Programs & Examples On #Scala 2.7

For issues relating to development with Scala, version 2.7.

ggplot geom_text font size control

Here are a few options for changing text / label sizes

library(ggplot2)

# Example data using mtcars

a <- aggregate(mpg ~ vs + am , mtcars, function(i) round(mean(i)))

p <- ggplot(mtcars, aes(factor(vs), y=mpg, fill=factor(am))) + 
            geom_bar(stat="identity",position="dodge") + 
            geom_text(data = a, aes(label = mpg), 
                            position = position_dodge(width=0.9),  size=20)

The size in the geom_text changes the size of the geom_text labels.

p <- p + theme(axis.text = element_text(size = 15)) # changes axis labels

p <- p + theme(axis.title = element_text(size = 25)) # change axis titles

p <- p + theme(text = element_text(size = 10)) # this will change all text size 
                                                             # (except geom_text)


For this And why size of 10 in geom_text() is different from that in theme(text=element_text()) ?

Yes, they are different. I did a quick manual check and they appear to be in the ratio of ~ (14/5) for geom_text sizes to theme sizes.

So a horrible fix for uniform sizes is to scale by this ratio

geom.text.size = 7
theme.size = (14/5) * geom.text.size

ggplot(mtcars, aes(factor(vs), y=mpg, fill=factor(am))) + 
  geom_bar(stat="identity",position="dodge") + 
  geom_text(data = a, aes(label = mpg), 
            position = position_dodge(width=0.9),  size=geom.text.size) + 
  theme(axis.text = element_text(size = theme.size, colour="black")) 

This of course doesn't explain why? and is a pita (and i assume there is a more sensible way to do this)

Delete files older than 3 months old in a directory using .NET

An SSIS type of example .. (if this helps anyone)

          public void Main()
          {
                 // TODO: Add your code here
        // Author: Allan F 10th May 2019

        //first part of process .. put any files of last Qtr (or older) in Archive area 
        //e.g. if today is 10May2019 then last quarter is 1Jan2019 to 31March2019 .. any files earlier than 31March2019 will be archived

        //string SourceFileFolder = "\\\\adlsaasf11\\users$\\aford05\\Downloads\\stage\\";
        string SourceFilesFolder = (string)Dts.Variables["SourceFilesFolder"].Value;
        string ArchiveFolder = (string)Dts.Variables["ArchiveFolder"].Value;
        string FilePattern = (string)Dts.Variables["FilePattern"].Value;
        string[] files = Directory.GetFiles(SourceFilesFolder, FilePattern);

        //DateTime date = new DateTime(2019, 2, 15);//commented out line .. just for testing the dates .. 

        DateTime date = DateTime.Now;
        int quarterNumber = (date.Month - 1) / 3 + 1;
        DateTime firstDayOfQuarter = new DateTime(date.Year, (quarterNumber - 1) * 3 + 1, 1);
        DateTime lastDayOfQuarter = firstDayOfQuarter.AddMonths(3).AddDays(-1);

        DateTime LastDayOfPriorQuarter = firstDayOfQuarter.AddDays(-1);
        int PrevQuarterNumber = (LastDayOfPriorQuarter.Month - 1) / 3 + 1;
        DateTime firstDayOfLastQuarter = new DateTime(LastDayOfPriorQuarter.Year, (PrevQuarterNumber - 1) * 3 + 1, 1);
        DateTime lastDayOfLastQuarter = firstDayOfLastQuarter.AddMonths(3).AddDays(-1);

        //MessageBox.Show("debug pt2: firstDayOfQuarter" + firstDayOfQuarter.ToString("dd/MM/yyyy"));
        //MessageBox.Show("debug pt2: firstDayOfLastQuarter" + firstDayOfLastQuarter.ToString("dd/MM/yyyy"));


        foreach (string file in files)
        {
            FileInfo fi = new FileInfo(file);

            //MessageBox.Show("debug pt2:" + fi.Name + " " + fi.CreationTime.ToString("dd/MM/yyyy HH:mm") + " " + fi.LastAccessTime.ToString("dd/MM/yyyy HH:mm") + " " + fi.LastWriteTime.ToString("dd/MM/yyyy HH:mm"));
            if (fi.LastWriteTime < firstDayOfQuarter)
            {

                try
                {

                    FileInfo fi2 = new FileInfo(ArchiveFolder);

                    //Ensure that the target does not exist.
                    //fi2.Delete();

                    //Copy the file.
                    fi.CopyTo(ArchiveFolder + fi.Name);
                    //Console.WriteLine("{0} was copied to {1}.", path, ArchiveFolder);

                    //Delete the old location file.
                    fi.Delete();
                    //Console.WriteLine("{0} was successfully deleted.", ArchiveFolder);

                }
                catch (Exception e)
                {
                    //do nothing
                    //Console.WriteLine("The process failed: {0}", e.ToString());
                }
            }
        }

        //second part of process .. delete any files in Archive area dated earlier than last qtr ..
        //e.g. if today is 10May2019 then last quarter is 1Jan2019 to 31March2019 .. any files earlier than 1Jan2019 will be deleted

        string[] archivefiles = Directory.GetFiles(ArchiveFolder, FilePattern);
        foreach (string archivefile in archivefiles)
        {
            FileInfo fi = new FileInfo(archivefile);
            if (fi.LastWriteTime < firstDayOfLastQuarter )
            {
                try
                {
                    fi.Delete();
                }
                catch (Exception e)
                {
                    //do nothing
                }
            }
        }


                 Dts.TaskResult = (int)ScriptResults.Success;
          }

Converting string from snake_case to CamelCase in Ruby

I feel a little uneasy to add more answers here. Decided to go for the most readable and minimal pure ruby approach, disregarding the nice benchmark from @ulysse-bn. While :class mode is a copy of @user3869936, the :method mode I don't see in any other answer here.

  def snake_to_camel_case(str, mode: :class)
    case mode
    when :class
      str.split('_').map(&:capitalize).join
    when :method
      str.split('_').inject { |m, p| m + p.capitalize }
    else
      raise "unknown mode #{mode.inspect}"
    end
  end

Result is:

[28] pry(main)> snake_to_camel_case("asd_dsa_fds", mode: :class)
=> "AsdDsaFds"
[29] pry(main)> snake_to_camel_case("asd_dsa_fds", mode: :method)
=> "asdDsaFds"

ALTER DATABASE failed because a lock could not be placed on database

In my scenario, there was no process blocking the database under sp_who2. However, we discovered because the database is much larger than our other databases that pending processes were still running which is why the database under the availability group still displayed as red/offline after we tried to 'resume data'by right clicking the paused database.

To check if you still have processes running just execute this command: select percent complete from sys.dm_exec_requests where percent_complete > 0

window.location.href not working

Try this

`var url = "http://stackoverflow.com";    
$(location).attr('href',url);`

Or you can do something like this

// similar behavior as an HTTP redirect
window.location.replace("http://stackoverflow.com");

// similar behavior as clicking on a link
window.location.href = "http://stackoverflow.com";

and add a return false at the end of your function call

Accessing members of items in a JSONArray with Java

In case it helps someone else, I was able to convert to an array by doing something like this,

JSONObject jsonObject = (JSONObject)new JSONParser().parse(jsonString);
((JSONArray) jsonObject).toArray()

...or you should be able to get the length

((JSONArray) myJsonArray).toArray().length

Clone only one branch

From the announcement Git 1.7.10 (April 2012):

  • git clone learned --single-branch option to limit cloning to a single branch (surprise!); tags that do not point into the history of the branch are not fetched.

Git actually allows you to clone only one branch, for example:

git clone -b mybranch --single-branch git://sub.domain.com/repo.git

Note: Also you can add another single branch or "undo" this action.

Ruby Hash to array of values

There is also this one:

hash = { foo: "bar", baz: "qux" }
hash.map(&:last) #=> ["bar", "qux"]

Why it works:

The & calls to_proc on the object, and passes it as a block to the method.

something {|i| i.foo }
something(&:foo)

Iterating each character in a string using Python

If you ever run in a situation where you need to get the next char of the word using __next__(), remember to create a string_iterator and iterate over it and not the original string (it does not have the __next__() method)

In this example, when I find a char = [ I keep looking into the next word while I don't find ], so I need to use __next__

here a for loop over the string wouldn't help

myString = "'string' 4 '['RP0', 'LC0']' '[3, 4]' '[3, '4']'"
processedInput = ""
word_iterator = myString.__iter__()
for idx, char in enumerate(word_iterator):
    if char == "'":
        continue

    processedInput+=char

    if char == '[':
        next_char=word_iterator.__next__()
        while(next_char != "]"):
          processedInput+=next_char
          next_char=word_iterator.__next__()
        else:
          processedInput+=next_char

Sort matrix according to first column in R

Creating a data.table with key=V1 automatically does this for you. Using Stephan's data foo

> require(data.table)
> foo.dt <- data.table(foo, key="V1")
> foo.dt
   V1  V2
1:  1 349
2:  1 393
3:  1 392
4:  2  94
5:  3  49
6:  3  32
7:  4 459

Read and write a text file in typescript

import * as fs from 'fs';
import * as path from 'path';

fs.readFile(path.join(__dirname, "filename.txt"), (err, data) => {
    if (err) throw err;
    console.log(data);
})

EDIT:

consider the project structure:

../readfile/
+-- filename.txt
+-- src
    +-- index.js
    +-- index.ts

consider the index.ts:

import * as fs from 'fs';
import * as path from 'path';

function lookFilesInDirectory(path_directory) {
    fs.stat(path_directory, (err, stat) => {
        if (!err) {
            if (stat.isDirectory()) {
                console.log(path_directory)
                fs.readdirSync(path_directory).forEach(file => {
                    console.log(`\t${file}`);
                });
                console.log();
            }
        }
    });
}

let path_view = './';
lookFilesInDirectory(path_view);
lookFilesInDirectory(path.join(__dirname, path_view));

if you have in the readfile folder and run tsc src/index.ts && node src/index.js, the output will be:

./
        filename.txt
        src

/home/andrei/scripts/readfile/src/
        index.js
        index.ts

that is, it depends on where you run the node.

the __dirname is directory name of the current module.

Is there a 'box-shadow-color' property?

Actually… there is! Sort of. box-shadow defaults to color, just like border does.

According to http://dev.w3.org/.../#the-box-shadow

The color is the color of the shadow. If the color is absent, the used color is taken from the ‘color’ property.

In practice, you have to change the color property and leave box-shadow without a color:

box-shadow: 1px 2px 3px;
color: #a00;

Support

  • Safari 6+
  • Chrome 20+ (at least)
  • Firefox 13+ (at least)
  • IE9+ (IE8 doesn't support box-shadow at all)

Demo

_x000D_
_x000D_
div {_x000D_
    box-shadow: 0 0 50px;_x000D_
    transition: 0.3s color;_x000D_
}_x000D_
.green {_x000D_
    color: green;_x000D_
}_x000D_
.red {_x000D_
    color: red;_x000D_
}_x000D_
div:hover {_x000D_
    color: yellow;_x000D_
}_x000D_
_x000D_
/*demo style*/_x000D_
body {_x000D_
    text-align: center;_x000D_
}_x000D_
div {_x000D_
    display: inline-block;_x000D_
    background: white;_x000D_
    height: 100px;_x000D_
    width: 100px;_x000D_
    margin: 30px;_x000D_
    border-radius: 50%;_x000D_
}
_x000D_
<div class="green"></div>_x000D_
<div class="red"></div>
_x000D_
_x000D_
_x000D_

The bug mentioned in the comment below has since been fixed :)

pointer to array c++

The parenthesis are superfluous in your example. The pointer doesn't care whether there's an array involved - it only knows that its pointing to an int

  int g[] = {9,8};
  int (*j) = g;

could also be rewritten as

  int g[] = {9,8};
  int *j = g;

which could also be rewritten as

  int g[] = {9,8};
  int *j = &g[0];

a pointer-to-an-array would look like

  int g[] = {9,8};
  int (*j)[2] = &g;

  //Dereference 'j' and access array element zero
  int n = (*j)[0];

There's a good read on pointer declarations (and how to grok them) at this link here: http://www.codeproject.com/Articles/7042/How-to-interpret-complex-C-C-declarations

How to rename with prefix/suffix?

In Bash and zsh you can do this with Brace Expansion. This simply expands a list of items in braces. For example:

# echo {vanilla,chocolate,strawberry}-ice-cream
vanilla-ice-cream chocolate-ice-cream strawberry-ice-cream

So you can do your rename as follows:

mv {,new.}original.filename

as this expands to:

mv original.filename new.original.filename

Change the background color of a pop-up dialog

Use setInverseBackgroundForced(true) on the alert dialog builder to invert the background.

Install .ipa to iPad with or without iTunes

You can go to the browser in Iphone/Ipad and type the URl where the IPA has been uploaded and can directly download it to your Iphone or Ipad and install and run it.... simple and sweet ;)

Check if a row exists, otherwise insert

Full solution is below (including cursor structure). Many thanks to Cassius Porcus for the begin trans ... commit code from posting above.

declare @mystat6 bigint
declare @mystat6p varchar(50)
declare @mystat6b bigint

DECLARE mycur1 CURSOR for

 select result1,picture,bittot from  all_Tempnogos2results11

 OPEN mycur1

 FETCH NEXT FROM mycur1 INTO @mystat6, @mystat6p , @mystat6b

 WHILE @@Fetch_Status = 0
 BEGIN

 begin tran /* default read committed isolation level is fine */

 if not exists (select * from all_Tempnogos2results11_uniq with (updlock, rowlock, holdlock)
                     where all_Tempnogos2results11_uniq.result1 = @mystat6 
                        and all_Tempnogos2results11_uniq.bittot = @mystat6b )
     insert all_Tempnogos2results11_uniq values (@mystat6 , @mystat6p , @mystat6b)

 --else
 --  /* update */

 commit /* locks are released here */

 FETCH NEXT FROM mycur1 INTO @mystat6 , @mystat6p , @mystat6b

 END

 CLOSE mycur1

 DEALLOCATE mycur1
 go

How can I create an Asynchronous function in Javascript?

This page walks you through the basics of creating an async javascript function.

Since ES2017, asynchronous javacript functions are much easier to write. You should also read more on Promises.

Java constant examples (Create a java file having only constants)

Neither one. Use final class for Constants declare them as public static final and static import all constants wherever necessary.

public final class Constants {

    private Constants() {
            // restrict instantiation
    }

    public static final double PI = 3.14159;
    public static final double PLANCK_CONSTANT = 6.62606896e-34;
}

Usage :

import static Constants.PLANCK_CONSTANT;
import static Constants.PI;//import static Constants.*;

public class Calculations {

        public double getReducedPlanckConstant() {
                return PLANCK_CONSTANT / (2 * PI);
        }
}

See wiki link : http://en.wikipedia.org/wiki/Constant_interface

How can you search Google Programmatically Java API

Indeed there is an API to search google programmatically. The API is called google custom search. For using this API, you will need an Google Developer API key and a cx key. A simple procedure for accessing google search from java program is explained in my blog.

Now dead, here is the Wayback Machine link.

Laravel Request::all() Should Not Be Called Statically

i make it work with a scope definition

public function pagar(\Illuminate\Http\Request $request) { //

Loop in Jade (currently known as "Pug") template engine

Using node I have a collection of stuff @stuff and access it like this:

- each stuff in stuffs
  p
    = stuff.sentence

Java Multithreading concept and join() method

join() is a instance method of java.lang.Thread class which we can use join() method to ensure all threads that started from main must end in order in which they started and also main should end in last. In other words waits for this thread to die.

Exception: join() method throws InterruptedException.

Thread state: When join() method is called on thread it goes from running to waiting state. And wait for thread to die.

synchronized block: Thread need not to acquire object lock before calling join() method i.e. join() method can be called from outside synchronized block.

Waiting time: join(): Waits for this thread to die.

public final void join() throws InterruptedException;

This method internally calls join(0). And timeout of 0 means to wait forever;

join(long millis) – synchronized method Waits at most millis milliseconds for this thread to die. A timeout of 0 means to wait forever.

public final synchronized void join(long millis)
    throws InterruptedException;

public final synchronized void join(long millis, int nanos)
    throws InterruptedException;

Example of join method

class MyThread implements Runnable {
     public void run() {
           String threadName = Thread.currentThread().getName();
           Printer.print("run() method of "+threadName);
           for(int i=0;i<4;i++){
                Printer.print("i="+i+" ,Thread="+threadName);
           }         
     }
}

public class TestJoin {
     public static void main(String...args) throws InterruptedException {
           Printer.print("start main()...");

           MyThread runnable = new MyThread();
           Thread thread1=new Thread(runnable);
           Thread thread2=new Thread(runnable);

           thread1.start();
           thread1.join();

           thread2.start();
           thread2.join();

           Printer.print("end main()");
     }
}

class Printer {
     public static void print(String str) {
           System.out.println(str);
     }
}

Output:
     start main()...
     run() method of Thread-0
     i=0 ,Thread=Thread-0
     i=1 ,Thread=Thread-0
     i=2 ,Thread=Thread-0
     i=3 ,Thread=Thread-0
     run() method of Thread-1
     i=0 ,Thread=Thread-1
     i=1 ,Thread=Thread-1
     i=2 ,Thread=Thread-1
     i=3 ,Thread=Thread-1
     end main()

Note: calling thread1.join() made main thread to wait until Thread-1 dies.

Let’s check a program to use join(long millis)

First, join(1000) will be called on Thread-1, but once 1000 millisec are up, main thread can resume and start thread2 (main thread won’t wait for Thread-1 to die).

class MyThread implements Runnable {
     public void run() {
           String threadName = Thread.currentThread().getName();
           Printer.print("run() method of "+threadName);
           for(int i=0;i<4;i++){
                try {
                     Thread.sleep(500);
                } catch (InterruptedException e) {
                     e.printStackTrace();
                }
                Printer.print("i="+i+" ,Thread="+threadName);
           }         
     }
}

public class TestJoin {
     public static void main(String...args) throws InterruptedException {
           Printer.print("start main()...");

           MyThread runnable = new MyThread();
           Thread thread1=new Thread(runnable);
           Thread thread2=new Thread(runnable);

           thread1.start();

           // once 1000 millisec are up,
           // main thread can resume and start thread2.
           thread1.join(1000);

           thread2.start();
           thread2.join();

           Printer.print("end main()");
     }
}

class Printer {
     public static void print(String str) {
           System.out.println(str);
     }
}

Output:
     start main()...
     run() method of Thread-0
     i=0 ,Thread=Thread-0
     run() method of Thread-1
     i=1 ,Thread=Thread-0
     i=2 ,Thread=Thread-0
     i=0 ,Thread=Thread-1
     i=1 ,Thread=Thread-1
     i=3 ,Thread=Thread-0
     i=2 ,Thread=Thread-1
     i=3 ,Thread=Thread-1
     end main()

For more information see my blog:

http://javaexplorer03.blogspot.in/2016/05/join-method-in-java.html

What do 1.#INF00, -1.#IND00 and -1.#IND mean?

From IEEE floating-point exceptions in C++ :

This page will answer the following questions.

  • My program just printed out 1.#IND or 1.#INF (on Windows) or nan or inf (on Linux). What happened?
  • How can I tell if a number is really a number and not a NaN or an infinity?
  • How can I find out more details at runtime about kinds of NaNs and infinities?
  • Do you have any sample code to show how this works?
  • Where can I learn more?

These questions have to do with floating point exceptions. If you get some strange non-numeric output where you're expecting a number, you've either exceeded the finite limits of floating point arithmetic or you've asked for some result that is undefined. To keep things simple, I'll stick to working with the double floating point type. Similar remarks hold for float types.

Debugging 1.#IND, 1.#INF, nan, and inf

If your operation would generate a larger positive number than could be stored in a double, the operation will return 1.#INF on Windows or inf on Linux. Similarly your code will return -1.#INF or -inf if the result would be a negative number too large to store in a double. Dividing a positive number by zero produces a positive infinity and dividing a negative number by zero produces a negative infinity. Example code at the end of this page will demonstrate some operations that produce infinities.

Some operations don't make mathematical sense, such as taking the square root of a negative number. (Yes, this operation makes sense in the context of complex numbers, but a double represents a real number and so there is no double to represent the result.) The same is true for logarithms of negative numbers. Both sqrt(-1.0) and log(-1.0) would return a NaN, the generic term for a "number" that is "not a number". Windows displays a NaN as -1.#IND ("IND" for "indeterminate") while Linux displays nan. Other operations that would return a NaN include 0/0, 0*8, and 8/8. See the sample code below for examples.

In short, if you get 1.#INF or inf, look for overflow or division by zero. If you get 1.#IND or nan, look for illegal operations. Maybe you simply have a bug. If it's more subtle and you have something that is difficult to compute, see Avoiding Overflow, Underflow, and Loss of Precision. That article gives tricks for computing results that have intermediate steps overflow if computed directly.

Lining up labels with radio buttons in bootstrap

Key insights for me were: - ensure that label content comes after the input-radio field - I tweaked my css to make everything a little closer

.radio-inline+.radio-inline {
    margin-left: 5px;
}

How do I find out which computer is the domain controller in Windows programmatically?

In C#/.NET 3.5 you could write a little program to do:

using (PrincipalContext context = new PrincipalContext(ContextType.Domain))
{
    string controller = context.ConnectedServer;
    Console.WriteLine( "Domain Controller:" + controller );
} 

This will list all the users in the current domain:

using (PrincipalContext context = new PrincipalContext(ContextType.Domain))
{
    using (UserPrincipal searchPrincipal = new UserPrincipal(context))
    {
       using (PrincipalSearcher searcher = new PrincipalSearcher(searchPrincipal))
       {
           foreach (UserPrincipal principal in searcher.FindAll())
           {
               Console.WriteLine( principal.SamAccountName);
           }
       }
    }
}

How do I hide an element on a click event anywhere outside of the element?

Try this, it's working perfect for me.

$(document).mouseup(function (e)
{
    var searchcontainer = $("#search_container");

    if (!searchcontainer.is(e.target) // if the target of the click isn't the container...
        && searchcontainer.has(e.target).length === 0) // ... nor a descendant of the container
    {
        searchcontainer.hide();
    }
});

Postgresql SELECT if string contains

A proper way to search for a substring is to use position function instead of like expression, which requires escaping %, _ and an escape character (\ by default):

SELECT id FROM TAG_TABLE WHERE position(tag_name in 'aaaaaaaaaaa')>0;

Getting the parent div of element

The property pDoc.parentElement or pDoc.parentNode will get you the parent element.

Java: String - add character n-times

In addition to the answers above, you should initialize the StringBuilder with an appropriate capacity, especially that you already know it. For example:

int capacity = existingString.length() + n * appendableString.length();
StringBuilder builder = new StringBuilder(capacity);

Strip first and last character from C string

Further to @pmg's answer, note that you can do both operations in one statement:

char mystr[] = "Nmy stringP";
char *p = mystr;
p++[strlen(p)-1] = 0;

This will likely work as expected but behavior is undefined in C standard.

Change the jquery show()/hide() animation?

There are the slideDown, slideUp, and slideToggle functions native to jquery 1.3+, and they work quite nicely...

https://api.jquery.com/category/effects/

You can use slideDown just like this:

$("test").slideDown("slow");

And if you want to combine effects and really go nuts I'd take a look at the animate function which allows you to specify a number of CSS properties to shape tween or morph into. Pretty fancy stuff, that.

Access Https Rest Service using Spring RestTemplate

You need to configure a raw HttpClient with SSL support, something like this:

@Test
public void givenAcceptingAllCertificatesUsing4_4_whenUsingRestTemplate_thenCorrect() 
throws ClientProtocolException, IOException {
    CloseableHttpClient httpClient
      = HttpClients.custom()
        .setSSLHostnameVerifier(new NoopHostnameVerifier())
        .build();
    HttpComponentsClientHttpRequestFactory requestFactory 
      = new HttpComponentsClientHttpRequestFactory();
    requestFactory.setHttpClient(httpClient);

    ResponseEntity<String> response 
      = new RestTemplate(requestFactory).exchange(
      urlOverHttps, HttpMethod.GET, null, String.class);
    assertThat(response.getStatusCode().value(), equalTo(200));
}

font: Baeldung

Insert current date/time using now() in a field using MySQL/PHP

The only reason I can think of is you are adding it as string 'now()', not function call now().
Or whatever else typo.

SELECT NOW();

to see if it returns correct value?

SVG gradient using CSS

2019 Answer

With brand new css properties you can have even more flexibility with variables aka custom properties

_x000D_
_x000D_
.shape {
  width:500px;
  height:200px;
}

.shape .gradient-bg {
  fill: url(#header-shape-gradient) #fff;
}

#header-shape-gradient {
  --color-stop: #f12c06;
  --color-bot: #faed34;
}
_x000D_
<svg viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg" preserveAspectRatio="none" class="shape">
  <defs>
    <linearGradient id="header-shape-gradient" x2="0.35" y2="1">
        <stop offset="0%" stop-color="var(--color-stop)" />
        <stop offset="30%" stop-color="var(--color-stop)" />
        <stop offset="100%" stop-color="var(--color-bot)" />
      </linearGradient>
  </defs>
  <g>
    <polygon class="gradient-bg" points="0,0 100,0 0,66" />
  </g>
</svg>
_x000D_
_x000D_
_x000D_

Just set a named variable for each stop in gradient and then customize as you like in css. You can even change their values dynamically with javascript, like:

document.querySelector('#header-shape-gradient').style.setProperty('--color-stop', "#f5f7f9");

Pandas sort by group aggregate and column

Here's a more concise approach...

df['a_bsum'] = df.groupby('A')['B'].transform(sum)
df.sort(['a_bsum','C'], ascending=[True, False]).drop('a_bsum', axis=1)

The first line adds a column to the data frame with the groupwise sum. The second line performs the sort and then removes the extra column.

Result:

    A       B           C
5   baz     -2.301539   True
2   baz     -0.528172   False
1   bar     -0.611756   True
4   bar      0.865408   False
3   foo     -1.072969   True
0   foo      1.624345   False

NOTE: sort is deprecated, use sort_values instead

How can I determine the type of an HTML element in JavaScript?

Sometimes you want element.constructor.name

document.createElement('div').constructor.name
// HTMLDivElement

document.createElement('a').constructor.name
// HTMLAnchorElement

document.createElement('foo').constructor.name
// HTMLUnknownElement

How to Generate unique file names in C#

I have been using the following code and its working fine. I hope this might help you.

I begin with a unique file name using a timestamp -

"context_" + DateTime.Now.ToString("yyyyMMddHHmmssffff")

C# code -

public static string CreateUniqueFile(string logFilePath, string logFileName, string fileExt)
    {
        try
        {
            int fileNumber = 1;

            //prefix with . if not already provided
            fileExt = (!fileExt.StartsWith(".")) ? "." + fileExt : fileExt;

            //Generate new name
            while (File.Exists(Path.Combine(logFilePath, logFileName + "-" + fileNumber.ToString() + fileExt)))
                fileNumber++;

            //Create empty file, retry until one is created
            while (!CreateNewLogfile(logFilePath, logFileName + "-" + fileNumber.ToString() + fileExt))
                fileNumber++;

            return logFileName + "-" + fileNumber.ToString() + fileExt;
        }
        catch (Exception)
        {
            throw;
        }
    }

    private static bool CreateNewLogfile(string logFilePath, string logFile)
    {
        try
        {
            FileStream fs = new FileStream(Path.Combine(logFilePath, logFile), FileMode.CreateNew);
            fs.Close();
            return true;
        }
        catch (IOException)   //File exists, can not create new
        {
            return false;
        }
        catch (Exception)     //Exception occured
        {
            throw;
        }
    }

How do I protect javascript files?

The only thing you can do is obfuscate your code to make it more difficult to read. No matter what you do, if you want the javascript to execute in their browser they'll have to have the code.

How to get first character of string?

charAt do not work if it has a parent prop
ex parent.child.chartAt(0)
use parent.child.slice(0, 1)

Sorting 1 million 8-decimal-digit numbers with 1 MB of RAM

Here's some working C++ code which solves the problem.

Proof that the memory constraints are satisfied:

Editor: There is no proof of the maximum memory requirements offered by the author either in this post or in his blogs. Since the number of bits necessary to encode a value depends on the values previously encoded, such a proof is likely non-trivial. The author notes that the largest encoded size he could stumble upon empirically was 1011732, and chose the buffer size 1013000 arbitrarily.

typedef unsigned int u32;

namespace WorkArea
{
    static const u32 circularSize = 253250;
    u32 circular[circularSize] = { 0 };         // consumes 1013000 bytes

    static const u32 stageSize = 8000;
    u32 stage[stageSize];                       // consumes 32000 bytes

    ...

Together, these two arrays take 1045000 bytes of storage. That leaves 1048576 - 1045000 - 2×1024 = 1528 bytes for remaining variables and stack space.

It runs in about 23 seconds on my Xeon W3520. You can verify that the program works using the following Python script, assuming a program name of sort1mb.exe.

from subprocess import *
import random

sequence = [random.randint(0, 99999999) for i in xrange(1000000)]

sorter = Popen('sort1mb.exe', stdin=PIPE, stdout=PIPE)
for value in sequence:
    sorter.stdin.write('%08d\n' % value)
sorter.stdin.close()

result = [int(line) for line in sorter.stdout]
print('OK!' if result == sorted(sequence) else 'Error!')

A detailed explanation of the algorithm can be found in the following series of posts:

How do I quickly rename a MySQL database (change schema name)?

in phpmyadmin you can easily rename the database

select database 

  goto operations tab

  in that rename Database to :

  type your new database name and click go

ask to drop old table and reload table data click OK in both

Your database is renamed

Can I have an onclick effect in CSS?

you can use :target

or to filter by class name, use .classname:target

or filter by id name using #idname:target

_x000D_
_x000D_
#id01:target {      
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.msg {
    display:none;
}

.close {        
    color:white;        
    width: 2rem;
    height: 2rem;
    background-color: black;
    text-align:center;
    margin:20px;
}
_x000D_
  
<a href="#id01">Open</a>

<div id="id01" class="msg">    
    <a href="" class="close">&times;</a>
    <p>Some text. Some text. Some text.</p>
    <p>Some text. Some text. Some text.</p>
</div>
_x000D_
_x000D_
_x000D_

How can I get the name of an html page in Javascript?

Current page: It's possible to do even shorter. This single line sound more elegant to find the current page's file name:

var fileName = location.href.split("/").slice(-1); 

or...

var fileName = location.pathname.split("/").slice(-1)

This is cool to customize nav box's link, so the link toward the current is enlighten by a CSS class.

JS:

$('.menu a').each(function() {
    if ($(this).attr('href') == location.href.split("/").slice(-1)){ $(this).addClass('curent_page'); }
});

CSS:

a.current_page { font-size: 2em; color: red; }

How to completely uninstall Android Studio on Mac?

Run the following commands in the terminal:

rm -Rf /Applications/Android\ Studio.app  
rm -Rf ~/Library/Preferences/AndroidStudio*  
rm -Rf ~/Library/Preferences/com.google.android.*  
rm -Rf ~/Library/Preferences/com.android.*  
rm -Rf ~/Library/Application\ Support/AndroidStudio*  
rm -Rf ~/Library/Logs/AndroidStudio*  
rm -Rf ~/Library/Caches/AndroidStudio*  
rm -Rf ~/.AndroidStudio*  
rm -Rf ~/.gradle  
rm -Rf ~/.android  
rm -Rf ~/Library/Android*  
rm -Rf /usr/local/var/lib/android-sdk/  

To delete all projects:

rm -Rf ~/AndroidStudioProjects  

Find all matches in workbook using Excel VBA

Using the Range.Find method, as pointed out above, along with a loop for each worksheet in the workbook, is the fastest way to do this. The following, for example, locates the string "Question?" in each worksheet and replaces it with the string "Answered!".

Sub FindAndExecute()

Dim Sh As Worksheet
Dim Loc As Range

For Each Sh In ThisWorkbook.Worksheets
    With Sh.UsedRange
        Set Loc = .Cells.Find(What:="Question?")
        If Not Loc Is Nothing Then
            Do Until Loc Is Nothing
                Loc.Value = "Answered!"
                Set Loc = .FindNext(Loc)
            Loop
        End If
    End With
    Set Loc = Nothing
Next

End Sub

Tab Escape Character?

Easy one! "\t"

Edit: In fact, here's something official: Escape Sequences

How can I mark a foreign key constraint using Hibernate annotations?

@JoinColumn(name="reference_column_name") annotation can be used above that property or field of class that is being referenced from some other entity.

How to set Android camera orientation properly?

I finally fixed this using the Google's camera app. It gets the phone's orientation by using a sensor and then sets the EXIF tag appropriately. The JPEG which comes out of the camera is not oriented automatically.

Also, the camera preview works properly only in the landscape mode. If you need your activity layout to be oriented in portrait, you will have to do it manually using the value from the orientation sensor.

How to Validate Google reCaptcha on Form Submit

var googleResponse = $('#g-recaptcha-response').val();

if(googleResponse=='')
{   
    $("#texterr").html("<span>Please check reCaptcha to continue.</span>");

    return false;
}

Return value from exec(@sql)

that's my procedure

CREATE PROC sp_count
    @CompanyId sysname,
    @codition sysname
    AS
    SET NOCOUNT ON
    CREATE TABLE #ctr
    ( NumRows int )

    DECLARE @intCount int
         , @vcSQL varchar(255)

    SELECT    @vcSQL = ' INSERT #ctr FROM dbo.Comm_Services 
                       WHERE CompanyId = '+@CompanyId+' and '+@condition+')'
    EXEC      (@vcSQL)

    IF @@ERROR = 0
    BEGIN
         SELECT    @intCount = NumRows
         FROM #ctr

         DROP TABLE #ctr
         RETURN @intCount
    END
    ELSE
    BEGIN
         DROP TABLE #ctr
         RETURN -1
    END
    GO

SQL ORDER BY multiple columns

yes,the sorting proceed differently. in first scenario, orders based on column1 and in addition to that process further by sorting colmun2 based on column1 .. in second scenario ,it orders completely based on column 1 only... please proceed with a simple example...u will get quickly..

Can Selenium WebDriver open browser windows silently in the background?

If you are using the Google Chrome driver, you can use this very simple code (it worked for me):

from selenium import webdriver
from selenium.webdriver.chrome.options import Options

chrome_options = Options()
chrome_options.add_argument("--headless")
driver = webdriver.Chrome('chromedriver2_win32/chromedriver.exe', options=chrome_options)
driver.get('https://www.anywebsite.com')

Kill process by name?

import psutil
pid_list=psutil.get_pid_list()
print pid_list
p = psutil.Process(1052)
print p.name
for i in pid_list:
    p = psutil.Process(i)
    p_name=p.name
    print str(i)+" "+str(p.name)
    if p_name=="PerfExp.exe":
        print "*"*20+" mam ho "+"*"*20
        p.kill()

Does List<T> guarantee insertion order?

As Bevan said, but keep in mind, that the list-index is 0-based. If you want to move an element to the front of the list, you have to insert it at index 0 (not 1 as shown in your example).

Python - round up to the nearest ten

This will round down correctly as well:

>>> n = 46
>>> rem = n % 10
>>> if rem < 5:
...     n = int(n / 10) * 10
... else:
...     n = int((n + 10) / 10) * 10
...
>>> 50

Printing the last column of a line in a file

maybe this works?

grep A1 file | tail -1 | awk '{print $NF}'

How to validate array in Laravel?

I have this array as my request data from a HTML+Vue.js data grid/table:

[0] => Array
    (
        [item_id] => 1
        [item_no] => 3123
        [size] => 3e
    )
[1] => Array
    (
        [item_id] => 2
        [item_no] => 7688
        [size] => 5b
    )

And use this to validate which works properly:

$this->validate($request, [
    '*.item_id' => 'required|integer',
    '*.item_no' => 'required|integer',
    '*.size'    => 'required|max:191',
]);

Excel Date to String conversion

If you are not using programming then do the following (1) select the column (2) right click and select Format Cells (3) Select "Custom" (4) Just Under "Type:" type dd/mm/yyyy hh:mm:ss

Getting the minimum of two values in SQL

Here is a trick if you want to calculate maximum(field, 0):

SELECT (ABS(field) + field)/2 FROM Table

returns 0 if field is negative, else, return field.

What is the advantage of using REST instead of non-REST HTTP?

Query-strings can be ignored by search engines.

"find: paths must precede expression:" How do I specify a recursive search that also finds files in the current directory?

From find manual:

NON-BUGS         

   Operator precedence surprises
   The command find . -name afile -o -name bfile -print will never print
   afile because this is actually equivalent to find . -name afile -o \(
   -name bfile -a -print \).  Remember that the precedence of -a is
   higher than that of -o and when there is no operator specified
   between tests, -a is assumed.

   “paths must precede expression” error message
   $ find . -name *.c -print
   find: paths must precede expression
   Usage: find [-H] [-L] [-P] [-Olevel] [-D ... [path...] [expression]

   This happens because *.c has been expanded by the shell resulting in
   find actually receiving a command line like this:
   find . -name frcode.c locate.c word_io.c -print
   That command is of course not going to work.  Instead of doing things
   this way, you should enclose the pattern in quotes or escape the
   wildcard:
   $ find . -name '*.c' -print
   $ find . -name \*.c -print

Edit a commit message in SourceTree Windows (already pushed to remote)

If the comment message includes non-English characters, using method provided by user456814, those characters will be replaced by question marks. (tested under sourcetree Ver2.5.5.0)

So I have to use the following method.

CAUTION: if the commit has been pulled by other members, changes below might cause chaos for them.

Step1: In the sourcetree main window, locate your repo tab, and click the "terminal" button to open the git command console.

Step2:

[Situation A]: target commit is the latest one.

1) In the git command console, input

git commit --amend -m "new comment message"

2) If the target commit has been pushed to remote, you have to push again by force. In the git command console, input

git push --force

[Situation B]: target commit is not the latest one.

1) In the git command console, input

git rebase -i HEAD~n

It is to squash the latest n commits. e.g. if you want to edit the message before the last one, n is 2. This command will open a vi window, the first word of each line is "pick", and you change the "pick" to "reword" for the line you want to edit. Then, input :wq to save&quit that vi window. Now, a new vi window will be open, in this window you input your new message. Also use :wq to save&quit.

2) If the target commit has been pushed to remote, you have to push again by force. In the git command console, input

git push --force


Finally: In the sourcetree main window, Press F5 to refresh.

Writing a VLOOKUP function in vba

        Public Function VLOOKUP1(ByVal lookup_value As String, ByVal table_array As Range, ByVal col_index_num As Integer) As String
        Dim i As Long

        For i = 1 To table_array.Rows.Count
            If lookup_value = table_array.Cells(table_array.Row + i - 1, 1) Then
                VLOOKUP1 = table_array.Cells(table_array.Row + i - 1, col_index_num)
                Exit For
            End If
        Next i

        End Function

Testing if a checkbox is checked with jQuery

Just use $(selector).is(':checked')

It returns a boolean value.

Do a "git export" (like "svn export")?

If you want something that works with submodules this might be worth a go.

Note:

  • MASTER_DIR = a checkout with your submodules checked out also
  • DEST_DIR = where this export will end up
  • If you have rsync, I think you'd be able to do the same thing with even less ball ache.

Assumptions:

  • You need to run this from the parent directory of MASTER_DIR ( i.e from MASTER_DIR cd .. )
  • DEST_DIR is assumed to have been created. This is pretty easy to modify to include the creation of a DEST_DIR if you wanted to

cd MASTER_DIR && tar -zcvf ../DEST_DIR/export.tar.gz --exclude='.git*' . && cd ../DEST_DIR/ && tar xvfz export.tar.gz && rm export.tar.gz

What is a mixin, and why are they useful?

Maybe an example from ruby can help:

You can include the mixin Comparable and define one function "<=>(other)", the mixin provides all those functions:

<(other)
>(other)
==(other)
<=(other)
>=(other)
between?(other)

It does this by invoking <=>(other) and giving back the right result.

"instance <=> other" returns 0 if both objects are equal, less than 0 if instance is bigger than other and more than 0 if other is bigger.

SQL Server copy all rows from one table into another i.e duplicate table

Duplicate your table into a table to be archived:

SELECT * INTO ArchiveTable FROM MyTable

Delete all entries in your table:

DELETE * FROM MyTable

How to copy and edit files in Android shell?

Since the permission policy on my device is a bit paranoid (cannot adb pull application data), I wrote a script to copy files recursively.

Note: this recursive file/folder copy script is intended for Android!

copy-r:

#! /system/bin/sh

src="$1"
dst="$2"
dir0=`pwd`

myfind() {
    local fpath=$1

    if [ -e "$fpath" ]
    then
    echo $fpath
    if [ -d "$fpath" ]
    then
        for fn in $fpath/*
        do
            myfind $fn
        done
    fi
    else
    : echo "$fpath not found"
    fi
}


if [ ! -z "$dst" ]
then
    if [ -d "$src" ]
    then
    echo 'the source is a directory'

    mkdir -p $dst

    if [[ "$dst" = /* ]]
    then
        : # Absolute path
    else
        # Relative path
        dst=`pwd`/$dst
    fi

    cd $src
    echo "COPYING files and directories from `pwd`"
    for fn in $(myfind .)
    do
        if [ -d $fn ]
        then
            echo "DIR  $dst/$fn"
            mkdir -p $dst/$fn
        else
            echo "FILE $dst/$fn"
            cat $fn >$dst/$fn
        fi
    done
    echo "DONE"
    cd $dir0

    elif [ -f "$src" ]
    then
    echo 'the source is a file'
    srcn="${src##*/}"
    if [ -z "$srcn" ]
    then
        srcn="$src"
    fi

    if [[ "$dst" = */ ]]
    then
        mkdir -p $dst
        echo "copying $src" '->' "$dst/$srcn"
        cat $src >$dst/$srcn
    elif [ -d "$dst" ]
    then
        echo "copying $src" '->' "$dst/$srcn"
        cat $src >$dst/$srcn
    else
        dstdir=${dst%/*}
        if [ ! -z "$dstdir" ]
        then
            mkdir -p $dstdir
        fi
        echo "copying $src" '->' "$dst"
        cat $src >$dst
    fi
    else
    echo "$src is neither a file nor a directory"
    fi
else
    echo "Use: copy-r src-dir dst-dir"
    echo "Use: copy-r src-file existing-dst-dir"
    echo "Use: copy-r src-file dst-dir/"
    echo "Use: copy-r src-file dst-file"
fi

Here I provide the source of a lightweight find for Android because on some devices this utility is missing. Instead of myfind one can use find, if it is defined on the device.

Installation:

$ adb push copy-r /sdcard/

Running within adb shell (rooted):

# . /sdcard/copy-r files/ /sdcard/files3 

or

# source /sdcard/copy-r files/ /sdcard/files3 

(The hash # above is the su prompt, while . is the command that causes the shell to run the specified file, almost the same as source).

After copying, I can adb pull the files from the sd-card.

Writing files to the app directory was trickier, I tried to set r/w permissions on files and its subdirectories, it did not work (well, it allowed me to read, but not write, which is strange), so I had to do:

        String[] cmdline = { "sh", "-c", "source /sdcard/copy-r /sdcard/files4 /data/data/com.example.myapp/files" }; 
        try {
            Runtime.getRuntime().exec(cmdline);
        } catch (IOException e) {
            e.printStackTrace();
        }

in the application's onCreate().

PS just in case someone needs the code to unprotect application's directories to enable adb shell access on a non-rooted phone,

        setRW(appContext.getFilesDir().getParentFile());

    public static void setRW(File... files) {
        for (File file : files) {
            if (file.isDirectory()) {
                setRW(file.listFiles()); // Calls same method again.
            } else {
            }
            file.setReadable(true, false);
            file.setWritable(true, false);
        }
    }

although for some unknown reason I could read but not write.

List of all special characters that need to be escaped in a regex

On @Sorin's suggestion of the Java Pattern docs, it looks like chars to escape are at least:

\.[{(*+?^$|

What is the difference between SQL and MySQL?

SQL - Structured Query Language. It is declarative computer language aimed at querying relational databases.

MySQL is a relational database - a piece of software optimized for data storage and retrieval. There are many such databases - Oracle, Microsoft SQL Server, SQLite and many others are examples of such.

Redirect output of mongo query to a csv file

Extending other answers:

I found @GEverding's answer most flexible. It also works with aggregation:

test_db.js

print("name,email");

db.users.aggregate([
    { $match: {} }
]).forEach(function(user) {
        print(user.name+","+user.email);
    }
});

Execute the following command to export results:

mongo test_db < ./test_db.js >> ./test_db.csv

Unfortunately, it adds additional text to the CSV file which requires processing the file before we can use it:

MongoDB shell version: 3.2.10 
connecting to: test_db

But we can make mongo shell stop spitting out those comments and only print what we have asked for by passing the --quiet flag

mongo --quiet test_db < ./test_db.js >> ./test_db.csv

How can I show three columns per row?

Even though the above answer appears to be correct, I wanted to add a (hopefully) more readable example that also stays in 3 columns form at different widths:

_x000D_
_x000D_
.flex-row-container {_x000D_
    background: #aaa;_x000D_
    display: flex;_x000D_
    flex-wrap: wrap;_x000D_
    align-items: center;_x000D_
    justify-content: center;_x000D_
}_x000D_
.flex-row-container > .flex-row-item {_x000D_
    flex: 1 1 30%; /*grow | shrink | basis */_x000D_
    height: 100px;_x000D_
}_x000D_
_x000D_
.flex-row-item {_x000D_
  background-color: #fff4e6;_x000D_
  border: 1px solid #f76707;_x000D_
}
_x000D_
<div class="flex-row-container">_x000D_
  <div class="flex-row-item">1</div>_x000D_
  <div class="flex-row-item">2</div>_x000D_
  <div class="flex-row-item">3</div>_x000D_
  <div class="flex-row-item">4</div>_x000D_
  <div class="flex-row-item">5</div>_x000D_
  <div class="flex-row-item">6</div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

Hope this helps someone else.

How do I implement a progress bar in C#?

This will Helpfull.Easy to implement,100% tested.

for(int i=1;i<linecount;i++)
{
 progressBar1.Value = i * progressBar1.Maximum / linecount;  //show process bar counts
 LabelTotal.Text = i.ToString() + " of " + linecount; //show number of count in lable
 int presentage = (i * 100) / linecount;
 LabelPresentage.Text = presentage.ToString() + " %"; //show precentage in lable
 Application.DoEvents(); keep form active in every loop
}

Split text with '\r\n'

This worked for me.

string stringSeparators = "\r\n";
string text = sr.ReadToEnd();
string lines = text.Replace(stringSeparators, "");
lines = lines.Replace("\\r\\n", "\r\n");
Console.WriteLine(lines);

The first replace replaces the \r\n from the text file's new lines, and the second replaces the actual \r\n text that is converted to \\r\\n when the files is read. (When the file is read \ becomes \\).

How to use activity indicator view on iPhone?

Take a look at the open source WordPress application. They have a very re-usable window they have created for displaying an "activity in progress" type display over top of whatever view your application is currently displaying.

http://iphone.trac.wordpress.org/browser/trunk

The files you want are:

  • WPActivityIndicator.xib
  • RoundedRectBlack.png
  • WPActivityIndicator.h
  • WPActivityIndicator.m

Then to show it use something like:

[[WPActivityIndicator sharedActivityIndicator] show];

And hide with:

[[WPActivityIndicator sharedActivityIndicator] hide];

Add zero-padding to a string

int num = 1;
num.ToString("0000");

How to close IPython Notebook properly?

Option 1

Open a different console and run

jupyter notebook stop [PORT]

The default [PORT] is 8888, so, assuming that Jupyter Notebooks is running on port 8888, just run

jupyter notebook stop

If it is on port 9000, then

jupyter notebook stop 9000

Option 2 (Source)

  1. Check runtime folder location

    jupyter --paths
    
  2. Remove all files in the runtime folder

    rm -r [RUNTIME FOLDER PATH]/*
    
  3. Use top to find any Jupyter Notebook running processes left and if so kill their PID.

    top | grep jupyter &
    kill [PID]
    

One can boilt it down to

TARGET_PORT=8888
kill -9 $(lsof -n -i4TCP:$TARGET_PORT | cut -f 2 -d " ")

Note: If one wants to launch one's Notebook on a specific IP/Port

jupyter notebook --ip=[ADD_IP] --port=[ADD_PORT] --allow-root &

I keep getting "Uncaught SyntaxError: Unexpected token o"

Another hints for Unexpected token errors. There are two major differences between javascript objects and json:

  1. json data must be always quoted with double quotes.
  2. keys must be quoted

Correct JSON

 {
    "english": "bag",
    "kana": "kaban",
    "kanji": "K"
}

Error JSON 1

 {
    'english': 'bag',
    'kana': 'kaban',
    'kanji': 'K'
 }

Error JSON 2

 {
    english: "bag",
    kana: "kaban",
    kanji: "K"
}

Remark

This is not a direct answer for that question. But it's an answer for Unexpected token errors. So it may be help others who stumple upon that question.

Closure in Java 7

A closure is a block of code that can be referenced (and passed around) with access to the variables of the enclosing scope.

Since Java 1.1, anonymous inner class have provided this facility in a highly verbose manner. They also have a restriction of only being able to use final (and definitely assigned) local variables. (Note, even non-final local variables are in scope, but cannot be used.)

Java SE 8 is intended to have a more concise version of this for single-method interfaces*, called "lambdas". Lambdas have much the same restrictions as anonymous inner classes, although some details vary randomly.

Lambdas are being developed under Project Lambda and JSR 335.

*Originally the design was more flexible allowing Single Abstract Methods (SAM) types. Unfortunately the new design is less flexible, but does attempt to justify allowing implementation within interfaces.

Android Studio - debug keystore

It is at the same location: ~/.android/debug.keystore

Initializing a static std::map<int, int> in C++

Here is another way that uses the 2-element data constructor. No functions are needed to initialize it. There is no 3rd party code (Boost), no static functions or objects, no tricks, just simple C++:

#include <map>
#include <string>

typedef std::map<std::string, int> MyMap;

const MyMap::value_type rawData[] = {
   MyMap::value_type("hello", 42),
   MyMap::value_type("world", 88),
};
const int numElems = sizeof rawData / sizeof rawData[0];
MyMap myMap(rawData, rawData + numElems);

Since I wrote this answer C++11 is out. You can now directly initialize STL containers using the new initializer list feature:

const MyMap myMap = { {"hello", 42}, {"world", 88} };

Linq to SQL how to do "where [column] in (list of values)"

I had been using the method in Jon Skeet's answer, but another one occurred to me using Concat. The Concat method performed slightly better in a limited test, but it's a hassle and I'll probably just stick with Contains, or maybe I'll write a helper method to do this for me. Either way, here's another option if anyone is interested:

The Method

// Given an array of id's
var ids = new Guid[] { ... };

// and a DataContext
var dc = new MyDataContext();

// start the queryable
var query = (
    from thing in dc.Things
    where thing.Id == ids[ 0 ]
    select thing 
);

// then, for each other id
for( var i = 1; i < ids.Count(); i++ ) {
    // select that thing and concat to queryable
    query.Concat(
        from thing in dc.Things
        where thing.Id == ids[ i ]
        select thing
    );
}

Performance Test

This was not remotely scientific. I imagine your database structure and the number of IDs involved in the list would have a significant impact.

I set up a test where I did 100 trials each of Concat and Contains where each trial involved selecting 25 rows specified by a randomized list of primary keys. I've run this about a dozen times, and most times the Concat method comes out 5 - 10% faster, although one time the Contains method won by just a smidgen.

How do I create a crontab through a script

Cron jobs usually are stored in a per-user file under /var/spool/cron

The simplest thing for you to do is probably just create a text file with the job configured, then copy it to the cron spool folder and make sure it has the right permissions (600).

Why is my CSS style not being applied?

I know this is an old post but I thought I might add a thought for people who come across a similar problem. I'm assuming that you are using ASP.NET MVC since you mentioned site.css.

Check your Bundles.config file to see if you have BundleTable.EnableOptimizations = true; If you don't, then it can be your problem since this allows the program to be bundles and "minified". Depending on if you run in debug mode or not this could have an effect.

How to extract numbers from a string in Python?

line2 = "hello 12 hi 89"
temp1 = re.findall(r'\d+', line2) # through regular expression
res2 = list(map(int, temp1))
print(res2)

Hi ,

you can search all the integers in the string through digit by using findall expression .

In the second step create a list res2 and add the digits found in string to this list

hope this helps

Regards, Diwakar Sharma

Use Fieldset Legend with bootstrap

Just wanted to summarize all the correct answers above in short. Because I had to spend lot of time to figure out which answer resolves the issue and what's going on behind the scenes.

There seems to be two problems of fieldset with bootstrap:

  1. The bootstrap sets the width to the legend as 100%. That is why it overlays the top border of the fieldset.
  2. There's a bottom border for the legend.

So, all we need to fix this is set the legend width to auto as follows:

legend.scheduler-border {
   width: auto; // fixes the problem 1
   border-bottom: none; // fixes the problem 2
}

PHP Swift mailer: Failed to authenticate on SMTP using 2 possible authenticators

I had the same issue, so I've disabled one setting on my WHM root login, which is as follows :

WHM > Home > Server Configuration > Tweak Settings > Restrict outgoing SMTP to root, exim, and mailman (FKA SMTP Tweak) [?]

JSTL if tag for equal strings

You can use scriptlets, however, this is not the way to go. Nowdays inline scriplets or JAVA code in your JSP files is considered a bad habit.

You should read up on JSTL a bit more. If the ansokanInfo object is in your request or session scope, printing the object (toString() method) like this: ${ansokanInfo} can give you some base information. ${ansokanInfo.pSystem} should call the object getter method. If this all works, you can use this:

<c:if test="${ ansokanInfo.pSystem  == 'NAT'}"> tataa </c:if>

How can I use iptables on centos 7?

With RHEL 7 / CentOS 7, firewalld was introduced to manage iptables. IMHO, firewalld is more suited for workstations than for server environments.

It is possible to go back to a more classic iptables setup. First, stop and mask the firewalld service:

systemctl stop firewalld
systemctl mask firewalld

Then, install the iptables-services package:

yum install iptables-services

Enable the service at boot-time:

systemctl enable iptables

Managing the service

systemctl [stop|start|restart] iptables

Saving your firewall rules can be done as follows:

service iptables save

or

/usr/libexec/iptables/iptables.init save

Reduce left and right margins in matplotlib plot

One way to automatically do this is the bbox_inches='tight' kwarg to plt.savefig.

E.g.

import matplotlib.pyplot as plt
import numpy as np
data = np.arange(3000).reshape((100,30))
plt.imshow(data)
plt.savefig('test.png', bbox_inches='tight')

Another way is to use fig.tight_layout()

import matplotlib.pyplot as plt
import numpy as np

xs = np.linspace(0, 1, 20); ys = np.sin(xs)

fig = plt.figure()
axes = fig.add_subplot(1,1,1)
axes.plot(xs, ys)

# This should be called after all axes have been added
fig.tight_layout()
fig.savefig('test.png')

Most efficient way to see if an ArrayList contains an object in Java

Even if the equals method were comparing those two fields, then logically, it would be just the same code as you doing it manually. OK, it might be "messy", but it's still the correct answer

HTTP 401 - what's an appropriate WWW-Authenticate header value?

When the user session times out, I send back an HTTP 204 status code. Note that the HTTP 204 status contains no content. On the client-side I do this:

xhr.send(null);
if (xhr.status == 204) 
    Reload();
else 
    dropdown.innerHTML = xhr.responseText;

Here is the Reload() function:

function Reload() {
    var oForm = document.createElement("form");
    document.body.appendChild(oForm);
    oForm.submit();
    }

Under what circumstances can I call findViewById with an Options Menu / Action Bar item?

I am trying to obtain a handle on one of the views in the Action Bar

I will assume that you mean something established via android:actionLayout in your <item> element of your <menu> resource.

I have tried calling findViewById(R.id.menu_item)

To retrieve the View associated with your android:actionLayout, call findItem() on the Menu to retrieve the MenuItem, then call getActionView() on the MenuItem. This can be done any time after you have inflated the menu resource.

Rename multiple files by replacing a particular pattern in the filenames using a shell script

Another option is:

for i in *001.jpg
do
  echo "mv $i yourstring${i#*001.jpg}"
done

remove echo after you have it right.

Parameter substitution with # will keep only the last part, so you can change its name.

Displaying Image in Java

Running your code shows an image for me, after adjusting the path. Can you verify that your image path is correct, try absolute path for instance?

C# Break out of foreach loop after X number of items

Or just use a regular for loop instead of foreach. A for loop is slightly faster (though you won't notice the difference except in very time critical code).

How to list the certificates stored in a PKCS12 keystore with keytool?

You can also use openssl to accomplish the same thing:

$ openssl pkcs12 -nokeys -info \
    -in </path/to/file.pfx> \
    -passin pass:<pfx's password>

MAC Iteration 2048
MAC verified OK
PKCS7 Encrypted data: pbeWithSHA1And40BitRC2-CBC, Iteration 2048
Certificate bag
Bag Attributes
    localKeyID: XX XX XX XX XX XX XX XX XX XX XX XX XX 48 54 A0 47 88 1D 90
    friendlyName: jedis-server
subject=/C=US/ST=NC/L=Raleigh/O=XXX Security/OU=XXX/CN=something1
issuer=/C=US/ST=NC/L=Raleigh/O=XXX Security/OU=XXXX/CN=something1
-----BEGIN CERTIFICATE-----
...
...
...
-----END CERTIFICATE-----
PKCS7 Data
Shrouded Keybag: pbeWithSHA1And3-KeyTripleDES-CBC, Iteration 2048

keytool error Keystore was tampered with, or password was incorrect

For me I solved it by changing passwords from Arabic letter to English letter, but first I went to the folder and deleted the generated key then it works.

Cross-reference (named anchor) in markdown

For most common markdown generators. You have a simple self generated anchor in each header. For instance with pandoc, the generated anchor will be a kebab case slug of your header.

 echo "# Hello, world\!" | pandoc
 # => <h1 id="hello-world">Hello, world!</h1>

Depending on which markdown parser you use, the anchor can change (take the exemple of symbolrush and La muerte Peluda answers, they are different!). See this babelmark where you can see generated anchors depending on your markdown implementation.

Bootstrap Carousel : Remove auto slide

You can do this 2 ways, via js or html (easist)

  1. Via js
$('.carousel').carousel({
  interval: false,
});

That will make the auto sliding stop because there no Milliseconds added and will never slider next.

  1. Via Html By adding data-interval="false" and removing data-ride="carousel"
<div id="carouselExampleCaptions" class="carousel slide" data-ride="carousel">

becomes:

<div id="carouselExampleCaptions" class="carousel slide" data-interval="false">

updated based on @webMan's comment

Creating a .p12 file

The openssl documentation says that file supplied as the -in argument must be in PEM format.

Turns out that, contrary to the CA's manual, the certificate returned by the CA which I stored in myCert.cer is not PEM format rather it is PKCS7.

In order to create my .p12, I had to first convert the certificate to PEM:

openssl pkcs7 -in myCert.cer -print_certs -out certs.pem

and then execute

openssl pkcs12 -export -out keyStore.p12 -inkey myKey.pem -in certs.pem

HTML email with Javascript

you can use html radio/checkbox input with labels and css to achieve the expanding effects you want.

Shared-memory objects in multiprocessing

I run into the same problem and wrote a little shared-memory utility class to work around it.

I'm using multiprocessing.RawArray (lockfree), and also the access to the arrays is not synchronized at all (lockfree), be careful not to shoot your own feet.

With the solution I get speedups by a factor of approx 3 on a quad-core i7.

Here's the code: Feel free to use and improve it, and please report back any bugs.

'''
Created on 14.05.2013

@author: martin
'''

import multiprocessing
import ctypes
import numpy as np

class SharedNumpyMemManagerError(Exception):
    pass

'''
Singleton Pattern
'''
class SharedNumpyMemManager:    

    _initSize = 1024

    _instance = None

    def __new__(cls, *args, **kwargs):
        if not cls._instance:
            cls._instance = super(SharedNumpyMemManager, cls).__new__(
                                cls, *args, **kwargs)
        return cls._instance        

    def __init__(self):
        self.lock = multiprocessing.Lock()
        self.cur = 0
        self.cnt = 0
        self.shared_arrays = [None] * SharedNumpyMemManager._initSize

    def __createArray(self, dimensions, ctype=ctypes.c_double):

        self.lock.acquire()

        # double size if necessary
        if (self.cnt >= len(self.shared_arrays)):
            self.shared_arrays = self.shared_arrays + [None] * len(self.shared_arrays)

        # next handle
        self.__getNextFreeHdl()        

        # create array in shared memory segment
        shared_array_base = multiprocessing.RawArray(ctype, np.prod(dimensions))

        # convert to numpy array vie ctypeslib
        self.shared_arrays[self.cur] = np.ctypeslib.as_array(shared_array_base)

        # do a reshape for correct dimensions            
        # Returns a masked array containing the same data, but with a new shape.
        # The result is a view on the original array
        self.shared_arrays[self.cur] = self.shared_arrays[self.cnt].reshape(dimensions)

        # update cnt
        self.cnt += 1

        self.lock.release()

        # return handle to the shared memory numpy array
        return self.cur

    def __getNextFreeHdl(self):
        orgCur = self.cur
        while self.shared_arrays[self.cur] is not None:
            self.cur = (self.cur + 1) % len(self.shared_arrays)
            if orgCur == self.cur:
                raise SharedNumpyMemManagerError('Max Number of Shared Numpy Arrays Exceeded!')

    def __freeArray(self, hdl):
        self.lock.acquire()
        # set reference to None
        if self.shared_arrays[hdl] is not None: # consider multiple calls to free
            self.shared_arrays[hdl] = None
            self.cnt -= 1
        self.lock.release()

    def __getArray(self, i):
        return self.shared_arrays[i]

    @staticmethod
    def getInstance():
        if not SharedNumpyMemManager._instance:
            SharedNumpyMemManager._instance = SharedNumpyMemManager()
        return SharedNumpyMemManager._instance

    @staticmethod
    def createArray(*args, **kwargs):
        return SharedNumpyMemManager.getInstance().__createArray(*args, **kwargs)

    @staticmethod
    def getArray(*args, **kwargs):
        return SharedNumpyMemManager.getInstance().__getArray(*args, **kwargs)

    @staticmethod    
    def freeArray(*args, **kwargs):
        return SharedNumpyMemManager.getInstance().__freeArray(*args, **kwargs)

# Init Singleton on module load
SharedNumpyMemManager.getInstance()

if __name__ == '__main__':

    import timeit

    N_PROC = 8
    INNER_LOOP = 10000
    N = 1000

    def propagate(t):
        i, shm_hdl, evidence = t
        a = SharedNumpyMemManager.getArray(shm_hdl)
        for j in range(INNER_LOOP):
            a[i] = i

    class Parallel_Dummy_PF:

        def __init__(self, N):
            self.N = N
            self.arrayHdl = SharedNumpyMemManager.createArray(self.N, ctype=ctypes.c_double)            
            self.pool = multiprocessing.Pool(processes=N_PROC)

        def update_par(self, evidence):
            self.pool.map(propagate, zip(range(self.N), [self.arrayHdl] * self.N, [evidence] * self.N))

        def update_seq(self, evidence):
            for i in range(self.N):
                propagate((i, self.arrayHdl, evidence))

        def getArray(self):
            return SharedNumpyMemManager.getArray(self.arrayHdl)

    def parallelExec():
        pf = Parallel_Dummy_PF(N)
        print(pf.getArray())
        pf.update_par(5)
        print(pf.getArray())

    def sequentialExec():
        pf = Parallel_Dummy_PF(N)
        print(pf.getArray())
        pf.update_seq(5)
        print(pf.getArray())

    t1 = timeit.Timer("sequentialExec()", "from __main__ import sequentialExec")
    t2 = timeit.Timer("parallelExec()", "from __main__ import parallelExec")

    print("Sequential: ", t1.timeit(number=1))    
    print("Parallel: ", t2.timeit(number=1))

How to tell which commit a tag points to in Git?

Just use git show <tag>

However, it also dumps commit diffs. To omit those diffs, use git log -1 <tag>. (Thanks to @DolphinDream and @demisx !)

Creating an iframe with given HTML dynamically

Thanks for your great question, this has caught me out a few times. When using dataURI HTML source, I find that I have to define a complete HTML document.

See below a modified example.

var html = '<html><head></head><body>Foo</body></html>';
var iframe = document.createElement('iframe');
iframe.src = 'data:text/html;charset=utf-8,' + encodeURI(html);

take note of the html content wrapped with <html> tags and the iframe.src string.

The iframe element needs to be added to the DOM tree to be parsed.

document.body.appendChild(iframe);

You will not be able to inspect the iframe.contentDocument unless you disable-web-security on your browser. You'll get a message

DOMException: Failed to read the 'contentDocument' property from 'HTMLIFrameElement': Blocked a frame with origin "http://localhost:7357" from accessing a cross-origin frame.

Detect Android phone via Javascript / jQuery

js version, catches iPad too:

var is_mobile = /mobile|android/i.test (navigator.userAgent);

Android: How to stretch an image to the screen width while maintaining aspect ratio?

I've been struggling with this problem in one form or another for AGES, thank you, Thank You, THANK YOU.... :)

I just wanted to point out that you can get a generalizable solution from what Bob Lee's done by just extending View and overriding onMeasure. That way you can use this with any drawable you want, and it won't break if there's no image:

    public class CardImageView extends View {
        public CardImageView(Context context, AttributeSet attrs, int defStyle) {
            super(context, attrs, defStyle);
        }

        public CardImageView(Context context, AttributeSet attrs) {
            super(context, attrs);
        }

        public CardImageView(Context context) {
            super(context);
        }

        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            Drawable bg = getBackground();
            if (bg != null) {
                int width = MeasureSpec.getSize(widthMeasureSpec);
                int height = width * bg.getIntrinsicHeight() / bg.getIntrinsicWidth();
                setMeasuredDimension(width,height);
            }
            else {
                super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            }
        }
    }

The ORDER BY clause is invalid in views, inline functions, derived tables, subqueries, and common table expressions

ORDER BY column OFFSET 0 ROWS

Surprisingly makes it work, what a strange feature.

A bigger example with a CTE as a way to temporarily "store" a long query to re-order it later:

;WITH cte AS (
    SELECT .....long select statement here....
)

SELECT * FROM 
(
    SELECT * FROM 
    ( -- necessary to nest selects for union to work with where & order clauses
        SELECT * FROM cte WHERE cte.MainCol= 1 ORDER BY cte.ColX asc OFFSET 0 ROWS 
    ) first
    UNION ALL
    SELECT * FROM 
    (  
        SELECT * FROM cte WHERE cte.MainCol = 0 ORDER BY cte.ColY desc OFFSET 0 ROWS 
    ) last
) as unionized
ORDER BY unionized.MainCol desc -- all rows ordered by this one
OFFSET @pPageSize * @pPageOffset ROWS -- params from stored procedure for pagination, not relevant to example
FETCH FIRST @pPageSize ROWS ONLY -- params from stored procedure for pagination, not relevant to example

So we get all results ordered by MainCol

But the results with MainCol = 1 get ordered by ColX

And the results with MainCol = 0 get ordered by ColY

jQuery: how to scroll to certain anchor/div on page load?

There's no need to use jQuery because this is native JavaScript functionality

element.scrollIntoView()

How can I quickly sum all numbers in a file?

You can use awk:

awk '{ sum += $1 } END { print sum }' file

CSS /JS to prevent dragging of ghost image?

You can set the draggable attribute to false in either the markup or JavaScript code.

_x000D_
_x000D_
// As a jQuery method: $('#myImage').attr('draggable', false);_x000D_
document.getElementById('myImage').setAttribute('draggable', false);
_x000D_
<img id="myImage" src="http://placehold.it/150x150">
_x000D_
_x000D_
_x000D_

How to set value to form control in Reactive Forms in Angular

To assign value to a single Form control/individually, I propose to use setValue in the following way:

this.editqueForm.get('user').setValue(this.question.user);

this.editqueForm.get('questioning').setValue(this.question.questioning);

How do I parse JSON with Ruby on Rails?

Parsing JSON in Rails is quite straightforward:

parsed_json = ActiveSupport::JSON.decode(your_json_string)

Let's suppose, the object you want to associate the shortUrl with is a Site object, which has two attributes - short_url and long_url. Than, to get the shortUrl and associate it with the appropriate Site object, you can do something like:

parsed_json["results"].each do |longUrl, convertedUrl|
  site = Site.find_by_long_url(longUrl)
  site.short_url = convertedUrl["shortUrl"]
  site.save
end

Redirecting unauthorized controller in ASP.NET MVC

You should build your own Authorize-filter attribute.

Here's mine to study ;)

Public Class RequiresRoleAttribute : Inherits ActionFilterAttribute
    Private _role As String

    Public Property Role() As String
        Get
            Return Me._role
        End Get
        Set(ByVal value As String)
            Me._role = value
        End Set
    End Property

    Public Overrides Sub OnActionExecuting(ByVal filterContext As System.Web.Mvc.ActionExecutingContext)
        If Not String.IsNullOrEmpty(Me.Role) Then
            If Not filterContext.HttpContext.User.Identity.IsAuthenticated Then
                Dim redirectOnSuccess As String = filterContext.HttpContext.Request.Url.AbsolutePath
                Dim redirectUrl As String = String.Format("?ReturnUrl={0}", redirectOnSuccess)
                Dim loginUrl As String = FormsAuthentication.LoginUrl + redirectUrl

                filterContext.HttpContext.Response.Redirect(loginUrl, True)
            Else
                Dim hasAccess As Boolean = filterContext.HttpContext.User.IsInRole(Me.Role)
                If Not hasAccess Then
                    Throw New UnauthorizedAccessException("You don't have access to this page. Only " & Me.Role & " can view this page.")
                End If
            End If
        Else
            Throw New InvalidOperationException("No Role Specified")
        End If

    End Sub
End Class

Invalid use side-effecting operator Insert within a function

Functions cannot be used to modify base table information, use a stored procedure.

How to truncate float values?

use numpy.round

import numpy as np
precision = 3
floats = [1.123123123, 2.321321321321]
new_float = np.round(floats, precision)

Is a view faster than a simple query?

Against all expectation, views are way slower in some circumstances.

I discovered this recently when I had problems with data which was pulled from Oracle which needed to be massaged into another format. Maybe 20k source rows. A small table. To do this we imported the oracle data as unchanged as I could into a table and then used views to extract data. We had secondary views based on those views. Maybe 3-4 levels of views.

One of the final queries, which extracted maybe 200 rows would take upwards of 45 minutes! That query was based on a cascade of views. Maybe 3-4 levels deep.

I could take each of the views in question, insert its sql into one nested query, and execute it in a couple of seconds.

We even found that we could even write each view into a temp table and query that in place of the view and it was still way faster than simply using nested views.

What was even odder was that performance was fine until we hit some limit of source rows being pulled into the database, performs just dropped off a cliff over the space of a couple of days - a few more source rows was all it took.

So, using queries which pull from views which pull from views is much slower than a nested query - which makes no sense for me.

How do I exit a foreach loop in C#?

During testing I found that foreach loop after break go to the loop beging and not out of the loop. So I changed foreach into for and break in this case work correctly- after break program flow goes out of the loop.

ansible: lineinfile for several lines?

I was able to do that by using \n in the line parameter.

It is specially useful if the file can be validated, and adding a single line generates an invalid file.

In my case, I was adding AuthorizedKeysCommand and AuthorizedKeysCommandUser to sshd_config, with the following command:

- lineinfile: dest=/etc/ssh/sshd_config line='AuthorizedKeysCommand /etc/ssh/ldap-keys\nAuthorizedKeysCommandUser nobody' validate='/usr/sbin/sshd -T -f %s'

Adding only one of the options generates a file that fails validation.

Is there a Python equivalent of the C# null-coalescing operator?

Addionally to @Bothwells answer (which I prefer) for single values, in order to null-checking assingment of function return values, you can use new walrus-operator (since python3.8):

def test():
    return

a = 2 if (x:= test()) is None else x

Thus, test function does not need to be evaluated two times (as in a = 2 if test() is None else test())

How to build a 'release' APK in Android Studio?

Follow this steps:

-Build
-Generate Signed Apk
-Create new

Then fill up "New Key Store" form. If you wand to change .jnk file destination then chick on destination and give a name to get Ok button. After finishing it you will get "Key store password", "Key alias", "Key password" Press next and change your the destination folder. Then press finish, thats all. :)

enter image description here

enter image description here enter image description here

enter image description here enter image description here

UITextField text change event

Swift Version tested:

//Somewhere in your UIViewController, like viewDidLoad(){ ... }
self.textField.addTarget(
        self, 
        action: #selector(SearchViewController.textFieldDidChange(_:)),
        forControlEvents: UIControlEvents.EditingChanged
)

Parameters explained:

self.textField //-> A UITextField defined somewhere in your UIViewController
self //-> UIViewController
.textFieldDidChange(_:) //-> Can be named anyway you like, as long as it is defined in your UIViewController

Then add the method you created above in your UIViewController:

//Gets called everytime the text changes in the textfield.
func textFieldDidChange(textField: UITextField){

    print("Text changed: " + textField.text!)

}

What is base 64 encoding used for?

Years ago, when mailing functionality was introduced, so that was utterly text based, as the time passed, need for attachments like image and media (audio,video etc) came into existence. When these attachments are sent over internet (which is basically in the form of binary data), the probability of binary data getting corrupt is high in its raw form. So, to tackle this problem BASE64 came along.

The problem with binary data is that it contains null characters which in some languages like C,C++ represent end of character string so sending binary data in raw form containing NULL bytes will stop a file from being fully read and lead in a corrupt data.

For Example :

In C and C++, this "null" character shows the end of a string. So "HELLO" is stored like this:

H E L L O

72 69 76 76 79 00

The 00 says "stop here".

Now let’s dive into how BASE64 encoding works.

Point to be noted : Length of the string should be in multiple of 3.

Example 1 :

String to be encoded : “ace”, Length=3

1) Convert each character to decimal.

a= 97, c= 99, e= 101

enter image description here

2) Change each decimal to 8-bit binary representation.

97= 01100001, 99= 01100011, 101= 01100101

Combined : 01100001 01100011 01100101

3) Seperate in a group of 6-bit.

011000 010110 001101 100101

4) Calculate binary to decimal

011000= 24, 010110= 22, 001101= 13, 100101= 37

5) Covert decimal characters to base64 using base64 chart.

24= Y, 22= W, 13= N, 37= l

“ace” => “YWNl”

enter image description here

Example 2 :

String to be encoded : “abcd” Length=4, it's not multiple of 3. So to make string length multiple of 3 , we must add 2 bit padding to make length= 6. Padding bit is represented by “=” sign.

Point to be noted : One padding bit equals two zeroes 00 so two padding bit equals four zeroes 0000.

So lets start the process :–

1) Convert each character to decimal.

a= 97, b= 98, c= 99, d= 100

2) Change each decimal to 8-bit binary representation.

97= 01100001, 98= 01100010, 99= 01100011, 100= 01100100

3) Separate in a group of 6-bit.

011000, 010110, 001001, 100011, 011001, 00

so the last 6-bit is not complete so we insert two padding bit which equals four zeroes “0000”.

011000, 010110, 001001, 100011, 011001, 000000 ==

Now, it is equal. Two equals sign at the end show that 4 zeroes were added (helps in decoding).

4) Calculate binary to decimal.

011000= 24, 010110= 22, 001001= 9, 100011= 35, 011001= 25, 000000=0 ==

5) Covert decimal characters to base64 using base64 chart.

24= Y, 22= W, 9= j, 35= j, 25= Z, 0= A ==

“abcd” => “YWJjZA==”

Extending the User model with custom fields in Django

The least painful and indeed Django-recommended way of doing this is through a OneToOneField(User) property.

Extending the existing User model

If you wish to store information related to User, you can use a one-to-one relationship to a model containing the fields for additional information. This one-to-one model is often called a profile model, as it might store non-auth related information about a site user.

That said, extending django.contrib.auth.models.User and supplanting it also works...

Substituting a custom User model

Some kinds of projects may have authentication requirements for which Django’s built-in User model is not always appropriate. For instance, on some sites it makes more sense to use an email address as your identification token instead of a username.

[Ed: Two warnings and a notification follow, mentioning that this is pretty drastic.]

I would definitely stay away from changing the actual User class in your Django source tree and/or copying and altering the auth module.

Simple (non-secure) hash function for JavaScript?

Check out this MD5 implementation for JavaScript. Its BSD Licensed and really easy to use. Example:

md5 = hex_md5("message to digest")

Angles between two n-dimensional vectors in Python

David Wolever's solution is good, but

If you want to have signed angles you have to determine if a given pair is right or left handed (see wiki for further info).

My solution for this is:

def unit_vector(vector):
    """ Returns the unit vector of the vector"""
    return vector / np.linalg.norm(vector)

def angle(vector1, vector2):
    """ Returns the angle in radians between given vectors"""
    v1_u = unit_vector(vector1)
    v2_u = unit_vector(vector2)
    minor = np.linalg.det(
        np.stack((v1_u[-2:], v2_u[-2:]))
    )
    if minor == 0:
        raise NotImplementedError('Too odd vectors =(')
    return np.sign(minor) * np.arccos(np.clip(np.dot(v1_u, v2_u), -1.0, 1.0))

It's not perfect because of this NotImplementedError but for my case it works well. This behaviour could be fixed (cause handness is determined for any given pair) but it takes more code that I want and have to write.

How to show shadow around the linearlayout in Android?

There is no such attribute in Android, to show a shadow. But possible ways to do it are:

  1. Add a plain LinearLayout with grey color, over which add your actual layout, with margin at bottom and right equal to 1 or 2 dp

  2. Have a 9-patch image with a shadow and set it as the background to your Linear layout

How do you clone a Git repository into a specific folder?

Basic Git Repository Cloning

You clone a repository with

git clone [url]

For example, if you want to clone the Stanford University Drupal Open Framework Git library called open_framework, you can do so like this:

$ git clone git://github.com/SU-SWS/open_framework.git

That creates a directory named open_framework (at your current local file system location), initializes a .git directory inside it, pulls down all the data for that repository, and checks out a working copy of the latest version. If you go into the newly created open_framework directory, you’ll see the project files in there, ready to be worked on or used.

Cloning a Repository Into a Specific Local Folder

If you want to clone the repository into a directory named something other than open_framework, you can specify that as the next command-line option:

$ git clone git:github.com/SU-SWS/open_framework.git mynewtheme

That command does the same thing as the previous one, but the target directory is called mynewtheme.

Git has a number of different transfer protocols you can use. The previous example uses the git:// protocol, but you may also see http(s):// or user@server:/path.git, which uses the SSH transfer protocol.

How to pass multiple parameters in a querystring

I use the AbsoluteUri and you can get it like this:

string myURI = Request.Url.AbsoluteUri;
 if (!WebSecurity.IsAuthenticated) {
        Response.Redirect("~/Login?returnUrl="
            + Request.Url.AbsoluteUri );

Then after you login:

var returnUrl = Request.QueryString["returnUrl"];
 if(WebSecurity.Login(username,password,true)){
                Context.RedirectLocal(returnUrl);

It works well for me.

Print array elements on separate lines in Bash?

Using for:

for each in "${alpha[@]}"
do
  echo "$each"
done

Using history; note this will fail if your values contain !:

history -p "${alpha[@]}"

Using basename; note this will fail if your values contain /:

basename -a "${alpha[@]}"

Using shuf; note that results might not come out in order:

shuf -e "${alpha[@]}"

removing table border

Use table style Border-collapse at the table level

httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName

If you don't have httpd.conf in folder /etc/apache2, you should have apache2.conf - simply add:

ServerName localhost

Then restart the apache2 service.

How to open/run .jar file (double-click not working)?

There are two different types of Java to download: The JDK, which is used to write Java programs, and the RE (runtime environment), which is used to actually run Java programs. Are you sure that you installed the RE instead of the SDK?

What does += mean in Python?

+= is the in-place addition operator.

It's the same as doing cnt = cnt + 1. For example:

>>> cnt = 0
>>> cnt += 2
>>> print cnt
2
>>> cnt += 42
>>> print cnt
44

The operator is often used in a similar fashion to the ++ operator in C-ish languages, to increment a variable by one in a loop (i += 1)

There are similar operator for subtraction/multiplication/division/power and others:

i -= 1 # same as i = i - 1
i *= 2 # i = i * 2
i /= 3 # i = i / 3
i **= 4 # i = i ** 4

The += operator also works on strings, for example:

>>> s = "Hi"
>>> s += " there"
>>> print s
Hi there

People tend to recommend against doing this for performance reason, but for the most scripts this really isn't an issue. To quote from the "Sequence Types" docs:

  1. If s and t are both strings, some Python implementations such as CPython can usually perform an in-place optimization for assignments of the form s=s+t or s+=t. When applicable, this optimization makes quadratic run-time much less likely. This optimization is both version and implementation dependent. For performance sensitive code, it is preferable to use the str.join() method which assures consistent linear concatenation performance across versions and implementations.

The str.join() method refers to doing the following:

mysentence = []
for x in range(100):
    mysentence.append("test")
" ".join(mysentence)

..instead of the more obvious:

mysentence = ""
for x in range(100):
    mysentence += " test"

The problem with the later is (aside from the leading-space), depending on the Python implementation, the Python interpreter will have to make a new copy of the string in memory every time you append (because strings are immutable), which will get progressively slower the longer the string to append is.. Whereas appending to a list then joining it together into a string is a consistent speed (regardless of implementation)

If you're doing basic string manipulation, don't worry about it. If you see a loop which is basically just appending to a string, consider constructing an array, then "".join()'ing it.

Importing a csv into mysql via command line

Try this command

 load data local infile 'file.csv' into table table
 fields terminated by ','
 enclosed by '"'
 lines terminated by '\n'
 (column1, column2, column3,...)

The fields here are the actual table fields that the data needs to sit in. The enclosed by and lines terminated by are optional and can help if you have columns enclosed with double-quotes such as Excel exports, etc.

For further details check the manual.

For setting the first row as the table column names, just ignore the row from being read and add the values in the command.

How do I make a semi transparent background?

If you want to make transparent background is gray, pls try:

   .transparent{
       background:rgba(1,1,1,0.5);
   }

Accessing Objects in JSON Array (JavaScript)

You can loop the array with a for loop and the object properties with for-in loops.

for (var i=0; i<result.length; i++)
    for (var name in result[i]) {
        console.log("Item name: "+name);
        console.log("Source: "+result[i][name].sourceUuid);
        console.log("Target: "+result[i][name].targetUuid);
    }

KeyListener, keyPressed versus keyTyped

keyPressed - when the key goes down
keyReleased - when the key comes up
keyTyped - when the unicode character represented by this key is sent by the keyboard to system input.

I personally would use keyReleased for this. It will fire only when they lift their finger up.

Note that keyTyped will only work for something that can be printed (I don't know if F5 can or not) and I believe will fire over and over again if the key is held down. This would be useful for something like... moving a character across the screen or something.

Label encoding across multiple columns in scikit-learn

You can easily do this though,

df.apply(LabelEncoder().fit_transform)

EDIT2:

In scikit-learn 0.20, the recommended way is

OneHotEncoder().fit_transform(df)

as the OneHotEncoder now supports string input. Applying OneHotEncoder only to certain columns is possible with the ColumnTransformer.

EDIT3:

Since this answer is over a year ago, and generated many upvotes (including a bounty), I should probably extend this further.

For inverse_transform and transform, you have to do a little bit of hack.

from collections import defaultdict
d = defaultdict(LabelEncoder)

With this, you now retain all columns LabelEncoder as dictionary.

# Encoding the variable
fit = df.apply(lambda x: d[x.name].fit_transform(x))

# Inverse the encoded
fit.apply(lambda x: d[x.name].inverse_transform(x))

# Using the dictionary to label future data
df.apply(lambda x: d[x.name].transform(x))

MOAR EDIT:

Using Neuraxle's FlattenForEach step, it's possible to do this as well to use the same LabelEncoder on all the flattened data at once:

FlattenForEach(LabelEncoder(), then_unflatten=True).fit_transform(df)

For using separate LabelEncoders depending for your columns of data, or if only some of your columns of data needs to be label-encoded and not others, then using a ColumnTransformer is a solution that allows for more control on your column selection and your LabelEncoder instances.

How can I get Android Wifi Scan Results into a list?

Wrap an ArrayAdapter around your List<ScanResult>. Override getView() to populate your rows with the ScanResult data. Here is a free excerpt from one of my books that covers how to create custom ArrayAdapters like this.

What are the parameters for the number Pipe - Angular 2

'1.0-0' will give you zero decimal places i.e. no decimals. e.g.$500

Node.js console.log() not logging anything

This can be confusing for anyone using nodejs for the first time. It is actually possible to pipe your node console output to the browser console. Take a look at connect-browser-logger on github

UPDATE: As pointed out by Yan, connect-browser-logger appears to be defunct. I would recommend NodeMonkey as detailed here : Output to Chrome console from Node.js

Requests (Caused by SSLError("Can't connect to HTTPS URL because the SSL module is not available.") Error in PyCharm requesting website

Windows Users need to set below paths:

  • ..\Anaconda3
  • ..\Anaconda3\scripts
  • ..\Anaconda3\Library\bin

Per user:

  1. Open Environment variable
  2. Click User Variable
  3. Close command prompt if already open and reopen it

System wide (requires restart):

  1. Open Environment variable
  2. Click System Variable
  3. Restart Windows

Address validation using Google Maps API

The answer depends upon the degree of confidence you place in the data and how your data is being used. For example, if you're using it for mailing or shipping, you'll want to be be confident that the data is correct. If you're just using it as another fraud-prevention mechanism then you could potentially allow a degree of error to creep into the data.

If you want any degree of real accuracy, you're need to go with a service that does real address verification and you're going to have to pay for it. As has been mentioned by Adam, address verification and validation at first seems simple and easy, but it's a black hole fraught with challenges and, unless you've some underlying data to work with, virtually impossible to do by yourself. Trust me, you're actually saving money by using a service. You're welcome to go down this road yourself to experience what I mean, but I can guarantee you'll see the light, so to speak, after even a few hours (or days) of spinning your wheels.

I should mention that I'm the founder of SmartyStreets. We do address validation and verification addresses and we offer this for the USA and international as well. I'm more than happy to personally answer any questions you have on the topic of address cleansing, standardization, and validation.

Java - Change int to ascii

Do you want to convert ints to chars?:

int yourInt = 33;
char ch = (char) yourInt;
System.out.println(yourInt);
System.out.println(ch);
// Output:
// 33
// !

Or do you want to convert ints to Strings?

int yourInt = 33;
String str = String.valueOf(yourInt);

Or what is it that you mean?

How to URL encode a string in Ruby

Nowadays, you should use ERB::Util.url_encode or CGI.escape. The primary difference between them is their handling of spaces:

>> ERB::Util.url_encode("foo/bar? baz&")
=> "foo%2Fbar%3F%20baz%26"

>> CGI.escape("foo/bar? baz&")
=> "foo%2Fbar%3F+baz%26"

CGI.escape follows the CGI/HTML forms spec and gives you an application/x-www-form-urlencoded string, which requires spaces be escaped to +, whereas ERB::Util.url_encode follows RFC 3986, which requires them to be encoded as %20.

See "What's the difference between URI.escape and CGI.escape?" for more discussion.

jquery - return value using ajax result on success

EDIT: This is quite old, and ugly, don't do this. You should use callbacks: https://stackoverflow.com/a/5316755/591257

EDIT 2: See the fetch API

Had same problem, solved it this way, using a global var. Not sure if it's the best but surely works. On error you get an empty string (myVar = ''), so you can handle that as needed.

var myVar = '';
function isSession(selector) {
  $.ajax({
    'type': 'POST',
    'url': '/order.html',
    'data': {
      'issession': 1,
      'selector': selector
    },
    'dataType': 'html',
    'success': function(data) {
      myVar = data;
    },
    'error': function() {
      alert('Error occured');
    }
  });
  return myVar;
}

Select multiple elements from a list

mylist[c(5,7,9)] should do it.

You want the sublists returned as sublists of the result list; you don't use [[]] (or rather, the function is [[) for that -- as Dason mentions in comments, [[ grabs the element.

TypeScript or JavaScript type casting

In typescript it is possible to do an instanceof check in an if statement and you will have access to the same variable with the Typed properties.

So let's say MarkerSymbolInfo has a property on it called marker. You can do the following:

if (symbolInfo instanceof MarkerSymbol) {
    // access .marker here
    const marker = symbolInfo.marker
}

It's a nice little trick to get the instance of a variable using the same variable without needing to reassign it to a different variable name.

Check out these two resources for more information:

TypeScript instanceof & JavaScript instanceof

The object 'DF__*' is dependent on column '*' - Changing int to double

When we try to drop a column which is depended upon then we see this kind of error:

The object 'DF__*' is dependent on column ''.

drop the constraint which is dependent on that column with:

ALTER TABLE TableName DROP CONSTRAINT dependent_constraint;

Example:

Msg 5074, Level 16, State 1, Line 1

The object 'DF__Employees__Colf__1273C1CD' is dependent on column 'Colf'.

Msg 4922, Level 16, State 9, Line 1

ALTER TABLE DROP COLUMN Colf failed because one or more objects access this column.

Drop Constraint(DF__Employees__Colf__1273C1CD):

ALTER TABLE Employees DROP CONSTRAINT DF__Employees__Colf__1273C1CD;

Then you can Drop Column:

Alter Table TableName Drop column ColumnName

How to insert multiple rows from array using CodeIgniter framework?

You could always use mysql's LOAD DATA:

LOAD DATA LOCAL INFILE '/full/path/to/file/foo.csv' INTO TABLE `footable` FIELDS TERMINATED BY ',' LINES TERMINATED BY '\r\n' 

to do bulk inserts rather than using a bunch of INSERT statements.

Multidimensional arrays in Swift

For future readers, here is an elegant solution(5x5):

var matrix = [[Int]](repeating: [Int](repeating: 0, count: 5), count: 5)

and a dynamic approach:

var matrix = [[Int]]() // creates an empty matrix
var row = [Int]() // fill this row
matrix.append(row) // add this row

Is there a color code for transparent in HTML?

When you have a 6 digit color code e.g. #ffffff, replace it with #ffffff00. Just add 2 zeros at the end to make the color transparent.

Here is an article describing the new standard in more depth: https://css-tricks.com/8-digit-hex-codes/

Regular expression to find URLs within a string

All of the above answers are not match for Unicode characters in URL, for example: http://google.com?query=d?c+filan+dã+search

For the solution, this one should work:

(ftp:\/\/|www\.|https?:\/\/){1}[a-zA-Z0-9u00a1-\uffff0-]{2,}\.[a-zA-Z0-9u00a1-\uffff0-]{2,}(\S*)

Bootstrap 3 collapsed menu doesn't close on click

 $(function(){ 
    var navMain = $("#your id");
    navMain.on("click", "a", null, function () {
      navMain.collapse('hide');
    });
});

What is the Record type in typescript?

A Record lets you create a new type from a Union. The values in the Union are used as attributes of the new type.

For example, say I have a Union like this:

type CatNames = "miffy" | "boris" | "mordred";

Now I want to create an object that contains information about all the cats, I can create a new type using the values in the CatName Union as keys.

type CatList = Record<CatNames, {age: number}>

If I want to satisfy this CatList, I must create an object like this:

const cats:CatList = {
  miffy: { age:99 },
  boris: { age:16 },
  mordred: { age:600 }
}

You get very strong type safety:

  • If I forget a cat, I get an error.
  • If I add a cat that's not allowed, I get an error.
  • If I later change CatNames, I get an error. This is especially useful because CatNames is likely imported from another file, and likely used in many places.

Real-world React example.

I used this recently to create a Status component. The component would receive a status prop, and then render an icon. I've simplified the code quite a lot here for illustrative purposes

I had a union like this:

type Statuses = "failed" | "complete";

I used this to create an object like this:

const icons: Record<
  Statuses,
  { iconType: IconTypes; iconColor: IconColors }
> = {
  failed: {
    iconType: "warning",
    iconColor: "red"
  },
  complete: {
    iconType: "check",
    iconColor: "green"
  };

I could then render by destructuring an element from the object into props, like so:

const Status = ({status}) => <Icon {...icons[status]} />

If the Statuses union is later extended or changed, I know my Status component will fail to compile and I'll get an error that I can fix immediately. This allows me to add additional error states to the app.

Note that the actual app had dozens of error states that were referenced in multiple places, so this type safety was extremely useful.

How to display the value of the bar on each bar with pyplot.barh()?

I have noticed api example code contains an example of barchart with the value of the bar displayed on each bar:

"""
========
Barchart
========

A bar plot with errorbars and height labels on individual bars
"""
import numpy as np
import matplotlib.pyplot as plt

N = 5
men_means = (20, 35, 30, 35, 27)
men_std = (2, 3, 4, 1, 2)

ind = np.arange(N)  # the x locations for the groups
width = 0.35       # the width of the bars

fig, ax = plt.subplots()
rects1 = ax.bar(ind, men_means, width, color='r', yerr=men_std)

women_means = (25, 32, 34, 20, 25)
women_std = (3, 5, 2, 3, 3)
rects2 = ax.bar(ind + width, women_means, width, color='y', yerr=women_std)

# add some text for labels, title and axes ticks
ax.set_ylabel('Scores')
ax.set_title('Scores by group and gender')
ax.set_xticks(ind + width / 2)
ax.set_xticklabels(('G1', 'G2', 'G3', 'G4', 'G5'))

ax.legend((rects1[0], rects2[0]), ('Men', 'Women'))


def autolabel(rects):
    """
    Attach a text label above each bar displaying its height
    """
    for rect in rects:
        height = rect.get_height()
        ax.text(rect.get_x() + rect.get_width()/2., 1.05*height,
                '%d' % int(height),
                ha='center', va='bottom')

autolabel(rects1)
autolabel(rects2)

plt.show()

output:

enter image description here

FYI What is the unit of height variable in "barh" of matplotlib? (as of now, there is no easy way to set a fixed height for each bar)

List distinct values in a vector in R

You can also use the sqldf package in R.

Z <- sqldf('SELECT DISTINCT tablename.columnname FROM tablename ')

Angularjs - display current date

A solution similar to the one of @Nick G. by using filter, but make the parameter meaningful:

Implement an filter called relativedate which calculate the date relative to current date by the given parameter as diff. As a result, (0 | relativedate) means today and (1 | relativedate) means tomorrow.

.filter('relativedate', ['$filter', function ($filter) {
  return function (rel, format) {
    let date = new Date();
    date.setDate(date.getDate() + rel);
    return $filter('date')(date, format || 'yyyy-MM-dd')
  };
}]);

and your html:

<div ng-app="myApp">
    <div>Yesterday: {{-1 | relativedate}}</div>
    <div>Today: {{0 | relativedate}}</div>
    <div>Tomorrow: {{1 | relativedate}}</div>
</div>

JUnit assertEquals(double expected, double actual, double epsilon)

Epsilon is your "fuzz factor," since doubles may not be exactly equal. Epsilon lets you describe how close they have to be.

If you were expecting 3.14159 but would take anywhere from 3.14059 to 3.14259 (that is, within 0.001), then you should write something like

double myPi = 22.0d / 7.0d; //Don't use this in real life!
assertEquals(3.14159, myPi, 0.001);

(By the way, 22/7 comes out to 3.1428+, and would fail the assertion. This is a good thing.)

What is the list of supported languages/locales on Android?

The best way to see the supported list is to start up the emulator in the latest version and open the "Custom Locale" app. This will list all of the supported languages and locales for that version of Android.

Custom Locale App

How to install and use "make" in Windows?

One solution that may helpful if you want to use the command line emulator cmder. You can install the package installer chocately. First we install chocately in windows command prompt using the following line:

@"%SystemRoot%\System32\WindowsPowerShell\v1.0\powershell.exe" -NoProfile -InputFormat None -ExecutionPolicy Bypass -Command "iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))" && SET "PATH=%PATH%;%ALLUSERSPROFILE%\chocolatey\bin"
refreshenv

After chocolatey is installed the choco command can be used to install make. Once installed, you will need add an alias to /cmder/config/user_aliases.cmd. The following line should be added:

make="path_to_chocolatey\chocolatey\bin\make.exe" $*

Make will then operate in the cmder environment.

'innerText' works in IE, but not in Firefox

jQuery provides a .text() method that can be used in any browser. For example:

$('#myElement').text("Foo");

What is the difference between document.location.href and document.location?

Here is an example of the practical significance of the difference and how it can bite you if you don't realize it (document.location being an object and document.location.href being a string):

We use MonoX Social CMS (http://mono-software.com) free version at http://social.ClipFlair.net and we wanted to add the language bar WebPart at some pages to localize them, but at some others (e.g. at discussions) we didn't want to use localization. So we made two master pages to use at all our .aspx (ASP.net) pages, in the first one we had the language bar WebPart and the other one had the following script to remove the /lng/el-GR etc. from the URLs and show the default (English in our case) language instead for those pages

<script>
  var curAddr = document.location; //MISTAKE
  var newAddr = curAddr.replace(new RegExp("/lng/[a-z]{2}-[A-Z]{2}", "gi"), "");
  if (curAddr != newAddr)
    document.location = newAddr;
</script>

But this code isn't working, replace function just returns Undefined (no exception thrown) so it tries to navigate to say x/lng/el-GR/undefined instead of going to url x. Checking it out with Mozilla Firefox's debugger (F12 key) and moving the cursor over the curAddr variable it was showing lots of info instead of some simple string value for the URL. Selecting Watch from that popup you could see in the watch pane it was writing "Location -> ..." instead of "..." for the url. That made me realize it was an object

One would have expected replace to throw an exception or something, but now that I think of it the problem was that it was trying to call some non-existent "replace" method on the URL object which seems to just give back "undefined" in Javascript.

The correct code in that case is:

<script>
  var curAddr = document.location.href; //CORRECT
  var newAddr = curAddr.replace(new RegExp("/lng/[a-z]{2}-[A-Z]{2}", "gi"), "");
  if (curAddr != newAddr)
    document.location = newAddr;
</script>

What does `set -x` do?

set -x enables a mode of the shell where all executed commands are printed to the terminal. In your case it's clearly used for debugging, which is a typical use case for set -x: printing every command as it is executed may help you to visualize the control flow of the script if it is not functioning as expected.

set +x disables it.

how to use the Box-Cox power transformation in R

Box and Cox (1964) suggested a family of transformations designed to reduce nonnormality of the errors in a linear model. In turns out that in doing this, it often reduces non-linearity as well.

Here is a nice summary of the original work and all the work that's been done since: http://www.ime.usp.br/~abe/lista/pdfm9cJKUmFZp.pdf

You will notice, however, that the log-likelihood function governing the selection of the lambda power transform is dependent on the residual sum of squares of an underlying model (no LaTeX on SO -- see the reference), so no transformation can be applied without a model.

A typical application is as follows:

library(MASS)

# generate some data
set.seed(1)
n <- 100
x <- runif(n, 1, 5)
y <- x^3 + rnorm(n)

# run a linear model
m <- lm(y ~ x)

# run the box-cox transformation
bc <- boxcox(y ~ x)

enter image description here

(lambda <- bc$x[which.max(bc$y)])
[1] 0.4242424

powerTransform <- function(y, lambda1, lambda2 = NULL, method = "boxcox") {

  boxcoxTrans <- function(x, lam1, lam2 = NULL) {

    # if we set lambda2 to zero, it becomes the one parameter transformation
    lam2 <- ifelse(is.null(lam2), 0, lam2)

    if (lam1 == 0L) {
      log(y + lam2)
    } else {
      (((y + lam2)^lam1) - 1) / lam1
    }
  }

  switch(method
         , boxcox = boxcoxTrans(y, lambda1, lambda2)
         , tukey = y^lambda1
  )
}


# re-run with transformation
mnew <- lm(powerTransform(y, lambda) ~ x)

# QQ-plot
op <- par(pty = "s", mfrow = c(1, 2))
qqnorm(m$residuals); qqline(m$residuals)
qqnorm(mnew$residuals); qqline(mnew$residuals)
par(op)

enter image description here

As you can see this is no magic bullet -- only some data can be effectively transformed (usually a lambda less than -2 or greater than 2 is a sign you should not be using the method). As with any statistical method, use with caution before implementing.

To use the two parameter Box-Cox transformation, use the geoR package to find the lambdas:

library("geoR")
bc2 <- boxcoxfit(x, y, lambda2 = TRUE)

lambda1 <- bc2$lambda[1]
lambda2 <- bc2$lambda[2]

EDITS: Conflation of Tukey and Box-Cox implementation as pointed out by @Yui-Shiuan fixed.

How can I commit files with git?

It sounds as if the only problem here is that the default editor that is launched is vi or vim, with which you're not familiar. (As quick tip, to exit that editor without saving changes, hit Esc a few times and then type :, q, ! and Enter.)

There are several ways to set up your default editor, and you haven't indicated which operating system you're using, so it's difficult to recommend one in particular. I'd suggest using:

 git config --global core.editor "name-of-your-editor"

... which sets a global git preference for a particular editor. Alternatively you can set the $EDITOR environment variable.

file_put_contents - failed to open stream: Permission denied

Realise this is pretty old now, but there's no need to manually write queries to a file like this. MySQL has logging support built in, you just need to enable it within your dev environment.

Take a look at the documentation for the 'general query log':

http://dev.mysql.com/doc/refman/5.1/en/query-log.html

How does @synchronized lock/unlock in Objective-C?

The Objective-C language level synchronization uses the mutex, just like NSLock does. Semantically there are some small technical differences, but it is basically correct to think of them as two separate interfaces implemented on top of a common (more primitive) entity.

In particular with a NSLock you have an explicit lock whereas with @synchronized you have an implicit lock associated with the object you are using to synchronize. The benefit of the language level locking is the compiler understands it so it can deal with scoping issues, but mechanically they behave basically the same.

You can think of @synchronized as a compiler rewrite:

- (NSString *)myString {
  @synchronized(self) {
    return [[myString retain] autorelease];
  }
}

is transformed into:

- (NSString *)myString {
  NSString *retval = nil;
  pthread_mutex_t *self_mutex = LOOK_UP_MUTEX(self);
  pthread_mutex_lock(self_mutex);
  retval = [[myString retain] autorelease];
  pthread_mutex_unlock(self_mutex);
  return retval;
}

That is not exactly correct because the actual transform is more complex and uses recursive locks, but it should get the point across.

AngularJS - ng-if check string empty value

You don't need to explicitly use qualifiers like item.photo == '' or item.photo != ''. Like in JavaScript, an empty string will be evaluated as false.

Your views will be much cleaner and readable as well.

_x000D_
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.0/angular.min.js"></script>_x000D_
<div ng-app init="item = {photo: ''}">_x000D_
   <div ng-if="item.photo"> show if photo is not empty</div>_x000D_
   <div ng-if="!item.photo"> show if photo is empty</div>_x000D_
  _x000D_
   <input type=text ng-model="item.photo" placeholder="photo" />_x000D_
</div
_x000D_
_x000D_
_x000D_

Updated to remove bug in Angular

Insert string at specified position

Just wanted to add something: I found tim cooper's answer very useful, I used it to make a method which accepts an array of positions and does the insert on all of them so here that is:

EDIT: Looks like my old function assumed $insertstr was only 1 character and that the array was sorted. This works for arbitrary character length.

function stringInsert($str, $pos, $insertstr) {
    if (!is_array($pos)) {
        $pos = array($pos);
    } else {
        asort($pos);
    }
    $insertionLength = strlen($insertstr);
    $offset = 0;
    foreach ($pos as $p) {
        $str = substr($str, 0, $p + $offset) . $insertstr . substr($str, $p + $offset);
        $offset += $insertionLength;
    }
    return $str;
}

How do I implement __getattribute__ without an infinite recursion error?

Actually, I believe you want to use the __getattr__ special method instead.

Quote from the Python docs:

__getattr__( self, name)

Called when an attribute lookup has not found the attribute in the usual places (i.e. it is not an instance attribute nor is it found in the class tree for self). name is the attribute name. This method should return the (computed) attribute value or raise an AttributeError exception.
Note that if the attribute is found through the normal mechanism, __getattr__() is not called. (This is an intentional asymmetry between __getattr__() and __setattr__().) This is done both for efficiency reasons and because otherwise __setattr__() would have no way to access other attributes of the instance. Note that at least for instance variables, you can fake total control by not inserting any values in the instance attribute dictionary (but instead inserting them in another object). See the __getattribute__() method below for a way to actually get total control in new-style classes.

Note: for this to work, the instance should not have a test attribute, so the line self.test=20 should be removed.

How to upload folders on GitHub

This is Web GUI of a GitHub repository:

enter image description here

Drag and drop your folder to the above area. When you upload too much folder/files, GitHub will notice you:

Yowza, that’s a lot of files. Try again with fewer than 100 files.

enter image description here

and add commit message

enter image description here

And press button Commit changes is the last step.

UPDATE multiple tables in MySQL using LEFT JOIN

UPDATE  t1
LEFT JOIN
        t2
ON      t2.id = t1.id
SET     t1.col1 = newvalue
WHERE   t2.id IS NULL

Note that for a SELECT it would be more efficient to use NOT IN / NOT EXISTS syntax:

SELECT  t1.*
FROM    t1
WHERE   t1.id NOT IN
        (
        SELECT  id
        FROM    t2
        )

See the article in my blog for performance details:

Unfortunately, MySQL does not allow using the target table in a subquery in an UPDATE statement, that's why you'll need to stick to less efficient LEFT JOIN syntax.

What's the syntax to import a class in a default package in Java?

You can't import classes from the default package. You should avoid using the default package except for very small example programs.

From the Java language specification:

It is a compile time error to import a type from the unnamed package.

What can cause intermittent ORA-12519 (TNS: no appropriate handler found) errors

I had the similar issue. It happened every time when I run a pack of database (Spring JDBC) tests with SpringJUnit4ClassRunner, so I resolved the issue putting @DirtiesContext annotation for each test in order to cleanup the application context and release all resources thus each test could run with a new initalization of the application context.

PHP prepend leading zero before single digit number, on-the-fly

You can use sprintf: http://php.net/manual/en/function.sprintf.php

<?php
$num = 4;
$num_padded = sprintf("%02d", $num);
echo $num_padded; // returns 04
?>

It will only add the zero if it's less than the required number of characters.

Edit: As pointed out by @FelipeAls:

When working with numbers, you should use %d (rather than %s), especially when there is the potential for negative numbers. If you're only using positive numbers, either option works fine.

For example:

sprintf("%04s", 10); returns 0010
sprintf("%04s", -10); returns 0-10

Where as:

sprintf("%04d", 10); returns 0010
sprintf("%04d", -10); returns -010

toBe(true) vs toBeTruthy() vs toBeTrue()

As you read through the examples below, just keep in mind this difference

true === true // true
"string" === true // false
1 === true // false
{} === true // false

But

Boolean("string") === true // true
Boolean(1) === true // true
Boolean({}) === true // true

1. expect(statement).toBe(true)

Assertion passes when the statement passed to expect() evaluates to true

expect(true).toBe(true) // pass
expect("123" === "123").toBe(true) // pass

In all other cases cases it would fail

expect("string").toBe(true) // fail
expect(1).toBe(true); // fail
expect({}).toBe(true) // fail

Even though all of these statements would evaluate to true when doing Boolean():

So you can think of it as 'strict' comparison

2. expect(statement).toBeTrue()

This one does exactly the same type of comparison as .toBe(true), but was introduced in Jasmine recently in version 3.5.0 on Sep 20, 2019

3. expect(statement).toBeTruthy()

toBeTruthy on the other hand, evaluates the output of the statement into boolean first and then does comparison

expect(false).toBeTruthy() // fail
expect(null).toBeTruthy() // fail
expect(undefined).toBeTruthy() // fail
expect(NaN).toBeTruthy() // fail
expect("").toBeTruthy() // fail
expect(0).toBeTruthy() // fail

And IN ALL OTHER CASES it would pass, for example

expect("string").toBeTruthy() // pass
expect(1).toBeTruthy() // pass
expect({}).toBeTruthy() // pass

Daylight saving time and time zone best practices

If your design can accommodate it, avoid local time conversion all together!

I know to some this might sound insane but think about UX: users process near, relative dates (today, yesterday, next Monday) faster than absolute dates (2010.09.17, Friday Sept 17) on glance. And when you think about it more, the accuracy of timezones (and DST) is more important the closer the date is to now(), so if you can express dates/datetimes in a relative format for +/- 1 or 2 weeks, the rest of the dates can be UTC and it wont matter too much to 95% of users.

This way you can store all dates in UTC and do the relative comparisons in UTC and simply show the user UTC dates outside of your Relative Date Threshold.

This can also apply to user input too (but generally in a more limited fashion). Selecting from a drop down that only has { Yesterday, Today, Tomorrow, Next Monday, Next Thursday } is so much simpler and easier for the user than a date picker. Date pickers are some of the most pain inducing components of form filling. Of course this will not work for all cases but you can see that it only takes a little clever design to make it very powerful.

How to get value of Radio Buttons?

To Get the Value when the radio button is checked

if (rdbtnSN06.IsChecked == true)
{
string RadiobuttonContent =Convert.ToString(rdbtnSN06.Content.ToString());
}
else
{
string RadiobuttonContent =Convert.ToString(rdbtnSN07.Content.ToString());
}

CSS media queries: max-width OR max-height

yes, using and, like:

@media screen and (max-width: 800px), 
       screen and (max-height: 600px) {
  ...
}

How to logout and redirect to login page using Laravel 5.4?

You can use the following in your controller:

return redirect('login')->with(Auth::logout());

Set cookie and get cookie with JavaScript

These are much much better references than w3schools (the most awful web reference ever made):

Examples derived from these references:

// sets the cookie cookie1
document.cookie = 'cookie1=test; expires=Sun, 1 Jan 2023 00:00:00 UTC; path=/'

// sets the cookie cookie2 (cookie1 is *not* overwritten)
document.cookie = 'cookie2=test; expires=Sun, 1 Jan 2023 00:00:00 UTC; path=/'

// remove cookie2
document.cookie = 'cookie2=; expires=Thu, 01 Jan 1970 00:00:00 UTC; path=/'

The Mozilla reference even has a nice cookie library you can use.

String's Maximum length in Java - calling length() method

I have a 2010 iMac with 8GB of RAM, running Eclipse Neon.2 Release (4.6.2) with Java 1.8.0_25. With the VM argument -Xmx6g, I ran the following code:

StringBuilder sb = new StringBuilder();
for (int i = 0; i < Integer.MAX_VALUE; i++) {
    try {
        sb.append('a');
    } catch (Throwable e) {
        System.out.println(i);
        break;
    }
}
System.out.println(sb.toString().length());

This prints:

Requested array size exceeds VM limit
1207959550

So, it seems that the max array size is ~1,207,959,549. Then I realized that we don't actually care if Java runs out of memory: we're just looking for the maximum array size (which seems to be a constant defined somewhere). So:

for (int i = 0; i < 1_000; i++) {
    try {
        char[] array = new char[Integer.MAX_VALUE - i];
        Arrays.fill(array, 'a');
        String string = new String(array);
        System.out.println(string.length());
    } catch (Throwable e) {
        System.out.println(e.getMessage());
        System.out.println("Last: " + (Integer.MAX_VALUE - i));
        System.out.println("Last: " + i);
    }
}

Which prints:

Requested array size exceeds VM limit
Last: 2147483647
Last: 0
Requested array size exceeds VM limit
Last: 2147483646
Last: 1
Java heap space
Last: 2147483645
Last: 2

So, it seems the max is Integer.MAX_VALUE - 2, or (2^31) - 3

P.S. I'm not sure why my StringBuilder maxed out at 1207959550 while my char[] maxed out at (2^31)-3. It seems that AbstractStringBuilder doubles the size of its internal char[] to grow it, so that probably causes the issue.

Validating file types by regular expression

Your regexp seems to validate both the file name and the extension. Is that what you need? I'll assume it's just the extension and would use a regexp like this:

\.(jpg|gif|doc|pdf)$

And set the matching to be case insensitive.

bash script use cut command at variable and store result at another variable

You can avoid the loop and cut etc by using:

awk -F ':' '{system("ping " $1);}' config.txt

However it would be better if you post a snippet of your config.txt

How to check if a subclass is an instance of a class at runtime?

You have to read the API carefully for this methods. Sometimes you can get confused very easily.

It is either:

if (B.class.isInstance(view))

API says: Determines if the specified Object (the parameter) is assignment-compatible with the object represented by this Class (The class object you are calling the method at)

or:

if (B.class.isAssignableFrom(view.getClass()))

API says: Determines if the class or interface represented by this Class object is either the same as, or is a superclass or superinterface of, the class or interface represented by the specified Class parameter

or (without reflection and the recommended one):

if (view instanceof B)

What is the main difference between PATCH and PUT request?

I spent couple of hours with google and found the answer here

PUT => If user can update all or just a portion of the record, use PUT (user controls what gets updated)

PUT /users/123/email
[email protected]

PATCH => If user can only update a partial record, say just an email address (application controls what can be updated), use PATCH.

PATCH /users/123
[description of changes]

Why Patch

PUT method need more bandwidth or handle full resources instead on partial. So PATCH was introduced to reduce the bandwidth.

Explanation about PATCH

PATCH is a method that is not safe, nor idempotent, and allows full and partial updates and side-effects on other resources.

PATCH is a method which enclosed entity contains a set of instructions describing how a resource currently residing on the origin server should be modified to produce a new version.

PATCH /users/123
[
  { "op": "replace", "path": "/email", "value": "[email protected]" }
]

Here more information about put and patch

How can I resolve "Your requirements could not be resolved to an installable set of packages" error?

I solved the same error, by adding "zizaco/entrust": "*" instead of the "zizaco/entrust": "~1.2".

SELECT * FROM X WHERE id IN (...) with Dapper ORM

Example for postgres:

string sql = "SELECT * FROM SomeTable WHERE id = ANY(@ids)"
var results = conn.Query(sql, new { ids = new[] { 1, 2, 3, 4, 5 }});

pandas: to_numeric for multiple columns

df.loc[:,'col':] = df.loc[:,'col':].apply(pd.to_numeric, errors = 'coerce')

Drop all duplicate rows across multiple columns in Python Pandas

Just want to add to Ben's answer on drop_duplicates:

keep : {‘first’, ‘last’, False}, default ‘first’

  • first : Drop duplicates except for the first occurrence.

  • last : Drop duplicates except for the last occurrence.

  • False : Drop all duplicates.

So setting keep to False will give you desired answer.

DataFrame.drop_duplicates(*args, **kwargs) Return DataFrame with duplicate rows removed, optionally only considering certain columns

Parameters: subset : column label or sequence of labels, optional Only consider certain columns for identifying duplicates, by default use all of the columns keep : {‘first’, ‘last’, False}, default ‘first’ first : Drop duplicates except for the first occurrence. last : Drop duplicates except for the last occurrence. False : Drop all duplicates. take_last : deprecated inplace : boolean, default False Whether to drop duplicates in place or to return a copy cols : kwargs only argument of subset [deprecated] Returns: deduplicated : DataFrame

What does set -e mean in a bash script?

As per bash - The Set Builtin manual, if -e/errexit is set, the shell exits immediately if a pipeline consisting of a single simple command, a list or a compound command returns a non-zero status.

By default, the exit status of a pipeline is the exit status of the last command in the pipeline, unless the pipefail option is enabled (it's disabled by default).

If so, the pipeline's return status of the last (rightmost) command to exit with a non-zero status, or zero if all commands exit successfully.

If you'd like to execute something on exit, try defining trap, for example:

trap onexit EXIT

where onexit is your function to do something on exit, like below which is printing the simple stack trace:

onexit(){ while caller $((n++)); do :; done; }

There is similar option -E/errtrace which would trap on ERR instead, e.g.:

trap onerr ERR

Examples

Zero status example:

$ true; echo $?
0

Non-zero status example:

$ false; echo $?
1

Negating status examples:

$ ! false; echo $?
0
$ false || true; echo $?
0

Test with pipefail being disabled:

$ bash -c 'set +o pipefail -e; true | true | true; echo success'; echo $?
success
0
$ bash -c 'set +o pipefail -e; false | false | true; echo success'; echo $?
success
0
$ bash -c 'set +o pipefail -e; true | true | false; echo success'; echo $?
1

Test with pipefail being enabled:

$ bash -c 'set -o pipefail -e; true | false | true; echo success'; echo $?
1

How to delete a folder and all contents using a bat file in windows?

  1. del /s /q c:\where ever the file is\*
  2. rmdir /s /q c:\where ever the file is\
  3. mkdir c:\where ever the file is\

CSS list-style-image size

I'm using:

_x000D_
_x000D_
li {_x000D_
 margin: 0;_x000D_
 padding: 36px 0 36px 84px;_x000D_
 list-style: none;_x000D_
 background-image: url("../../images/checked_red.svg");_x000D_
 background-repeat: no-repeat;_x000D_
 background-position: left center;_x000D_
 background-size: 40px;_x000D_
}
_x000D_
_x000D_
_x000D_

where background-size set the background image size.