to calculate very short and precise program executions, such as unit testing and benchmarking. Thus, for overall program execution, milliseconds are preferable.

How do I send a file as an email attachment using Linux command line?

From looking at man mailx, the mailx program does not have an option for attaching a file. You could use another program such as mutt.

echo "This is the message body" | mutt -a file.to.attach -s "subject of message" [email protected]

Command line options for mutt can be shown with mutt -h.

Is it possible to put CSS @media rules inline?

Problem

No, Media Queries cannot be used in this way

<span style="@media (...) { ... }"></span>

Solution

But if you want provided a specific behavior usable on the fly AND responsive, you can use the style markup and not the attribute.

e.i.

<style scoped>
.on-the-fly-behavior {
    background-image: url('particular_ad.png'); 
}
@media (max-width: 300px) {
    .on-the-fly-behavior {
        background-image: url('particular_ad_small.png');
    }
}
</style>
<span class="on-the-fly-behavior"></span>

See the code working in live on CodePen

In my Blog for example, I inject a <style> markup in <head> just after <link> declaration for CSS and it's contain the content of a textarea provided beside of real content textarea for create extra-class on the fly when I wrote an artitle.

Note : the scoped attribute is a part of HTML5 specification. If you do not use it, the validator will blame you but browsers currently not support the real purpose : scoped the content of <style> only on immediatly parent element and that element's child elements. Scoped is not mandatory if the <style> element is in <head> markup.


UPDATE: I advice to always use rules in the mobile first way so previous code should be:

<style scoped>
/* 0 to 299 */
.on-the-fly-behavior {
    background-image: url('particular_ad_small.png'); 
}
/* 300 to X */
@media (min-width: 300px) { /* or 301 if you want really the same as previously.  */
    .on-the-fly-behavior {   
        background-image: url('particular_ad.png');
    }
}
</style>
<span class="on-the-fly-behavior"></span>

int to unsigned int conversion

You can convert an int to an unsigned int. The conversion is valid and well-defined.

Since the value is negative, UINT_MAX + 1 is added to it so that the value is a valid unsigned quantity. (Technically, 2N is added to it, where N is the number of bits used to represent the unsigned type.)

In this case, since int on your platform has a width of 32 bits, 62 is subtracted from 232, yielding 4,294,967,234.

How to generate serial version UID in Intellij

IntelliJ IDEA Plugins / GenerateSerialVersionUID https://plugins.jetbrains.com/plugin/?idea&id=185

very nice, very easy to install. you can install that from plugins menu, select install from disk, select the jar file you unpacked in the lib folder. restart, control + ins, and it pops up to generate serial UID from menu. love it. :-)

Zsh: Conda/Pip installs command not found

  1. Find the right version of your anaconda

  2. Put it to ~/.zshrc via command vim ~/.zshrc

    • Anaconda 2 export PATH="/User/<your-username>/anaconda2/bin:$PATH"
    • Anaconda 3 export PATH="/User/<your-username>/anaconda3/bin:$PATH"
    • Or if you install Anaconda in root directory:
    • Anaconda 2 export PATH="/anaconda2/bin:$PATH"
    • Anaconda 3 export PATH="/anaconda3/bin:$PATH"
  3. Restart the zsh source ~/.zshrc

Delete many rows from a table using id in Mysql

Something like this might make it a bit easier, you could obviously use a script to generate this, or even excel

DELETE FROM tablename WHERE id IN (
1,
2,
3,
4,
5,
6
);

How do I join two lines in vi?

This should do it:

J

How can I recover a lost commit in Git?

git reflog is your friend. Find the commit that you want to be on in that list and you can reset to it (for example:git reset --hard e870e41).

(If you didn't commit your changes... you might be in trouble - commit early, and commit often!)

Programmatically shut down Spring Boot application

This will make sure that the SpringBoot application is closed properly and the resources are released back to the operating system,

@Autowired
private ApplicationContext context;

@GetMapping("/shutdown-app")
public void shutdownApp() {

    int exitCode = SpringApplication.exit(context, (ExitCodeGenerator) () -> 0);
    System.exit(exitCode);
}

SQL RANK() versus ROW_NUMBER()

Also, pay attention to ORDER BY in PARTITION (Standard AdventureWorks db is used for example) when using RANK.

SELECT as1.SalesOrderID, as1.SalesOrderDetailID, RANK() OVER (PARTITION BY as1.SalesOrderID ORDER BY as1.SalesOrderID ) ranknoequal , RANK() OVER (PARTITION BY as1.SalesOrderID ORDER BY as1.SalesOrderDetailId ) ranknodiff FROM Sales.SalesOrderDetail as1 WHERE SalesOrderId = 43659 ORDER BY SalesOrderDetailId;

Gives result:

SalesOrderID SalesOrderDetailID rank_same_as_partition rank_salesorderdetailid
43659 1 1 1
43659 2 1 2
43659 3 1 3
43659 4 1 4
43659 5 1 5
43659 6 1 6
43659 7 1 7
43659 8 1 8
43659 9 1 9
43659 10 1 10
43659 11 1 11
43659 12 1 12

But if change order by to (use OrderQty :

SELECT as1.SalesOrderID, as1.OrderQty, RANK() OVER (PARTITION BY as1.SalesOrderID ORDER BY as1.SalesOrderID ) ranknoequal , RANK() OVER (PARTITION BY as1.SalesOrderID ORDER BY as1.OrderQty ) rank_orderqty FROM Sales.SalesOrderDetail as1 WHERE SalesOrderId = 43659 ORDER BY OrderQty;

Gives:

SalesOrderID OrderQty rank_salesorderid rank_orderqty
43659 1 1 1
43659 1 1 1
43659 1 1 1
43659 1 1 1
43659 1 1 1
43659 1 1 1
43659 2 1 7
43659 2 1 7
43659 3 1 9
43659 3 1 9
43659 4 1 11
43659 6 1 12

Notice how the Rank changes when we use OrderQty (rightmost column second table) in ORDER BY and how it changes when we use SalesOrderDetailID (rightmost column first table) in ORDER BY.

How to determine CPU and memory consumption from inside a process?

Windows

Some of the above values are easily available from the appropriate WIN32 API, I just list them here for completeness. Others, however, need to be obtained from the Performance Data Helper library (PDH), which is a bit "unintuitive" and takes a lot of painful trial and error to get to work. (At least it took me quite a while, perhaps I've been only a bit stupid...)

Note: for clarity all error checking has been omitted from the following code. Do check the return codes...!


  • Total Virtual Memory:

    #include "windows.h"
    
    MEMORYSTATUSEX memInfo;
    memInfo.dwLength = sizeof(MEMORYSTATUSEX);
    GlobalMemoryStatusEx(&memInfo);
    DWORDLONG totalVirtualMem = memInfo.ullTotalPageFile;
    

    Note: The name "TotalPageFile" is a bit misleading here. In reality this parameter gives the "Virtual Memory Size", which is size of swap file plus installed RAM.

  • Virtual Memory currently used:

    Same code as in "Total Virtual Memory" and then

     DWORDLONG virtualMemUsed = memInfo.ullTotalPageFile - memInfo.ullAvailPageFile;
    
  • Virtual Memory currently used by current process:

    #include "windows.h"
    #include "psapi.h"
    
    PROCESS_MEMORY_COUNTERS_EX pmc;
    GetProcessMemoryInfo(GetCurrentProcess(), (PROCESS_MEMORY_COUNTERS*)&pmc, sizeof(pmc));
    SIZE_T virtualMemUsedByMe = pmc.PrivateUsage;
    



  • Total Physical Memory (RAM):

    Same code as in "Total Virtual Memory" and then

    DWORDLONG totalPhysMem = memInfo.ullTotalPhys;
    
  • Physical Memory currently used:

    Same code as in "Total Virtual Memory" and then

    DWORDLONG physMemUsed = memInfo.ullTotalPhys - memInfo.ullAvailPhys;
    
  • Physical Memory currently used by current process:

    Same code as in "Virtual Memory currently used by current process" and then

    SIZE_T physMemUsedByMe = pmc.WorkingSetSize;
    



  • CPU currently used:

    #include "TCHAR.h"
    #include "pdh.h"
    
    static PDH_HQUERY cpuQuery;
    static PDH_HCOUNTER cpuTotal;
    
    void init(){
        PdhOpenQuery(NULL, NULL, &cpuQuery);
        // You can also use L"\\Processor(*)\\% Processor Time" and get individual CPU values with PdhGetFormattedCounterArray()
        PdhAddEnglishCounter(cpuQuery, L"\\Processor(_Total)\\% Processor Time", NULL, &cpuTotal);
        PdhCollectQueryData(cpuQuery);
    }
    
    double getCurrentValue(){
        PDH_FMT_COUNTERVALUE counterVal;
    
        PdhCollectQueryData(cpuQuery);
        PdhGetFormattedCounterValue(cpuTotal, PDH_FMT_DOUBLE, NULL, &counterVal);
        return counterVal.doubleValue;
    }
    
  • CPU currently used by current process:

    #include "windows.h"
    
    static ULARGE_INTEGER lastCPU, lastSysCPU, lastUserCPU;
    static int numProcessors;
    static HANDLE self;
    
    void init(){
        SYSTEM_INFO sysInfo;
        FILETIME ftime, fsys, fuser;
    
        GetSystemInfo(&sysInfo);
        numProcessors = sysInfo.dwNumberOfProcessors;
    
        GetSystemTimeAsFileTime(&ftime);
        memcpy(&lastCPU, &ftime, sizeof(FILETIME));
    
        self = GetCurrentProcess();
        GetProcessTimes(self, &ftime, &ftime, &fsys, &fuser);
        memcpy(&lastSysCPU, &fsys, sizeof(FILETIME));
        memcpy(&lastUserCPU, &fuser, sizeof(FILETIME));
    }
    
    double getCurrentValue(){
        FILETIME ftime, fsys, fuser;
        ULARGE_INTEGER now, sys, user;
        double percent;
    
        GetSystemTimeAsFileTime(&ftime);
        memcpy(&now, &ftime, sizeof(FILETIME));
    
        GetProcessTimes(self, &ftime, &ftime, &fsys, &fuser);
        memcpy(&sys, &fsys, sizeof(FILETIME));
        memcpy(&user, &fuser, sizeof(FILETIME));
        percent = (sys.QuadPart - lastSysCPU.QuadPart) +
            (user.QuadPart - lastUserCPU.QuadPart);
        percent /= (now.QuadPart - lastCPU.QuadPart);
        percent /= numProcessors;
        lastCPU = now;
        lastUserCPU = user;
        lastSysCPU = sys;
    
        return percent * 100;
    }
    

Linux

On Linux the choice that seemed obvious at first was to use the POSIX APIs like getrusage() etc. I spent some time trying to get this to work, but never got meaningful values. When I finally checked the kernel sources themselves, I found out that apparently these APIs are not yet completely implemented as of Linux kernel 2.6!?

In the end I got all values via a combination of reading the pseudo-filesystem /proc and kernel calls.

  • Total Virtual Memory:

    #include "sys/types.h"
    #include "sys/sysinfo.h"
    
    struct sysinfo memInfo;
    
    sysinfo (&memInfo);
    long long totalVirtualMem = memInfo.totalram;
    //Add other values in next statement to avoid int overflow on right hand side...
    totalVirtualMem += memInfo.totalswap;
    totalVirtualMem *= memInfo.mem_unit;
    
  • Virtual Memory currently used:

    Same code as in "Total Virtual Memory" and then

    long long virtualMemUsed = memInfo.totalram - memInfo.freeram;
    //Add other values in next statement to avoid int overflow on right hand side...
    virtualMemUsed += memInfo.totalswap - memInfo.freeswap;
    virtualMemUsed *= memInfo.mem_unit;
    
  • Virtual Memory currently used by current process:

    #include "stdlib.h"
    #include "stdio.h"
    #include "string.h"
    
    int parseLine(char* line){
        // This assumes that a digit will be found and the line ends in " Kb".
        int i = strlen(line);
        const char* p = line;
        while (*p <'0' || *p > '9') p++;
        line[i-3] = '\0';
        i = atoi(p);
        return i;
    }
    
    int getValue(){ //Note: this value is in KB!
        FILE* file = fopen("/proc/self/status", "r");
        int result = -1;
        char line[128];
    
        while (fgets(line, 128, file) != NULL){
            if (strncmp(line, "VmSize:", 7) == 0){
                result = parseLine(line);
                break;
            }
        }
        fclose(file);
        return result;
    }
    



  • Total Physical Memory (RAM):

    Same code as in "Total Virtual Memory" and then

    long long totalPhysMem = memInfo.totalram;
    //Multiply in next statement to avoid int overflow on right hand side...
    totalPhysMem *= memInfo.mem_unit;
    
  • Physical Memory currently used:

    Same code as in "Total Virtual Memory" and then

    long long physMemUsed = memInfo.totalram - memInfo.freeram;
    //Multiply in next statement to avoid int overflow on right hand side...
    physMemUsed *= memInfo.mem_unit;
    
  • Physical Memory currently used by current process:

    Change getValue() in "Virtual Memory currently used by current process" as follows:

    int getValue(){ //Note: this value is in KB!
        FILE* file = fopen("/proc/self/status", "r");
        int result = -1;
        char line[128];
    
        while (fgets(line, 128, file) != NULL){
            if (strncmp(line, "VmRSS:", 6) == 0){
                result = parseLine(line);
                break;
            }
        }
        fclose(file);
        return result;
    }
    



  • CPU currently used:

    #include "stdlib.h"
    #include "stdio.h"
    #include "string.h"
    
    static unsigned long long lastTotalUser, lastTotalUserLow, lastTotalSys, lastTotalIdle;
    
    void init(){
        FILE* file = fopen("/proc/stat", "r");
        fscanf(file, "cpu %llu %llu %llu %llu", &lastTotalUser, &lastTotalUserLow,
            &lastTotalSys, &lastTotalIdle);
        fclose(file);
    }
    
    double getCurrentValue(){
        double percent;
        FILE* file;
        unsigned long long totalUser, totalUserLow, totalSys, totalIdle, total;
    
        file = fopen("/proc/stat", "r");
        fscanf(file, "cpu %llu %llu %llu %llu", &totalUser, &totalUserLow,
            &totalSys, &totalIdle);
        fclose(file);
    
        if (totalUser < lastTotalUser || totalUserLow < lastTotalUserLow ||
            totalSys < lastTotalSys || totalIdle < lastTotalIdle){
            //Overflow detection. Just skip this value.
            percent = -1.0;
        }
        else{
            total = (totalUser - lastTotalUser) + (totalUserLow - lastTotalUserLow) +
                (totalSys - lastTotalSys);
            percent = total;
            total += (totalIdle - lastTotalIdle);
            percent /= total;
            percent *= 100;
        }
    
        lastTotalUser = totalUser;
        lastTotalUserLow = totalUserLow;
        lastTotalSys = totalSys;
        lastTotalIdle = totalIdle;
    
        return percent;
    }
    
  • CPU currently used by current process:

    #include "stdlib.h"
    #include "stdio.h"
    #include "string.h"
    #include "sys/times.h"
    #include "sys/vtimes.h"
    
    static clock_t lastCPU, lastSysCPU, lastUserCPU;
    static int numProcessors;
    
    void init(){
        FILE* file;
        struct tms timeSample;
        char line[128];
    
        lastCPU = times(&timeSample);
        lastSysCPU = timeSample.tms_stime;
        lastUserCPU = timeSample.tms_utime;
    
        file = fopen("/proc/cpuinfo", "r");
        numProcessors = 0;
        while(fgets(line, 128, file) != NULL){
            if (strncmp(line, "processor", 9) == 0) numProcessors++;
        }
        fclose(file);
    }
    
    double getCurrentValue(){
        struct tms timeSample;
        clock_t now;
        double percent;
    
        now = times(&timeSample);
        if (now <= lastCPU || timeSample.tms_stime < lastSysCPU ||
            timeSample.tms_utime < lastUserCPU){
            //Overflow detection. Just skip this value.
            percent = -1.0;
        }
        else{
            percent = (timeSample.tms_stime - lastSysCPU) +
                (timeSample.tms_utime - lastUserCPU);
            percent /= (now - lastCPU);
            percent /= numProcessors;
            percent *= 100;
        }
        lastCPU = now;
        lastSysCPU = timeSample.tms_stime;
        lastUserCPU = timeSample.tms_utime;
    
        return percent;
    }
    

TODO: Other Platforms

I would assume, that some of the Linux code also works for the Unixes, except for the parts that read the /proc pseudo-filesystem. Perhaps on Unix these parts can be replaced by getrusage() and similar functions? If someone with Unix know-how could edit this answer and fill in the details?!

How do I query for all dates greater than a certain date in SQL Server?

To sum it all up, the correct answer is :

select * from db where Date >= '20100401'  (Format of date yyyymmdd)

This will avoid any problem with other language systems and will use the index.

mysqld_safe Directory '/var/run/mysqld' for UNIX socket file don't exists

You may try the following if your database does not have any data OR you have another away to restore that data. You will need to know the Ubuntu server root password but not the mysql root password.

It is highly probably that many of us have installed "mysql_secure_installation" as this is a best practice. Navigate to bin directory where mysql_secure_installation exist. It can be found in the /bin directory on Ubuntu systems. By rerunning the installer, you will be prompted about whether to change root database password.

How to convert JSON to a Ruby hash

What about the following snippet?

require 'json'
value = '{"val":"test","val1":"test1","val2":"test2"}'
puts JSON.parse(value) # => {"val"=>"test","val1"=>"test1","val2"=>"test2"}

Bootstrap 3 navbar active li not changing background-color

Did you include "bootstrap-theme.css" files on your code?

In "bootstrap-theme.min.css" files, background-image about ".active" is existed for "navbar" (check this screenshot: http://i.imgur.com/1etLIyY.png).

It will re-declare your style code, and then it will be effected on your code.

So after you delete or re-declare them (background-image), you can use your background color style about the ".active" tag.

How to keep onItemSelected from firing off on a newly instantiated Spinner?

I need to use mSpinner in ViewHolder, so the flag mOldPosition is set in the anonymous inner class.

mSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            int mOldPosition = mSpinner.getSelectedItemPosition();

            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long l) {
                if (mOldPosition != position) {
                    mOldPosition = position;
                    //Do something
                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {
                //Do something
            }
        });

Provide static IP to docker containers via docker-compose

I was facing some difficulties with an environment variable that is with custom name (not with container name /port convention for KAPACITOR_BASE_URL and KAPACITOR_ALERTS_ENDPOINT). If we give service name in this case it wouldn't resolve the ip as

KAPACITOR_BASE_URL:  http://kapacitor:9092

In above http://[**kapacitor**]:9092 would not resolve to http://172.20.0.2:9092

I resolved the static IPs issues using subnetting configurations.

version: "3.3"

networks:
  frontend:
    ipam:
      config:
        - subnet: 172.20.0.0/24
services:
    db:
        image: postgres:9.4.4
        networks:
            frontend:
                ipv4_address: 172.20.0.5
        ports:
            - "5432:5432"
        volumes:
            - postgres_data:/var/lib/postgresql/data

    redis:
        image: redis:latest
        networks:
            frontend:
                ipv4_address: 172.20.0.6
        ports:
            - "6379"

    influxdb:
        image: influxdb:latest
        ports:
            - "8086:8086"
            - "8083:8083"
        volumes:
            - ../influxdb/influxdb.conf:/etc/influxdb/influxdb.conf
            - ../influxdb/inxdb:/var/lib/influxdb
        networks:
            frontend:
                ipv4_address: 172.20.0.4
        environment:
          INFLUXDB_HTTP_AUTH_ENABLED: "false"
          INFLUXDB_ADMIN_ENABLED: "true"
          INFLUXDB_USERNAME: "db_username"
          INFLUXDB_PASSWORD: "12345678"
          INFLUXDB_DB: db_customers

    kapacitor:
        image: kapacitor:latest
        ports: 
            - "9092:9092"
        networks:
            frontend:
                ipv4_address: 172.20.0.2
        depends_on:
            - influxdb
        volumes:
            - ../kapacitor/kapacitor.conf:/etc/kapacitor/kapacitor.conf
            - ../kapacitor/kapdb:/var/lib/kapacitor
        environment:
          KAPACITOR_INFLUXDB_0_URLS_0: http://influxdb:8086

    web:
        build: .
        environment:
          RAILS_ENV: $RAILS_ENV
        command: bundle exec rails s -b 0.0.0.0
        ports:
            - "3000:3000"
        networks:
            frontend:
                ipv4_address: 172.20.0.3
        links:
            - db
            - kapacitor
        depends_on:
            - db
        volumes:
            - .:/var/app/current
        environment:
          DATABASE_URL: postgres://postgres@db
          DATABASE_USERNAME: postgres
          DATABASE_PASSWORD: postgres
          INFLUX_URL: http://influxdb:8086
          INFLUX_USER: db_username
          INFLUX_PWD: 12345678
          KAPACITOR_BASE_URL:  http://172.20.0.2:9092
          KAPACITOR_ALERTS_ENDPOINT: http://172.20.0.3:3000

volumes:
  postgres_data:

Is string in array?

As mentioned many times in the thread above, it's dependent on the framework in use. .Net Framework 3 and above has the .Contains() or Exists() methods for arrays. For other frameworks below, can do the following trick instead of looping through array...

((IList<string>)"Your String Array Here").Contains("Your Search String Here")

Not too sure on efficiency... Dave

VBA equivalent to Excel's mod function

Be very careful with the Excel MOD(a,b) function and the VBA a Mod b operator. Excel returns a floating point result and VBA an integer.

In Excel =Mod(90.123,90) returns 0.123000000000005 instead of 0.123 In VBA 90.123 Mod 90 returns 0

They are certainly not equivalent!

Equivalent are: In Excel: =Round(Mod(90.123,90),3) returning 0.123 and In VBA: ((90.123 * 1000) Mod 90000)/1000 returning also 0.123

pandas: best way to select all columns whose names start with X

Just perform a list comprehension to create your columns:

In [28]:

filter_col = [col for col in df if col.startswith('foo')]
filter_col
Out[28]:
['foo.aa', 'foo.bars', 'foo.fighters', 'foo.fox', 'foo.manchu']
In [29]:

df[filter_col]
Out[29]:
   foo.aa  foo.bars  foo.fighters  foo.fox foo.manchu
0     1.0         0             0        2         NA
1     2.1         0             1        4          0
2     NaN         0           NaN        1          0
3     4.7         0             0        0          0
4     5.6         0             0        0          0
5     6.8         1             0        5          0

Another method is to create a series from the columns and use the vectorised str method startswith:

In [33]:

df[df.columns[pd.Series(df.columns).str.startswith('foo')]]
Out[33]:
   foo.aa  foo.bars  foo.fighters  foo.fox foo.manchu
0     1.0         0             0        2         NA
1     2.1         0             1        4          0
2     NaN         0           NaN        1          0
3     4.7         0             0        0          0
4     5.6         0             0        0          0
5     6.8         1             0        5          0

In order to achieve what you want you need to add the following to filter the values that don't meet your ==1 criteria:

In [36]:

df[df[df.columns[pd.Series(df.columns).str.startswith('foo')]]==1]
Out[36]:
   bar.baz  foo.aa  foo.bars  foo.fighters  foo.fox foo.manchu nas.foo
0      NaN       1       NaN           NaN      NaN        NaN     NaN
1      NaN     NaN       NaN             1      NaN        NaN     NaN
2      NaN     NaN       NaN           NaN        1        NaN     NaN
3      NaN     NaN       NaN           NaN      NaN        NaN     NaN
4      NaN     NaN       NaN           NaN      NaN        NaN     NaN
5      NaN     NaN         1           NaN      NaN        NaN     NaN

EDIT

OK after seeing what you want the convoluted answer is this:

In [72]:

df.loc[df[df[df.columns[pd.Series(df.columns).str.startswith('foo')]] == 1].dropna(how='all', axis=0).index]
Out[72]:
   bar.baz  foo.aa  foo.bars  foo.fighters  foo.fox foo.manchu nas.foo
0      5.0     1.0         0             0        2         NA      NA
1      5.0     2.1         0             1        4          0       0
2      6.0     NaN         0           NaN        1          0       1
5      6.8     6.8         1             0        5          0       0

How to use Regular Expressions (Regex) in Microsoft Excel both in-cell and loops

Here is my attempt:

Function RegParse(ByVal pattern As String, ByVal html As String)
    Dim regex   As RegExp
    Set regex = New RegExp

    With regex
        .IgnoreCase = True  'ignoring cases while regex engine performs the search.
        .pattern = pattern  'declaring regex pattern.
        .Global = False     'restricting regex to find only first match.

        If .Test(html) Then         'Testing if the pattern matches or not
            mStr = .Execute(html)(0)        '.Execute(html)(0) will provide the String which matches with Regex
            RegParse = .Replace(mStr, "$1") '.Replace function will replace the String with whatever is in the first set of braces - $1.
        Else
            RegParse = "#N/A"
        End If

    End With
End Function

Disable a link in Bootstrap

I just created my own version using CSS. As I need to disabled, then when document is ready use jQuery to make active. So that way a user cannot click on a button until after the document is ready. So i can substitute with AJAX instead. The way I came up with, was to add a class to the anchor tag itself and remove the class when document is ready. Could re-purpose this for your needs.

CSS:

a.disabled{
    pointer-events: none;
    cursor: default;
}

HTML:

<a class="btn btn-info disabled">Link Text</a>

JS:

$(function(){
    $('a.disabled').on('click',function(event){
        event.preventDefault();
    }).removeClass('disabled');
});

What is the use of static constructors?

Static constructor called only the first instance of the class created. and used to perform a particular action that needs to be performed only once in the life cycle of the class.

How do I get a YouTube video thumbnail from the YouTube API?

A simple PHP function I created for the YouTube thumbnail and the types are

  • default
  • hqdefault
  • mqdefault
  • sddefault
  • maxresdefault

 

function get_youtube_thumb($link,$type){

    $video_id = explode("?v=", $link);

    if (empty($video_id[1])){
        $video_id = explode("/v/", $link);
        $video_id = explode("&", $video_id[1]);
        $video_id = $video_id[0];
    }
    $thumb_link = "";

    if($type == 'default'   || $type == 'hqdefault' ||
       $type == 'mqdefault' || $type == 'sddefault' ||
       $type == 'maxresdefault'){

        $thumb_link = 'http://img.youtube.com/vi/'.$video_id.'/'.$type.'.jpg';

    }elseif($type == "id"){
        $thumb_link = $video_id;
    }
    return $thumb_link;}

Checking for duplicate strings in JavaScript array

You could take a Set and filter the values who are alreday seen.

_x000D_
_x000D_
var array = ["q", "w", "w", "e", "i", "u", "r"],_x000D_
    seen = array.filter((s => v => s.has(v) || !s.add(v))(new Set));_x000D_
_x000D_
console.log(seen);
_x000D_
_x000D_
_x000D_

How could I use requests in asyncio?

To use requests (or any other blocking libraries) with asyncio, you can use BaseEventLoop.run_in_executor to run a function in another thread and yield from it to get the result. For example:

import asyncio
import requests

@asyncio.coroutine
def main():
    loop = asyncio.get_event_loop()
    future1 = loop.run_in_executor(None, requests.get, 'http://www.google.com')
    future2 = loop.run_in_executor(None, requests.get, 'http://www.google.co.uk')
    response1 = yield from future1
    response2 = yield from future2
    print(response1.text)
    print(response2.text)

loop = asyncio.get_event_loop()
loop.run_until_complete(main())

This will get both responses in parallel.

With python 3.5 you can use the new await/async syntax:

import asyncio
import requests

async def main():
    loop = asyncio.get_event_loop()
    future1 = loop.run_in_executor(None, requests.get, 'http://www.google.com')
    future2 = loop.run_in_executor(None, requests.get, 'http://www.google.co.uk')
    response1 = await future1
    response2 = await future2
    print(response1.text)
    print(response2.text)

loop = asyncio.get_event_loop()
loop.run_until_complete(main())

See PEP0492 for more.

TextView - setting the text size programmatically doesn't seem to work

Please see this link for more information on setting the text size in code. Basically it says:

public void setTextSize (int unit, float size)

Since: API Level 1 Set the default text size to a given unit and value. See TypedValue for the possible dimension units. Related XML Attributes

android:textSize Parameters

unit The desired dimension unit.
size The desired size in the given units.

Center a 'div' in the middle of the screen, even when the page is scrolled up or down?

Correct Method is

.PopupPanel
{
    border: solid 1px black;
    position: fixed;
    left: 50%;
    top: 50%;
    background-color: white;
    z-index: 100;
    height: 400px;
    margin-top: -200px;

    width: 600px;
    margin-left: -300px;
}

Forcing a postback

By using Server.Transfer("YourCurrentPage.aspx"); we can easily acheive this and it is better than Response.Redirect(); coz Server.Transfer() will save you the round trip.

super() fails with error: TypeError "argument 1 must be type, not classobj" when parent does not inherit from object

Your problem is that class B is not declared as a "new-style" class. Change it like so:

class B(object):

and it will work.

super() and all subclass/superclass stuff only works with new-style classes. I recommend you get in the habit of always typing that (object) on any class definition to make sure it is a new-style class.

Old-style classes (also known as "classic" classes) are always of type classobj; new-style classes are of type type. This is why you got the error message you saw:

TypeError: super() argument 1 must be type, not classobj

Try this to see for yourself:

class OldStyle:
    pass

class NewStyle(object):
    pass

print type(OldStyle)  # prints: <type 'classobj'>

print type(NewStyle) # prints <type 'type'>

Note that in Python 3.x, all classes are new-style. You can still use the syntax from the old-style classes but you get a new-style class. So, in Python 3.x you won't have this problem.

How to check if a table exists in MS Access for vb macros

I know the question is already answered, but I find that the existing answers are not valid:
they will return True for linked tables with a non working back-end.
Using DCount can be much slower, but is more reliable.

Function IsTable(sTblName As String) As Boolean
    'does table exists and work ?
    'note: finding the name in the TableDefs collection is not enough,
    '      since the backend might be invalid or missing

    On Error GoTo hell
    Dim x
    x = DCount("*", sTblName)
    IsTable = True
    Exit Function
hell:
    Debug.Print Now, sTblName, Err.Number, Err.Description
    IsTable = False

End Function

Running an executable in Mac Terminal

Unix will only run commands if they are available on the system path, as you can view by the $PATH variable

echo $PATH

Executables located in directories that are not on the path cannot be run unless you specify their full location. So in your case, assuming the executable is in the current directory you are working with, then you can execute it as such

./my-exec

Where my-exec is the name of your program.

How to use jQuery with Angular?

//installing jquerynpm install jquery --save

//installing type defintion for the jquerytypings install dt~jquery --global --save

//adding jquery library into build configuration file as specified(in "angular-cli-build.js" file)

vendorNpmFiles: [
  .........
  .........
  'jquery/dist/jquery.min.js'
]

//run the build to add the jquery library in the build ng build

//adding the relative path configuration(in system-config.js) /** Map relative paths to URLs. */ const map: any = { ....., ......., 'jquery': 'vendor/jquery/dist' };

/** User packages configuration. */
const packages: any = {
......,
'jquery':{ main: 'jquery.min',
format: 'global',
defaultExtension: 'js'}};

//import the jquery library in your component file

import 'jquery';

below is the code snipppet of my sample component

import { Component } from '@angular/core';
import 'jquery';
@Component({
  moduleId: module.id,
  selector: 'app-root',
  templateUrl: 'app.component.html',  
  styleUrls: ['app.component.css']
})
export class AppComponent {
  list:Array<number> = [90,98,56,90];
  title = 'app works!';
  isNumber:boolean = jQuery.isNumeric(89)  
  constructor(){}
}

How to create a simple checkbox in iOS?

Yeah, no checkbox for you in iOS (-:

Here, this is what I did to create a checkbox:

UIButton *checkbox;
BOOL checkBoxSelected;
checkbox = [[UIButton alloc] initWithFrame:CGRectMake(x,y,20,20)];
// 20x20 is the size of the checkbox that you want
// create 2 images sizes 20x20 , one empty square and
// another of the same square with the checkmark in it
// Create 2 UIImages with these new images, then:

[checkbox setBackgroundImage:[UIImage imageNamed:@"notselectedcheckbox.png"]
                    forState:UIControlStateNormal];
[checkbox setBackgroundImage:[UIImage imageNamed:@"selectedcheckbox.png"]
                    forState:UIControlStateSelected];
[checkbox setBackgroundImage:[UIImage imageNamed:@"selectedcheckbox.png"]
                    forState:UIControlStateHighlighted];
checkbox.adjustsImageWhenHighlighted=YES;
[checkbox addTarget:(nullable id) action:(nonnull SEL) forControlEvents:(UIControlEvents)];
[self.view addSubview:checkbox];

Now in the target method do the following:

-(void)checkboxSelected:(id)sender
{
    checkBoxSelected = !checkBoxSelected; /* Toggle */
    [checkbox setSelected:checkBoxSelected];
}

That's it!

Input text dialog Android

If you want some space at left and right of input view, you can add some padding like

private fun showAlertWithTextInputLayout(context: Context) {
    val textInputLayout = TextInputLayout(context)
    textInputLayout.setPadding(
        resources.getDimensionPixelOffset(R.dimen.dp_19), // if you look at android alert_dialog.xml, you will see the message textview have margin 14dp and padding 5dp. This is the reason why I use 19 here
        0,
        resources.getDimensionPixelOffset(R.dimen.dp_19),
        0
    )
    val input = EditText(context)
    textInputLayout.hint = "Email"
    textInputLayout.addView(input)

    val alert = AlertDialog.Builder(context)
        .setTitle("Reset Password")
        .setView(textInputLayout)
        .setMessage("Please enter your email address")
        .setPositiveButton("Submit") { dialog, _ ->
            // do some thing with input.text
            dialog.cancel()
        }
        .setNegativeButton("Cancel") { dialog, _ ->
            dialog.cancel()
        }.create()

    alert.show()
}

dimens.xml

<dimen name="dp_19">19dp</dimen>

Hope it help

GROUP BY with MAX(DATE)

You cannot include non-aggregated columns in your result set which are not grouped. If a train has only one destination, then just add the destination column to your group by clause, otherwise you need to rethink your query.

Try:

SELECT t.Train, t.Dest, r.MaxTime
FROM (
      SELECT Train, MAX(Time) as MaxTime
      FROM TrainTable
      GROUP BY Train
) r
INNER JOIN TrainTable t
ON t.Train = r.Train AND t.Time = r.MaxTime

403 Access Denied on Tomcat 8 Manager App without prompting for user/password

  1. Go and Check if a user is created or not if no please create a user by opening a file in /apache-tomcat-9.0.20/tomcat-users.xml add a line into it

    <user username="tomcat" password="tomcat" roles="admin-gui,manager-gui,manager-script" />

  2. Goto /apache-tomcat-9.0.20/webapps/manager/META-INF/ open context.xml comment everything in context tag example:

<Context antiResourceLocking="false" privileged="true" >
     <!--Valve className="org.apache.catalina.valves.RemoteAddrValve"
            allow="127\.\d+\.\d+\.\d+|::1|0:0:0:0:0:0:0:1" /-->
   </Context>

How to check if an excel cell is empty using Apache POI?

Try below code:

String empty = "-";
if (row.getCell(3) == null || row.getCell(3).getCellType() == Cell.CELL_TYPE_BLANK) {
    upld.setValue(empty);
} else {
    upld.setValue(row.getCell(3).getStringCellValue());
}

How to make a local variable (inside a function) global

Simply declare your variable outside any function:

globalValue = 1

def f(x):
    print(globalValue + x)

If you need to assign to the global from within the function, use the global statement:

def f(x):
    global globalValue
    print(globalValue + x)
    globalValue += 1

How do you fix the "element not interactable" exception?

I have found that using Thread.sleep(milliseconds) helps almost all the time for me. It takes time for the element to load hence it is not interactable. So i put Thread.sleep() after selecting each value. So far this has helped me avoid the error.

try {Thread.sleep(3000);} catch (InterruptedException e) {e.printStackTrace();}

        Select nationalityDropdown=new Select(driver.findElement(By.id("ContentPlaceHolderMain_ddlNationality")));

        nationalityDropdown.selectByValue("Indian");

        try {Thread.sleep(3000);} catch (InterruptedException e) {e.printStackTrace();}     

Quicksort: Choosing the pivot

Don't try and get too clever and combine pivoting strategies. If you combined median of 3 with random pivot by picking the median of the first, last and a random index in the middle, then you'll still be vulnerable to many of the distributions which send median of 3 quadratic (so its actually worse than plain random pivot)

E.g a pipe organ distribution (1,2,3...N/2..3,2,1) first and last will both be 1 and the random index will be some number greater than 1, taking the median gives 1 (either first or last) and you get an extermely unbalanced partitioning.

SEVERE: Unable to create initial connections of pool - tomcat 7 with context.xml file

When you encounter exceptions like this, the most useful information is generally at the bottom of the stacktrace:

Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
  at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
  ...
  at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:246)

The problem is that Tomcat can't find com.mysql.jdbc.Driver. This is usually caused by the JAR containing the MySQL driver not being where Tomcat expects to find it (namely in the webapps/<yourwebapp>/WEB-INF/lib directory).

How to modify existing XML file with XmlDocument and XmlNode in C#

You need to do something like this:

// instantiate XmlDocument and load XML from file
XmlDocument doc = new XmlDocument();
doc.Load(@"D:\test.xml");

// get a list of nodes - in this case, I'm selecting all <AID> nodes under
// the <GroupAIDs> node - change to suit your needs
XmlNodeList aNodes = doc.SelectNodes("/Equipment/DataCollections/GroupAIDs/AID");

// loop through all AID nodes
foreach (XmlNode aNode in aNodes)
{
   // grab the "id" attribute
   XmlAttribute idAttribute = aNode.Attributes["id"];

   // check if that attribute even exists...
   if (idAttribute != null)
   {
      // if yes - read its current value
      string currentValue = idAttribute.Value;

      // here, you can now decide what to do - for demo purposes,
      // I just set the ID value to a fixed value if it was empty before
      if (string.IsNullOrEmpty(currentValue))
      {
         idAttribute.Value = "515";
      }
   }
}

// save the XmlDocument back to disk
doc.Save(@"D:\test2.xml");

What's sizeof(size_t) on 32-bit vs the various 64-bit data models?

size_t is defined by the C standard to be the unsigned integer return type of the sizeof operator (C99 6.3.5.4.4), and the argument of malloc and friends (C99 7.20.3.3 etc). The actual range is set such that the maximum (SIZE_MAX) is at least 65535 (C99 7.18.3.2).

However, this doesn't let us determine sizeof(size_t). The implementation is free to use any representation it likes for size_t - so there is no upper bound on size - and the implementation is also free to define a byte as 16-bits, in which case size_t can be equivalent to unsigned char.

Putting that aside, however, in general you'll have 32-bit size_t on 32-bit programs, and 64-bit on 64-bit programs, regardless of the data model. Generally the data model only affects static data; for example, in GCC:

`-mcmodel=small'
     Generate code for the small code model: the program and its
     symbols must be linked in the lower 2 GB of the address space.
     Pointers are 64 bits.  Programs can be statically or dynamically
     linked.  This is the default code model.

`-mcmodel=kernel'
     Generate code for the kernel code model.  The kernel runs in the
     negative 2 GB of the address space.  This model has to be used for
     Linux kernel code.

`-mcmodel=medium'
     Generate code for the medium model: The program is linked in the
     lower 2 GB of the address space but symbols can be located
     anywhere in the address space.  Programs can be statically or
     dynamically linked, but building of shared libraries are not
     supported with the medium model.

`-mcmodel=large'
     Generate code for the large model: This model makes no assumptions
     about addresses and sizes of sections.

You'll note that pointers are 64-bit in all cases; and there's little point to having 64-bit pointers but not 64-bit sizes, after all.

Python - How to sort a list of lists by the fourth element in each list?

Use sorted() with a key as follows -

>>> unsorted_list = [['a','b','c','5','d'],['e','f','g','3','h'],['i','j','k','4','m']]
>>> sorted(unsorted_list, key = lambda x: int(x[3]))
[['e', 'f', 'g', '3', 'h'], ['i', 'j', 'k', '4', 'm'], ['a', 'b', 'c', '5', 'd']]

The lambda returns the fourth element of each of the inner lists and the sorted function uses that to sort those list. This assumes that int(elem) will not fail for the list.

Or use itemgetter (As Ashwini's comment pointed out, this method would not work if you have string representations of the numbers, since they are bound to fail somewhere for 2+ digit numbers)

>>> from operator import itemgetter
>>> sorted(unsorted_list, key = itemgetter(3))
[['e', 'f', 'g', '3', 'h'], ['i', 'j', 'k', '4', 'm'], ['a', 'b', 'c', '5', 'd']]

Oracle SQL : timestamps in where clause

For everyone coming to this thread with fractional seconds in your timestamp use:

to_timestamp('2018-11-03 12:35:20.419000', 'YYYY-MM-DD HH24:MI:SS.FF')

Proper way to use **kwargs in Python

I suggest something like this

def testFunc( **kwargs ):
    options = {
            'option1' : 'default_value1',
            'option2' : 'default_value2',
            'option3' : 'default_value3', }

    options.update(kwargs)
    print options

testFunc( option1='new_value1', option3='new_value3' )
# {'option2': 'default_value2', 'option3': 'new_value3', 'option1': 'new_value1'}

testFunc( option2='new_value2' )
# {'option1': 'default_value1', 'option3': 'default_value3', 'option2': 'new_value2'}

And then use the values any way you want

dictionaryA.update(dictionaryB) adds the contents of dictionaryB to dictionaryA overwriting any duplicate keys.

Specifying Style and Weight for Google Fonts

They use regular CSS.

Just use your regular font family like this:

font-family: 'Open Sans', sans-serif;

Now you decide what "weight" the font should have by adding

for semi-bold

font-weight:600;

for bold (700)

font-weight:bold;

for extra bold (800)

font-weight:800;

Like this its fallback proof, so if the google font should "fail" your backup font Arial/Helvetica(Sans-serif) use the same weight as the google font.

Pretty smart :-)

Note that the different font weights have to be specifically imported via the link tag url (family query param of the google font url) in the header.

For example the following link will include both weights 400 and 700:

<link href='fonts.googleapis.com/css?family=Comfortaa:400,700'; rel='stylesheet' type='text/css'>

How do I search for a pattern within a text file using Python combining regex & string/file operations and store instances of the pattern?

Doing it in one bulk read:

import re

textfile = open(filename, 'r')
filetext = textfile.read()
textfile.close()
matches = re.findall("(<(\d{4,5})>)?", filetext)

Line by line:

import re

textfile = open(filename, 'r')
matches = []
reg = re.compile("(<(\d{4,5})>)?")
for line in textfile:
    matches += reg.findall(line)
textfile.close()

But again, the matches that returns will not be useful for anything except counting unless you added an offset counter:

import re

textfile = open(filename, 'r')
matches = []
offset = 0
reg = re.compile("(<(\d{4,5})>)?")
for line in textfile:
    matches += [(reg.findall(line),offset)]
    offset += len(line)
textfile.close()

But it still just makes more sense to read the whole file in at once.

What does random.sample() method in python do?

According to documentation:

random.sample(population, k)

Return a k length list of unique elements chosen from the population sequence. Used for random sampling without replacement.

Basically, it picks k unique random elements, a sample, from a sequence:

>>> import random
>>> c = list(range(0, 15))
>>> c
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14]
>>> random.sample(c, 5)
[9, 2, 3, 14, 11]

random.sample works also directly from a range:

>>> c = range(0, 15)
>>> c
range(0, 15)
>>> random.sample(c, 5)
[12, 3, 6, 14, 10]

In addition to sequences, random.sample works with sets too:

>>> c = {1, 2, 4}
>>> random.sample(c, 2)
[4, 1]

However, random.sample doesn't work with arbitrary iterators:

>>> c = [1, 3]
>>> random.sample(iter(c), 5)
TypeError: Population must be a sequence or set.  For dicts, use list(d).

PHP array value passes to next row

Change the checkboxes so that the name includes the index inside the brackets:

<input type="checkbox" class="checkbox_veh" id="checkbox_addveh<?php echo $i; ?>" <?php if ($vehicle_feature[$i]->check) echo "checked"; ?> name="feature[<?php echo $i; ?>]" value="<?php echo $vehicle_feature[$i]->id; ?>"> 

The checkboxes that aren't checked are never submitted. The boxes that are checked get submitted, but they get numbered consecutively from 0, and won't have the same indexes as the other corresponding input fields.

How can I check if two segments intersect?

Calculate the intersection point of the lines laying on your segments (it means basically to solve a linear equation system), then check whether is it between the starting and ending points of your segments.

Xcode 10 Error: Multiple commands produce

If you develop private cocoapod, and had already added it via Podfile,

remove it from Embedded Binaries section:

Embedded Binaries in test app

How to check if a table is locked in sql server

Better yet, consider sp_getapplock which is designed for this. Or use SET LOCK_TIMEOUT

Otherwise, you'd have to do something with sys.dm_tran_locks which I'd use only for DBA stuff: not for user defined concurrency.

How can I install packages using pip according to the requirements.txt file from a local directory?

Often, you will want a fast install from local archives, without probing PyPI.

First, download the archives that fulfill your requirements:

$ pip install --download <DIR> -r requirements.txt

Then, install using –find-links and –no-index:

$ pip install --no-index --find-links=[file://]<DIR> -r requirements.txt

How do I put an already-running process under nohup?

Simple and easiest steps

  1. Ctrl + Z ----------> Suspends the process
  2. bg --------------> Resumes and runs background
  3. disown %1 -------------> required only if you need to detach from the terminal

How do I check two or more conditions in one <c:if>?

Recommendation:

when you have more than one condition with and and or is better separate with () to avoid verification problems

<c:if test="${(not validID) and (addressIso == 'US' or addressIso == 'BR')}">

how to initialize a char array?

Absent a really good reason to do otherwise, I'd probably use:

std::vector<char> msg(65546, '\0');

How to access a DOM element in React? What is the equilvalent of document.getElementById() in React

Disclaimer: While the top answer is probably a better solution, as a beginner it's a lot to take in when all you want is something very simple. This is intended as a more direct answer to your original question "How can I select certain elements in React"

I think the confusion in your question is because you have React components which you are being passed the id "Progress1", "Progress2" etc. I believe this is not setting the html attribute 'id', but the React component property. e.g.

class ProgressBar extends React.Component {
    constructor(props) {
        super(props)
        this.state = {
            id: this.props.id    <--- ID set from <ProgressBar id="Progress1"/>
        }
    }        
}

As mentioned in some of the answers above you absolutely can use document.querySelector inside of your React app, but you have to be clear that it is selecting the html output of your components' render methods. So assuming your render output looks like this:

render () {
    const id = this.state.id
    return (<div id={"progress-bar-" + id}></div>)
}

Then you can elsewhere do a normal javascript querySelector call like this:

let element = document.querySelector('#progress-bar-Progress1')

how to change any data type into a string in python

Use formatting:

"%s" % (x)

Example:

x = time.ctime(); str = "%s" % (x); print str

Output: Thu Jan 11 20:40:05 2018

Leave out quotes when copying from cell

It's also possible to remove these double-quotes by placing your result on the "Clean" function.

Example:

=CLEAN("1"&CHAR(9)&"SOME NOTES FOR LINE 1."&CHAR(9)&"2"&CHAR(9)&"SOME NOTES FOR LINE 2.")

The output will be pasted without the double-quotes on other programs such as Notepad++.

WPF Image Dynamically changing Image source during runtime

Hey, this one is kind of ugly but it's one line only:

imgTitle.Source = new BitmapImage(new Uri(@"pack://application:,,,/YourAssembly;component/your_image.png"));

Can we instantiate an abstract class directly?

You can't directly instantiate an abstract class, but you can create an anonymous class when there is no concrete class:

public class AbstractTest {
    public static void main(final String... args) {
        final Printer p = new Printer() {
            void printSomethingOther() {
                System.out.println("other");
            }
            @Override
            public void print() {
                super.print();
                System.out.println("world");
                printSomethingOther(); // works fine
            }
        };
        p.print();
        //p.printSomethingOther(); // does not work
    }
}

abstract class Printer {
    public void print() {
        System.out.println("hello");
    }
}

This works with interfaces, too.

Graph visualization library in JavaScript

As guruz mentioned, the JIT has several lovely graph/tree layouts, including quite appealing RGraph and HyperTree visualizations.

Also, I've just put up a super simple SVG-based implementation at github (no dependencies, ~125 LOC) that should work well enough for small graphs displayed in modern browsers.

Spring Data JPA findOne() change to Optional how to use this?

Optional api provides methods for getting the values. You can check isPresent() for the presence of the value and then make a call to get() or you can make a call to get() chained with orElse() and provide a default value.

The last thing you can try doing is using @Query() over a custom method.

LAST_INSERT_ID() MySQL

This enables you to insert a row into 2 different tables and creates a reference to both tables too.

START TRANSACTION;
INSERT INTO accounttable(account_username) 
    VALUES('AnAccountName');
INSERT INTO profiletable(profile_account_id) 
    VALUES ((SELECT account_id FROM accounttable WHERE account_username='AnAccountName'));
    SET @profile_id = LAST_INSERT_ID(); 
UPDATE accounttable SET `account_profile_id` = @profile_id;
COMMIT;

How do I pass an object to HttpClient.PostAsync and serialize as a JSON body?

@arad good point. In fact I just found this extension method (.NET 5.0):

PostAsJsonAsync<TValue>(HttpClient, String, TValue, CancellationToken)

from https://docs.microsoft.com/en-us/dotnet/api/system.net.http.json.httpclientjsonextensions.postasjsonasync?view=net-5.0

So one can now:

var data = new { foo = "Hello"; bar = 42; };
var response = await _Client.PostAsJsonAsync(_Uri, data, cancellationToken);

Can I execute a function after setState is finished updating?

With hooks in React 16.8 onward, it's easy to do this with useEffect

I've created a CodeSandbox to demonstrate this.

useEffect(() => {
  // code to be run when state variables in
  // dependency array changes
}, [stateVariables, thatShould, triggerChange])

Basically, useEffect synchronises with state changes and this can be used to render the canvas

import React, { useState, useEffect, useRef } from "react";
import { Stage, Shape } from "@createjs/easeljs";
import "./styles.css";

export default function App() {
  const [rows, setRows] = useState(10);
  const [columns, setColumns] = useState(10);
  let stage = useRef()

  useEffect(() => {
    stage.current = new Stage("canvas");
    var rectangles = [];
    var rectangle;
    //Rows
    for (var x = 0; x < rows; x++) {
      // Columns
      for (var y = 0; y < columns; y++) {
        var color = "Green";
        rectangle = new Shape();
        rectangle.graphics.beginFill(color);
        rectangle.graphics.drawRect(0, 0, 32, 44);
        rectangle.x = y * 33;
        rectangle.y = x * 45;

        stage.current.addChild(rectangle);

        var id = rectangle.x + "_" + rectangle.y;
        rectangles[id] = rectangle;
      }
    }
    stage.current.update();
  }, [rows, columns]);

  return (
    <div>
      <div className="canvas-wrapper">
        <canvas id="canvas" width="400" height="300"></canvas>
        <p>Rows: {rows}</p>
        <p>Columns: {columns}</p>
      </div>
      <div className="array-form">
        <form>
          <label>Number of Rows</label>
          <select
            id="numRows"
            value={rows}
            onChange={(e) => setRows(e.target.value)}
          >
            {getOptions()}
          </select>
          <label>Number of Columns</label>
          <select
            id="numCols"
            value={columns}
            onChange={(e) => setColumns(e.target.value)}
          >
            {getOptions()}
          </select>
        </form>
      </div>
    </div>
  );
}

const getOptions = () => {
  const options = [1, 2, 5, 10, 12, 15, 20];
  return (
    <>
      {options.map((option) => (
        <option key={option} value={option}>
          {option}
        </option>
      ))}
    </>
  );
};

Hexadecimal value 0x00 is a invalid character

I'm using IronPython here (same as .NET API) and reading the file as UTF-8 in order to properly handle the BOM fixed the problem for me:

xmlFile = Path.Combine(directory_str, 'file.xml')
doc = XPathDocument(XmlTextReader(StreamReader(xmlFile.ToString(), Encoding.UTF8)))

It would work as well with the XmlDocument:

doc = XmlDocument()
doc.Load(XmlTextReader(StreamReader(xmlFile.ToString(), Encoding.UTF8)))

C++ Calling a function from another class

in A you have used a definition of B which is not given until then , that's why the compiler is giving error .

Add column to SQL query results

Manually add it when you build the query:

SELECT 'Site1' AS SiteName, t1.column, t1.column2
FROM t1

UNION ALL
SELECT 'Site2' AS SiteName, t2.column, t2.column2
FROM t2

UNION ALL
...

EXAMPLE:

DECLARE @t1 TABLE (column1 int, column2 nvarchar(1))
DECLARE @t2 TABLE (column1 int, column2 nvarchar(1))

INSERT INTO @t1
SELECT 1, 'a'
UNION SELECT 2, 'b'

INSERT INTO @t2
SELECT 3, 'c'
UNION SELECT 4, 'd'


SELECT 'Site1' AS SiteName, t1.column1, t1.column2
FROM @t1 t1

UNION ALL
SELECT 'Site2' AS SiteName, t2.column1, t2.column2
FROM @t2 t2

RESULT:

SiteName  column1  column2
Site1       1      a
Site1       2      b
Site2       3      c
Site2       4      d

PHP substring extraction. Get the string before the first '/' or the whole string

You can also use this one line solution

list($substring) = explode("/", $string);

Android: disabling highlight on listView click

If you are using ArrayAdapter or BaseAdapter to populate the list items. Override the isEnabled method and return false.

 @Override
  public boolean isEnabled (int position) {
    return false;
  }

Password Protect a SQLite DB. Is it possible?

I know this is an old question but wouldn't the simple solution be to just protect the file at the OS level? Just prevent the users from accessing the file and then they shouldn't be able to touch it. This is just a guess and I'm not sure if this is an ideal solution.

MongoDB: exception in initAndListen: 20 Attempted to create a lock file on a read-only directory: /data/db, terminating

Nice solutions, but I wonder why nobody is giving the solution for windows.

If you are using windows you just have to "Run as Administrator" the cmd.

Full examples of using pySerial package

import serial
ser = serial.Serial(0)  # open first serial port
print ser.portstr       # check which port was really used
ser.write("hello")      # write a string
ser.close()             # close port

use https://pythonhosted.org/pyserial/ for more examples

Is there a way to crack the password on an Excel VBA Project?

ElcomSoft makes Advanced Office Password Breaker and Advanced Office Password Recovery products which may apply to this case, as long as the document was created in Office 2007 or prior.

Open file by its full path in C++

Normally one uses the backslash character as the path separator in Windows. So:

ifstream file;
file.open("C:\\Demo.txt", ios::in);

Keep in mind that when written in C++ source code, you must use the double backslash because the backslash character itself means something special inside double quoted strings. So the above refers to the file C:\Demo.txt.

Why is an OPTIONS request sent and can I disable it?

After spending a whole day and a half trying to work through a similar problem I found it had to do with IIS.

My Web API project was set up as follows:

// WebApiConfig.cs
public static void Register(HttpConfiguration config)
{
    var cors = new EnableCorsAttribute("*", "*", "*");
    config.EnableCors(cors);
    //...
}

I did not have CORS specific config options in the web.config > system.webServer node like I have seen in so many posts

No CORS specific code in the global.asax or in the controller as a decorator

The problem was the app pool settings.

The managed pipeline mode was set to classic (changed it to integrated) and the Identity was set to Network Service (changed it to ApplicationPoolIdentity)

Changing those settings (and refreshing the app pool) fixed it for me.

Vue.js unknown custom element

I had the same error

[Vue warn]: Unknown custom element: - did you register the component correctly? For recursive components, make sure to provide the "name" option.

however, I totally forgot to run npm install && npm run dev to compiling the js files.

maybe this helps newbies like me.

How to change the default docker registry from docker.io to my private registry?

UPDATE: Following your comment, it is not currently possible to change the default registry, see this issue for more info.

You should be able to do this, substituting the host and port to your own:

docker pull localhost:5000/registry-demo

If the server is remote/has auth you may need to log into the server with:

docker login https://<YOUR-DOMAIN>:8080

Then running:

docker pull <YOUR-DOMAIN>:8080/test-image

Angular ReactiveForms: Producing an array of checkbox values?

Add my 5 cents) My question model

{
   name: "what_is_it",
   options:[
     {
      label: 'Option name',
      value: '1'
     },
     {
      label: 'Option name 2',
      value: '2'
     }
   ]
}

template.html

<div class="question"  formGroupName="{{ question.name }}">
<div *ngFor="let opt of question.options; index as i" class="question__answer" >
  <input 
    type="checkbox" id="{{question.name}}_{{i}}"
    [name]="question.name" class="hidden question__input" 
    [value]="opt.value" 
    [formControlName]="opt.label"
   >
  <label for="{{question.name}}_{{i}}" class="question__label question__label_checkbox">
      {{opt.label}}
  </label>
</div>

component.ts

 onSubmit() {
    let formModel = {};
    for (let key in this.form.value) {
      if (typeof this.form.value[key] !== 'object') { 
        formModel[key] = this.form.value[key]
      } else { //if formgroup item
        formModel[key] = '';
        for (let k in this.form.value[key]) {
          if (this.form.value[key][k])
            formModel[key] = formModel[key] + k + ';'; //create string with ';' separators like 'a;b;c'
        }
      }
    }
     console.log(formModel)
   }

Select first 10 distinct rows in mysql

Try this SELECT DISTINCT 10 * ...

SQL How to correctly set a date variable value and use it?

Your syntax is fine, it will return rows where LastAdDate lies within the last 6 months;

select cast('01-jan-1970' as datetime) as LastAdDate into #PubAdvTransData 
    union select GETDATE()
    union select NULL
    union select '01-feb-2010'

DECLARE @sp_Date DATETIME = DateAdd(m, -6, GETDATE())

SELECT * FROM #PubAdvTransData pat
     WHERE (pat.LastAdDate > @sp_Date)

>2010-02-01 00:00:00.000
>2010-04-29 21:12:29.920

Are you sure LastAdDate is of type DATETIME?

Unlocking tables if thread is lost

With Sequel Pro:

Restarting the app unlocked my tables. It resets the session connection.

NOTE: I was doing this for a site on my local machine.

How do you calculate log base 2 in Java for integers?

If you are thinking about using floating-point to help with integer arithmetics, you have to be careful.

I usually try to avoid FP calculations whenever possible.

Floating-point operations are not exact. You can never know for sure what will (int)(Math.log(65536)/Math.log(2)) evaluate to. For example, Math.ceil(Math.log(1<<29) / Math.log(2)) is 30 on my PC where mathematically it should be exactly 29. I didn't find a value for x where (int)(Math.log(x)/Math.log(2)) fails (just because there are only 32 "dangerous" values), but it does not mean that it will work the same way on any PC.

The usual trick here is using "epsilon" when rounding. Like (int)(Math.log(x)/Math.log(2)+1e-10) should never fail. The choice of this "epsilon" is not a trivial task.

More demonstration, using a more general task - trying to implement int log(int x, int base):

The testing code:

static int pow(int base, int power) {
    int result = 1;
    for (int i = 0; i < power; i++)
        result *= base;
    return result;
}

private static void test(int base, int pow) {
    int x = pow(base, pow);
    if (pow != log(x, base))
        System.out.println(String.format("error at %d^%d", base, pow));
    if(pow!=0 && (pow-1) != log(x-1, base))
        System.out.println(String.format("error at %d^%d-1", base, pow));
}

public static void main(String[] args) {
    for (int base = 2; base < 500; base++) {
        int maxPow = (int) (Math.log(Integer.MAX_VALUE) / Math.log(base));
        for (int pow = 0; pow <= maxPow; pow++) {
            test(base, pow);
        }
    }
}

If we use the most straight-forward implementation of logarithm,

static int log(int x, int base)
{
    return (int) (Math.log(x) / Math.log(base));
}

this prints:

error at 3^5
error at 3^10
error at 3^13
error at 3^15
error at 3^17
error at 9^5
error at 10^3
error at 10^6
error at 10^9
error at 11^7
error at 12^7
...

To completely get rid of errors I had to add epsilon which is between 1e-11 and 1e-14. Could you have told this before testing? I definitely could not.

How can I extract audio from video with ffmpeg?

Here's what I just used:

ffmpeg -i my.mkv -map 0:3 -vn -b:a 320k my.mp3

Options explanation:

  • my.mkv is a source video file, you can use other formats as well
  • -map 0:3 means I want 3rd stream from video file. Put your N there - video files often has multiple audio streams; you can omit it or use -map 0:a to take the default audio stream. Run ffprobe my.mkv to see what streams does the video file have.
  • my.mp3 is a target audio filename, and ffmpeg figures out I want an MP3 from its extension. In my case the source audio stream is ac3 DTS and just copying wasn't what I wanted
  • 320k is a desired target bitrate
  • -vn means I don't want video in target file

Coarse-grained vs fine-grained

In the context of services:

http://en.wikipedia.org/wiki/Service_Granularity_Principle

By definition a coarse-grained service operation has broader scope than a fine-grained service, although the terms are relative. The former typically requires increased design complexity but can reduce the number of calls required to complete a task.

A fine grained service interface is about the same like chatty interface.

vertical-align with Bootstrap 3

Flex behaviors are natively supported since Bootstrap 4. Add d-flex align-items-center in the row div. You no longer need to modify your CSS content.

Simple example: http://jsfiddle.net/vgks6L74/

<!-- language: html -->
<div class="row d-flex align-items-center">
  <div class="col-5 border border-dark" style="height:10em">  Big </div>
  <div class="col-2 border border-danger" style="height:3em"> Small </div>
</div>

With your example: http://jsfiddle.net/7zwtL702/

<!-- language: html -->
<div class="row d-flex align-items-center">
    <div class="col-5">
        <div class="border border-dark" style="height:10em">Big</div>
    </div>
    <div class="col-2">
        <div class="border border-danger" style="height:3em">Small</div>
   </div>
</div>

Source: Flex · Bootstrap

grep a tab in UNIX

The answer is simpler. Write your grep and within the quote type the tab key, it works well at least in ksh

grep "  " *

What is the coolest thing you can do in <10 lines of simple code? Help me inspire beginners!

When I first figured out the bash forkbomb, I thought it was really sweet. So simple, yet neat in what it can do:

:(){ :|:& };:

Key hash for Android-Facebook app

You can get key hash from SHA-1 key. Its very simple you need to get your SHA-1(Signed APK) key from Play Store check below image.enter image description here

Now Copy that SHA-1 key and past it in this website http://tomeko.net also check below image to get your Key Hash.

enter image description here

How can I get Eclipse to show .* files?

Spring Tool Suite 4

Version: 4.9.0.RELEASE Build Id: 202012132054

For Mac:

enter image description here

How to POST using HTTPclient content type = application/x-www-form-urlencoded

The best solution for me is:

// Add key/value
var dict = new Dictionary<string, string>();
dict.Add("Content-Type", "application/x-www-form-urlencoded");

// Execute post method
using (var response = httpClient.PostAsync(path, new FormUrlEncodedContent(dict))){}

Hidden Features of C#?

The delegate syntax have evolved over successive versions of C#, but I still find them difficult to remember. Fortunately the Action<> and Func<> delegates are easy to remember.

For example:

  • Action<int> is a delegate method that takes a single int argument and returns void.
  • Func<int> is a delegate method that takes no arguments and returns an int.
  • Func<int, bool> is a delegate method that takes a single int argument and returns a bool.

These features were introduced in version 3.5 of the .NET framework.

JBoss default password

as suggested in other posts, probably you don't have any user defined. it's not advisable to manually edit the configuration files. you should use the add-user (.sh or .cmd) utility as explained in https://access.redhat.com/documentation/en-US/JBoss_Enterprise_Application_Platform/6/html/Installation_Guide/chap-Getting_Started_with_JBoss_Enterprise_Application_Platform_6.html#Add_the_Initial_User_for_the_Management_Interfaces

How to add default signature in Outlook

I like Mozzi's answer but found that it did not retain the default fonts that are user specific. The text all appeared in a system font as normal text. The code below retains the user's favourite fonts, while making it only a little longer. It is based on Mozzi's approach, uses a regular expression to replace the default body text and places the user's chosen Body text where it belongs by using GetInspector.WordEditor. I found that the call to GetInspector did not populate the HTMLbody as dimitry streblechenko says above in this thread, at least, not in Office 2010, so the object is still displayed in my code. In passing, please note that it is important that the MailItem is created as an Object, not as a straightforward MailItem - see here for more. (Oh, and sorry to those of different tastes, but I prefer longer descriptive variable names so that I can find routines!)

Public Function GetSignedMailItemAsObject(ByVal ToAddress As String, _
                      ByVal Subject As String, _
                      ByVal Body As String, _
                      SignatureName As String) As Object
'================================================================================================================='Creates a new MailItem in HTML format as an Object.
'Body, if provided, replaces all text in the default message.
'A Signature is appended at the end of the message.
'If SignatureName is invalid any existing default signature is left in place.
'=================================================================================================================
' REQUIRED REFERENCES
' VBScript regular expressions (5.5)
' Microsoft Scripting Runtime
'=================================================================================================================
Dim OlM As Object               'Do not define this as Outlook.MailItem.  If you do, some things will work and some won't (i.e. SendUsingAccount)
Dim Signature As String
Dim Doc As Word.Document
Dim Regex As New VBScript_RegExp_55.RegExp       '(can also use use Object if VBScript is not Referenced)

Set OlM = Application.CreateItem(olMailItem)
With OlM
    .To = ToAddress
    .Subject = Subject
    'SignatureName is the exactname that you gave your signature in the Message>Insert>Signature Dialog
    Signature = GetSignature(SignatureName)
    If Signature <> vbNullString Then
'        Should really strip the terminal </body tag out of signature by removing all characters from the start of the tag
'        but Outlook seems to handle this OK if you don't bother.
        .Display                                'Needed.  Without it, there is no existing HTMLbody available to work with.
        Set Doc = OlM.GetInspector.WordEditor   'Get any existing body with the WordEditor and delete all of it
        Doc.Range(Doc.Content.Start, Doc.Content.End) = vbNullString 'Delete all existing content - we don't want any default signature
        'Preserve all local email formatting by placing any new body text, followed by the Signature, into the empty HTMLbody.
        With Regex
            .IgnoreCase = True                  'Case insensitive
            .Global = False                     'Regex finds only the first match
            .MultiLine = True                   'In case there are stray EndOfLines (there shouldn't be in HTML but Word exports of HTML can be dire)
            .Pattern = "(<body.*)(?=<\/body)"   'Look for the whole HTMLbody but do NOT include the terminal </body tag in the value returned
            OlM.HTMLbody = .Replace(OlM.HTMLbody, "$1" & Signature)
        End With ' Regex
        Doc.Range(Doc.Content.Start, Doc.Content.Start) = Body 'Place the required Body before the signature (it will get the default style)
        .Close olSave                           'Close the Displayed MailItem (actually Object) and Save it.  If it is left open some later updates may fail.
    End If ' Signature <> vbNullString
End With ' OlM
Set GetSignedMailItemAsObject = OlM
End Function

Private Function GetSignature(sigName As String) As String
Dim oTextStream As Scripting.TextStream
Dim oSig As Object
Dim appDataDir, Signature, sigPath, fileName As String
Dim FileSys As Scripting.FileSystemObject        'Requires Microsoft Scripting Runtime to be available
    appDataDir = Environ("APPDATA") & "\Microsoft\Signatures"
    sigPath = appDataDir & "\" & sigName & ".htm"
    Set FileSys = CreateObject("Scripting.FileSystemObject")
    Set oTextStream = FileSys.OpenTextFile(sigPath)
    Signature = oTextStream.ReadAll
    ' fix relative references to images, etc. in Signature
    ' by making them absolute paths, OL will find the image
    fileName = Replace(sigName, ".htm", "") & "_files/"
    Signature = Replace(Signature, fileName, appDataDir & "\" & fileName)
    GetSignature = Signature
End Function

How to allow only numeric (0-9) in HTML inputbox using jQuery?

Another approach is below. This will take care of pasting also. [it is for alpha-numeric validation]

//Input Validation
var existingLogDescription = "";

$('.logDescription').keydown(function (event) {
    existingLogDescription = this.value;

});


$('.logDescription').keyup(function () {
    if (this.value.match(/[^a-zA-Z0-9 ]/g)) {
        alert("Log Description should contain alpha-numeric values only");
        this.value = this.value.replace(/[^a-zA-Z0-9 ]/g, '');
        this.value = existingLogDescription;
    }
});

Access denied for user 'homestead'@'localhost' (using password: YES)

in my case, after restarting my server the problem was gone.

exit/close the "php artisan serve" command and

re-run the command "php artisan serve" command.

How to disable javax.swing.JButton in java?

This works.

public class TestButton {

public TestButton() {
    JFrame f = new JFrame();
    f.setSize(new Dimension(200,200));
    JPanel p = new JPanel();
    p.setLayout(new FlowLayout());

    final JButton stop = new JButton("Stop");
    final JButton start = new JButton("Start");
    p.add(start);
    p.add(stop);
    f.getContentPane().add(p);
    stop.setEnabled(false);
    stop.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            start.setEnabled(true);
            stop.setEnabled(false);

        }
    });

    start.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            start.setEnabled(false);
            stop.setEnabled(true);

        }
    });
    f.setVisible(true);
}

/**
 * @param args
 */
public static void main(String[] args) {
    new TestButton();

}

}

How to simulate a mouse click using JavaScript?

An easier and more standard way to simulate a mouse click would be directly using the event constructor to create an event and dispatch it.

Though the MouseEvent.initMouseEvent() method is kept for backward compatibility, creating of a MouseEvent object should be done using the MouseEvent() constructor.

var evt = new MouseEvent("click", {
    view: window,
    bubbles: true,
    cancelable: true,
    clientX: 20,
    /* whatever properties you want to give it */
});
targetElement.dispatchEvent(evt);

Demo: http://jsfiddle.net/DerekL/932wyok6/

This works on all modern browsers. For old browsers including IE, MouseEvent.initMouseEvent will have to be used unfortunately though it's deprecated.

var evt = document.createEvent("MouseEvents");
evt.initMouseEvent("click", canBubble, cancelable, view,
                   detail, screenX, screenY, clientX, clientY,
                   ctrlKey, altKey, shiftKey, metaKey,
                   button, relatedTarget);
targetElement.dispatchEvent(evt);

TypeError: Invalid dimensions for image data when plotting array with imshow()

There is a (somewhat) related question on StackOverflow:

Here the problem was that an array of shape (nx,ny,1) is still considered a 3D array, and must be squeezed or sliced into a 2D array.

More generally, the reason for the Exception

TypeError: Invalid dimensions for image data

is shown here: matplotlib.pyplot.imshow() needs a 2D array, or a 3D array with the third dimension being of shape 3 or 4!

You can easily check this with (these checks are done by imshow, this function is only meant to give a more specific message in case it's not a valid input):

from __future__ import print_function
import numpy as np

def valid_imshow_data(data):
    data = np.asarray(data)
    if data.ndim == 2:
        return True
    elif data.ndim == 3:
        if 3 <= data.shape[2] <= 4:
            return True
        else:
            print('The "data" has 3 dimensions but the last dimension '
                  'must have a length of 3 (RGB) or 4 (RGBA), not "{}".'
                  ''.format(data.shape[2]))
            return False
    else:
        print('To visualize an image the data must be 2 dimensional or '
              '3 dimensional, not "{}".'
              ''.format(data.ndim))
        return False

In your case:

>>> new_SN_map = np.array([1,2,3])
>>> valid_imshow_data(new_SN_map)
To visualize an image the data must be 2 dimensional or 3 dimensional, not "1".
False

The np.asarray is what is done internally by matplotlib.pyplot.imshow so it's generally best you do it too. If you have a numpy array it's obsolete but if not (for example a list) it's necessary.


In your specific case you got a 1D array, so you need to add a dimension with np.expand_dims()

import matplotlib.pyplot as plt
a = np.array([1,2,3,4,5])
a = np.expand_dims(a, axis=0)  # or axis=1
plt.imshow(a)
plt.show()

enter image description here

or just use something that accepts 1D arrays like plot:

a = np.array([1,2,3,4,5])
plt.plot(a)
plt.show()

enter image description here

Add "Are you sure?" to my excel button, how can I?

On your existing button code, simply insert this line before the procedure:

If MsgBox("This will erase everything! Are you sure?", vbYesNo) = vbNo Then Exit Sub

This will force it to quit if the user presses no.

How can you detect the version of a browser?

_x000D_
_x000D_
navigator.sayswho= (function(){_x000D_
    var ua= navigator.userAgent, tem, _x000D_
    M= ua.match(/(opera|chrome|safari|firefox|msie|trident(?=\/))\/?\s*(\d+)/i) || [];_x000D_
    if(/trident/i.test(M[1])){_x000D_
        tem=  /\brv[ :]+(\d+)/g.exec(ua) || [];_x000D_
        return 'IE '+(tem[1] || '');_x000D_
    }_x000D_
    if(M[1]=== 'Chrome'){_x000D_
        tem= ua.match(/\b(OPR|Edge)\/(\d+)/);_x000D_
        if(tem!= null) return tem.slice(1).join(' ').replace('OPR', 'Opera');_x000D_
    }_x000D_
    M= M[2]? [M[1], M[2]]: [navigator.appName, navigator.appVersion, '-?'];_x000D_
    if((tem= ua.match(/version\/(\d+)/i))!= null) M.splice(1, 1, tem[1]);_x000D_
    return M.join(' ');_x000D_
})();_x000D_
_x000D_
console.log(navigator.sayswho); // outputs: `Chrome 62`
_x000D_
_x000D_
_x000D_

How to make phpstorm display line numbers by default?

For PhpStorm version 9 on Windows.
FileSettingsEditorGeneralAppearence then check Show line numbers

How should I use Outlook to send code snippets?

Would sending the mail as plain-text sort this?

"How to Send a Plain Text Message in Outlook":

  • Select Actions | New Mail Message Using | Plain Text from the menu in Outlook.
  • Create your message as usual.
  • Click Send to deliver it.

Being plain text it shouldn't screw up your code, with "smart" quotes, auto-capitalisation and such.

Another possible option, if this is a common problem within the company perhaps you could setup an internal code-paste site, there's plenty of open-source ones around, like Open Pastebin

What is the difference between git clone and checkout?

The man page for checkout: http://git-scm.com/docs/git-checkout

The man page for clone: http://git-scm.com/docs/git-clone

To sum it up, clone is for fetching repositories you don't have, checkout is for switching between branches in a repository you already have.

Note: for those who have a SVN/CVS background and new to Git, the equivalent of git clone in SVN/CVS is checkout. The same wording of different terms is often confusing.

Convert a string date into datetime in Oracle

Try this: TO_DATE('2011-07-28T23:54:14Z', 'YYYY-MM-DD"T"HH24:MI:SS"Z"')

How can I draw circle through XML Drawable - Android?

no need for the padding or the corners.

here's a sample:

<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="oval" >
    <gradient android:startColor="#FFFF0000" android:endColor="#80FF00FF"
        android:angle="270"/>
</shape>

based on :

https://stackoverflow.com/a/10104037/878126

ASP.NET Identity DbContext confusion

I would use a single Context class inheriting from IdentityDbContext. This way you can have the context be aware of any relations between your classes and the IdentityUser and Roles of the IdentityDbContext. There is very little overhead in the IdentityDbContext, it is basically a regular DbContext with two DbSets. One for the users and one for the roles.

How to export a table dataframe in PySpark to csv?

For Apache Spark 2+, in order to save dataframe into single csv file. Use following command

query.repartition(1).write.csv("cc_out.csv", sep='|')

Here 1 indicate that I need one partition of csv only. you can change it according to your requirements.

Set HTTP header for one request

Try this, perhaps it works ;)

.factory('authInterceptor', function($location, $q, $window) {


return {
    request: function(config) {
      config.headers = config.headers || {};

      config.headers.Authorization = 'xxxx-xxxx';

      return config;
    }
  };
})

.config(function($httpProvider) {
  $httpProvider.interceptors.push('authInterceptor');
})

And make sure your back end works too, try this. I'm using RESTful CodeIgniter.

class App extends REST_Controller {
    var $authorization = null;

    public function __construct()
    {
        parent::__construct();
        header('Access-Control-Allow-Origin: *');
        header("Access-Control-Allow-Headers: X-API-KEY, Origin, X-Requested-With, Content-Type, Accept, Access-Control-Request-Method, Authorization");
        header("Access-Control-Allow-Methods: GET, POST, OPTIONS, PUT, DELETE");
        if ( "OPTIONS" === $_SERVER['REQUEST_METHOD'] ) {
            die();
        }

        if(!$this->input->get_request_header('Authorization')){
            $this->response(null, 400);    
        }

        $this->authorization = $this->input->get_request_header('Authorization');
    }

}

Excel: macro to export worksheet as CSV file without leaving my current Excel sheet

As per my comment on @neves post, I slightly improved this by adding the xlPasteFormats as well as values part so dates go across as dates - I mostly save as CSV for bank statements, so needed dates.

Sub ExportAsCSV()

    Dim MyFileName As String
    Dim CurrentWB As Workbook, TempWB As Workbook

    Set CurrentWB = ActiveWorkbook
    ActiveWorkbook.ActiveSheet.UsedRange.Copy

    Set TempWB = Application.Workbooks.Add(1)
    With TempWB.Sheets(1).Range("A1")
        .PasteSpecial xlPasteValues
        .PasteSpecial xlPasteFormats
    End With

    'Dim Change below to "- 4"  to become compatible with .xls files
    MyFileName = CurrentWB.Path & "\" & Left(CurrentWB.Name, Len(CurrentWB.Name) - 5) & ".csv"

    Application.DisplayAlerts = False
    TempWB.SaveAs Filename:=MyFileName, FileFormat:=xlCSV, CreateBackup:=False, Local:=True
    TempWB.Close SaveChanges:=False
    Application.DisplayAlerts = True
End Sub

Laravel orderBy on a relationship

I believe you can also do:

$sortDirection = 'desc';

$user->with(['comments' => function ($query) use ($sortDirection) {
    $query->orderBy('column', $sortDirection);
}]);

That allows you to run arbitrary logic on each related comment record. You could have stuff in there like:

$query->where('timestamp', '<', $someTime)->orderBy('timestamp', $sortDirection);

Difference between Hashing a Password and Encrypting it

Encrypted vs Hashed Passwords

As shown in the above image, if the password is encrypted it is always a hidden secret where someone can extract the plain text password. However when password is hashed, you are relaxed as there is hardly any method of recovering the password from the hash value.


Extracted from Encrypted vs Hashed Passwords - Which is better?

Is encryption good?

Plain text passwords can be encrypted using symmetric encryption algorithms like DES, AES or with any other algorithms and be stored inside the database. At the authentication (confirming the identity with user name and password), application will decrypt the encrypted password stored in database and compare with user provided password for equality. In this type of an password handling approach, even if someone get access to database tables the passwords will not be simply reusable. However there is a bad news in this approach as well. If somehow someone obtain the cryptographic algorithm along with the key used by your application, he/she will be able to view all the user passwords stored in your database by decryption. "This is the best option I got", a software developer may scream, but is there a better way?

Cryptographic hash function (one-way-only)

Yes there is, may be you have missed the point here. Did you notice that there is no requirement to decrypt and compare? If there is one-way-only conversion approach where the password can be converted into some converted-word, but the reverse operation (generation of password from converted-word) is impossible. Now even if someone gets access to the database, there is no way that the passwords be reproduced or extracted using the converted-words. In this approach, there will be hardly anyway that some could know your users' top secret passwords; and this will protect the users using the same password across multiple applications. What algorithms can be used for this approach?

Where are static variables stored in C and C++?

Data declared in a compilation unit will go into the .BSS or the .Data of that files output. Initialised data in BSS, uninitalised in DATA.

The difference between static and global data comes in the inclusion of symbol information in the file. Compilers tend to include the symbol information but only mark the global information as such.

The linker respects this information. The symbol information for the static variables is either discarded or mangled so that static variables can still be referenced in some way (with debug or symbol options). In neither case can the compilation units gets affected as the linker resolves local references first.

Way to create multiline comments in Bash?

Note: I updated this answer based on comments and other answers, so comments prior to May 22nd 2020 may no longer apply. Also I noticed today that some IDE's like VS Code and PyCharm do not recognize a HEREDOC marker that contains spaces, whereas bash has no problem with it, so I'm updating this answer again.

Bash does not provide a builtin syntax for multi-line comment but there are hacks using existing bash syntax that "happen to work now".

Personally I think the simplest (ie least noisy, least weird, easiest to type, most explicit) is to use a quoted HEREDOC, but make it obvious what you are doing, and use the same HEREDOC marker everywhere:

<<'###BLOCK-COMMENT'
line 1
line 2

line 3
line 4
###BLOCK-COMMENT

Single-quoting the HEREDOC marker avoids some shell parsing side-effects, such as weird subsitutions that would cause crash or output, and even parsing of the marker itself. So the single-quotes give you more freedom on the open-close comment marker.

For example the following uses a triple hash which kind of suggests multi-line comment in bash. This would crash the script if the single quotes were absent. Even if you remove ###, the FOO{} would crash the script (or cause bad substitution to be printed if no set -e) if it weren't for the single quotes:

set -e

<<'###BLOCK-COMMENT'
something something ${FOO{}} something
more comment
###BLOCK-COMMENT

ls

You could of course just use

set -e

<<'###'
something something ${FOO{}} something
more comment
###

ls

but the intent of this is definitely less clear to a reader unfamiliar with this trickery.

Note my original answer used '### BLOCK COMMENT', which is fine if you use vanilla vi/vim but today I noticed that PyCharm and VS Code don't recognize the closing marker if it has spaces.

Nowadays any good editor allows you to press ctrl-/ or similar, to un/comment the selection. Everyone definitely understands this:

# something something ${FOO{}} something
# more comment
# yet another line of comment

although admittedly, this is not nearly as convenient as the block comment above if you want to re-fill your paragraphs.

There are surely other techniques, but there doesn't seem to be a "conventional" way to do it. It would be nice if ###> and ###< could be added to bash to indicate start and end of comment block, seems like it could be pretty straightforward.

SVG: text inside rect

You can use foreignobject for more control and placing rich HTML content over rect or circle

_x000D_
_x000D_
    <svg width="250" height="250" xmlns="http://www.w3.org/2000/svg">_x000D_
        <rect x="0" y="0" width="250" height="250" fill="aquamarine" />_x000D_
        <foreignobject x="0" y="0" width="250" height="250">_x000D_
            <body xmlns="http://www.w3.org/1999/xhtml">_x000D_
                <div>Here is a long text that runs more than one line and works as a paragraph</div>_x000D_
                <br />_x000D_
                <div>This is <u>UNDER LINE</u> one</div>_x000D_
                <br />_x000D_
                <div>This is <b>BOLD</b> one</div>_x000D_
                <br />_x000D_
                <div>This is <i>Italic</i> one</div>_x000D_
            </body>_x000D_
        </foreignobject>_x000D_
    </svg>
_x000D_
_x000D_
_x000D_

enter image description here

Printing prime numbers from 1 through 100

Using the rules of divisibility prime numbers can be found out in O(n) and it`s really effecient Rules of Divisibility

The solution would be based on the individual digits of the number...

How to set background color of HTML element using css properties in JavaScript

Javascript:

document.getElementById("ID").style.background = "colorName"; //JS ID

document.getElementsByClassName("ClassName")[0].style.background = "colorName"; //JS Class

Jquery:

$('#ID/.className').css("background","colorName") // One style

$('#ID/.className').css({"background":"colorName","color":"colorname"}); //Multiple style

How to put individual tags for a scatter plot

Perhaps use plt.annotate:

import numpy as np
import matplotlib.pyplot as plt

N = 10
data = np.random.random((N, 4))
labels = ['point{0}'.format(i) for i in range(N)]

plt.subplots_adjust(bottom = 0.1)
plt.scatter(
    data[:, 0], data[:, 1], marker='o', c=data[:, 2], s=data[:, 3] * 1500,
    cmap=plt.get_cmap('Spectral'))

for label, x, y in zip(labels, data[:, 0], data[:, 1]):
    plt.annotate(
        label,
        xy=(x, y), xytext=(-20, 20),
        textcoords='offset points', ha='right', va='bottom',
        bbox=dict(boxstyle='round,pad=0.5', fc='yellow', alpha=0.5),
        arrowprops=dict(arrowstyle = '->', connectionstyle='arc3,rad=0'))

plt.show()

enter image description here

What's the whole point of "localhost", hosts and ports at all?

" In computer networking, a network host, Internet host, host, or Internet node is a computer connected to the Internet - or more generically - to any type of data network. A network host can host information resources as well as application software for providing network services. "-Wikipedia

Local host is a special name given to the local machine or that you are working on, ussually its IP Address is 127.0.0.1. However you can define it to be anything.

There are multiple Network services running on each host for example Apache/IIS( Http Web Server),Mail Clients, FTP clients etc. Each service has a specific port associated with it. You can think of it as this.

In every home, there is one mailbox and multiple people. The mailbox is a host. Your own home mailbox is a localhost. Each person in a home has a room. All letters for that person are sent to his room, hence the room number is a port.

Automatic exit from Bash shell script on error

Use it in conjunction with pipefail.

set -e
set -o pipefail

-e (errexit): Abort the script at the first error, when a command exits with non-zero status (except in until or while loops, if-tests, and list constructs)

-o pipefail: Causes a pipeline to return the exit status of the last command in the pipe that returned a non-zero return value.

Chapter 33. Options

JS Client-Side Exif Orientation: Rotate and Mirror JPEG Images

I am using mixed solution (php+css).

Containers are needed for:

  • div.imgCont2 container needed to rotate;
  • div.imgCont1 container needed to zoomOut - width:150%;
  • div.imgCont container needed for scrollbars, when image is zoomOut.

.

<?php
    $image_url = 'your image url.jpg';
    $exif = @exif_read_data($image_url,0,true);
    $orientation = @$exif['IFD0']['Orientation'];
?>

<style>
.imgCont{
    width:100%;
    overflow:auto;
}
.imgCont2[data-orientation="8"]{
    transform:rotate(270deg);
    margin:15% 0;
}
.imgCont2[data-orientation="6"]{
    transform:rotate(90deg);
    margin:15% 0;
}
.imgCont2[data-orientation="3"]{
    transform:rotate(180deg);
}
img{
    width:100%;
}
</style>

<div class="imgCont">
  <div class="imgCont1">
    <div class="imgCont2" data-orientation="<?php echo($orientation) ?>">
      <img src="<?php echo($image_url) ?>">
    </div>
  </div>
</div>

Elegant ways to support equivalence ("equality") in Python classes

Consider this simple problem:

class Number:

    def __init__(self, number):
        self.number = number


n1 = Number(1)
n2 = Number(1)

n1 == n2 # False -- oops

So, Python by default uses the object identifiers for comparison operations:

id(n1) # 140400634555856
id(n2) # 140400634555920

Overriding the __eq__ function seems to solve the problem:

def __eq__(self, other):
    """Overrides the default implementation"""
    if isinstance(other, Number):
        return self.number == other.number
    return False


n1 == n2 # True
n1 != n2 # True in Python 2 -- oops, False in Python 3

In Python 2, always remember to override the __ne__ function as well, as the documentation states:

There are no implied relationships among the comparison operators. The truth of x==y does not imply that x!=y is false. Accordingly, when defining __eq__(), one should also define __ne__() so that the operators will behave as expected.

def __ne__(self, other):
    """Overrides the default implementation (unnecessary in Python 3)"""
    return not self.__eq__(other)


n1 == n2 # True
n1 != n2 # False

In Python 3, this is no longer necessary, as the documentation states:

By default, __ne__() delegates to __eq__() and inverts the result unless it is NotImplemented. There are no other implied relationships among the comparison operators, for example, the truth of (x<y or x==y) does not imply x<=y.

But that does not solve all our problems. Let’s add a subclass:

class SubNumber(Number):
    pass


n3 = SubNumber(1)

n1 == n3 # False for classic-style classes -- oops, True for new-style classes
n3 == n1 # True
n1 != n3 # True for classic-style classes -- oops, False for new-style classes
n3 != n1 # False

Note: Python 2 has two kinds of classes:

  • classic-style (or old-style) classes, that do not inherit from object and that are declared as class A:, class A(): or class A(B): where B is a classic-style class;

  • new-style classes, that do inherit from object and that are declared as class A(object) or class A(B): where B is a new-style class. Python 3 has only new-style classes that are declared as class A:, class A(object): or class A(B):.

For classic-style classes, a comparison operation always calls the method of the first operand, while for new-style classes, it always calls the method of the subclass operand, regardless of the order of the operands.

So here, if Number is a classic-style class:

  • n1 == n3 calls n1.__eq__;
  • n3 == n1 calls n3.__eq__;
  • n1 != n3 calls n1.__ne__;
  • n3 != n1 calls n3.__ne__.

And if Number is a new-style class:

  • both n1 == n3 and n3 == n1 call n3.__eq__;
  • both n1 != n3 and n3 != n1 call n3.__ne__.

To fix the non-commutativity issue of the == and != operators for Python 2 classic-style classes, the __eq__ and __ne__ methods should return the NotImplemented value when an operand type is not supported. The documentation defines the NotImplemented value as:

Numeric methods and rich comparison methods may return this value if they do not implement the operation for the operands provided. (The interpreter will then try the reflected operation, or some other fallback, depending on the operator.) Its truth value is true.

In this case the operator delegates the comparison operation to the reflected method of the other operand. The documentation defines reflected methods as:

There are no swapped-argument versions of these methods (to be used when the left argument does not support the operation but the right argument does); rather, __lt__() and __gt__() are each other’s reflection, __le__() and __ge__() are each other’s reflection, and __eq__() and __ne__() are their own reflection.

The result looks like this:

def __eq__(self, other):
    """Overrides the default implementation"""
    if isinstance(other, Number):
        return self.number == other.number
    return NotImplemented

def __ne__(self, other):
    """Overrides the default implementation (unnecessary in Python 3)"""
    x = self.__eq__(other)
    if x is NotImplemented:
        return NotImplemented
    return not x

Returning the NotImplemented value instead of False is the right thing to do even for new-style classes if commutativity of the == and != operators is desired when the operands are of unrelated types (no inheritance).

Are we there yet? Not quite. How many unique numbers do we have?

len(set([n1, n2, n3])) # 3 -- oops

Sets use the hashes of objects, and by default Python returns the hash of the identifier of the object. Let’s try to override it:

def __hash__(self):
    """Overrides the default implementation"""
    return hash(tuple(sorted(self.__dict__.items())))

len(set([n1, n2, n3])) # 1

The end result looks like this (I added some assertions at the end for validation):

class Number:

    def __init__(self, number):
        self.number = number

    def __eq__(self, other):
        """Overrides the default implementation"""
        if isinstance(other, Number):
            return self.number == other.number
        return NotImplemented

    def __ne__(self, other):
        """Overrides the default implementation (unnecessary in Python 3)"""
        x = self.__eq__(other)
        if x is not NotImplemented:
            return not x
        return NotImplemented

    def __hash__(self):
        """Overrides the default implementation"""
        return hash(tuple(sorted(self.__dict__.items())))


class SubNumber(Number):
    pass


n1 = Number(1)
n2 = Number(1)
n3 = SubNumber(1)
n4 = SubNumber(4)

assert n1 == n2
assert n2 == n1
assert not n1 != n2
assert not n2 != n1

assert n1 == n3
assert n3 == n1
assert not n1 != n3
assert not n3 != n1

assert not n1 == n4
assert not n4 == n1
assert n1 != n4
assert n4 != n1

assert len(set([n1, n2, n3, ])) == 1
assert len(set([n1, n2, n3, n4])) == 2

What's the difference between JavaScript and JScript?

JScript is Microsoft's equivalent of JavaScript.
Java is an Oracle product and used to be a Sun product.

Oracle bought Sun.

JavaScript + Microsoft = JScript

How to format current time using a yyyyMMddHHmmss format?

Use

fmt.Println(t.Format("20060102150405"))

as Go uses following constants to format date,refer here

const (
    stdLongMonth      = "January"
    stdMonth          = "Jan"
    stdNumMonth       = "1"
    stdZeroMonth      = "01"
    stdLongWeekDay    = "Monday"
    stdWeekDay        = "Mon"
    stdDay            = "2"
    stdUnderDay       = "_2"
    stdZeroDay        = "02"
    stdHour           = "15"
    stdHour12         = "3"
    stdZeroHour12     = "03"
    stdMinute         = "4"
    stdZeroMinute     = "04"
    stdSecond         = "5"
    stdZeroSecond     = "05"
    stdLongYear       = "2006"
    stdYear           = "06"
    stdPM             = "PM"
    stdpm             = "pm"
    stdTZ             = "MST"
    stdISO8601TZ      = "Z0700"  // prints Z for UTC
    stdISO8601ColonTZ = "Z07:00" // prints Z for UTC
    stdNumTZ          = "-0700"  // always numeric
    stdNumShortTZ     = "-07"    // always numeric
    stdNumColonTZ     = "-07:00" // always numeric
)

Converting data frame column from character to numeric

If we need only one column to be numeric

yyz$b <- as.numeric(as.character(yyz$b))

But, if all the columns needs to changed to numeric, use lapply to loop over the columns and convert to numeric by first converting it to character class as the columns were factor.

yyz[] <- lapply(yyz, function(x) as.numeric(as.character(x)))

Both the columns in the OP's post are factor because of the string "n/a". This could be easily avoided while reading the file using na.strings = "n/a" in the read.table/read.csv or if we are using data.frame, we can have character columns with stringsAsFactors=FALSE (the default is stringsAsFactors=TRUE)


Regarding the usage of apply, it converts the dataset to matrix and matrix can hold only a single class. To check the class, we need

lapply(yyz, class)

Or

sapply(yyz, class)

Or check

str(yyz)

SyntaxError: Cannot use import statement outside a module

in the package.json write { "type": "module" }

it fixed my problem, I had the same problem

How to implement onBackPressed() in Fragments?

public class MyActivity extends Activity {

    protected OnBackPressedListener onBackPressedListener;

    public interface OnBackPressedListener {
        void doBack();
    }

    public void setOnBackPressedListener(OnBackPressedListener onBackPressedListener) {
        this.onBackPressedListener = onBackPressedListener;
    }

    @Override
    public void onBackPressed() {
        if (onBackPressedListener != null)
            onBackPressedListener.doBack();
        else
            super.onBackPressed();
    } 

    @Override
    protected void onDestroy() {
        onBackPressedListener = null;
        super.onDestroy();
    }
}

in your fragment add the following, dont forget to implement mainactivity's interface.

public class MyFragment extends Framgent implements MyActivity.OnBackPressedListener {
    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
         ((MyActivity) getActivity()).setOnBackPressedListener(this);
    }

@Override
public void doBack() {
    //BackPressed in activity will call this;
}

}

Counting repeated characters in a string in Python

Grand Performance Comparison

Scroll to the end for a TL;DR graph

Since I had "nothing better to do" (understand: I had just a lot of work), I decided to do a little performance contest. I assembled the most sensible or interesting answers and did some simple timeit in CPython 3.5.1 on them. I tested them with only one string, which is a typical input in my case:

>>> s = 'ZDXMZKMXFDKXZFKZ'
>>> len(s)
16

Be aware that results might vary for different inputs, be it different length of the string or different number of distinct characters, or different average number of occurrences per character.


Don't reinvent the wheel

Python has made it simple for us. The collections.Counter class does exactly what we want and a lot more. Its usage is by far the simplest of all the methods mentioned here.

taken from @oefe, nice find

>>> timeit('Counter(s)', globals=locals())
8.208566107001388

Counter goes the extra mile, which is why it takes so long.

¿Dictionary, comprende?

Let's try using a simple dict instead. First, let's do it declaratively, using dict comprehension.

I came up with this myself...

>>> timeit('{c: s.count(c) for c in s}', globals=locals())
4.551155784000002

This will go through s from beginning to end, and for each character it will count the number of its occurrences in s. Since s contains duplicate characters, the above method searches s several times for the same character. The result is naturally always the same. So let's count the number of occurrences just once for each character.

I came up with this myself, and so did @IrshadBhat

>>> timeit('{c: s.count(c) for c in set(s)}', globals=locals())
3.1484066140001232

Better. But we still have to search through the string to count the occurrences. One search for each distinct character. That means we're going to read the string more than once. We can do better than that! But for that, we have to get off our declarativist high horse and descend into an imperative mindset.

Exceptional code

AKA Gotta catch 'em all!

inspired by @anthony

>>> timeit('''
... d = {}
... for c in s:
...   try:
...     d[c] += 1
...   except KeyError:
...     d[c] = 1
... ''', globals=locals())
3.7060273620008957

Well, it was worth a try. If you dig into the Python source (I can't say with certainty because I have never really done that), you will probably find that when you do except ExceptionType, Python has to check whether the exception raised is actually of ExceptionType or some other type. Just for the heck of it, let's see how long will it take if we omit that check and catch all exceptions.

made by @anthony

>>> timeit('''
... d = {}
... for c in s:
...   try:
...     d[c] += 1
...   except:
...     d[c] = 1
... ''', globals=locals())
3.3506563019982423

It does save some time, so one might be tempted to use this as some sort of optimization.
Don't do that! Or actually do. Do it now:

INTERLUDE 1

import time
while True:
  try:
    time.sleep(1)
  except:
    print("You're trapped in your own trap!")

You see? It catches KeyboardInterrupt, besides other things. In fact, it catches all the exceptions there are. Including ones you might not have even heard about, like SystemExit.

INTERLUDE 2

import sys
try:
  print("Goodbye. I'm going to die soon.")
  sys.exit()
except:
  print('BACK FROM THE DEAD!!!')

Now back to counting letters and numbers and other characters.

Playing catch-up

Exceptions aren't the way to go. You have to try hard to catch up with them, and when you finally do, they just throw up on you and then raise their eyebrows like it's your fault. Luckily brave fellows have paved our way so we can do away with exceptions, at least in this little exercise.

The dict class has a nice method – get – which allows us to retrieve an item from a dictionary, just like d[k]. Except when the key k is not in the dictionary, it can return a default value. Let's use that method instead of fiddling with exceptions.

credit goes to @Usman

>>> timeit('''
... d = {}
... for c in s:
...   d[c] = d.get(c, 0) + 1
... ''', globals=locals())
3.2133633289995487

Almost as fast as the set-based dict comprehension. On larger inputs, this one would probably be even faster.

Use the right tool for the job

For at least mildly knowledgeable Python programmer, the first thing that comes to mind is probably defaultdict. It does pretty much the same thing as the version above, except instead of a value, you give it a value factory. That might cause some overhead, because the value has to be "constructed" for each missing key individually. Let's see how it performs.

hope @AlexMartelli won't crucify me for from collections import defaultdict

>>> timeit('''
... dd = defaultdict(int)
... for c in s:
...   dd[c] += 1
... ''', globals=locals())
3.3430528169992613

Not that bad. I'd say the increase in execution time is a small tax to pay for the improved readability. However, we also favor performance, and we will not stop here. Let's take it further and prepopulate the dictionary with zeros. Then we won't have to check every time if the item is already there.

hats off to @sqram

>>> timeit('''
... d = dict.fromkeys(s, 0)
... for c in s:
...   d[c] += 1
... ''', globals=locals())
2.6081761489986093

That's good. Over three times as fast as Counter, yet still simple enough. Personally, this is my favorite in case you don't want to add new characters later. And even if you do, you can still do it. It's just less convenient than it would be in other versions:

d.update({ c: 0 for c in set(other_string) - d.keys() })


Practicality beats purity (except when it's not really practical)

Now a bit different kind of counter. @IdanK has come up with something interesting. Instead of using a hash table (a.k.a. dictionary a.k.a. dict), we can avoid the risk of hash collisions and consequent overhead of their resolution. We can also avoid the overhead of hashing the key, and the extra unoccupied table space. We can use a list. The ASCII values of characters will be indices and their counts will be values. As @IdanK has pointed out, this list gives us constant time access to a character's count. All we have to do is convert each character from str to int using the built-in function ord. That will give us an index into the list, which we will then use to increment the count of the character. So what we do is this: we initialize the list with zeros, do the job, and then convert the list into a dict. This dict will only contain those characters which have non-zero counts, in order to make it compliant with other versions.

As a side note, this technique is used in a linear-time sorting algorithm known as count sort or counting sort. It's very efficient, but the range of values being sorted is limited, since each value has to have its own counter. To sort a sequence of 32-bit integers, 4.3 billion counters would be needed.

>>> timeit('''
... counts = [0 for _ in range(256)]
... for c in s:
...   counts[ord(c)] += 1
... d = {chr(i): count for i,count in enumerate(counts) if count != 0}
... ''', globals=locals())
25.438595562001865

Ouch! Not cool! Let's try and see how long it takes when we omit building the dictionary.

>>> timeit('''
... counts = [0 for _ in range(256)]
... for c in s:
...   counts[ord(c)] += 1
... ''', globals=locals())
10.564866792999965

Still bad. But wait, what's [0 for _ in range(256)]? Can't we write it more simply? How about [0] * 256? That's cleaner. But will it perform better?

>>> timeit('''
... counts = [0] * 256
... for c in s:
...   counts[ord(c)] += 1
... ''', globals=locals())
3.290163638001104

Considerably. Now let's put the dictionary back in.

>>> timeit('''
... counts = [0] * 256
... for c in s:
...   counts[ord(c)] += 1
... d = {chr(i): count for i,count in enumerate(counts) if count != 0}
... ''', globals=locals())
18.000623562998953

Almost six times slower. Why does it take so long? Because when we enumerate(counts), we have to check every one of the 256 counts and see if it's zero. But we already know which counts are zero and which are not.

>>> timeit('''
... counts = [0] * 256
... for c in s:
...   counts[ord(c)] += 1
... d = {c: counts[ord(c)] for c in set(s)}
... ''', globals=locals())
5.826531438000529

It probably won't get much better than that, at least not for such a small input. Plus it's only usable for 8-bit EASCII characters. ? ?????!

And the winner is...

>>> timeit('''
... d = {}
... for c in s:
...   if c in d:
...     d[c] += 1
...   else:
...     d[c] = 1
... ''', globals=locals())
1.8509794599995075

Yep. Even if you have to check every time whether c is in d, for this input it's the fastest way. No pre-population of d will make it faster (again, for this input). It's a lot more verbose than Counter or defaultdict, but also more efficient.


That's all folks

This little exercise teaches us a lesson: when optimizing, always measure performance, ideally with your expected inputs. Optimize for the common case. Don't presume something is actually more efficient just because its asymptotic complexity is lower. And last but not least, keep readability in mind. Try to find a compromise between "computer-friendly" and "human-friendly".



UPDATE

I have been informed by @MartijnPieters of the function collections._count_elements available in Python 3.

Help on built-in function _count_elements in module _collections:

_count_elements(...)
    _count_elements(mapping, iterable) -> None

    Count elements in the iterable, updating the mappping

This function is implemented in C, so it should be faster, but this extra performance comes at a price. The price is incompatibility with Python 2 and possibly even future versions, since we're using a private function.

From the documentation:

[...] a name prefixed with an underscore (e.g. _spam) should be treated as a non-public part of the API (whether it is a function, a method or a data member). It should be considered an implementation detail and subject to change without notice.

That said, if you still want to save those 620 nanoseconds per iteration:

>>> timeit('''
... d = {}
... _count_elements(d, s)
... ''', globals=locals())
1.229239897998923



UPDATE 2: Large strings

I thought it might be a good idea to re-run the tests on some larger input, since a 16 character string is such a small input that all the possible solutions were quite comparably fast (1,000 iterations in under 30 milliseconds).

I decided to use the complete works of Shakespeare as a testing corpus, which turned out to be quite a challenge (since it's over 5MiB in size ). I just used the first 100,000 characters of it, and I had to limit the number of iterations from 1,000,000 to 1,000.

import urllib.request
url = 'https://ocw.mit.edu/ans7870/6/6.006/s08/lecturenotes/files/t8.shakespeare.txt'
s = urllib.request.urlopen(url).read(100_000)

collections.Counter was really slow on a small input, but the tables have turned

Counter(s)

=> 7.63926783799991

Naïve T(n2) time dictionary comprehension simply doesn't work

{c: s.count(c) for c in s}

=> 15347.603935000052s (tested on 10 iterations; adjusted for 1000)

Smart T(n) time dictionary comprehension works fine

{c: s.count(c) for c in set(s)}

=> 8.882608592999986

Exceptions are clumsy and slow

d = {}
for c in s:
  try:
    d[c] += 1
  except KeyError:
    d[c] = 1

=> 21.26615508399982

Omitting the exception type check doesn't save time (since the exception is only thrown a few times)

d = {}
for c in s:
  try:
    d[c] += 1
  except:
    d[c] = 1

=> 21.943328911999743

dict.get looks nice but runs slow

d = {}
for c in s:
  d[c] = d.get(c, 0) + 1

=> 28.530086210000007

collections.defaultdict isn't very fast either

dd = defaultdict(int)
for c in s:
  dd[c] += 1

=> 19.43012963199999

dict.fromkeys requires reading the (very long) string twice

d = dict.fromkeys(s, 0)
for c in s:
  d[c] += 1

=> 22.70960557699999

Using list instead of dict is neither nice nor fast

counts = [0 for _ in range(256)]
for c in s:
  counts[ord(c)] += 1

d = {chr(i): count for i,count in enumerate(counts) if count != 0}

=> 26.535474792000002

Leaving out the final conversion to dict doesn't help

counts = [0 for _ in range(256)]
for c in s:
  counts[ord(c)] += 1

=> 26.27811567400005

It doesn't matter how you construct the list, since it's not the bottleneck

counts = [0] * 256
for c in s:
  counts[ord(c)] += 1

=> 25.863524940000048


counts = [0] * 256
for c in s:
  counts[ord(c)] += 1

d = {chr(i): count for i,count in enumerate(counts) if count != 0}

=> 26.416733378000004

If you convert list to dict the "smart" way, it's even slower (since you iterate over the string twice)

counts = [0] * 256
for c in s:
  counts[ord(c)] += 1

d = {c: counts[ord(c)] for c in set(s)}

=> 29.492915620000076

The dict.__contains__ variant may be fast for small strings, but not so much for big ones

d = {}
for c in s:
  if c in d:
    d[c] += 1
  else:
    d[c] = 1

=> 23.773295123000025

collections._count_elements is about as fast as collections.Counter (which uses _count_elements internally)

d = {}
_count_elements(d, s)

=> 7.5814381919999505


Final verdict: Use collections.Counter unless you cannot or don't want to :)



Appendix: NumPy

The numpy package provides a method numpy.unique which accomplishes (almost) precisely what we want.

The way this method works is very different from all the above methods:

  • It first sorts a copy of the input using Quicksort, which is an O(n2) time operation in the worst case, albeit O(n log n) on average and O(n) in the best case.

  • Then it creates a "mask" array containing True at indices where a run of the same values begins, viz. at indices where the value differs from the previous value. Repeated values produce False in the mask. Example: [5,5,5,8,9,9] produces a mask [True, False, False, True, True, False].

  • This mask is then used to extract the unique values from the sorted input - unique_chars in the code below. In our example, they would be [5, 8, 9].

  • Positions of the True values in the mask are taken into an array, and the length of the input is appended at the end of this array. For the above example, this array would be [0, 3, 4, 6].

  • For this array, differences between its elements are calculated, eg. [3, 1, 2]. These are the respective counts of the elements in the sorted array - char_counts in the code below.

  • Finally, we create a dictionary by zipping unique_chars and char_counts: {5: 3, 8: 1, 9: 2}.


import numpy as np

def count_chars(s):
  # The following statement needs to be changed for different input types.
  # Our input `s` is actually of type `bytes`, so we use `np.frombuffer`.
  # For inputs of type `str`, change `np.frombuffer` to `np.fromstring`
  #  or transform the input into a `bytes` instance.
  arr = np.frombuffer(s, dtype=np.uint8)

  unique_chars, char_counts = np.unique(arr, return_counts=True)

  return dict(zip(unique_chars, char_counts))

For the test input (first 100,000 characters of the complete works of Shakespeare), this method performs better than any other tested here. But note that on a different input, this approach might yield worse performance than the other methods. Pre-sortedness of the input and number of repetitions per element are important factors affecting the performance.

count_chars(s)

=> 2.960809530000006


If you are thinking about using this method because it's over twice as fast as collections.Counter, consider this:

  • collections.Counter has linear time complexity. numpy.unique is linear at best, quadratic at worst.

  • The speedup is not really that significant - you save ~3.5 milliseconds per iteration on an input of length 100,000.

  • Using numpy.unique obviously requires numpy.

That considered, it seems reasonable to use Counter unless you need to be really fast. And in that case, you better know what you're doing or else you'll end up being slower with numpy than without it.



Appendix 2: A somewhat useful plot

I ran the 13 different methods above on prefixes of the complete works of Shakespeare and made an interactive plot. Note that in the plot, both prefixes and durations are displayed in logarithmic scale (the used prefixes are of exponentially increasing length). Click on the items in the legend to show/hide them in the plot.

Interactive plot (click!)

Click to open!

How to get DateTime.Now() in YYYY-MM-DDThh:mm:ssTZD format using C#

use zzz instead of TZD

Example:

DateTime.Now.ToString("yyyy-MM-ddThh:mm:sszzz");

Response:

2011-08-09T11:50:00:02+02:00

How to check if a variable is empty in python?

See also this previous answer which recommends the not keyword

How to check if a list is empty in Python?

It generalizes to more than just lists:

>>> a = ""
>>> not a
True

>>> a = []
>>> not a
True

>>> a = 0
>>> not a
True

>>> a = 0.0
>>> not a
True

>>> a = numpy.array([])
>>> not a
True

Notably, it will not work for "0" as a string because the string does in fact contain something - a character containing "0". For that you have to convert it to an int:

>>> a = "0"
>>> not a
False

>>> a = '0'
>>> not int(a)
True

SQL Server: UPDATE a table by using ORDER BY

IF OBJECT_ID('tempdb..#TAB') IS NOT NULL
BEGIN
    DROP TABLE #TAB
END

CREATE TABLE #TAB(CH1 INT,CH2 INT,CH3 INT)

DECLARE @CH2 INT = NULL , @CH3 INT=NULL,@SPID INT=NULL,@SQL NVARCHAR(4000)='', @ParmDefinition NVARCHAR(50)= '',
@RET_MESSAGE AS VARCHAR(8000)='',@RET_ERROR INT=0


SET @ParmDefinition='@SPID INT,@CH2 INT OUTPUT,@CH3 INT OUTPUT'

SET @SQL='UPDATE T
            SET CH1=@SPID,@CH2= T.CH2,@CH3= T.CH3
            FROM #TAB T WITH(ROWLOCK)
            INNER JOIN (
                        SELECT TOP(1)  CH1,CH2,CH3
                        FROM
                        #TAB WITH(NOLOCK)
                        WHERE CH1 IS NULL
                        ORDER BY CH2 DESC) V ON T.CH2= V.CH2 AND T.CH3= V.CH3' 

INSERT INTO #TAB
(CH2 ,CH3 )
SELECT 1,2 UNION ALL
SELECT 2,3 UNION ALL
SELECT 3,4

BEGIN TRY
    WHILE EXISTS(SELECT TOP 1 1 FROM #TAB WHERE CH1 IS NULL)
    BEGIN

        EXECUTE @RET_ERROR = sp_executesql @SQL, @ParmDefinition,@SPID =@@SPID,  @CH2=@CH2 OUTPUT,@CH3=@CH3 OUTPUT;  

        SELECT * FROM #TAB
        SELECT @CH2,@CH3

    END

END TRY
BEGIN CATCH

    SET @RET_ERROR=ERROR_NUMBER()
    SET @RET_MESSAGE =  '@ERROR_NUMBER : ' + CAST(ERROR_NUMBER()  AS VARCHAR(255)) + '@ERROR_SEVERITY  :' + CAST( ERROR_SEVERITY()  AS VARCHAR(255)) 
    + '@ERROR_STATE :' + CAST(ERROR_STATE() AS VARCHAR(255)) + '@ERROR_LINE :' + CAST( ERROR_LINE() AS VARCHAR(255)) 
    +  '@ERROR_MESSAGE :' + ERROR_MESSAGE()  ;

    SELECT @RET_ERROR,@RET_MESSAGE;

END CATCH

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 set environment variables in Jenkins?

In my case, I had configure environment variables using the following option and it worked-

Manage Jenkins -> Configure System -> Global Properties -> Environment Variables -> Add

Read line by line in bash script

If you want to use each of the lines of the file as command-line params for your application you can use the xargs command.

xargs -a <params_file> <command>

A params file with:

a
b
c
d

and the file tr.py:

import sys
print sys.argv

The execution of

xargs -a params ./tr.py

gives the result:

['./tr.py', 'a', 'b', 'c', 'd']

Adding text to ImageView in Android

You can use the TextView for the same purpose, But if you want to use the same with the ImageView then you have to create a class and extends the ImageView then use onDraw() method to paint the text on to the canvas. for more details visit to http://developer.android.com/reference/android/graphics/Canvas.html

Show and hide divs at a specific time interval using jQuery

here is a jQuery plugin I came up with:

$.fn.cycle = function(timeout){
    var $all_elem = $(this)

    show_cycle_elem = function(index){
        if(index == $all_elem.length) return; //you can make it start-over, if you want
        $all_elem.hide().eq(index).fadeIn()
        setTimeout(function(){show_cycle_elem(++index)}, timeout);
    }
    show_cycle_elem(0);
}

You need to have a common classname for all the divs you wan to cycle, use it like this:

$("div.cycleme").cycle(5000)

Best way to check function arguments?

This checks the type of input arguments upon calling the function:

def func(inp1:int=0,inp2:str="*"):

    for item in func.__annotations__.keys():
        assert isinstance(locals()[item],func.__annotations__[item])

    return (something)

first=7
second="$"
print(func(first,second))

Also check with second=9 (it must give assertion error)

How to export data with Oracle SQL Developer?

In version 3, they changed "export" to "unload". It still functions more or less the same.

How can I use goto in Javascript?

const
    start = 0,
    more = 1,
    pass = 2,
    loop = 3,
    skip = 4,
    done = 5;

var label = start;


while (true){
    var goTo = null;
    switch (label){
        case start:
            console.log('start');
        case more:
            console.log('more');
        case pass:
            console.log('pass');
        case loop:
            console.log('loop');
            goTo = pass; break;
        case skip:
            console.log('skip');
        case done:
            console.log('done');

    }
    if (goTo == null) break;
    label = goTo;
}

Simultaneously merge multiple data.frames in a list

When you have a list of dfs, and a column contains the "ID", but in some lists, some IDs are missing, then you may use this version of Reduce / Merge in order to join multiple Dfs of missing Row Ids or labels:

Reduce(function(x, y) merge(x=x, y=y, by="V1", all.x=T, all.y=T), list_of_dfs)

How do I fix the error 'Named Pipes Provider, error 40 - Could not open a connection to' SQL Server'?

I have suggested below steps to resolve your issue How do I fix the error 'Named Pipes Provider, error 40 - Could not open a connection to' SQL Server'

  1. Check for working fine SQL Server Services services or not.
  2. Also check for working in good condition SQL Server (MSSQLSERVER).
  3. Also check for working fine SQL Server Browser.
  4. Delete all earlier Aliases, now create new aliases as per your requirements.
  5. Now check for working of SQL Server Default Port 1433
  6. Next click on Client Protocols in instance, then click on TCP/IP, now click on mouse right click, open the Property, here you can make assure your working fine your default port SQL 1433.
  7. Open your SQL Server Management Studio, then right click, click on "Property" option and then click on Connections tab, then finally tick for Allow remote Connections to this server.
  8. Check for right working or your Ping IP Host.

This action could not be completed. Try Again (-22421)

Flaky network connection ...

I've had this in the past and it eventually just fixed itself.
But this weekend I tried for days consecutively without success.
However, on a hunch, I've just had success now by changing to a different network and then submitting.

Get the ID of a drawable in ImageView

As of today, there is no support on this function. However, I found a little hack on this one.

 imageView.setImageResource(R.drawable.ic_star_black_48dp);
 imageView.setTag(R.drawable.ic_star_black_48dp);

So if you want to get the ID of the view, just get it's tag.

if (imageView.getTag() != null) {
   int resourceID = (int) imageView.getTag();

   //
   // drawable id.
   //   
}

Java NIO FileChannel versus FileOutputstream performance / usefulness

Answering the "usefulness" part of the question:

One rather subtle gotcha of using FileChannel over FileOutputStream is that performing any of its blocking operations (e.g. read() or write()) from a thread that's in interrupted state will cause the channel to close abruptly with java.nio.channels.ClosedByInterruptException.

Now, this could be a good thing if whatever the FileChannel was used for is part of the thread's main function, and design took this into account.

But it could also be pesky if used by some auxiliary feature such as a logging function. For example, you can find your logging output suddenly closed if the logging function happens to be called by a thread that's also interrupted.

It's unfortunate this is so subtle because not accounting for this can lead to bugs that affect write integrity.[1][2]

How do I check if an array includes a value in JavaScript?

This may be a detailed and easy solution.

//plain array
var arr = ['a', 'b', 'c'];
var check = arr.includes('a');
console.log(check); //returns true
if (check)
{
   // value exists in array
   //write some codes
}

// array with objects
var arr = [
      {x:'a', y:'b'},
      {x:'p', y:'q'}
  ];

// if you want to check if x:'p' exists in arr
var check = arr.filter(function (elm){
    if (elm.x == 'p')
    {
       return elm; // returns length = 1 (object exists in array)
    }
});

// or y:'q' exists in arr
var check = arr.filter(function (elm){
    if (elm.y == 'q')
    {
       return elm; // returns length = 1 (object exists in array)
    }
});

// if you want to check, if the entire object {x:'p', y:'q'} exists in arr
var check = arr.filter(function (elm){
    if (elm.x == 'p' && elm.y == 'q')
    {
       return elm; // returns length = 1 (object exists in array)
    }
});

// in all cases
console.log(check.length); // returns 1

if (check.length > 0)
{
   // returns true
   // object exists in array
   //write some codes
}

Regex pattern to match at least 1 number and 1 character in a string

Maybe a bit late, but this is my RE:

/^(\w*(\d+[a-zA-Z]|[a-zA-Z]+\d)\w*)+$/

Explanation:

\w* -> 0 or more alphanumeric digits, at the beginning

\d+[a-zA-Z]|[a-zA-Z]+\d -> a digit + a letter OR a letter + a digit

\w* -> 0 or more alphanumeric digits, again

I hope it was understandable

Keep only first n characters in a string?

You could use String.slice:

var str = '12345678value';
var strshortened = str.slice(0,8);
alert(strshortened); //=> '12345678'

Using this, a String extension could be:

String.prototype.truncate = String.prototype.truncate ||
  function (n){
    return this.slice(0,n);
  };
var str = '12345678value';
alert(str.truncate(8)); //=> '12345678'

See also

Java: How to access methods from another class

Maybe you need some dependency injection

public class Alpha {

    private Beta cbeta;

    public Alpha(Beta beta) {
        this.cbeta = beta;
    }

    public void DoSomethingAlpha() {
        this.cbeta.DoSomethingBeta();
    }
}

and then

Alpha cAlpha = new Alpha(new Beta());   

Find row in datatable with specific id

Make a string criteria to search for, like this:

string searchExpression = "ID = 5"

Then use the .Select() method of the DataTable object, like this:

DataRow[] foundRows = YourDataTable.Select(searchExpression);

Now you can loop through the results, like this:

int numberOfCalls;
bool result;
foreach(DataRow dr in foundRows)
{
    // Get value of Calls here
    result = Int32.TryParse(dr["Calls"], out numberOfCalls);

    // Optionally, you can check the result of the attempted try parse here
    // and do something if you wish
    if(result)
    {
        // Try parse to 32-bit integer worked

    }
    else
    {
        // Try parse to 32-bit integer failed

    }
}

Modulo operation with negative numbers

I believe it's more useful to think of mod as it's defined in abstract arithmetic; not as an operation, but as a whole different class of arithmetic, with different elements, and different operators. That means addition in mod 3 is not the same as the "normal" addition; that is; integer addition.

So when you do:

5 % -3

You are trying to map the integer 5 to an element in the set of mod -3. These are the elements of mod -3:

{ 0, -2, -1 }

So:

0 => 0, 1 => -2, 2 => -1, 3 => 0, 4 => -2, 5 => -1

Say you have to stay up for some reason 30 hours, how many hours will you have left of that day? 30 mod -24.

But what C implements is not mod, it's a remainder. Anyway, the point is that it does make sense to return negatives.

Converting a date string to a DateTime object using Joda Time library

I know this is an old question, but I wanted to add that, as of JodaTime 2.0, you can do this with a one-liner:

DateTime date = DateTime.parse("04/02/2011 20:27:05", 
                  DateTimeFormat.forPattern("dd/MM/yyyy HH:mm:ss"));

What is the actual use of Class.forName("oracle.jdbc.driver.OracleDriver") while connecting to a database?

An alternative would to use the jdbc.drivers System property to specify your required drivers(s) on the command line when you start the JVM.

How to programmatically set drawableLeft on Android button?

Worked for me. To set drawable at the right

tvBioLive.setCompoundDrawablesWithIntrinsicBounds(0, 0, R.drawable.ic_close_red_400_24dp, 0)

Passing a method parameter using Task.Factory.StartNew

For passing a single integer I agree with Reed Copsey's answer. If in the future you are going to pass more complicated constucts I personally like to pass all my variables as an Anonymous Type. It will look something like this:

foreach(int id in myIdsToCheck)
{
    Task.Factory.StartNew( (Object obj) => 
        {
           var data = (dynamic)obj;
           CheckFiles(data.id, theBlockingCollection,
               cancelCheckFile.Token, 
               TaskCreationOptions.LongRunning, 
               TaskScheduler.Default);
        }, new { id = id }); // Parameter value
}

You can learn more about it in my blog

Get date from input form within PHP

Validate the INPUT.

$time = strtotime($_POST['dateFrom']);
if ($time) {
  $new_date = date('Y-m-d', $time);
  echo $new_date;
} else {
   echo 'Invalid Date: ' . $_POST['dateFrom'];
  // fix it.
}

VBA for filtering columns

Here's a different approach. The heart of it was created by turning on the Macro Recorder and filtering the columns per your specifications. Then there's a bit of code to copy the results. It will run faster than looping through each row and column:

Sub FilterAndCopy()
Dim LastRow As Long

Sheets("Sheet2").UsedRange.Offset(0).ClearContents
With Worksheets("Sheet1")
    .Range("$A:$E").AutoFilter
    .Range("$A:$E").AutoFilter field:=1, Criteria1:="#N/A"
    .Range("$A:$E").AutoFilter field:=2, Criteria1:="=String1", Operator:=xlOr, Criteria2:="=string2"
    .Range("$A:$E").AutoFilter field:=3, Criteria1:=">0"
    .Range("$A:$E").AutoFilter field:=5, Criteria1:="Number"
    LastRow = .Range("A" & .Rows.Count).End(xlUp).Row
    .Range("A1:A" & LastRow).SpecialCells(xlCellTypeVisible).EntireRow.Copy _
            Destination:=Sheets("Sheet2").Range("A1")
End With
End Sub

As a side note, your code has more loops and counter variables than necessary. You wouldn't need to loop through the columns, just through the rows. You'd then check the various cells of interest in that row, much like you did.

MessageBox with YesNoCancel - No & Cancel triggers same event

This should work fine:

Dim result As DialogResult = MessageBox.Show("message", "caption", MessageBoxButtons.YesNoCancel)
If result = DialogResult.Cancel Then
    MessageBox.Show("Cancel pressed")
ElseIf result = DialogResult.No Then
    MessageBox.Show("No pressed")
ElseIf result = DialogResult.Yes Then
    MessageBox.Show("Yes pressed")
End If

Rails how to run rake task

If you aren't sure how to run a rake task, first find out first what tasks you have and it will also list the commands to run the tasks.

Run rake --tasks on the terminal.

It will list the tasks like the following:

rake gobble:dev:prime             
rake gobble:dev:reset_number_of_kits                                    
rake gobble:dev:scrub_prod_data

You can then run your task with: rake gobble:dev:prime as listed.

How to Right-align flex item?

As easy as

.main {
    display: flex;
    flex-direction:row-reverse;
}

How to print jquery object/array

var arrofobject = [{"id":"197","category":"Damskie"},{"id":"198","category":"M\u0119skie"}];

$.each(arrofobject, function(index, val) {
    console.log(val.category);
});

Send and receive messages through NSNotificationCenter in Objective-C?

SWIFT 5.1 of selected answer for newbies

class TestClass {
    deinit {
        // If you don't remove yourself as an observer, the Notification Center
        // will continue to try and send notification objects to the deallocated
        // object.
        NotificationCenter.default.removeObserver(self)
    }

    init() {
        super.init()

        // Add this instance of TestClass as an observer of the TestNotification.
        // We tell the notification center to inform us of "TestNotification"
        // notifications using the receiveTestNotification: selector. By
        // specifying object:nil, we tell the notification center that we are not
        // interested in who posted the notification. If you provided an actual
        // object rather than nil, the notification center will only notify you
        // when the notification was posted by that particular object.

        NotificationCenter.default.addObserver(self, selector: #selector(receiveTest(_:)), name: NSNotification.Name("TestNotification"), object: nil)
    }

    @objc func receiveTest(_ notification: Notification?) {
        // [notification name] should always be @"TestNotification"
        // unless you use this method for observation of other notifications
        // as well.

        if notification?.name.isEqual(toString: "TestNotification") != nil {
            print("Successfully received the test notification!")
        }
    }
}

... somewhere else in another class ...

 func someMethod(){
        // All instances of TestClass will be notified
        NotificationCenter.default.post(name: NSNotification.Name(rawValue: "TestNotification"), object: self)
 }

Proxy with urllib2

In Addition to the accepted answer: My scipt gave me an error

File "c:\Python23\lib\urllib2.py", line 580, in proxy_open
    if '@' in host:
TypeError: iterable argument required

Solution was to add http:// in front of the proxy string:

proxy = urllib2.ProxyHandler({'http': 'http://proxy.xy.z:8080'})
opener = urllib2.build_opener(proxy)
urllib2.install_opener(opener)
urllib2.urlopen('http://www.google.com')

Using Lato fonts in my css (@font-face)

Font Squirrel has a wonderful web font generator.

I think you should find what you need here to generate OTF fonts and the needed CSS to use them. It will even support older IE versions.

How do I make a JAR from a .java file?

This can be done without terminal, directly from IDE. Netbeans, for example.

  1. Create a separate project with packages (Create Project - Java - Java Class Library).
  2. Put your .java classes there.
  3. Build this project.
  4. Go to your project folder and find build and dist folders there.
  5. Find .jar file in your dist folder.
  6. Get your other project and add this .jar file to project libraries.
  7. You can now reference classes from this library and its methods directly from code, if import is automatically done for you.

Change navbar text color Bootstrap

Make it the following:

.nav.navbar-nav.navbar-right li a {
    color: blue;
}

The above will target the specific links, which is what you want, versus styling the entire list blue, which is what you were initially doing. Here is a JsFiddle.

The other way would be creating another class and implementing it like so:

HTML

<li><a href="#" class="color-me"><span class="glyphicon glyphicon-list-alt"></span> R&eacute;sum&eacute;</a></li>

CSS

.color-me{
    color:blue;
}

Also demonstrated in this JsFiddle

ASP.NET MVC Html.ValidationSummary(true) does not display model errors

In my case it was not working because of the return.

Instead of using:

return RedirectToAction("Rescue", "CarteiraEtapaInvestimento", new { id = investimento.Id, idCarteiraEtapaResgate = etapaDoResgate.Id });

I used:

return View("ViewRescueCarteiraEtapaInvestimento", new CarteiraEtapaInvestimentoRescueViewModel { Investimento = investimento, ValorResgate = investimentoViewModel.ValorResgate });

It´s a Model, so it is obvius that ModelState.AddModelError("keyName","Message"); must work with a model.

This answer show why. Adding validation with DataAnnotations

How to dismiss a Twitter Bootstrap popover by clicking outside?

Most simple, most fail safe version, works with any bootstrap version.

Demo: http://jsfiddle.net/guya/24mmM/

Demo 2: Not dismissing when clicking inside the popover content http://jsfiddle.net/guya/fjZja/

Demo 3: Multiple popovers: http://jsfiddle.net/guya/6YCjW/


Simply calling this line will dismiss all popovers:

$('[data-original-title]').popover('hide');

Dismiss all popovers when clicking outside with this code:

$('html').on('click', function(e) {
  if (typeof $(e.target).data('original-title') == 'undefined') {
    $('[data-original-title]').popover('hide');
  }
});

The snippet above attach a click event on the body. When the user click on a popover, it'll behave as normal. When the user click on something that is not a popover it'll close all popovers.

It'll also work with popovers that are initiated with Javascript, as opposed to some other examples that will not work. (see the demo)

If you don't want to dismiss when clicking inside the popover content, use this code (see link to 2nd demo):

$('html').on('click', function(e) {
  if (typeof $(e.target).data('original-title') == 'undefined' && !$(e.target).parents().is('.popover.in')) {
    $('[data-original-title]').popover('hide');
  }
});