shell script. how to extract string using regular expressions

One way would be with sed. For example:

echo $name | sed -e 's?http://www\.??'

Normally the sed regular expressions are delimited by `/', but you can use '?' since you're searching for '/'. Here's another bash trick. @DigitalTrauma's answer reminded me that I ought to suggest it. It's similar:

echo ${name#http://www.}

(DigitalTrauma also gets credit for reminding me that the "http://" needs to be handled.)

Where do I call the BatchNormalization function in Keras?

This thread has some considerable debate about whether BN should be applied before non-linearity of current layer or to the activations of the previous layer.

Although there is no correct answer, the authors of Batch Normalization say that It should be applied immediately before the non-linearity of the current layer. The reason ( quoted from original paper) -

"We add the BN transform immediately before the nonlinearity, by normalizing x = Wu+b. We could have also normalized the layer inputs u, but since u is likely the output of another nonlinearity, the shape of its distribution is likely to change during training, and constraining its first and second moments would not eliminate the covariate shift. In contrast, Wu + b is more likely to have a symmetric, non-sparse distribution, that is “more Gaussian” (Hyv¨arinen & Oja, 2000); normalizing it is likely to produce activations with a stable distribution."

Python Regex - How to Get Positions and Values of Matches

import re
p = re.compile("[a-z]")
for m in p.finditer('a1b2c3d4'):
    print(m.start(), m.group())

Create folder in Android

Add this permission in Manifest,
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

File folder = new File(Environment.getExternalStorageDirectory() + 
                             File.separator + "TollCulator");
boolean success = true;
if (!folder.exists()) {
    success = folder.mkdirs();
}
if (success) {
    // Do something on success
} else {
    // Do something else on failure 
}

when u run the application go too DDMS->File Explorer->mnt folder->sdcard folder->toll-creation folder

Finding a substring within a list in Python

I'd just use a simple regex, you can do something like this

import re
old_list = ['abc123', 'def456', 'ghi789']
new_list = [x for x in old_list if re.search('abc', x)]
for item in new_list:
    print item

Replace one character with another in Bash

Try this for paths:

echo \"hello world\"|sed 's/ /+/g'|sed 's/+/\/g'|sed 's/\"//g'

It replaces the space inside the double-quoted string with a + sing, then replaces the + sign with a backslash, then removes/replaces the double-quotes.

I had to use this to replace the spaces in one of my paths in Cygwin.

echo \"$(cygpath -u $JAVA_HOME)\"|sed 's/ /+/g'|sed 's/+/\\/g'|sed 's/\"//g'

I'm getting favicon.ico error

The answers above didn't work for me. I found a very good article for Favicon, explaining:

what is a Favicon;
why does Favicon.ico show up as a 404 in the log files;
why should You use a Favicon;
how to make a Favicon using FavIcon from Pics or other Favicon creator;
how to get Your Favicon to show.

So I created Favicon using FavIcon from Pics. Put it in folder (named favicon) and add this code in <head> tag:

<link rel="shortcut icon" href="favicon/favicon.ico">
<link rel="icon" type="image/gif" href="favicon/animated_favicon1.gif">

Now there is no error and I see my Favicon:

Invalid date in safari

This will not work alert(new Date('2010-11-29')); safari have some weird/strict way of processing date format alert(new Date(String('2010-11-29'))); try like this.

(Or)

Using Moment js will solve the issue though, After ios 14 the safari gets even weird

Try this alert(moment(String("2015-12-31 00:00:00")));

Moment JS

Create code first, many to many, with additional fields in association table

I'll just post the code to do this using the fluent API mapping.

public class User {
    public int UserID { get; set; }
    public string Username { get; set; }
    public string Password { get; set; }

    public ICollection<UserEmail> UserEmails { get; set; }
}

public class Email {
    public int EmailID { get; set; }
    public string Address { get; set; }

    public ICollection<UserEmail> UserEmails { get; set; }
}

public class UserEmail {
    public int UserID { get; set; }
    public int EmailID { get; set; }
    public bool IsPrimary { get; set; }
}

On your DbContext derived class you could do this:

public class MyContext : DbContext {
    protected override void OnModelCreating(DbModelBuilder builder) {
        // Primary keys
        builder.Entity<User>().HasKey(q => q.UserID);
        builder.Entity<Email>().HasKey(q => q.EmailID);
        builder.Entity<UserEmail>().HasKey(q => 
            new { 
                q.UserID, q.EmailID
            });

        // Relationships
        builder.Entity<UserEmail>()
            .HasRequired(t => t.Email)
            .WithMany(t => t.UserEmails)
            .HasForeignKey(t => t.EmailID)

        builder.Entity<UserEmail>()
            .HasRequired(t => t.User)
            .WithMany(t => t.UserEmails)
            .HasForeignKey(t => t.UserID)
    }
}

It has the same effect as the accepted answer, with a different approach, which is no better nor worse.

What is the difference between children and childNodes in JavaScript?

Good answers so far, I want to only add that you could check the type of a node using nodeType:

yourElement.nodeType

This will give you an integer: (taken from here)

| Value |             Constant             |                          Description                          |  |
|-------|----------------------------------|---------------------------------------------------------------|--|
|    1  | Node.ELEMENT_NODE                | An Element node such as <p> or <div>.                         |  |
|    2  | Node.ATTRIBUTE_NODE              | An Attribute of an Element. The element attributes            |  |
|       |                                  | are no longer implementing the Node interface in              |  |
|       |                                  | DOM4 specification.                                           |  |
|    3  | Node.TEXT_NODE                   | The actual Text of Element or Attr.                           |  |
|    4  | Node.CDATA_SECTION_NODE          | A CDATASection.                                               |  |
|    5  | Node.ENTITY_REFERENCE_NODE       | An XML Entity Reference node. Removed in DOM4 specification.  |  |
|    6  | Node.ENTITY_NODE                 | An XML <!ENTITY ...> node. Removed in DOM4 specification.     |  |
|    7  | Node.PROCESSING_INSTRUCTION_NODE | A ProcessingInstruction of an XML document                    |  |
|       |                                  | such as <?xml-stylesheet ... ?> declaration.                  |  |
|    8  | Node.COMMENT_NODE                | A Comment node.                                               |  |
|    9  | Node.DOCUMENT_NODE               | A Document node.                                              |  |
|   10  | Node.DOCUMENT_TYPE_NODE          | A DocumentType node e.g. <!DOCTYPE html> for HTML5 documents. |  |
|   11  | Node.DOCUMENT_FRAGMENT_NODE      | A DocumentFragment node.                                      |  |
|   12  | Node.NOTATION_NODE               | An XML <!NOTATION ...> node. Removed in DOM4 specification.   |  |

Note that according to Mozilla:

The following constants have been deprecated and should not be used anymore: Node.ATTRIBUTE_NODE, Node.ENTITY_REFERENCE_NODE, Node.ENTITY_NODE, Node.NOTATION_NODE

PostgreSQL create table if not exists

I created a generic solution out of the existing answers which can be reused for any table:

CREATE OR REPLACE FUNCTION create_if_not_exists (table_name text, create_stmt text)
RETURNS text AS
$_$
BEGIN

IF EXISTS (
    SELECT *
    FROM   pg_catalog.pg_tables 
    WHERE    tablename  = table_name
    ) THEN
   RETURN 'TABLE ' || '''' || table_name || '''' || ' ALREADY EXISTS';
ELSE
   EXECUTE create_stmt;
   RETURN 'CREATED';
END IF;

END;
$_$ LANGUAGE plpgsql;

Usage:

select create_if_not_exists('my_table', 'CREATE TABLE my_table (id integer NOT NULL);');

It could be simplified further to take just one parameter if one would extract the table name out of the query parameter. Also I left out the schemas.

Combining paste() and expression() functions in plot labels

If x^2 and y^2 were expressions already given in the variable squared, this solves the problem:

labNames <- c('xLab','yLab')
squared <- c(expression('x'^2), expression('y'^2))

xlab <- eval(bquote(expression(.(labNames[1]) ~ .(squared[1][[1]]))))
ylab <- eval(bquote(expression(.(labNames[2]) ~ .(squared[2][[1]]))))

plot(c(1:10), xlab = xlab, ylab = ylab)

Please note the [[1]] behind squared[1]. It gives you the content of "expression(...)" between the brackets without any escape characters.

How to skip "are you sure Y/N" when deleting files in batch files

Use del /F /Q to force deletion of read-only files (/F) and directories and not ask to confirm (/Q) when deleting via wildcard.

Get the current date and time

use DateTime.Now

try this:

DateTime.Now.ToString("yyyy/MM/dd HH:mm:ss")

MIN and MAX in C

If you need min/max in order to avoid an expensive branch, you shouldn't use the ternary operator, as it will compile down to a jump. The link below describes a useful method for implementing a min/max function without branching.

http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax

Accessing member of base class

Working example. Notes below.

class Animal {
    constructor(public name) {
    }

    move(meters) {
        alert(this.name + " moved " + meters + "m.");
    }
}

class Snake extends Animal {
    move() {
        alert(this.name + " is Slithering...");
        super.move(5);
    }
}

class Horse extends Animal {
    move() {
        alert(this.name + " is Galloping...");
        super.move(45);
    }
}

var sam = new Snake("Sammy the Python");
var tom: Animal = new Horse("Tommy the Palomino");

sam.move();
tom.move(34);

You don't need to manually assign the name to a public variable. Using public name in the constructor definition does this for you.
You don't need to call super(name) from the specialised classes.
Using this.name works.

Notes on use of super.

This is covered in more detail in section 4.9.2 of the language specification.

The behaviour of the classes inheriting from Animal is not dissimilar to the behaviour in other languages. You need to specify the super keyword in order to avoid confusion between a specialised function and the base class function. For example, if you called move() or this.move() you would be dealing with the specialised Snake or Horse function, so using super.move() explicitly calls the base class function.

There is no confusion of properties, as they are the properties of the instance. There is no difference between super.name and this.name - there is simply this.name. Otherwise you could create a Horse that had different names depending on whether you were in the specialized class or the base class.

Failed to decode downloaded font

In my case when downloading a template the font files were just empty files. Probably an issue with the download. Chrome gave this generic error about it. I thought at first the solution of changing from woff to font-woff solved it, but it only made Chrome ignore the fonts. My solution was finding the fonts one by one and downloading/replacing them.

How to remove specific elements in a numpy array

Using np.delete is the fastest way to do it, if we know the indices of the elements that we want to remove. However, for completeness, let me add another way of "removing" array elements using a boolean mask created with the help of np.isin. This method allows us to remove the elements by specifying them directly or by their indices:

import numpy as np
a = np.array([1, 2, 3, 4, 5, 6, 7, 8, 9])

Remove by indices:

indices_to_remove = [2, 3, 6]
a = a[~np.isin(np.arange(a.size), indices_to_remove)]

Remove by elements (don't forget to recreate the original a since it was rewritten in the previous line):

elements_to_remove = a[indices_to_remove]  # [3, 4, 7]
a = a[~np.isin(a, elements_to_remove)]

What are database normal forms and can you give examples?

1NF is the most basic of normal forms - each cell in a table must contain only one piece of information, and there can be no duplicate rows.

2NF and 3NF are all about being dependent on the primary key. Recall that a primary key can be made up of multiple columns. As Chris said in his response:

The data depends on the key [1NF], the whole key [2NF] and nothing but the key [3NF] (so help me Codd).

2NF

Say you have a table containing courses that are taken in a certain semester, and you have the following data:

|-----Primary Key----|               uh oh |
                                           V
CourseID | SemesterID | #Places  | Course Name  |
------------------------------------------------|
IT101    |   2009-1   | 100      | Programming  |
IT101    |   2009-2   | 100      | Programming  |
IT102    |   2009-1   | 200      | Databases    |
IT102    |   2010-1   | 150      | Databases    |
IT103    |   2009-2   | 120      | Web Design   |

This is not in 2NF, because the fourth column does not rely upon the entire key - but only a part of it. The course name is dependent on the Course's ID, but has nothing to do with which semester it's taken in. Thus, as you can see, we have duplicate information - several rows telling us that IT101 is programming, and IT102 is Databases. So we fix that by moving the course name into another table, where CourseID is the ENTIRE key.

Primary Key |

CourseID    |  Course Name |
---------------------------|
IT101       | Programming  |
IT102       | Databases    |
IT103       | Web Design   |

No redundancy!

3NF

Okay, so let's say we also add the name of the teacher of the course, and some details about them, into the RDBMS:

|-----Primary Key----|                           uh oh |
                                                       V
Course  |  Semester  |  #Places   |  TeacherID  | TeacherName  |
---------------------------------------------------------------|
IT101   |   2009-1   |  100       |  332        |  Mr Jones    |
IT101   |   2009-2   |  100       |  332        |  Mr Jones    |
IT102   |   2009-1   |  200       |  495        |  Mr Bentley  |
IT102   |   2010-1   |  150       |  332        |  Mr Jones    |
IT103   |   2009-2   |  120       |  242        |  Mrs Smith   |

Now hopefully it should be obvious that TeacherName is dependent on TeacherID - so this is not in 3NF. To fix this, we do much the same as we did in 2NF - take the TeacherName field out of this table, and put it in its own, which has TeacherID as the key.

 Primary Key |

 TeacherID   | TeacherName  |
 ---------------------------|
 332         |  Mr Jones    |
 495         |  Mr Bentley  |
 242         |  Mrs Smith   |

No redundancy!!

One important thing to remember is that if something is not in 1NF, it is not in 2NF or 3NF either. So each additional Normal Form requires everything that the lower normal forms had, plus some extra conditions, which must all be fulfilled.

Unable to find a @SpringBootConfiguration when doing a JpaTest

In my case I was using the Test class from wrong package. when I replaced import org.junit.Test; with import org.junit.jupiter.api.Test; it worked.

Which versions of SSL/TLS does System.Net.WebRequest support?

This is an important question. The SSL 3 protocol (1996) is irreparably broken by the Poodle attack published 2014. The IETF have published "SSLv3 MUST NOT be used". Web browsers are ditching it. Mozilla Firefox and Google Chrome have already done so.

Two excellent tools for checking protocol support in browsers are SSL Lab's client test and https://www.howsmyssl.com/ . The latter does not require Javascript, so you can try it from .NET's HttpClient:

// set proxy if you need to
// WebRequest.DefaultWebProxy = new WebProxy("http://localhost:3128");

File.WriteAllText("howsmyssl-httpclient.html", new HttpClient().GetStringAsync("https://www.howsmyssl.com").Result);

// alternative using WebClient for older framework versions
// new WebClient().DownloadFile("https://www.howsmyssl.com/", "howsmyssl-webclient.html");

The result is damning:

Your client is using TLS 1.0, which is very old, possibly susceptible to the BEAST attack, and doesn't have the best cipher suites available on it. Additions like AES-GCM, and SHA256 to replace MD5-SHA-1 are unavailable to a TLS 1.0 client as well as many more modern cipher suites.

That's concerning. It's comparable to 2006's Internet Explorer 7.

To list exactly which protocols a HTTP client supports, you can try the version-specific test servers below:

var test_servers = new Dictionary<string, string>();
test_servers["SSL 2"] = "https://www.ssllabs.com:10200";
test_servers["SSL 3"] = "https://www.ssllabs.com:10300";
test_servers["TLS 1.0"] = "https://www.ssllabs.com:10301";
test_servers["TLS 1.1"] = "https://www.ssllabs.com:10302";
test_servers["TLS 1.2"] = "https://www.ssllabs.com:10303";

var supported = new Func<string, bool>(url =>
{
    try { return new HttpClient().GetAsync(url).Result.IsSuccessStatusCode; }
    catch { return false; }
});

var supported_protocols = test_servers.Where(server => supported(server.Value));
Console.WriteLine(string.Join(", ", supported_protocols.Select(x => x.Key)));

I'm using .NET Framework 4.6.2. I found HttpClient supports only SSL 3 and TLS 1.0. That's concerning. This is comparable to 2006's Internet Explorer 7.

Update: It turns HttpClient does support TLS 1.1 and 1.2, but you have to turn them on manually at System.Net.ServicePointManager.SecurityProtocol. See https://stackoverflow.com/a/26392698/284795

I don't know why it uses bad protocols out-the-box. That seems a poor setup choice, tantamount to a major security bug (I bet plenty of applications don't change the default). How can we report it?

How can I select an element by name with jQuery?

You can use any attribute as selector with [attribute_name=value].

$('td[name=tcol1]').hide();

How to read file with space separated values in pandas

add delim_whitespace=True argument, it's faster than regex.

What is the $$hashKey added to my JSON.stringify result

Angular adds this to keep track of your changes, so it knows when it needs to update the DOM.

If you use angular.toJson(obj) instead of JSON.stringify(obj) then Angular will strip out these internal-use values for you.

Also, if you change your repeat expression to use the track by {uniqueProperty} suffix, Angular won't have to add $$hashKey at all. For example

<ul>
    <li ng-repeat="link in navLinks track by link.href">
        <a ng-href="link.href">{{link.title}}</a>
    </li>
</ul>

Just always remember you need the "link." part of the expression - I always tend to forget that. Just track by href will surely not work.

How to include a sub-view in Blade templates?

EDIT: Below was the preferred solution in 2014. Nowadays you should use @include, as mentioned in the other answer.

In Laravel views the dot is used as folder separator. So for example I have this code

return View::make('auth.details', array('id' => $id));

which points to app/views/auth/details.blade.php

And to include a view inside a view you do like this:

file: layout.blade.php

<html>
  <html stuff>
  @yield('content')
</html>

file: hello.blade.php

@extends('layout')

@section('content')
  <html stuff>
@stop

Firebug-like debugger for Google Chrome

Forget everything you all needs this browser independent inspector , dom updater

https://goggles.webmaker.org/en-US

just bookmark and go to any webpage and click that bookmark..

this is actually Mozilla project Goggles , amazing amazing amazing...

Java Loop every minute

`ScheduledExecutorService`

The Answer by Lee is close, but only runs once. The Question seems to be asking to run indefinitely until an external state changes (until the response from a web site/service changes).

The ScheduledExecutorService interface is part of the java.util.concurrent package built into Java 5 and later as a more modern replacement for the old Timer class.

Here is a complete example. Call either scheduleAtFixedRate or scheduleWithFixedDelay.

ScheduledExecutorService executor = Executors.newScheduledThreadPool ( 1 );

Runnable r = new Runnable () {
    @Override
    public void run () {
        try {  // Always wrap your Runnable with a try-catch as any uncaught Exception causes the ScheduledExecutorService to silently terminate.
            System.out.println ( "Now: " + Instant.now () );  // Our task at hand in this example: Capturing the current moment in UTC.
            if ( Boolean.FALSE ) {  // Add your Boolean test here to see if the external task is fonud to be completed, as described in this Question.
                executor.shutdown ();  // 'shutdown' politely asks ScheduledExecutorService to terminate after previously submitted tasks are executed.
            }

        } catch ( Exception e ) {
            System.out.println ( "Oops, uncaught Exception surfaced at Runnable in ScheduledExecutorService." );
        }
    }
};

try {
    executor.scheduleAtFixedRate ( r , 0L , 5L , TimeUnit.SECONDS ); // ( runnable , initialDelay , period , TimeUnit )
    Thread.sleep ( TimeUnit.MINUTES.toMillis ( 1L ) ); // Let things run a minute to witness the background thread working.
} catch ( InterruptedException ex ) {
    Logger.getLogger ( App.class.getName () ).log ( Level.SEVERE , null , ex );
} finally {
    System.out.println ( "ScheduledExecutorService expiring. Politely asking ScheduledExecutorService to terminate after previously submitted tasks are executed." );
    executor.shutdown ();
}

Expect output like this:

Now: 2016-12-27T02:52:14.951Z
Now: 2016-12-27T02:52:19.955Z
Now: 2016-12-27T02:52:24.951Z
Now: 2016-12-27T02:52:29.951Z
Now: 2016-12-27T02:52:34.953Z
Now: 2016-12-27T02:52:39.952Z
Now: 2016-12-27T02:52:44.951Z
Now: 2016-12-27T02:52:49.953Z
Now: 2016-12-27T02:52:54.953Z
Now: 2016-12-27T02:52:59.951Z
Now: 2016-12-27T02:53:04.952Z
Now: 2016-12-27T02:53:09.951Z
ScheduledExecutorService expiring. Politely asking ScheduledExecutorService to terminate after previously submitted tasks are executed.
Now: 2016-12-27T02:53:14.951Z

Stopping a CSS3 Animation on last frame

The best way seems to put the final state at the main part of css. Like here, i put width to 220px, so that it finally becomes 220px. But starting to 0px;

div.menu-item1 {
  font-size: 20px;
  border: 2px solid #fff;
  width: 220px;
  animation: slide 1s;
  -webkit-animation: slide 1s; /* Safari and Chrome */
}
@-webkit-keyframes slide { /* Safari and Chrome */
  from {width:0px;}
  to {width:220px;}
}

How to set the height of an input (text) field in CSS?

The best way to do this is:

input.heighttext{
  padding: 20px 10px;
  line-height: 28px;
}

Get most recent file in a directory on Linux

ls -t | head -n1

This command actually gives the latest modified file in the current working directory.

Declaring a xsl variable and assigning value to it

No, unlike in a lot of other languages, XSLT variables cannot change their values after they are created. You can however, avoid extraneous code with a technique like this:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" indent="yes" omit-xml-declaration="yes"/>

  <xsl:variable name="mapping">
    <item key="1" v1="A" v2="B" />
    <item key="2" v1="X" v2="Y" />
  </xsl:variable>
  <xsl:variable name="mappingNode"
                select="document('')//xsl:variable[@name = 'mapping']" />

  <xsl:template match="....">
    <xsl:variable name="testVariable" select="'1'" />

    <xsl:variable name="values" select="$mappingNode/item[@key = $testVariable]" />

    <xsl:variable name="variable1" select="$values/@v1" />
    <xsl:variable name="variable2" select="$values/@v2" />
  </xsl:template>
</xsl:stylesheet>

In fact, once you've got the values variable, you may not even need separate variable1 and variable2 variables. You could just use $values/@v1 and $values/@v2 instead.

R memory management / cannot allocate vector of size n Mb

Consider whether you really need all this data explicitly, or can the matrix be sparse? There is good support in R (see Matrix package for e.g.) for sparse matrices.

Keep all other processes and objects in R to a minimum when you need to make objects of this size. Use gc() to clear now unused memory, or, better only create the object you need in one session.

If the above cannot help, get a 64-bit machine with as much RAM as you can afford, and install 64-bit R.

If you cannot do that there are many online services for remote computing.

If you cannot do that the memory-mapping tools like package ff (or bigmemory as Sascha mentions) will help you build a new solution. In my limited experience ff is the more advanced package, but you should read the High Performance Computing topic on CRAN Task Views.

Understanding lambda in python and using it to pass multiple arguments

Why do you need to state both 'x' and 'y' before the ':'?

You could actually in some situations(when you have only one argument) do not put the x and y before ":".

>>> flist = []
>>> for i in range(3):
...     flist.append(lambda : i)

but the i in the lambda will be bound by name, so,

>>> flist[0]()
2
>>> flist[2]()
2
>>>

different from what you may want.

C#: Limit the length of a string?

foo = foo.Substring(0,5);

FirstOrDefault: Default value other than null

I know its been a while but Ill add to this, based on the most popular answer but with a little extension Id like to share the below:

static class ExtensionsThatWillAppearOnIEnumerables
{
    public static T FirstOr<T>(this IEnumerable<T> source, Func<T, bool> predicate, Func<T> alternate)
    {
        var thing = source.FirstOrDefault(predicate);
        if (thing != null)
            return thing;
        return alternate();
    }
}

This allows me to call it inline as such with my own example I was having issues with:

_controlDataResolvers.FirstOr(x => x.AppliesTo(item.Key), () => newDefaultResolver()).GetDataAsync(conn, item.ToList())

So for me I just wanted a default resolver to be used inline, I can do my usual check and then pass in a function so a class isn't instantiated even if unused, its a function to execute when required instead!

Plot data in descending order as appears in data frame

You want reorder(). Here is an example with dummy data

set.seed(42)
df <- data.frame(Category = sample(LETTERS), Count = rpois(26, 6))

require("ggplot2")

p1 <- ggplot(df, aes(x = Category, y = Count)) +
         geom_bar(stat = "identity")

p2 <- ggplot(df, aes(x = reorder(Category, -Count), y = Count)) +
         geom_bar(stat = "identity")

require("gridExtra")
grid.arrange(arrangeGrob(p1, p2))

Giving:

enter image description here

Use reorder(Category, Count) to have Category ordered from low-high.

add to array if it isn't there already

With array_flip() it could look like this:

$flipped = array_flip($opts);
$flipped[$newValue] = 1;
$opts = array_keys($flipped);

With array_unique() - like this:

$opts[] = $newValue;
$opts = array_values(array_unique($opts));

Notice that array_values(...) — you need it if you're exporting array to JavaScript in JSON form. array_unique() alone would simply unset duplicate keys, without rebuilding the remaining elements'. So, after converting to JSON this would produce object, instead of array.

>>> json_encode(array_unique(['a','b','b','c']))
=> "{"0":"a","1":"b","3":"c"}"

>>> json_encode(array_values(array_unique(['a','b','b','c'])))
=> "["a","b","c"]"

How to turn on WCF tracing?

The following configuration taken from MSDN can be applied to enable tracing on your WCF service.

<configuration>
  <system.diagnostics>
    <sources>
      <source name="System.ServiceModel"
              switchValue="Information, ActivityTracing"
              propagateActivity="true" >
        <listeners>
             <add name="xml"/>
        </listeners>
      </source>
      <source name="System.ServiceModel.MessageLogging">
        <listeners>
            <add name="xml"/>
        </listeners>
      </source>
      <source name="myUserTraceSource"
              switchValue="Information, ActivityTracing">
        <listeners>
            <add name="xml"/>
        </listeners>
      </source>
    </sources>
    <sharedListeners>
        <add name="xml"
             type="System.Diagnostics.XmlWriterTraceListener"
             initializeData="Error.svclog" />
    </sharedListeners>
  </system.diagnostics>
</configuration>

To view the log file, you can use "C:\Program Files\Microsoft SDKs\Windows\v7.0A\bin\SvcTraceViewer.exe".

If "SvcTraceViewer.exe" is not on your system, you can download it from the "Microsoft Windows SDK for Windows 7 and .NET Framework 4" package here:

Windows SDK Download

You don't have to install the entire thing, just the ".NET Development / Tools" part.

When/if it bombs out during installation with a non-sensical error, Petopas' answer to Windows 7 SDK Installation Failure solved my issue.

How to fix "could not find a base address that matches schema http"... in WCF

The solution is to define a custom binding inside your Web.Config file and set the security mode to "Transport". Then you just need to use the bindingConfiguration property inside your endpoint definition to point to your custom binding.

See here: Scott's Blog: WCF Bindings Needed For HTTPS

HTML table sort

Check if you could go with any of the below mentioned JQuery plugins. Simply awesome and provide wide range of options to work through, and less pains to integrate. :)

https://github.com/paulopmx/Flexigrid - Flexgrid
http://datatables.net/index - Data tables.
https://github.com/tonytomov/jqGrid

If not, you need to have a link to those table headers that calls a server-side script to invoke the sort.

Run JavaScript code on window close or page refresh?

Sometimes you may want to let the server know that the user is leaving the page. This is useful, for example, to clean up unsaved images stored temporarily on the server, to mark that user as "offline", or to log when they are done their session.

Historically, you would send an AJAX request in the beforeunload function, however this has two problems. If you send an asynchronous request, there is no guarantee that the request would be executed correctly. If you send a synchronous request, it is more reliable, but the browser would hang until the request has finished. If this is a slow request, this would be a huge inconvenience to the user.

Later came navigator.sendBeacon(). By using the sendBeacon() method, the data is transmitted asynchronously to the web server when the User Agent has an opportunity to do so, without delaying the unload or affecting the performance of the next navigation. This solves all of the problems with submission of analytics data: the data is sent reliably, it's sent asynchronously, and it doesn't impact the loading of the next page.

Unless you are targeting only desktop users, sendBeacon() should not be used with unload or beforeunload since these do not reliably fire on mobile devices. Instead you can listen to the visibilitychange event. This event will fire every time your page is visible and the user switches tabs, switches apps, goes to the home screen, answers a phone call, navigates away from the page, closes the tab, refreshes, etc.

Here is an example of its usage:

document.addEventListener('visibilitychange', function() {
    if (document.visibilityState == 'hidden') { 
        navigator.sendBeacon("/log.php", analyticsData);
    }
});

When the user returns to the page, document.visibilityState will change to 'visible', so you can also handle that event as well.

sendBeacon() is supported in:

Edge 14
Firefox 31
Chrome 39
Safari 11.1
Opera 26
iOS Safari 11.4

It is NOT currently supported in:

Internet Explorer
Opera Mini

Here is a polyfill for sendBeacon() in case you need to add support for unsupported browsers. If the method is not available in the browser, it will send a synchronous AJAX request instead.

Update:

It might be worth mentioning that sendBeacon() only sends POST requests. If you need to send a request using any other method, an alternative would be to use the fetch API with the keepalive flag set to true, which causes it to behave the same way as sendBeacon(). Browser support for the fetch API is about the same.

fetch(url, {
   method: ..., 
   body: ...,            
   headers: ...,       
   credentials: 'include',
   mode: 'no-cors',
   keepalive: true,
})

C# ListView Column Width Auto

Expanding a bit on Fredrik's answer, if you want to set the column's auto-resize width on the fly for example: setting the first column's auto-size width to 70:

myListView.Columns[0].AutoResize(ColumnHeaderAutoResizeStyle.None);
myListView.Columns[0].Width = 70;
myListView.Columns[0].AutoResize(ColumnHeaderAutoResizeStyle.ColumnContent);

How can I give eclipse more memory than 512M?

Here is how i increased the memory allocation of eclipse Juno:

enter image description here

I have a total of 4GB on my system and when im working on eclipse, i dont run any other heavy softwares along side it. So I allocated 2Gb.

The thing i noticed is that the difference between min and max values should be of 512. The next value should be let say 2048 min + 512 = 2560max

Here is the heap value inside eclipse after setting -Xms2048m -Xmx2560m:

enter image description here

Why would a JavaScript variable start with a dollar sign?

While you can simply use it to prefix your identifiers, it's supposed to be used for generated code, such as replacement tokens in a template, for example.

Calling filter returns <filter object at ... >

It's an iterator returned by the filter function.

If you want a list, just do

list(filter(f, range(2, 25)))

Nonetheless, you can just iterate over this object with a for loop.

for e in filter(f, range(2, 25)):
    do_stuff(e)

Java 8 stream map on entry set

Question might be a little dated, but you could simply use AbstractMap.SimpleEntry<> as follows:

private Map<String, AttributeType> mapConfig(
    Map<String, String> input, String prefix) {
       int subLength = prefix.length();
       return input.entrySet()
          .stream()
          .map(e -> new AbstractMap.SimpleEntry<>(
               e.getKey().substring(subLength),
               AttributeType.GetByName(e.getValue()))
          .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));

any other Pair-like value object would work too (ie. ApacheCommons Pair tuple).

Undefined columns selected when subsetting data frame

You want rows where that condition is true so you need a comma:

data[data$Ozone > 14, ]

react-native - Fit Image in containing View, not the whole screen size

I think it's because you didn't specify the width and height for the item.

If you only want to have 2 images in a row, you can try something like this instead of using flex:

item: {
    width: '50%',
    height: '100%',
    overflow: 'hidden',
    alignItems: 'center',
    backgroundColor: 'orange',
    position: 'relative',
    margin: 10,
},

This works for me, hope it helps.

Python Hexadecimal

Use the format() function with a '02x' format.

>>> format(255, '02x')
'ff'
>>> format(2, '02x')
'02'

The 02 part tells format() to use at least 2 digits and to use zeros to pad it to length, x means lower-case hexadecimal.

The Format Specification Mini Language also gives you X for uppercase hex output, and you can prefix the field width with # to include a 0x or 0X prefix (depending on wether you used x or X as the formatter). Just take into account that you need to adjust the field width to allow for those extra 2 characters:

>>> format(255, '02X')
'FF'
>>> format(255, '#04x')
'0xff'
>>> format(255, '#04X')
'0XFF'

Counter increment in Bash loop not working

Try to use

COUNTER=$((COUNTER+1))

instead of

COUNTER=$((COUNTER))

Getting only hour/minute of datetime

I would recommend keeping the object you have, and just utilizing the properties that you want, rather than removing the resolution you already have.

If you want to print it in a certain format you may want to look at this...That way you can preserve your resolution further down the line.

That being said you can create a new DateTime object using only the properties you want as @romkyns has in his answer.

Show space, tab, CRLF characters in editor of Visual Studio

For those who are looking for a button toggle:

The name of this command is View white space in GUI menu (Edit -> Advanced -> View white space).

The name of this command in the Add command popup is Toggle Visual Space.

javac error: Class names are only accepted if annotation processing is explicitly requested

How you can reproduce this cryptic error on the Ubuntu terminal:

Put this in a file called Main.java:

public Main{
    public static void main(String[] args){
        System.out.println("ok");
    }
}

Then compile it like this:

user@defiant /home/user $ javac Main
error: Class names, 'Main', are only accepted if 
annotation processing is explicitly requested
1 error

It's because you didn't specify .java at the end of Main.

Do it like this, and it works:

user@defiant /home/user $ javac Main.java
user@defiant /home/user $

Slap your forehead now and grumble that the error message is so cryptic.

TypeError : Unhashable type

The real reason because set does not work is the fact, that it uses the hash function to distinguish different values. This means that sets only allows hashable objects. Why a list is not hashable is already pointed out.

jQuery validation plugin: accept only alphabetical characters?

Just a small addition to Nick's answer (which works great !) :

If you want to allow spaces in between letters, for example , you may restrict to enter only letters in full name, but it should allow space as well - just list the space as below with a comma. And in the same way if you need to allow any other specific character:

jQuery.validator.addMethod("lettersonly", function(value, element) 
{
return this.optional(element) || /^[a-z," "]+$/i.test(value);
}, "Letters and spaces only please");

How to make g++ search for header files in a specific directory?

Headers included with #include <> will be searched in all default directories , but you can also add your own location in the search path with -I command line arg.

I saw your edit you could install your headers in default locations usually

 /usr/local/include
 libdir/gcc/target/version/include
 /usr/target/include
 /usr/include

Confirm with compiler docs though.

Line break in HTML with '\n'

You should consider replacing your line breaks with <br/>. In HTML a line break will only stand for new line in your code.

Alternatively you can use some other HTML markups like placing your lines in paragraphs:

<p>Sample line</p>
<p>Another line</p>

or other wrappers like for instance <div>sample</div> with CSS attribute: display: block.

You can also use <pre>. The content of pre will have its HTML styling ignored. In other words it will display pure HTML with normal \n line breaks.

How can I add a key/value pair to a JavaScript object?

According to Property Accessors defined in ECMA-262(http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf, P67), there are two ways you can do to add properties to a exists object. All these two way, the Javascript engine will treat them the same.

The first way is to use dot notation:

obj.key3 = value3;

But this way, you should use a IdentifierName after dot notation.

The second way is to use bracket notation:

obj["key3"] = value3;

and another form:

var key3 = "key3";
obj[key3] = value3;

This way, you could use a Expression (include IdentifierName) in the bracket notation.

How to use jQuery to select a dropdown option?

if your options have a value, you can do this:

$('select').val("the-value-of-the-option-you-want-to-select");

'select' would be the id of your select or a class selector. or if there is just one select, you can use the tag as it is in the example.

Java equivalent to Explode and Implode(PHP)

String.split() can provide you with a replacement for explode()

For a replacement of implode() I'd advice you to write either a custom function or use Apache Commons's StringUtils.join() functions.

Ifelse statement in R with multiple conditions

Based on suggestions from @jaimedash and @Old_Mortality I found a solution:

DF$Den <- ifelse(DF$Denial1 < 1 & !is.na(DF$Denial1) | DF$Denial2 < 1 &  
!is.na(DF$Denial2) | DF$Denial3 < 1 & !is.na(DF$Denial3), "0", "1")

Then to ensure a value of NA if all values of the conditional variables are NA:

DF$Den <- ifelse(is.na(DF$Denial1) & is.na(DF$Denial2) & is.na(DF$Denial3), 
NA, DF$Den)

How can I make grep print the lines below and above each matching line?

grep's -A 1 option will give you one line after; -B 1 will give you one line before; and -C 1 combines both to give you one line both before and after, -1 does the same.

Two Divs next to each other, that then stack with responsive change

Do like this:

HTML

<div class="parent">
    <div class="child"></div>
    <div class="child"></div>
</div>

CSS

.parent{
    width: 400px;
    background: red;
}
.child{
    float: left;
    width:200px;
    background:green;
    height: 100px;
}

This is working jsfiddle. Change child width to more then 200px and they will stack.

How to cherry-pick from a remote branch?

The commit should be present in your local, check by using git log.

If the commit is not present then try git fetch to update the local with the latest remote.

How do I find the data directory for a SQL Server instance?

It depends on whether default path is set for data and log files or not.

If the path is set explicitly at Properties => Database Settings => Database default locations then SQL server stores it at Software\Microsoft\MSSQLServer\MSSQLServer in DefaultData and DefaultLog values.

However, if these parameters aren't set explicitly, SQL server uses Data and Log paths of master database.

Bellow is the script that covers both cases. This is simplified version of the query that SQL Management Studio runs.

Also, note that I use xp_instance_regread instead of xp_regread, so this script will work for any instance, default or named.

declare @DefaultData nvarchar(512)
exec master.dbo.xp_instance_regread N'HKEY_LOCAL_MACHINE', N'Software\Microsoft\MSSQLServer\MSSQLServer', N'DefaultData', @DefaultData output

declare @DefaultLog nvarchar(512)
exec master.dbo.xp_instance_regread N'HKEY_LOCAL_MACHINE', N'Software\Microsoft\MSSQLServer\MSSQLServer', N'DefaultLog', @DefaultLog output

declare @DefaultBackup nvarchar(512)
exec master.dbo.xp_instance_regread N'HKEY_LOCAL_MACHINE', N'Software\Microsoft\MSSQLServer\MSSQLServer', N'BackupDirectory', @DefaultBackup output

declare @MasterData nvarchar(512)
exec master.dbo.xp_instance_regread N'HKEY_LOCAL_MACHINE', N'Software\Microsoft\MSSQLServer\MSSQLServer\Parameters', N'SqlArg0', @MasterData output
select @MasterData=substring(@MasterData, 3, 255)
select @MasterData=substring(@MasterData, 1, len(@MasterData) - charindex('\', reverse(@MasterData)))

declare @MasterLog nvarchar(512)
exec master.dbo.xp_instance_regread N'HKEY_LOCAL_MACHINE', N'Software\Microsoft\MSSQLServer\MSSQLServer\Parameters', N'SqlArg2', @MasterLog output
select @MasterLog=substring(@MasterLog, 3, 255)
select @MasterLog=substring(@MasterLog, 1, len(@MasterLog) - charindex('\', reverse(@MasterLog)))

select 
    isnull(@DefaultData, @MasterData) DefaultData, 
    isnull(@DefaultLog, @MasterLog) DefaultLog,
    isnull(@DefaultBackup, @MasterLog) DefaultBackup

You can achieve the same result by using SMO. Bellow is C# sample, but you can use any other .NET language or PowerShell.

using (var connection = new SqlConnection("Data Source=.;Integrated Security=SSPI"))
{
    var serverConnection = new ServerConnection(connection);
    var server = new Server(serverConnection);
    var defaultDataPath = string.IsNullOrEmpty(server.Settings.DefaultFile) ? server.MasterDBPath : server.Settings.DefaultFile;
    var defaultLogPath = string.IsNullOrEmpty(server.Settings.DefaultLog) ? server.MasterDBLogPath : server.Settings.DefaultLog;
}

It is so much simpler in SQL Server 2012 and above, assuming you have default paths set (which is probably always a right thing to do):

select 
    InstanceDefaultDataPath = serverproperty('InstanceDefaultDataPath'),
    InstanceDefaultLogPath = serverproperty('InstanceDefaultLogPath')

Set Colorbar Range in matplotlib

Use the CLIM function (equivalent to CAXIS function in MATLAB):

plt.pcolor(X, Y, v, cmap=cm)
plt.clim(-4,4)  # identical to caxis([-4,4]) in MATLAB
plt.show()

How to center the elements in ConstraintLayout

add these tag in your view

    app:layout_constraintCircleRadius="0dp"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.5"
    app:layout_constraintStart_toStartOf="parent"

and you can right click in design mode and choose center.

Could not find method android() for arguments

My issue was inside of my app.gradle. I ran into this issue when I moved

apply plugin: "com.android.application"

from the top line to below a line with

apply from:

I switched the plugin back to the top and violá

My exact error was

Could not find method android() for arguments [dotenv_wke4apph61tdae6bfodqe7sj$_run_closure1@5d9d91a5] on project ':app' of type org.gradle.api.Project.

The top of my app.gradle now looks like this

project.ext.envConfigFiles = [
        debug: ".env",
        release: ".env",
        anothercustombuild: ".env",
]


apply from: project(':react-native-config').projectDir.getPath() + "/dotenv.gradle"
apply plugin: "com.android.application"

How to print a stack trace in Node.js?

Any Error object has a stack member that traps the point at which it was constructed.

var stack = new Error().stack
console.log( stack )

or more simply:

console.trace("Here I am!")

Template not provided using create-react-app

Using the command npm uninstall -g create-react-app didn't work for me.

But this worked:

yarn global remove create-react-app

and then:

npx create-react-app my-app

How can I view the source code for a function?

For non-primitive functions, R base includes a function called body() that returns the body of function. For instance the source of the print.Date() function can be viewed:

body(print.Date)

will produce this:

{
    if (is.null(max)) 
        max <- getOption("max.print", 9999L)
    if (max < length(x)) {
        print(format(x[seq_len(max)]), max = max, ...)
        cat(" [ reached getOption(\"max.print\") -- omitted", 
            length(x) - max, "entries ]\n")
    }
    else print(format(x), max = max, ...)
    invisible(x)
}

If you are working in a script and want the function code as a character vector, you can get it.

capture.output(print(body(print.Date)))

will get you:

[1] "{"                                                                   
[2] "    if (is.null(max)) "                                              
[3] "        max <- getOption(\"max.print\", 9999L)"                      
[4] "    if (max < length(x)) {"                                          
[5] "        print(format(x[seq_len(max)]), max = max, ...)"              
[6] "        cat(\" [ reached getOption(\\\"max.print\\\") -- omitted\", "
[7] "            length(x) - max, \"entries ]\\n\")"                      
[8] "    }"                                                               
[9] "    else print(format(x), max = max, ...)"                           
[10] "    invisible(x)"                                                    
[11] "}"

Why would I want to do such a thing? I was creating a custom S3 object (x, where class(x) = "foo") based on a list. One of the list members (named "fun") was a function and I wanted print.foo() to display the function source code, indented. So I ended up with the following snippet in print.foo():

sourceVector = capture.output(print(body(x[["fun"]])))
cat(paste0("      ", sourceVector, "\n"))

which indents and displays the code associated with x[["fun"]].

Edit 2020-12-31

A less circuitous way to get the same character vector of source code is:

sourceVector = deparse(body(x$fun))

How do you add swap to an EC2 instance?

Swap should take place on the Instance Storage (ephemeral) disk and not an EBS device. Swapping will cause a lot of IO and will increase cost on EBS. EBS is also slower than the Instance Store and the Instance Store comes free with certain types of EC2 Instances.

It will usually be mounted to /mnt but if not run

sudo mount /dev/xvda2 /mnt

To then create a swap file on this device do the following for a 4GB swapfile

sudo dd if=/dev/zero of=/mnt/swapfile bs=1M count=4096

Make sure no other user can view the swap file

sudo chown root:root /mnt/swapfile
sudo chmod 600 /mnt/swapfile

Make and Flag as swap

sudo mkswap /mnt/swapfile
sudo swapon /mnt/swapfile

Add/Make sure the following are in your /etc/fstab

/dev/xvda2      /mnt    auto    defaults,nobootwait,comment=cloudconfig 0   2
/mnt/swapfile swap swap defaults 0 0

lastly enable swap

sudo swapon -a

Delete element in a slice

I'm getting an index out of range error with the accepted answer solution. Reason: When range start, it is not iterate value one by one, it is iterate by index. If you modified a slice while it is in range, it will induce some problem.

Old Answer:

chars := []string{"a", "a", "b"}

for i, v := range chars {
    fmt.Printf("%+v, %d, %s\n", chars, i, v)
    if v == "a" {
        chars = append(chars[:i], chars[i+1:]...)
    }
}
fmt.Printf("%+v", chars)

Expected :

[a a b], 0, a
[a b], 0, a
[b], 0, b
Result: [b]

Actual:

// Autual
[a a b], 0, a
[a b], 1, b
[a b], 2, b
Result: [a b]

Correct Way (Solution):

chars := []string{"a", "a", "b"}

for i := 0; i < len(chars); i++ {
    if chars[i] == "a" {
        chars = append(chars[:i], chars[i+1:]...)
        i-- // form the remove item index to start iterate next item
    }
}

fmt.Printf("%+v", chars)

Source: https://dinolai.com/notes/golang/golang-delete-slice-item-in-range-problem.html

How do I escape a single quote in SQL Server?

2 ways to work around this:

for ' you can simply double it in the string, e.g. select 'I''m happpy' -- will get: I'm happy

For any charactor you are not sure of: in sql server you can get any char's unicode by select unicode(':') (you keep the number)

So this case you can also select 'I'+nchar(39)+'m happpy'

Passing javascript variable to html textbox

This was a problem for me, too. One reason for doing this (in my case) was that I needed to convert a client-side event (a javascript variable being modified) to a server-side variable (for that variable to be used in php). Hence populating a form with a javascript variable (eg a sessionStorage key/value) and converting it to a $_POST variable.

<form name='formName'>
<input name='inputName'>
</form>

<script>
document.formName.inputName.value=var
</script>

Html code as IFRAME source rather than a URL

iframe srcdoc: This attribute contains HTML content, which will override src attribute. If a browser does not support the srcdoc attribute, it will fall back to the URL in the src attribute.

Let's understand it with an example

<iframe 
    name="my_iframe" 
    srcdoc="<h1 style='text-align:center; color:#9600fa'>Welcome to iframes</h1>"
    src="https://www.birthdaycalculatorbydate.com/"
    width="500px"
    height="200px"
></iframe>

Original content is taken from iframes.

Converting from hex to string

string str = "47-61-74-65-77-61-79-53-65-72-76-65-72";
string[] parts = str.Split('-');

foreach (string val in parts)
{ 
    int x;
    if (int.TryParse(val, out x))
    {
         Console.Write(string.Format("{0:x2} ", x);
    }
}
Console.WriteLine();

You can split the string at the -
Convert the text to ints (int.TryParse)
Output the int as a hex string {0:x2}

How to resolve "git pull,fatal: unable to access 'https://github.com...\': Empty reply from server"

You can try for following solutions step by step one of them should work for you.

I have tried all three steps but STEP 4 worked for me. Because I was using two different git accounts

STEP 1:

git init
git add README.md
git commit -m "first commit"
git remote add origin https://github.com/XXXX/YYYY.git
git push -u origin master

STEP 2

Check your current branch git branch if you are not on branch git checkout branch_name.
To create new branch use git checkout -b "new branch name" to switch on new branch use above command

STEP 3

In the special case that you are creating a new repository starting from an old repository that you used as a template (Don't do this if this is not your case). Completely erase the git files of the old repository so you can start a new one:

rm -rf .git and repeat STEP 1

STEP 4

On windows, you can try putting write credentials or remove git credentials from the control panel by following way and repeat STEP 1

Go to Win -> Control Panel -> Credential Manager -> Windows Credentials

Why does my 'git branch' have no master?

I ran into the same issue and figured out the problem. When you initialize a repository there aren't actually any branches. When you start a project run git add . and then git commit and the master branch will be created.

Without checking anything in you have no master branch. In that case you need to follow the steps other people here have suggested.

How are iloc and loc different?

In my opinion, the accepted answer is confusing, since it uses a DataFrame with only missing values. I also do not like the term position-based for .iloc and instead, prefer integer location as it is much more descriptive and exactly what .iloc stands for. The key word is INTEGER - .iloc needs INTEGERS.

See my extremely detailed blog series on subset selection for more

.ix is deprecated and ambiguous and should never be used

Because .ix is deprecated we will only focus on the differences between .loc and .iloc.

Before we talk about the differences, it is important to understand that DataFrames have labels that help identify each column and each index. Let's take a look at a sample DataFrame:

df = pd.DataFrame({'age':[30, 2, 12, 4, 32, 33, 69],
                   'color':['blue', 'green', 'red', 'white', 'gray', 'black', 'red'],
                   'food':['Steak', 'Lamb', 'Mango', 'Apple', 'Cheese', 'Melon', 'Beans'],
                   'height':[165, 70, 120, 80, 180, 172, 150],
                   'score':[4.6, 8.3, 9.0, 3.3, 1.8, 9.5, 2.2],
                   'state':['NY', 'TX', 'FL', 'AL', 'AK', 'TX', 'TX']
                   },
                  index=['Jane', 'Nick', 'Aaron', 'Penelope', 'Dean', 'Christina', 'Cornelia'])

All the words in bold are the labels. The labels, age, color, food, height, score and state are used for the columns. The other labels, Jane, Nick, Aaron, Penelope, Dean, Christina, Cornelia are used for the index.

The primary ways to select particular rows in a DataFrame are with the .loc and .iloc indexers. Each of these indexers can also be used to simultaneously select columns but it is easier to just focus on rows for now. Also, each of the indexers use a set of brackets that immediately follow their name to make their selections.

.loc selects data only by labels

We will first talk about the .loc indexer which only selects data by the index or column labels. In our sample DataFrame, we have provided meaningful names as values for the index. Many DataFrames will not have any meaningful names and will instead, default to just the integers from 0 to n-1, where n is the length of the DataFrame.

There are three different inputs you can use for .loc

A string
A list of strings
Slice notation using strings as the start and stop values

Selecting a single row with .loc with a string

To select a single row of data, place the index label inside of the brackets following .loc.

df.loc['Penelope']

This returns the row of data as a Series

age           4
color     white
food      Apple
height       80
score       3.3
state        AL
Name: Penelope, dtype: object

Selecting multiple rows with .loc with a list of strings

df.loc[['Cornelia', 'Jane', 'Dean']]

This returns a DataFrame with the rows in the order specified in the list:

Selecting multiple rows with .loc with slice notation

Slice notation is defined by a start, stop and step values. When slicing by label, pandas includes the stop value in the return. The following slices from Aaron to Dean, inclusive. Its step size is not explicitly defined but defaulted to 1.

df.loc['Aaron':'Dean']

Complex slices can be taken in the same manner as Python lists.

.iloc selects data only by integer location

Let's now turn to .iloc. Every row and column of data in a DataFrame has an integer location that defines it. This is in addition to the label that is visually displayed in the output. The integer location is simply the number of rows/columns from the top/left beginning at 0.

There are three different inputs you can use for .iloc

An integer
A list of integers
Slice notation using integers as the start and stop values

Selecting a single row with .iloc with an integer

df.iloc[4]

This returns the 5th row (integer location 4) as a Series

age           32
color       gray
food      Cheese
height       180
score        1.8
state         AK
Name: Dean, dtype: object

Selecting multiple rows with .iloc with a list of integers

df.iloc[[2, -2]]

This returns a DataFrame of the third and second to last rows:

Selecting multiple rows with .iloc with slice notation

df.iloc[:5:3]

Simultaneous selection of rows and columns with .loc and .iloc

One excellent ability of both .loc/.iloc is their ability to select both rows and columns simultaneously. In the examples above, all the columns were returned from each selection. We can choose columns with the same types of inputs as we do for rows. We simply need to separate the row and column selection with a comma.

For example, we can select rows Jane, and Dean with just the columns height, score and state like this:

df.loc[['Jane', 'Dean'], 'height':]

This uses a list of labels for the rows and slice notation for the columns

We can naturally do similar operations with .iloc using only integers.

df.iloc[[1,4], 2]
Nick      Lamb
Dean    Cheese
Name: food, dtype: object

Simultaneous selection with labels and integer location

.ix was used to make selections simultaneously with labels and integer location which was useful but confusing and ambiguous at times and thankfully it has been deprecated. In the event that you need to make a selection with a mix of labels and integer locations, you will have to make both your selections labels or integer locations.

For instance, if we want to select rows Nick and Cornelia along with columns 2 and 4, we could use .loc by converting the integers to labels with the following:

col_names = df.columns[[2, 4]]
df.loc[['Nick', 'Cornelia'], col_names]

Or alternatively, convert the index labels to integers with the get_loc index method.

labels = ['Nick', 'Cornelia']
index_ints = [df.index.get_loc(label) for label in labels]
df.iloc[index_ints, [2, 4]]

Boolean Selection

The .loc indexer can also do boolean selection. For instance, if we are interested in finding all the rows wher age is above 30 and return just the food and score columns we can do the following:

df.loc[df['age'] > 30, ['food', 'score']]

You can replicate this with .iloc but you cannot pass it a boolean series. You must convert the boolean Series into a numpy array like this:

df.iloc[(df['age'] > 30).values, [2, 4]]

Selecting all rows

It is possible to use .loc/.iloc for just column selection. You can select all the rows by using a colon like this:

df.loc[:, 'color':'score':2]

The indexing operator, `[]`, can select rows and columns too but not simultaneously.

Most people are familiar with the primary purpose of the DataFrame indexing operator, which is to select columns. A string selects a single column as a Series and a list of strings selects multiple columns as a DataFrame.

df['food']

Jane          Steak
Nick           Lamb
Aaron         Mango
Penelope      Apple
Dean         Cheese
Christina     Melon
Cornelia      Beans
Name: food, dtype: object

Using a list selects multiple columns

df[['food', 'score']]

What people are less familiar with, is that, when slice notation is used, then selection happens by row labels or by integer location. This is very confusing and something that I almost never use but it does work.

df['Penelope':'Christina'] # slice rows by label

df[2:6:2] # slice rows by integer location

The explicitness of .loc/.iloc for selecting rows is highly preferred. The indexing operator alone is unable to select rows and columns simultaneously.

df[3:5, 'color']
TypeError: unhashable type: 'slice'

Determine if a String is an Integer in Java

Or simply

mystring.matches("\\d+")

though it would return true for numbers larger than an int

Is it possible to use the instanceof operator in a switch statement?

Unfortunately, it is not possible out of the box since the switch-case statement expects a constant expression. To overcome this, one way would be to use enum values with the class names e.g.

public enum MyEnum {
   A(A.class.getName()), 
   B(B.class.getName()),
   C(C.class.getName());

private String refClassname;
private static final Map<String, MyEnum> ENUM_MAP;

MyEnum (String refClassname) {
    this.refClassname = refClassname;
}

static {
    Map<String, MyEnum> map = new ConcurrentHashMap<String, MyEnum>();
    for (MyEnum instance : MyEnum.values()) {
        map.put(instance.refClassname, instance);
    }
    ENUM_MAP = Collections.unmodifiableMap(map);
}

public static MyEnum get(String name) {
    return ENUM_MAP.get(name);
 }
}

With that is is possible to use the switch statement like this

MyEnum type = MyEnum.get(clazz.getName());
switch (type) {
case A:
    ... // it's A class
case B:
    ... // it's B class
case C:
    ... // it's C class
}

Disable validation of HTML5 form elements

you can add some javascript to surpress those obnoxious validation bubbles and add your own validators.

document.addEventListener('invalid', (function(){
    return function(e) {
      //prevent the browser from showing default error bubble / hint
      e.preventDefault();
      // optionally fire off some custom validation handler
      // myValidation();
    };
})(), true);

MySQL compare now() (only date, not time) with a datetime field

Use DATE(NOW()) to compare dates

DATE(NOW()) will give you the date part of current date and DATE(duedate) will give you the date part of the due date. then you can easily compare the dates

So you can compare it like

DATE(NOW()) = DATE(duedate)

DATE(duedate) = CURDATE()

See here

Adding an HTTP Header to the request in a servlet filter

Extend HttpServletRequestWrapper, override the header getters to return the parameters as well:

public class AddParamsToHeader extends HttpServletRequestWrapper {
    public AddParamsToHeader(HttpServletRequest request) {
        super(request);
    }

    public String getHeader(String name) {
        String header = super.getHeader(name);
        return (header != null) ? header : super.getParameter(name); // Note: you can't use getParameterValues() here.
    }

    public Enumeration getHeaderNames() {
        List<String> names = Collections.list(super.getHeaderNames());
        names.addAll(Collections.list(super.getParameterNames()));
        return Collections.enumeration(names);
    }
}

..and wrap the original request with it:

chain.doFilter(new AddParamsToHeader((HttpServletRequest) request), response);

That said, I personally find this a bad idea. Rather give it direct access to the parameters or pass the parameters to it.

document .click function for touch device

can you use jqTouch or jquery mobile ? there it's much easier to handle touch events. If not then you need to simulate click on touch device, follow this articles:

iphone-touch-events-in-javascript

A touch demo

How to specify the port an ASP.NET Core application is hosted on?

If using dotnet run

dotnet run --urls="http://localhost:5001"

What to do with "Unexpected indent" in python?

Python uses spacing at the start of the line to determine when code blocks start and end. Errors you can get are:

Unexpected indent. This line of code has more spaces at the start than the one before, but the one before is not the start of a subblock (e.g. if/while/for statement). All lines of code in a block must start with exactly the same string of whitespace. For instance:

>>> def a():
...   print "foo"
...     print "bar"
IndentationError: unexpected indent

This one is especially common when running python interactively: make sure you don't put any extra spaces before your commands. (Very annoying when copy-and-pasting example code!)

>>>   print "hello"
IndentationError: unexpected indent

Unindent does not match any outer indentation level. This line of code has fewer spaces at the start than the one before, but equally it does not match any other block it could be part of. Python cannot decide where it goes. For instance, in the following, is the final print supposed to be part of the if clause, or not?

>>> if user == "Joey":
...     print "Super secret powers enabled!"
...   print "Revealing super secrets"
IndendationError: unindent does not match any outer indentation level

Expected an indented block. This line of code has the same number of spaces at the start as the one before, but the last line was expected to start a block (e.g. if/while/for statement, function definition).

>>> def foo():
... print "Bar"
IndentationError: expected an indented block

If you want a function that doesn't do anything, use the "no-op" command pass:

>>> def foo():
...     pass

Mixing tabs and spaces is allowed (at least on my version of Python), but Python assumes tabs are 8 characters long, which may not match your editor. Just say "no" to tabs. Most editors allow them to be automatically replaced by spaces.

The best way to avoid these issues is to always use a consistent number of spaces when you indent a subblock, and ideally use a good IDE that solves the problem for you. This will also make your code more readable.

ModalPopupExtender OK Button click event not firing?

None of the previous answers worked for me. I called the postback of the button on the OnOkScript event.

<div>
    <cc1:ModalPopupExtender PopupControlID="Panel1" 
         ID="ModalPopupExtender1"
         runat="server" TargetControlID="LinkButton1" OkControlID="Ok" 
         OnOkScript="__doPostBack('Ok','')">
    </cc1:ModalPopupExtender>

    <asp:LinkButton ID="LinkButton1" runat="server">LinkButton</asp:LinkButton> 
</div>        


<asp:Panel ID="Panel1" runat="server">
    <asp:Button ID="Ok" runat="server" Text="Ok" onclick="Ok_Click" />            
</asp:Panel>

How to use jQuery to get the current value of a file input field

I don't think there is any real legitimate way to access this via the DOM. It would be a security risk that browsers have of late locked down on to prevent drive-by uploads.

Very simple C# CSV reader

You can try the some thing like the below LINQ snippet.

string[] allLines = File.ReadAllLines(@"E:\Temp\data.csv");

    var query = from line in allLines
                let data = line.Split(',')
                select new
                {
                    Device = data[0],
                    SignalStrength = data[1],
                    Location = data[2], 
                    Time = data[3],
                    Age = Convert.ToInt16(data[4])
                };

UPDATE: Over a period of time, things evolved. As of now, I would prefer to use this library http://www.aspnetperformance.com/post/LINQ-to-CSV-library.aspx

How to run multiple sites on one apache instance

Your question is mixing a few different concepts. You started out saying you wanted to run sites on the same server using the same domain, but in different folders. That doesn't require any special setup. Once you get the single domain running, you just create folders under that docroot.

Based on the rest of your question, what you really want to do is run various sites on the same server with their own domain names.

The best documentation you'll find on the topic is the virtual host documentation in the apache manual.

There are two types of virtual hosts: name-based and IP-based. Name-based allows you to use a single IP address, while IP-based requires a different IP for each site. Based on your description above, you want to use name-based virtual hosts.

The initial error you were getting was due to the fact that you were using different ports than the NameVirtualHost line. If you really want to have sites served from ports other than 80, you'll need to have a NameVirtualHost entry for each port.

Assuming you're starting from scratch, this is much simpler than it may seem.

If you are using 2.3 or earlier, the first thing you need to do is tell Apache that you're going to use name-based virtual hosts.

NameVirtualHost *:80

If you are using 2.4 or later do not add a NameVirtualHost line. Version 2.4 of Apache deprecated the NameVirtualHost directive, and it will be removed in a future version.

Now your vhost definitions:

<VirtualHost *:80>
    DocumentRoot "/home/user/site1/"
    ServerName site1
</VirtualHost>

<VirtualHost *:80>
    DocumentRoot "/home/user/site2/"
    ServerName site2
</VirtualHost>

You can run as many sites as you want on the same port. The ServerName being different is enough to tell Apache which vhost to use. Also, the ServerName directive is always the domain/hostname and should never include a path.

If you decide to run sites on a port other than 80, you'll always have to include the port number in the URL when accessing the site. So instead of going to http://example.com you would have to go to http://example.com:81

get enum name from enum value

Say we have:

public enum MyEnum {
  Test1, Test2, Test3
}

To get the name of a enum variable use name():

MyEnum e = MyEnum.Test1;
String name = e.name(); // Returns "Test1"

To get the enum from a (string) name, use valueOf():

String name = "Test1";
MyEnum e = Enum.valueOf(MyEnum.class, name);

If you require integer values to match enum fields, extend the enum class:

public enum MyEnum {
  Test1(1), Test2(2), Test3(3);

  public final int value;

  MyEnum(final int value) {
     this.value = value;
  }
}

Now you can use:

MyEnum e = MyEnum.Test1;
int value = e.value; // = 1

And lookup the enum using the integer value:

MyEnum getValue(int value) {
  for(MyEnum e: MyEunm.values()) {
    if(e.value == value) {
      return e;
    }
  }
  return null;// not found
}

How do I fix the error "Only one usage of each socket address (protocol/network address/port) is normally permitted"?

I faced similar problem on windows server 2012 STD 64 bit , my problem is resolved after updating windows with all available windows updates.

How to remove default chrome style for select Input?

Mixin for Less

.appearance (@value: none) {
    -webkit-appearance:     @value;
    -moz-appearance:        @value;
    -ms-appearance:         @value;
    -o-appearance:          @value;
    appearance:             @value;
}

Why is "throws Exception" necessary when calling a function?

Basically, if you are not handling the exception in the same place as you are throwing it, then you can use "throws exception" at the definition of the function.

How do I find out what License has been applied to my SQL Server installation?

SELECT SERVERPROPERTY('LicenseType') as Licensetype, 
       SERVERPROPERTY('NumLicenses') as LicenseNumber,
       SERVERPROPERTY('productversion') as Productverion, 
       SERVERPROPERTY ('productlevel')as ProductLevel, 
       SERVERPROPERTY ('edition') as SQLEdition,@@VERSION as SQLversion

I had installed evaluation edition.Refer screenshot

What's the difference between getRequestURI and getPathInfo methods in HttpServletRequest?

Let's break down the full URL that a client would type into their address bar to reach your servlet:

http://www.example.com:80/awesome-application/path/to/servlet/path/info?a=1&b=2#boo

The parts are:

scheme: http
hostname: www.example.com
port: 80
context path: awesome-application
servlet path: path/to/servlet
path info: path/info
query: a=1&b=2
fragment: boo

The request URI (returned by getRequestURI) corresponds to parts 4, 5 and 6.

(incidentally, even though you're not asking for this, the method getRequestURL would give you parts 1, 2, 3, 4, 5 and 6).

Now:

part 4 (the context path) is used to select your particular application out of many other applications that may be running in the server
part 5 (the servlet path) is used to select a particular servlet out of many other servlets that may be bundled in your application's WAR
part 6 (the path info) is interpreted by your servlet's logic (e.g. it may point to some resource controlled by your servlet).
part 7 (the query) is also made available to your servlet using getQueryString
part 8 (the fragment) is not even sent to the server and is relevant and known only to the client

The following always holds (except for URL encoding differences):

requestURI = contextPath + servletPath + pathInfo

The following example from the Servlet 3.0 specification is very helpful:

Note: image follows, I don't have the time to recreate in HTML:

Laravel view not found exception

Somewhat embarrassingly, I discovered another rather trivial cause for this error: I had a full stop in the filename of my blade file (eg resources/views/pages/user.invitation.blade.php). It really did make sense at the time!

I was trying to reference it like so: view('pages.user.invitation')

but of course Laravel was looking for the file at resources/views/pages/user/invitation.blade.php and throwing the view not found.

Hope this helps someone.

Convert int to ASCII and back in Python

What about BASE58 encoding the URL? Like for example flickr does.

# note the missing lowercase L and the zero etc.
BASE58 = '123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ' 
url = ''
while node_id >= 58:
    div, mod = divmod(node_id, 58)
    url = BASE58[mod] + url
    node_id = int(div)

return 'http://short.com/%s' % BASE58[node_id] + url

Turning that back into a number isn't a big deal either.

Spring 3.0 - Unable to locate Spring NamespaceHandler for XML schema namespace [http://www.springframework.org/schema/security]

I got this error while deploying to Virgo. The solution was to add this to my bundle imports:

org.springframework.transaction.config;version="[3.1,3.2)",

I noticed in the Spring jars under META-INF there is a spring.schemas and a spring.handlers section, and the class that they point to (in this case org.springframework.transaction.config.TxNamespaceHandler) must be imported.

How to run php files on my computer

3 easy steps to run your PHP program is:

The easiest way is to install MAMP!
Do a 2-minute setup of MAMP.
Open the localhost server in your browser at the created port to see your program up and runing!

Selenium 2.53 not working on Firefox 47

New Selenium libraries are now out, according to: https://github.com/SeleniumHQ/selenium/issues/2110

The download page http://www.seleniumhq.org/download/ seems not to be updated just yet, but by adding 1 to the minor version in the link, I could download the C# version: http://selenium-release.storage.googleapis.com/2.53/selenium-dotnet-2.53.1.zip

It works for me with Firefox 47.0.1.

As a side note, I was able build just the webdriver.xpi Firefox extension from the master branch in GitHub, by running ./go //javascript/firefox-driver:webdriver:run – which gave an error message but did build the build/javascript/firefox-driver/webdriver.xpi file, which I could rename (to avoid a name clash) and successfully load with the FirefoxProfile.AddExtension method. That was a reasonable workaround without having to rebuild the entire Selenium library.

AssertNull should be used or AssertNotNull

Use assertNotNull(obj). assert means must be.

Way to run Excel macros from command line or batch file?

You can check if Excel is already open. There is no need to create another isntance

   If CheckAppOpen("excel.application")  Then
           'MsgBox "App Loaded"
            Set xlApp = GetObject(, "excel.Application")   
   Else
            ' MsgBox "App Not Loaded"
            Set  wrdApp = CreateObject(,"excel.Application")   
   End If

Compute mean and standard deviation by group for multiple variables in a data.frame

Here is probably the simplest way to go about it (with a reproducible example):

library(plyr)
df <- data.frame(ID=rep(1:3, 3), Obs_1=rnorm(9), Obs_2=rnorm(9), Obs_3=rnorm(9))
ddply(df, .(ID), summarize, Obs_1_mean=mean(Obs_1), Obs_1_std_dev=sd(Obs_1),
  Obs_2_mean=mean(Obs_2), Obs_2_std_dev=sd(Obs_2))

   ID  Obs_1_mean Obs_1_std_dev  Obs_2_mean Obs_2_std_dev
1  1 -0.13994642     0.8258445 -0.15186380     0.4251405
2  2  1.49982393     0.2282299  0.50816036     0.5812907
3  3 -0.09269806     0.6115075 -0.01943867     1.3348792

EDIT: The following approach saves you a lot of typing when dealing with many columns.

ddply(df, .(ID), colwise(mean))

  ID      Obs_1      Obs_2      Obs_3
1  1 -0.3748831  0.1787371  1.0749142
2  2 -1.0363973  0.0157575 -0.8826969
3  3  1.0721708 -1.1339571 -0.5983944

ddply(df, .(ID), colwise(sd))

  ID     Obs_1     Obs_2     Obs_3
1  1 0.8732498 0.4853133 0.5945867
2  2 0.2978193 1.0451626 0.5235572
3  3 0.4796820 0.7563216 1.4404602

Where can I find the Tomcat 7 installation folder on Linux AMI in Elastic Beanstalk?

In my case on Ubuntu 16.04 server, and default tomcat installation it's under:

/var/lib/tomcat8

Add one year in current date PYTHON

You can use Python-dateutil's relativedelta to increment a datetime object while remaining sensitive to things like leap years and month lengths. Python-dateutil comes packaged with matplotlib if you already have that. You can do the following:

from dateutil.relativedelta import relativedelta

new_date = old_date + relativedelta(years=1)

(This answer was given by @Max to a similar question).

But if your date is a string (i.e. not already a datetime object) you can convert it using datetime:

from datetime import datetime
from dateutil.relativedelta import relativedelta

your_date_string = "April 1, 2012"
format_string = "%B %d, %Y"

datetime_object = datetime.strptime(your_date_string, format_string).date()
new_date = datetime_object + relativedelta(years=1)
new_date_string = datetime.strftime(new_date, format_string).replace(' 0', ' ')

new_date_string will contain "April 1, 2013".

NB: Unfortunately, datetime only outputs day values as "decimal numbers" - i.e. with leading zeros if they're single digit numbers. The .replace() at the end is a workaround to deal with this issue copied from @Alex Martelli (see this question for his and other approaches to this problem).

How to git-cherry-pick only changes to certain files?

Use git merge --squash branch_name this will get all changes from the other branch and will prepare a commit for you. Now remove all unneeded changes and leave the one you want. And git will not know that there was a merge.

How to call a function from a string stored in a variable?

For the sake of completeness, you can also use eval():

$functionName = "foo()";
eval($functionName);

However, call_user_func() is the proper way.

Get the index of a certain value in an array in PHP

The problem is that you don't have a numerical index on your array.
Using array_values() will create a zero indexed array that you can then search using array_search() bypassing the need to use a for loop.

$list = ['string1', 'string2', 'string3'];
$index = array_search('string2',array_values($list));

Force decimal point instead of comma in HTML5 number input (client-side)

Have you considered using Javascript for this?

$('input').val($('input').val().replace(',', '.'));

scp copy directory to another server with private key auth

The command looks quite fine. Could you try to run -v (verbose mode) and then we can figure out what it is wrong on the authentication?

Also as mention in the other answer, maybe could be this issue - that you need to convert the keys (answered already here): How to convert SSH keypairs generated using PuttyGen(Windows) into key-pairs used by ssh-agent and KeyChain(Linux) OR http://winscp.net/eng/docs/ui_puttygen (depending what you need)

How to move an entire div element up x pixels?

$('#div_id').css({marginTop: '-=15px'});

This will alter the css for the element with the id "div_id"

To get the effect you want I recommend adding the code above to a callback function in your animation (that way the div will be moved up after the animation is complete):

$('#div_id').animate({...}, function () {
    $('#div_id').css({marginTop: '-=15px'});
});

And of course you could animate the change in margin like so:

$('#div_id').animate({marginTop: '-=15px'});

Here are the docs for .css() in jQuery: http://api.jquery.com/css/

And here are the docs for .animate() in jQuery: http://api.jquery.com/animate/

When should I use a trailing slash in my URL?

Other answers here seem to favor omitting the trailing slash. There is one case in which a trailing slash will help with search engine optimization (SEO). That is the case that your document has what appears to be a file extension that is not .html. This becomes an issue with sites that are rating websites. They might choose between these two urls:

http://mysite.example.com/rated.example.com
http://mysite.example.com/rated.example.com/

In such a case, I would choose the one with the trailing slash. That is because the .com extension is an extension for Windows executable command files. Search engines and virus checkers often dislike URLs that appear that they may contain malware distributed through such mechanisms. The trailing slash seems to mitigate any concerns, allowing the page to rank in search engines and get by virus checkers.

If your URLs have no . in the file portion, then I would recommend omitting the trailing slash for simplicity.

Java's L number (long) specification

I hope you won't mind a slight tangent, but thought you may be interested to know that besides F (for float), D (for double), and L (for long), a proposal has been made to add suffixes for byte and short—Y and S respectively. This would eliminate to the need to cast to bytes when using literal syntax for byte (or short) arrays. Quoting the example from the proposal:

MAJOR BENEFIT: Why is the platform better if the proposal is adopted?

cruddy code like
 byte[] stuff = { 0x00, 0x7F, (byte)0x80,  (byte)0xFF};
can be recoded as
 byte[] ufum7 = { 0x00y, 0x7Fy, 0x80y, 0xFFy };

Joe Darcy is overseeing Project Coin for Java 7, and his blog has been an easy way to track these proposals.

Eclipse change project files location

There is now a plugin (since end of 2012) that can take care of this: gensth/ProjectLocationUpdater on GitHub.

How do I create a WPF Rounded Corner container?

If you're trying to put a button in a rounded-rectangle border, you should check out msdn's example. I found this by googling for images of the problem (instead of text). Their bulky outer rectangle is (thankfully) easy to remove.

Note that you will have to redefine the button's behavior (since you've changed the ControlTemplate). That is, you will need to define the button's behavior when clicked using a Trigger tag (Property="IsPressed" Value="true") in the ControlTemplate.Triggers tag. Hope this saves someone else the time I lost :)

AngularJS not detecting Access-Control-Allow-Origin header?

I was sending requests from angularjs using $http service to bottle running on http://localhost:8090/ and I had to apply CORS otherwise I got request errors like "No 'Access-Control-Allow-Origin' header is present on the requested resource"

from bottle import hook, route, run, request, abort, response

#https://github.com/defnull/bottle/blob/master/docs/recipes.rst#using-the-hooks-plugin

@hook('after_request')
def enable_cors():
    response.headers['Access-Control-Allow-Origin'] = '*'
    response.headers['Access-Control-Allow-Methods'] = 'POST, GET, OPTIONS, PUT'
    response.headers['Access-Control-Allow-Headers'] = 'Origin, X-Requested-With, Content-Type, Accept'

Getting error: ISO C++ forbids declaration of with no type

Your declaration is int ttTreeInsert(int value);

However, your definition/implementation is

ttTree::ttTreeInsert(int value)
{
}

Notice that the return type int is missing in the implementation. Instead it should be

int ttTree::ttTreeInsert(int value)
{
    return 1; // or some valid int
}

Get and set position with jQuery .offset()

Here is an option. This is just for the x coordinates.

var div1Pos = $("#div1").offset();
var div1X = div1Pos.left;
$('#div2').css({left: div1X});

Why use static_cast<int>(x) instead of (int)x?

The main reason is that classic C casts make no distinction between what we call static_cast<>(), reinterpret_cast<>(), const_cast<>(), and dynamic_cast<>(). These four things are completely different.

A static_cast<>() is usually safe. There is a valid conversion in the language, or an appropriate constructor that makes it possible. The only time it's a bit risky is when you cast down to an inherited class; you must make sure that the object is actually the descendant that you claim it is, by means external to the language (like a flag in the object). A dynamic_cast<>() is safe as long as the result is checked (pointer) or a possible exception is taken into account (reference).

A reinterpret_cast<>() (or a const_cast<>()) on the other hand is always dangerous. You tell the compiler: "trust me: I know this doesn't look like a foo (this looks as if it isn't mutable), but it is".

The first problem is that it's almost impossible to tell which one will occur in a C-style cast without looking at large and disperse pieces of code and knowing all the rules.

Let's assume these:

class CDerivedClass : public CMyBase {...};
class CMyOtherStuff {...} ;

CMyBase  *pSomething; // filled somewhere

Now, these two are compiled the same way:

CDerivedClass *pMyObject;
pMyObject = static_cast<CDerivedClass*>(pSomething); // Safe; as long as we checked

pMyObject = (CDerivedClass*)(pSomething); // Same as static_cast<>
                                     // Safe; as long as we checked
                                     // but harder to read

However, let's see this almost identical code:

CMyOtherStuff *pOther;
pOther = static_cast<CMyOtherStuff*>(pSomething); // Compiler error: Can't convert

pOther = (CMyOtherStuff*)(pSomething);            // No compiler error.
                                                  // Same as reinterpret_cast<>
                                                  // and it's wrong!!!

As you can see, there is no easy way to distinguish between the two situations without knowing a lot about all the classes involved.

The second problem is that the C-style casts are too hard to locate. In complex expressions it can be very hard to see C-style casts. It is virtually impossible to write an automated tool that needs to locate C-style casts (for example a search tool) without a full blown C++ compiler front-end. On the other hand, it's easy to search for "static_cast<" or "reinterpret_cast<".

pOther = reinterpret_cast<CMyOtherStuff*>(pSomething);
      // No compiler error.
      // but the presence of a reinterpret_cast<> is 
      // like a Siren with Red Flashing Lights in your code.
      // The mere typing of it should cause you to feel VERY uncomfortable.

That means that, not only are C-style casts more dangerous, but it's a lot harder to find them all to make sure that they are correct.

Make an Android button change background on click through XML

In the latest version of the SDK, you would use the setBackgroundResource method.

public void onClick(View v) {
   if(v == ButtonName) {
     ButtonName.setBackgroundResource(R.drawable.ImageResource);
   }
}

How do I kill an Activity when the Back button is pressed?

add this to your activity

@Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
    if ((keyCode == KeyEvent.KEYCODE_BACK))
    {
        finish();
    }
    return super.onKeyDown(keyCode, event);
}

force css grid container to fill full screen of device

Two important CSS properties to set for full height pages are these:

Allow the body to grow as high as the content in it requires.
```
html { height: 100%; }
```
Force the body not to get any smaller than then window height.
```
body { min-height: 100%; }
```

What you do with your gird is irrelevant as long as you use fractions or percentages you should be safe in all cases.

Have a look at this common dashboard layout.

Remove all newlines from inside a string

If the file includes a line break in the middle of the text neither strip() nor rstrip() will not solve the problem,

strip family are used to trim from the began and the end of the string

replace() is the way to solve your problem

>>> my_name = "Landon\nWO"
>>> print my_name
   Landon
   WO

>>> my_name = my_name.replace('\n','')
>>> print my_name
LandonWO

Unexpected token ILLEGAL in webkit

It doesn't apply to this particular code example, but as Google food, since I got the same error message:

<script>document.write('<script src="…"></script>');</script>

will give this error but

<script>document.write('<script src="…"><'+'/script>');</script>

will not.

Further explanation here: Why split the <script> tag when writing it with document.write()?

Crontab Day of the Week syntax

You can also use day names like Mon for Monday, Tue for Tuesday, etc. It's more human friendly.

find filenames NOT ending in specific extensions on Unix?

find  /data1/batch/source/export   -type f -not  -name "*.dll" -not -name "*.exe"

Ruby max integer

Reading the friendly manual? Who'd want to do that?

start = Time.now
largest_known_fixnum = 1
smallest_known_bignum = nil

until smallest_known_bignum == largest_known_fixnum + 1
  if smallest_known_bignum.nil?
    next_number_to_try = largest_known_fixnum * 1000
  else
    next_number_to_try = (smallest_known_bignum + largest_known_fixnum) / 2 # Geometric mean would be more efficient, but more risky
  end

  if next_number_to_try <= largest_known_fixnum ||
       smallest_known_bignum && next_number_to_try >= smallest_known_bignum
    raise "Can't happen case" 
  end

  case next_number_to_try
    when Bignum then smallest_known_bignum = next_number_to_try
    when Fixnum then largest_known_fixnum = next_number_to_try
    else raise "Can't happen case"
  end
end

finish = Time.now
puts "The largest fixnum is #{largest_known_fixnum}"
puts "The smallest bignum is #{smallest_known_bignum}"
puts "Calculation took #{finish - start} seconds"

How to config Tomcat to serve images from an external folder outside webapps?

You could have a redirect servlet. In you web.xml you'd have:

<servlet>
    <servlet-name>images</servlet-name>
    <servlet-class>com.example.images.ImageServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>images</servlet-name>
    <url-pattern>/images/*</url-pattern>
</servlet-mapping>

All your images would be in "/images", which would be intercepted by the servlet. It would then read in the relevant file in whatever folder and serve it right back out. For example, say you have a gif in your images folder, c:\Server_Images\smilie.gif. In the web page would be <img src="http:/example.com/app/images/smilie.gif".... In the servlet, HttpServletRequest.getPathInfo() would yield "/smilie.gif". Which the servlet would find in the folder.

Angular 2: Passing Data to Routes?

You can't pass objects using router params, only strings because it needs to be reflected in the URL. It would be probably a better approach to use a shared service to pass data around between routed components anyway.

The old router allows to pass data but the new (RC.1) router doesn't yet.

Update

data was re-introduced in RC.4 How do I pass data in Angular 2 components while using Routing?

How to verify element present or visible in selenium 2 (Selenium WebDriver)

I used java print statements for easy understanding.

To check Element Present:

if(driver.findElements(By.xpath("value")).size() != 0){
System.out.println("Element is Present");
}else{
System.out.println("Element is Absent");
}

if(driver.findElement(By.xpath("value"))!= null){
System.out.println("Element is Present");
}else{
System.out.println("Element is Absent");
}

To check Visible:

if( driver.findElement(By.cssSelector("a > font")).isDisplayed()){
System.out.println("Element is Visible");
}else{
System.out.println("Element is InVisible");
}

To check Enable:

if( driver.findElement(By.cssSelector("a > font")).isEnabled()){
System.out.println("Element is Enable");
}else{
System.out.println("Element is Disabled");
}

To check text present

if(driver.getPageSource().contains("Text to check")){
System.out.println("Text is present");
}else{
System.out.println("Text is absent");
}

How to check if a variable exists in a FreeMarker template?

I think a lot of people are wanting to be able to check to see if their variable is not empty as well as if it exists. I think that checking for existence and emptiness is a good idea in a lot of cases, and makes your template more robust and less prone to silly errors. In other words, if you check to make sure your variable is not null AND not empty before using it, then your template becomes more flexible, because you can throw either a null variable or an empty string into it, and it will work the same in either case.

<#if p?? && p?has_content>1</#if>

Let's say you want to make sure that p is more than just whitespace. Then you could trim it before checking to see if it has_content.

<#if p?? && p?trim?has_content>1</#if>

UPDATE

Please ignore my suggestion -- has_content is all that is needed, as it does a null check along with the empty check. Doing p?? && p?has_content is equivalent to p?has_content, so you may as well just use has_content.

Unfortunately Launcher3 has stopped working error in android studio?

It appears to be relate to the graphics driver. In the emulator configuration, changing Emulated Graphics to Software - GLES 2.0 caused the crashes to stop.

How can I insert binary file data into a binary SQL field using a simple insert statement?

If you mean using a literal, you simply have to create a binary string:

insert into Files (FileId, FileData) values (1, 0x010203040506)

And you will have a record with a six byte value for the FileData field.

You indicate in the comments that you want to just specify the file name, which you can't do with SQL Server 2000 (or any other version that I am aware of).

You would need a CLR stored procedure to do this in SQL Server 2005/2008 or an extended stored procedure (but I'd avoid that at all costs unless you have to) which takes the filename and then inserts the data (or returns the byte string, but that can possibly be quite long).

In regards to the question of only being able to get data from a SP/query, I would say the answer is yes, because if you give SQL Server the ability to read files from the file system, what do you do when you aren't connected through Windows Authentication, what user is used to determine the rights? If you are running the service as an admin (God forbid) then you can have an elevation of rights which shouldn't be allowed.

Find oldest/youngest datetime object in a list

Datetimes are comparable; so you can use max(datetimes_list) and min(datetimes_list)

Using AES encryption in C#

If you just want to use the built-in crypto provider RijndaelManaged, check out the following help article (it also has a simple code sample):

http://msdn.microsoft.com/en-us/library/system.security.cryptography.rijndaelmanaged.aspx

And just in case you need the sample in a hurry, here it is in all its plagiarized glory:

using System;
using System.IO;
using System.Security.Cryptography;

namespace RijndaelManaged_Example
{
    class RijndaelExample
    {
        public static void Main()
        {
            try
            {

                string original = "Here is some data to encrypt!";

                // Create a new instance of the RijndaelManaged 
                // class.  This generates a new key and initialization  
                // vector (IV). 
                using (RijndaelManaged myRijndael = new RijndaelManaged())
                {

                    myRijndael.GenerateKey();
                    myRijndael.GenerateIV();
                    // Encrypt the string to an array of bytes. 
                    byte[] encrypted = EncryptStringToBytes(original, myRijndael.Key, myRijndael.IV);

                    // Decrypt the bytes to a string. 
                    string roundtrip = DecryptStringFromBytes(encrypted, myRijndael.Key, myRijndael.IV);

                    //Display the original data and the decrypted data.
                    Console.WriteLine("Original:   {0}", original);
                    Console.WriteLine("Round Trip: {0}", roundtrip);
                }

            }
            catch (Exception e)
            {
                Console.WriteLine("Error: {0}", e.Message);
            }
        }
        static byte[] EncryptStringToBytes(string plainText, byte[] Key, byte[] IV)
        {
            // Check arguments. 
            if (plainText == null || plainText.Length <= 0)
                throw new ArgumentNullException("plainText");
            if (Key == null || Key.Length <= 0)
                throw new ArgumentNullException("Key");
            if (IV == null || IV.Length <= 0)
                throw new ArgumentNullException("IV");
            byte[] encrypted;
            // Create an RijndaelManaged object 
            // with the specified key and IV. 
            using (RijndaelManaged rijAlg = new RijndaelManaged())
            {
                rijAlg.Key = Key;
                rijAlg.IV = IV;

                // Create a decryptor to perform the stream transform.
                ICryptoTransform encryptor = rijAlg.CreateEncryptor(rijAlg.Key, rijAlg.IV);

                // Create the streams used for encryption. 
                using (MemoryStream msEncrypt = new MemoryStream())
                {
                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                        {

                            //Write all data to the stream.
                            swEncrypt.Write(plainText);
                        }
                        encrypted = msEncrypt.ToArray();
                    }
                }
            }


            // Return the encrypted bytes from the memory stream. 
            return encrypted;

        }

        static string DecryptStringFromBytes(byte[] cipherText, byte[] Key, byte[] IV)
        {
            // Check arguments. 
            if (cipherText == null || cipherText.Length <= 0)
                throw new ArgumentNullException("cipherText");
            if (Key == null || Key.Length <= 0)
                throw new ArgumentNullException("Key");
            if (IV == null || IV.Length <= 0)
                throw new ArgumentNullException("IV");

            // Declare the string used to hold 
            // the decrypted text. 
            string plaintext = null;

            // Create an RijndaelManaged object 
            // with the specified key and IV. 
            using (RijndaelManaged rijAlg = new RijndaelManaged())
            {
                rijAlg.Key = Key;
                rijAlg.IV = IV;

                // Create a decrytor to perform the stream transform.
                ICryptoTransform decryptor = rijAlg.CreateDecryptor(rijAlg.Key, rijAlg.IV);

                // Create the streams used for decryption. 
                using (MemoryStream msDecrypt = new MemoryStream(cipherText))
                {
                    using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                    {
                        using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                        {

                            // Read the decrypted bytes from the decrypting stream 
                            // and place them in a string.
                            plaintext = srDecrypt.ReadToEnd();
                        }
                    }
                }

            }

            return plaintext;

        }
    }
}

VBA Subscript out of range - error 9

Subscript out of Range error occurs when you try to reference an Index for a collection that is invalid.

Most likely, the index in Windows does not actually include .xls. The index for the window should be the same as the name of the workbook displayed in the title bar of Excel.

As a guess, I would try using this:

Windows("Data Sheet - " & ComboBox_Month.Value & " " & TextBox_Year.Value).Activate

How to use data-binding with Fragment

If you are using ViewModel and LiveData This is the sufficient syntax

Kotlin Syntax:

override fun onCreateView(
    inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {
    return MartianDataBinding.inflate(
        inflater,
        container,
        false
    ).apply {
        lifecycleOwner = viewLifecycleOwner
        vm = viewModel    // Attach your view model here
    }.root
}

Converting HTML to XML

I did found a way to convert (even bad) html into well formed XML. I started to base this on the DOM loadHTML function. However during time several issues occurred and I optimized and added patches to correct side effects.

  function tryToXml($dom,$content) {
    if(!$content) return false;

    // xml well formed content can be loaded as xml node tree
    $fragment = $dom->createDocumentFragment();
    // wonderfull appendXML to add an XML string directly into the node tree!

    // aappendxml will fail on a xml declaration so manually skip this when occurred
    if( substr( $content,0, 5) == '<?xml' ) {
      $content = substr($content,strpos($content,'>')+1);
      if( strpos($content,'<') ) {
        $content = substr($content,strpos($content,'<'));
      }
    }

    // if appendXML is not working then use below htmlToXml() for nasty html correction
    if(!@$fragment->appendXML( $content )) {
      return $this->htmlToXml($dom,$content);
    }

    return $fragment;
  }



  // convert content into xml
  // dom is only needed to prepare the xml which will be returned
  function htmlToXml($dom, $content, $needEncoding=false, $bodyOnly=true) {

    // no xml when html is empty
    if(!$content) return false;

    // real content and possibly it needs encoding
    if( $needEncoding ) {
      // no need to convert character encoding as loadHTML will respect the content-type (only)
      $content =  '<meta http-equiv="Content-Type" content="text/html;charset='.$this->encoding.'">' . $content;
    }

    // return a dom from the content
    $domInject = new DOMDocument("1.0", "UTF-8");
    $domInject->preserveWhiteSpace = false;
    $domInject->formatOutput = true;

    // html type
    try {
      @$domInject->loadHTML( $content );
    } catch(Exception $e){
      // do nothing and continue as it's normal that warnings will occur on nasty HTML content
    }
        // to check encoding: echo $dom->encoding
        $this->reworkDom( $domInject );

    if( $bodyOnly ) {
      $fragment = $dom->createDocumentFragment();

      // retrieve nodes within /html/body
      foreach( $domInject->documentElement->childNodes as $elementLevel1 ) {
       if( $elementLevel1->nodeName == 'body' and $elementLevel1->nodeType == XML_ELEMENT_NODE ) {
         foreach( $elementLevel1->childNodes as $elementInject ) {
           $fragment->insertBefore( $dom->importNode($elementInject, true) );
         }
        }
      }
    } else {
      $fragment = $dom->importNode($domInject->documentElement, true);
    }

    return $fragment;
  }



    protected function reworkDom( $node, $level = 0 ) {

        // start with the first child node to iterate
        $nodeChild = $node->firstChild;

        while ( $nodeChild )  {
            $nodeNextChild = $nodeChild->nextSibling;

            switch ( $nodeChild->nodeType ) {
                case XML_ELEMENT_NODE:
                    // iterate through children element nodes
                    $this->reworkDom( $nodeChild, $level + 1);
                    break;
                case XML_TEXT_NODE:
                case XML_CDATA_SECTION_NODE:
                    // do nothing with text, cdata
                    break;
                case XML_COMMENT_NODE:
                    // ensure comments to remove - sign also follows the w3c guideline
                    $nodeChild->nodeValue = str_replace("-","_",$nodeChild->nodeValue);
                    break;
                case XML_DOCUMENT_TYPE_NODE:  // 10: needs to be removed
                case XML_PI_NODE: // 7: remove PI
                    $node->removeChild( $nodeChild );
                    $nodeChild = null; // make null to test later
                    break;
                case XML_DOCUMENT_NODE:
                    // should not appear as it's always the root, just to be complete
                    // however generate exception!
                case XML_HTML_DOCUMENT_NODE:
                    // should not appear as it's always the root, just to be complete
                    // however generate exception!
                default:
                    throw new exception("Engine: reworkDom type not declared [".$nodeChild->nodeType. "]");
            }
            $nodeChild = $nodeNextChild;
        } ;
    }

Now this also allows to add more html pieces into one XML which I needed to use myself. In general it can be used like this:

        $c='<p>test<font>two</p>';
    $dom=new DOMDocument('1.0', 'UTF-8');

$n=$dom->appendChild($dom->createElement('info')); // make a root element

if( $valueXml=tryToXml($dom,$c) ) {
  $n->appendChild($valueXml);
}
    echo '<pre/>'. htmlentities($dom->saveXml($n)). '</pre>';

In this example '<p>test<font>two</p>' will nicely be outputed in well formed XML as '<info><p>test<font>two</font></p></info>'. The info root tag is added as it will also allow to convert '<p>one</p><p>two</p>' which is not XML as it has not one root element. However if you html does for sure have one root element then the extra root <info> tag can be skipped.

With this I'm getting real nice XML out of unstructured and even corrupted HTML!

I hope it's a bit clear and might contribute to other people to use it.

How do I revert an SVN commit?

svn merge -c -M PATH

This saved my life.

I was having the same issue, after reverting back also I was not seeing old code. After running the above command I got a clean old version code.

mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in

That query is failing and returning false.

Put this after mysqli_query() to see what's going on.

if (!$check1_res) {
    printf("Error: %s\n", mysqli_error($con));
    exit();
}

For more information:

http://www.php.net/manual/en/mysqli.error.php

Modelling an elevator using Object-Oriented Analysis and Design

Donald Knuth's The Art of Computer Programming Vol.1 has a demonstration of elevator and the data-structures. Knuth presents a very thorough discussion and program.

Knuth(1997) "Information Structures", The Art of Computer Programming Vol. 1 pp.302-308

SUM of grouped COUNT in SQL Query

You can use union to joining rows.

select Name, count(*) as Count from yourTable group by Name
union all
select "SUM" as Name, count(*) as Count from yourTable

How can I control the width of a label tag?

Using CSS, of course...

label { display: block; width: 100px; }

The width attribute is deprecated, and CSS should always be used to control these kinds of presentational styles.

How to verify Facebook access token?

You can simply request https://graph.facebook.com/me?access_token=xxxxxxxxxxxxxxxxx if you get an error, the token is invalid. If you get a JSON object with an id property then it is valid.

Unfortunately this will only tell you if your token is valid, not if it came from your app.

What does numpy.random.seed(0) do?

All the answers above show the implementation of np.random.seed() in code. I'll try my best to explain briefly why it actually happens. Computers are machines that are designed based on predefined algorithms. Any output from a computer is the result of the algorithm implemented on the input. So when we request a computer to generate random numbers, sure they are random but the computer did not just come up with them randomly!

So when we write np.random.seed(any_number_here) the algorithm will output a particular set of numbers that is unique to the argument any_number_here. It's almost like a particular set of random numbers can be obtained if we pass the correct argument. But this will require us to know about how the algorithm works which is quite tedious.

So, for example if I write np.random.seed(10) the particular set of numbers that I obtain will remain the same even if I execute the same line after 10 years unless the algorithm changes.

Ignore parent padding

In large this question has been answered but in small parts by everyone. I dealt with this just a minute ago.

I wanted to have a button tray at the bottom of a panel where the panel has 30px all around. The button tray had to be flush bottom and sides.

.panel
{
  padding: 30px;
}

.panel > .actions
{
  margin: -30px;
  margin-top: 30px;
  padding: 30px;
  width: auto;
}

I did a demo here with more flesh to drive the idea. However the key elements above are offset any parent padding with matching negative margins on the child. Then most critical if you want to run the child full-width then set width to auto. (as mentioned in a comment above by schlingel).

SQL Server: Filter output of sp_who2

Extension of the first and best answer... I have created a stored procedure on the master database that you can then pass parameters to .. such as the name of the database:

USE master
GO

CREATE PROCEDURE sp_who_db
(
    @sDBName varchar(200)   = null,
    @sStatus varchar(200)   = null,
    @sCommand varchar(200)  = null,
    @nCPUTime int           = null
)
AS
DECLARE @Table TABLE
(
    SPID INT,
    Status VARCHAR(MAX),
    LOGIN VARCHAR(MAX),
    HostName VARCHAR(MAX),
    BlkBy VARCHAR(MAX),
    DBName VARCHAR(MAX),
    Command VARCHAR(MAX),
    CPUTime INT,
    DiskIO INT,
    LastBatch VARCHAR(MAX),
    ProgramName VARCHAR(MAX),
    SPID_1 INT,
    REQUESTID INT
)

INSERT INTO @Table EXEC sp_who2

SELECT  *
    FROM    @Table
    WHERE   (@sDBName IS NULL OR DBName = @sDBName)
    AND     (@sStatus IS NULL OR Status = @sStatus)
    AND     (@sCommand IS NULL OR Command = @sCommand)
    AND     (@nCPUTime IS NULL OR CPUTime > @nCPUTime)
GO

I might extend it to add an order by parameter or even a kill paramatmer so it kills all connections to a particular data

Node.js: what is ENOSPC error and how to solve?

It indicates that the VS Code file watcher is running out of handles because the workspace is large and contains many files. The max limit of watches has been reacherd, you can viewed the limit by running:

cat /proc/sys/fs/inotify/max_user_watches

run below code resolve this issue:

fs.inotify.max_user_watches=524288

Typedef function pointer?

typedef is used to alias types; in this case you're aliasing FunctionFunc to void(*)().

Indeed the syntax does look odd, have a look at this:

typedef   void      (*FunctionFunc)  ( );
//         ^                ^         ^
//     return type      type name  arguments

No, this simply tells the compiler that the FunctionFunc type will be a function pointer, it doesn't define one, like this:
```
FunctionFunc x;
void doSomething() { printf("Hello there\n"); }
x = &doSomething;

x(); //prints "Hello there"
```

Extend a java class from one file in another java file

Just put the two files in the same directory. Here's an example:

Person.java

public class Person {
  public String name;

  public Person(String name) {
    this.name = name;
  }

  public String toString() {
    return name;
  }
}

Student.java

public class Student extends Person {
  public String somethingnew;

  public Student(String name) {
    super(name);
    somethingnew = "surprise!";
  }

  public String toString() {
    return super.toString() + "\t" + somethingnew;
  }

  public static void main(String[] args) {
    Person you = new Person("foo");
    Student me = new Student("boo");

    System.out.println("Your name is " + you);
    System.out.println("My name is " + me);
  }
}

Running Student (since it has the main function) yields us the desired outcome:

Your name is foo
My name is boo  surprise!

How to configure Glassfish Server in Eclipse manually

I had the same issue. Not able to install neither using Marketplace nor Servers tab.

Following is the alternative.

1) Help -> Install New Software

2) Use url : http://download.oracle.com/otn_software/oepe/12.1.3.6/luna/repository Above is the OEPE tool provided by oracle for EE development.

3) From all the suggestions, select glassfish tools.

4) Install it.

5) Restart eclipse.

Eclipse 4.4.2 Luna JDK : 1.8

Import Excel Spreadsheet Data to an EXISTING sql table?

You can copy-paste data from en excel-sheet to an SQL-table by doing so:

Select the data in Excel and press Ctrl + C
In SQL Server Management Studio right click the table and choose Edit Top 200 Rows
Scroll to the bottom and select the entire empty row by clicking on the row header
Paste the data by pressing Ctrl + V

Note: Often tables have a first column which is an ID-column with an auto generated/incremented ID. When you paste your data it will start inserting the leftmost selected column in Excel into the leftmost column in SSMS thus inserting data into the ID-column. To avoid that keep an empty column at the leftmost part of your selection in order to skip that column in SSMS. That will result in SSMS inserting the default data which is the auto generated ID.

Furthermore you can skip other columns by having empty columns at the same ordinal positions in the Excel sheet selection as those columns to be skipped. That will make SSMS insert the default value (or NULL where no default value is specified).

How do you reverse a string in place in C or C++?

#include <cstdio>
#include <cstdlib>
#include <string>

void strrev(char *str)
{
        if( str == NULL )
                return;

        char *end_ptr = &str[strlen(str) - 1];
        char temp;
        while( end_ptr > str )
        {
                temp = *str;
                *str++ = *end_ptr;
                *end_ptr-- = temp;
        }
}

int main(int argc, char *argv[])
{
        char buffer[32];

        strcpy(buffer, "testing");
        strrev(buffer);
        printf("%s\n", buffer);

        strcpy(buffer, "a");
        strrev(buffer);
        printf("%s\n", buffer);

        strcpy(buffer, "abc");
        strrev(buffer);
        printf("%s\n", buffer);

        strcpy(buffer, "");
        strrev(buffer);
        printf("%s\n", buffer);

        strrev(NULL);

        return 0;
}

This code produces this output:

gnitset
a
cba

List of Java class file format major version numbers?

These come from the class version. If you try to load something compiled for java 6 in a java 5 runtime you'll get the error, incompatible class version, got 50, expected 49. Or something like that.

See here in byte offset 7 for more info.

Additional info can also be found here.

How to replace all strings to numbers contained in each string in Notepad++?

In Notepad++ to replace, hit Ctrl+H to open the Replace menu.

Then if you check the "Regular expression" button and you want in your replacement to use a part of your matching pattern, you must use "capture groups" (read more on google). For example, let's say that you want to match each of the following lines

value="4"
value="403"
value="200"
value="201"
value="116"
value="15"

using the .*"\d+" pattern and want to keep only the number. You can then use a capture group in your matching pattern, using parentheses ( and ), like that: .*"(\d+)". So now in your replacement you can simply write $1, where $1 references to the value of the 1st capturing group and will return the number for each successful match. If you had two capture groups, for example (.*)="(\d+)", $1 will return the string value and $2 will return the number.

So by using:

Find: .*"(\d+)"

Replace: $1

It will return you

Please note that there many alternate and better ways of matching the aforementioned pattern. For example the pattern value="([0-9]+)" would be better, since it is more specific and you will be sure that it will match only these lines. It's even possible of making the replacement without the use of capture groups, but this is a slightly more advanced topic, so I'll leave it for now :)

Sorting rows in a data table

Maybe the following can help:

DataRow[] dataRows = table.Select().OrderBy(u => u["EmailId"]).ToArray();

Here, you can use other Lambda expression queries too.

Pretty-Printing JSON with PHP

print_r pretty print for PHP

Example PHP

function print_nice($elem,$max_level=10,$print_nice_stack=array()){
    if(is_array($elem) || is_object($elem)){
        if(in_array($elem,$print_nice_stack,true)){
            echo "<font color=red>RECURSION</font>";
            return;
        }
        $print_nice_stack[]=&$elem;
        if($max_level<1){
            echo "<font color=red>nivel maximo alcanzado</font>";
            return;
        }
        $max_level--;
        echo "<table border=1 cellspacing=0 cellpadding=3 width=100%>";
        if(is_array($elem)){
            echo '<tr><td colspan=2 style="background-color:#333333;"><strong><font color=white>ARRAY</font></strong></td></tr>';
        }else{
            echo '<tr><td colspan=2 style="background-color:#333333;"><strong>';
            echo '<font color=white>OBJECT Type: '.get_class($elem).'</font></strong></td></tr>';
        }
        $color=0;
        foreach($elem as $k => $v){
            if($max_level%2){
                $rgb=($color++%2)?"#888888":"#BBBBBB";
            }else{
                $rgb=($color++%2)?"#8888BB":"#BBBBFF";
            }
            echo '<tr><td valign="top" style="width:40px;background-color:'.$rgb.';">';
            echo '<strong>'.$k."</strong></td><td>";
            print_nice($v,$max_level,$print_nice_stack);
            echo "</td></tr>";
        }
        echo "</table>";
        return;
    }
    if($elem === null){
        echo "<font color=green>NULL</font>";
    }elseif($elem === 0){
        echo "0";
    }elseif($elem === true){
        echo "<font color=green>TRUE</font>";
    }elseif($elem === false){
        echo "<font color=green>FALSE</font>";
    }elseif($elem === ""){
        echo "<font color=green>EMPTY STRING</font>";
    }else{
        echo str_replace("\n","<strong><font color=red>*</font></strong><br>\n",$elem);
    }
}

Fatal error: Class 'PHPMailer' not found

This is just namespacing. Look at the examples for reference - you need to either use the namespaced class or reference it absolutely, for example:

use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception;

//Load composer's autoloader
require 'vendor/autoload.php';

How to get data from database in javascript based on the value passed to the function

The error is coming as your query is getting formed as

SELECT * FROM Employ where number = parseInt(val);

I dont know which DB you are using but no DB will understand parseInt.

What you can do is use a variable say temp and store the value of parseInt(val) in temp variable and make the query as

SELECT * FROM Employ where number = temp;

ALTER TABLE ADD COLUMN IF NOT EXISTS in SQLite

Here is my solution, but in python (I tried and failed to find any post on the topic related to python):

# modify table for legacy version which did not have leave type and leave time columns of rings3 table.
sql = 'PRAGMA table_info(rings3)' # get table info. returns an array of columns.
result = inquire (sql) # call homemade function to execute the inquiry
if len(result)<= 6: # if there are not enough columns add the leave type and leave time columns
    sql = 'ALTER table rings3 ADD COLUMN leave_type varchar'
    commit(sql) # call homemade function to execute sql
    sql = 'ALTER table rings3 ADD COLUMN leave_time varchar'
    commit(sql)

I used PRAGMA to get the table information. It returns a multidimensional array full of information about columns - one array per column. I count the number of arrays to get the number of columns. If there are not enough columns, then I add the columns using the ALTER TABLE command.

How can I access iframe elements with Javascript?

Using jQuery you can use contents(). For example:

var inside = $('#one').contents();

Use of alloc init instead of new

For a side note, I personally use [Foo new] if I want something in init to be done without using it's return value anywhere. If you do not use the return of [[Foo alloc] init] anywhere then you will get a warning. More or less, I use [Foo new] for eye candy.

Pinging servers in Python

There is a module called pyping that can do this. It can be installed with pip

pip install pyping

It is pretty simple to use, however, when using this module, you need root access due to the fact that it is crafting raw packets under the hood.

import pyping

r = pyping.ping('google.com')

if r.ret_code == 0:
    print("Success")
else:
    print("Failed with {}".format(r.ret_code))

How do I set the eclipse.ini -vm option?

-vm

C:\Program Files\Java\jdk1.5.0_06\bin\javaw.exe

Remember, no quotes, no matter if your path has spaces (as opposed to command line execution).

See here: Find the JRE for Eclipse

MySQL "ERROR 1005 (HY000): Can't create table 'foo.#sql-12c_4' (errno: 150)"

Check that BOTH tables have the same ENGINE. For example if you have:

CREATE Table FOO ();

and:

CREATE Table BAR () ENGINE=INNODB;

If you try to create a constraint from table BAR to table FOO, it will not work on certain MySQL versions.

Fix the issue by following:

CREATE Table FOO () ENGINE=INNODB;

R - argument is of length zero in if statement

The same error message results not only for null but also for e.g. factor(0). In this case, the query must be if(length(element) > 0 & otherCondition) or better check both cases with if(!is.null(element) & length(element) > 0 & otherCondition).

How do I replace a double-quote with an escape-char double-quote in a string using JavaScript?

You need to use a global regular expression for this. Try it this way:

str.replace(/"/g, '\\"');

Check out regex syntax and options for the replace function in Using Regular Expressions with JavaScript.

Can not run Java Applets in Internet Explorer 11 using JRE 7u51

If you are running Windows 7 64-bit, I would strongly suggest you download the 64-bit Java installer. There is no sense in downloading the x86 installer on an x64 based OS.

That corrected the problem for me.

Any way to exit bash script, but not quitting the terminal

I think that this happens because you are running it on source mode with the dot

. myscript.sh

You should run that in a subshell:

/full/path/to/script/myscript.sh

'source' http://ss64.com/bash/source.html

Get width in pixels from element with style set with %?

You can use offsetWidth. Refer to this post and question for more.

_x000D_

console.log("width:" + document.getElementsByTagName("div")[0].offsetWidth + "px");

_x000D_

div {border: 1px solid #F00;}

_x000D_

<div style="width: 100%; height: 10px;"></div>

_x000D_

How to place div side by side

<div class="container" style="width: 100%;">
    <div class="sidebar" style="width: 200px; float: left;">
        Sidebar
    </div>
    <div class="content" style="margin-left: 202px;">
        content 
    </div>
</div>

This will be cross browser compatible. Without the margin-left you will run into issues with content running all the way to the left if you content is longer than your sidebar.

How to do sed like text replace with python?

Cecil Curry has a great answer, however his answer only works for multiline regular expressions. Multiline regular expressions are more rarely used, but they are handy sometimes.

Here is an improvement upon his sed_inplace function that allows it to function with multiline regular expressions if asked to do so.

WARNING: In multiline mode, it will read the entire file in, and then perform the regular expression substitution, so you'll only want to use this mode on small-ish files - don't try to run this on gigabyte-sized files when running in multiline mode.

import re, shutil, tempfile

def sed_inplace(filename, pattern, repl, multiline = False):
    '''
    Perform the pure-Python equivalent of in-place `sed` substitution: e.g.,
    `sed -i -e 's/'${pattern}'/'${repl}' "${filename}"`.
    '''
    re_flags = 0
    if multiline:
        re_flags = re.M

    # For efficiency, precompile the passed regular expression.
    pattern_compiled = re.compile(pattern, re_flags)

    # For portability, NamedTemporaryFile() defaults to mode "w+b" (i.e., binary
    # writing with updating). This is usually a good thing. In this case,
    # however, binary writing imposes non-trivial encoding constraints trivially
    # resolved by switching to text writing. Let's do that.
    with tempfile.NamedTemporaryFile(mode='w', delete=False) as tmp_file:
        with open(filename) as src_file:
            if multiline:
                content = src_file.read()
                tmp_file.write(pattern_compiled.sub(repl, content))
            else:
                for line in src_file:
                    tmp_file.write(pattern_compiled.sub(repl, line))

    # Overwrite the original file with the munged temporary file in a
    # manner preserving file attributes (e.g., permissions).
    shutil.copystat(filename, tmp_file.name)
    shutil.move(tmp_file.name, filename)

from os.path import expanduser
sed_inplace('%s/.gitconfig' % expanduser("~"), r'^(\[user\]$\n[ \t]*name = ).*$(\n[ \t]*email = ).*', r'\1John Doe\[email protected]', multiline=True)

How to make ConstraintLayout work with percentage values?

Using Guidelines you can change the positioning to be percentage based

<android.support.constraint.Guideline
android:id="@+id/guideline"
android:layout_width="1dp"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.5"/>

You can also use this way

android:layout_width="0dp"
app:layout_constraintWidth_default="percent"
app:layout_constraintWidth_percent="0.4"

What does AND 0xFF do?

it clears the all the bits that are not in the first byte

How can I format DateTime to web UTC format?

Why don't just use The Round-trip ("O", "o") Format Specifier?

The "O" or "o" standard format specifier represents a custom date and time format string using a pattern that preserves time zone information and emits a result string that complies with ISO 8601. For DateTime values, this format specifier is designed to preserve date and time values along with the DateTime.Kind property in text. The formatted string can be parsed back by using the DateTime.Parse(String, IFormatProvider, DateTimeStyles) or DateTime.ParseExact method if the styles parameter is set to DateTimeStyles.RoundtripKind.

The "O" or "o" standard format specifier corresponds to the "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffffffK" custom format string for DateTime values and to the "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffffffzzz" custom format string for DateTimeOffset values. In this string, the pairs of single quotation marks that delimit individual characters, such as the hyphens, the colons, and the letter "T", indicate that the individual character is a literal that cannot be changed. The apostrophes do not appear in the output string.

The O" or "o" standard format specifier (and the "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffffffK" custom format string) takes advantage of the three ways that ISO 8601 represents time zone information to preserve the Kind property of DateTime values:

public class Example
{
   public static void Main()
   {
       DateTime dat = new DateTime(2009, 6, 15, 13, 45, 30, 
                                   DateTimeKind.Unspecified);
       Console.WriteLine("{0} ({1}) --> {0:O}", dat, dat.Kind); 

       DateTime uDat = new DateTime(2009, 6, 15, 13, 45, 30, 
                                    DateTimeKind.Utc);
       Console.WriteLine("{0} ({1}) --> {0:O}", uDat, uDat.Kind);

       DateTime lDat = new DateTime(2009, 6, 15, 13, 45, 30, 
                                    DateTimeKind.Local);
       Console.WriteLine("{0} ({1}) --> {0:O}\n", lDat, lDat.Kind);

       DateTimeOffset dto = new DateTimeOffset(lDat);
       Console.WriteLine("{0} --> {0:O}", dto);
   }
}
// The example displays the following output: 
//    6/15/2009 1:45:30 PM (Unspecified) --> 2009-06-15T13:45:30.0000000 
//    6/15/2009 1:45:30 PM (Utc) --> 2009-06-15T13:45:30.0000000Z 
//    6/15/2009 1:45:30 PM (Local) --> 2009-06-15T13:45:30.0000000-07:00 
//     
//    6/15/2009 1:45:30 PM -07:00 --> 2009-06-15T13:45:30.0000000-07:00

How to get the Power of some Integer in Swift language?

Trying to combine the overloading, I tried to use generics but couldn't make it work. I finally figured to use NSNumber instead of trying to overload or use generics. This simplifies to the following:

typealias Dbl = Double // Shorter form
infix operator ** {associativity left precedence 160}
func ** (lhs: NSNumber, rhs: NSNumber) -> Dbl {return pow(Dbl(lhs), Dbl(rhs))}

The following code is the same function as above but implements error checking to see if the parameters can be converted to Doubles successfully.

func ** (lhs: NSNumber, rhs: NSNumber) -> Dbl {
    // Added (probably unnecessary) check that the numbers converted to Doubles
    if (Dbl(lhs) ?? Dbl.NaN) != Dbl.NaN && (Dbl(rhs) ?? Dbl.NaN) != Dbl.NaN {
        return pow(Dbl(lhs), Dbl(rhs))
    } else {
        return Double.NaN
    }
}

How to load URL in UIWebView in Swift?

Swift 3 - Xcode 8.1

 @IBOutlet weak var myWebView: UIWebView!

    override func viewDidLoad() {
            super.viewDidLoad()

            let url = URL (string: "https://ir.linkedin.com/in/razipour1993")
            let requestObj = URLRequest(url: url!)
            myWebView.loadRequest(requestObj)

        }

Excel Formula: Count cells where value is date

There is no interactive solution in Excel because some functions are not vector-friendly, like CELL, above quoted. For example, it's possible counting all the numbers whose absolute value is less than 3, because ABS is accepted inside a formula array.

So I've used the following array formula (Ctrl+Shift+Enter after edit with no curly brackets)

             ={SUM(IF(ABS(F1:F15)<3,1,0))}

If Column F has

It counts 3! (-2,2 and 1). In order to show how ABS is array-friendly function let's do a simple test: Select G1:G5, digit =ABS(F1:F5) in the formula bar and press Ctrl+Shift+Enter. It's like someone write Abs(F1:F5)(1), Abs(F1:F5)(2), etc.

                   F    G
          1 ...    2  =ABS(F1:F5) => 2 
          2 ....   4  =ABS(F1:F5) => 4
          3 ....  -2  =ABS(F1:F5) => 2
          4 ....   1  =ABS(F1:F5) => 1
          5 .....  5  =ABS(F1:F5) => 5

Now I put some mixed data, including 2 date values.

                   F
          1 ...    Fab-25-2012
          2 ....   4
          3 ....   May-5-2013
          4 ....   Ball
          5 .....  5

In this case, CELL fails and return 1

             ={SUM(IF(CELL("format",F1:F15)="D4",1,0))}

It happens because CELL return the format of first cell of the range. (D4 is a m-d-y format)

So the only thing left is programming! A UDF(User defined Function) for formula array must return a variant array:

Function TypeCell(R As Range) As Variant
Dim V() As Variant
Dim Cel As Range
Dim I As Integer
Application.Volatile '// For revaluation in interactive environment
ReDim V(R.Cells.Count - 1) As Variant
I = 0
For Each Cel In R
   V(I) = VarType(Cel) '// Output array has the same size of input range.
   I = I + 1
Next Cel
TypeCell = V
End Function

Now is easy (the constant VbDate is 7):

             =SUM(IF(TypeCell(F1:F5)=7,1,0))

It shows 2. That technique can be used for any shape of cells. I've tested vertical, horizontal and rectangular shapes, since you fill using for each order inside the function.

SSL Error When installing rubygems, Unable to pull data from 'https://rubygems.org/

The answer is no longer valid. Since I have encountered the issue with older Windows ruby right now I'll post the answer.

When I wanted to install an activesupport gem:

gem in activesupport --version 5.1.6

ERROR:  Could not find a valid gem 'activesupport' (= 5.1.6), here is why:
          Unable to download data from https://rubygems.org/ - SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B
: certificate verify failed (https://api.rubygems.org/specs.4.8.gz)

The following steps need to copy only the certificates from newer windows ruby. Take the latest ruby (or at least ruby 2.4.0) and do the following:

copy certificates from these directories (adjust to your needs):
C:\prg_sdk\rubies\Ruby-2.4\lib\ruby\2.4.0\rubygems\ssl_certs\rubygems.org
C:\prg_sdk\rubies\Ruby-2.4\lib\ruby\2.4.0\rubygems\ssl_certs\index.rubygems.org

to destination (again adjust to what you need):
C:\prg_sdk\rubies\Ruby231-p112-x64\lib\ruby\2.3.0\rubygems\ssl_certs

PHP Warning: mysqli_connect(): (HY000/2002): Connection refused

In case anyone else comes by this issue, the default port on MAMP for mysql is 8889, but the port that php expects to use for mysql is 3306. So you need to open MAMP, go to preferences, and change the MAMP mysql port to 3306, then restart the mysql server. Now the connection should be successful with host=localhost, user=root, pass=root.

Fastest way to check if a value exists in a list

Or use __contains__:

sequence.__contains__(value)

Demo:

>>> l = [1, 2, 3]
>>> l.__contains__(3)
True
>>>

Laravel blank white screen

Try this, in the public/index.php page

error_reporting(E_ALL);
ini_set('error_reporting', E_ALL);
ini_set("display_errors", 1);

Rollback to an old Git commit in a public repo

To rollback to a specific commit:

git reset --hard commit_sha

To rollback 10 commits back:

git reset --hard HEAD~10

You can use "git revert" as in the following post if you don't want to rewrite the history

How to revert Git repository to a previous commit?

openssl s_client using a proxy

Even with openssl v1.1.0 I had some problems passing our proxy, e.g. s_client: HTTP CONNECT failed: 400 Bad Request That forced me to write a minimal Java-class to show the SSL-Handshake

    public static void main(String[] args) throws IOException, URISyntaxException {
    HttpHost proxy = new HttpHost("proxy.my.company", 8080);
    DefaultProxyRoutePlanner routePlanner = new DefaultProxyRoutePlanner(proxy);
    CloseableHttpClient httpclient = HttpClients.custom()
            .setRoutePlanner(routePlanner)
            .build();
    URI uri = new URIBuilder()
            .setScheme("https")
            .setHost("www.myhost.com")
            .build();
    HttpGet httpget = new HttpGet(uri);
    httpclient.execute(httpget);
}

With following dependency:

    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.5.2</version>
        <type>jar</type>
    </dependency>

you can run it with Java SSL Logging turned on

This should produce nice output like

trustStore provider is :
init truststore
adding as trusted cert:
  Subject: CN=Equifax Secure Global eBusiness CA-1, O=Equifax Secure Inc., C=US
  Issuer:  CN=Equifax Secure Global eBusiness CA-1, O=Equifax Secure Inc., C=US
  Algorithm: RSA; Serial number: 0xc3517
  Valid from Mon Jun 21 06:00:00 CEST 1999 until Mon Jun 22 06:00:00 CEST 2020

adding as trusted cert:
  Subject: CN=SecureTrust CA, O=SecureTrust Corporation, C=US
  Issuer:  CN=SecureTrust CA, O=SecureTrust Corporation, C=US
(....)

How do AX, AH, AL map onto EAX?

No, that's not quite right.

EAX is the full 32-bit value
AX is the lower 16-bits
AL is the lower 8 bits
AH is the bits 8 through 15 (zero-based)

So AX is composed of AH:AL halves, and is itself the low half of EAX. (The upper half of EAX isn't directly accessible as a 16-bit register; you can shift or rotate EAX if you want to get at it.)

For completeness, in addition to the above, which was based on a 32-bit CPU, 64-bit Intel/AMD CPUs have

RAX, which hold a 64-bit value, and where EAX is mapped to the lower 32 bits.

All of this also applies to EBX/RBX, ECX/RCX, and EDX/RDX. The other registers like EDI/RDI have a DI low 16-bit partial register, but no high-8 part, and the low-8 DIL is only accessible in 64-bit mode: Assembly registers in 64-bit architecture

Writing AL, AH, or AX merges into the full AX/EAX/RAX, leaving other bytes unmodified for historical reasons. (In 32 or 64-bit code, prefer a movzx eax, byte [mem] or movzx eax, word [mem] load if you don't specifically want this merging: Why doesn't GCC use partial registers?)

Writing EAX zero-extends into RAX. (Why do x86-64 instructions on 32-bit registers zero the upper part of the full 64-bit register?)

How to get screen dimensions as pixels in Android

I think it's simplest

private fun checkDisplayResolution() {
    val displayMetrics = DisplayMetrics().also {
        windowManager.defaultDisplay.getMetrics(it)
    }

    Log.i(TAG, "display width: ${displayMetrics.widthPixels}")
    Log.i(TAG, "display height: ${displayMetrics.heightPixels}")
    Log.i(TAG, "display width dpi: ${displayMetrics.xdpi}")
    Log.i(TAG, "display height dpi: ${displayMetrics.ydpi}")
    Log.i(TAG, "display density: ${displayMetrics.density}")
    Log.i(TAG, "display scaled density: ${displayMetrics.scaledDensity}")
}

How to use vagrant in a proxy environment?

If your proxy requires authentication it is better to set the environment variable rather than storing your password in the Vagrantfile. Also your Vagrantfile can be used by others easily who are not behind a proxy.

For Mac/Linux (in Bash)

export http_proxy="http://user:password@host:port"
export https_proxy="http://user:password@host:port"
vagrant plugin install vagrant-proxyconf

then

export VAGRANT_HTTP_PROXY=${http_proxy}
export VAGRANT_HTTPS_PROXY=${https_proxy}
export VAGRANT_NO_PROXY="127.0.0.1"
vagrant up

For Windows use set instead of export.

set http_proxy=http://user:password@host:port
set https_proxy=https://user:password@host:port
vagrant plugin install vagrant-proxyconf

then

set VAGRANT_HTTP_PROXY=%http_proxy%
set VAGRANT_HTTPS_PROXY=%https_proxy%
set VAGRANT_NO_PROXY="127.0.0.1"
vagrant up

Invalid argument supplied for foreach()

Warning invalid argument supplied for foreach() display tweets. go to /wp-content/plugins/display-tweets-php. Then insert this code on line number 591, It will run perfectly.

if (is_array($tweets)) {
    foreach ($tweets as $tweet) 
    {
        ...
    }
}

How can I uninstall Ruby on ubuntu?

If you used rbenv to install it, you can use

rbenv versions

to see which versions you have installed.

Then, use the uninstall command:

rbenv uninstall [-f|--force] <version>

for example:

rbenv uninstall 2.4.0  # Uninstall Ruby 2.4.0

If you installed Rails, it will be removed, too.

remove double quotes from Json return data using Jquery

The stringfy method is not for parsing JSON, it's for turning an object into a JSON string.

The JSON is parsed by jQuery when you load it, you don't need to parse the data to use it. Just use the string in the data:

$('div#ListingData').text(data.data.items[0].links[1].caption);

How to prevent scanf causing a buffer overflow in C?

Directly using scanf(3) and its variants poses a number of problems. Typically, users and non-interactive use cases are defined in terms of lines of input. It's rare to see a case where, if enough objects are not found, more lines will solve the problem, yet that's the default mode for scanf. (If a user didn't know to enter a number on the first line, a second and third line will probably not help.)

At least if you fgets(3) you know how many input lines your program will need, and you won't have any buffer overflows...

Move textfield when keyboard appears swift

I created a Swift 3 protocol to handle the keyboard appearance / disappearance

import UIKit

protocol KeyboardHandler: class {

var bottomConstraint: NSLayoutConstraint! { get set }

    func keyboardWillShow(_ notification: Notification)
    func keyboardWillHide(_ notification: Notification)
    func startObservingKeyboardChanges()
    func stopObservingKeyboardChanges()
}


extension KeyboardHandler where Self: UIViewController {

    func startObservingKeyboardChanges() {

        // NotificationCenter observers
        NotificationCenter.default.addObserver(forName: NSNotification.Name.UIKeyboardWillShow, object: nil, queue: nil) { [weak self] notification in
          self?.keyboardWillShow(notification)
        }

        // Deal with rotations
        NotificationCenter.default.addObserver(forName: NSNotification.Name.UIKeyboardWillChangeFrame, object: nil, queue: nil) { [weak self] notification in
          self?.keyboardWillShow(notification)
        }

        // Deal with keyboard change (emoji, numerical, etc.)
        NotificationCenter.default.addObserver(forName: NSNotification.Name.UITextInputCurrentInputModeDidChange, object: nil, queue: nil) { [weak self] notification in
          self?.keyboardWillShow(notification)
        }

        NotificationCenter.default.addObserver(forName: NSNotification.Name.UIKeyboardWillHide, object: nil, queue: nil) { [weak self] notification in
          self?.keyboardWillHide(notification)
        }
    }


    func keyboardWillShow(_ notification: Notification) {

      let verticalPadding: CGFloat = 20 // Padding between the bottom of the view and the top of the keyboard

      guard let value = notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue else { return }
      let keyboardHeight = value.cgRectValue.height

      // Here you could have more complex rules, like checking if the textField currently selected is actually covered by the keyboard, but that's out of this scope.
      self.bottomConstraint.constant = keyboardHeight + verticalPadding

      UIView.animate(withDuration: 0.1, animations: { () -> Void in
          self.view.layoutIfNeeded()
      })
  }


  func keyboardWillHide(_ notification: Notification) {
      self.bottomConstraint.constant = 0

      UIView.animate(withDuration: 0.1, animations: { () -> Void in
          self.view.layoutIfNeeded()
      })
  }


  func stopObservingKeyboardChanges() {
      NotificationCenter.default.removeObserver(self)
  }

}

Then, to implement it in a UIViewController, do the following:

let the viewController conform to this protocol :

class FormMailVC: UIViewControlle, KeyboardHandler {

start observing keyboard changes in viewWillAppear:

// MARK: - View controller life cycle
override func viewWillAppear(_ animated: Bool) {
  super.viewWillAppear(animated)
  startObservingKeyboardChanges()
}

stop observing keyboard changes in viewWillDisappear:

override func viewWillDisappear(_ animated: Bool) {
  super.viewWillDisappear(animated)
  stopObservingKeyboardChanges()
}

create an IBOutlet for the bottom constraint from the storyboard:
```
// NSLayoutConstraints
@IBOutlet weak var bottomConstraint: NSLayoutConstraint!
```
(I recommend having all of your UI embedded inside a "contentView", and linking to this property the bottom constraint from this contentView to the bottom layout guide)
change the constraint priority of the top constraint to 250 (low)

This is to let the whole content view slide upwards when the keyboard appears. The priority must be lower than any other constraint priority in the subviews, including content hugging priorities / content compression resistance priorities.

Make sure that your Autolayout has enough constraints to determine how the contentView should slide up.

You may have to add a "greater than equal" constraint for this:

And here you go!

ReactJS - Get Height of an element

Using with hooks :

This answer would be helpful if your content dimension changes after loading.

onreadystatechange : Occurs when the load state of the data that belongs to an element or a HTML document changes. The onreadystatechange event is fired on a HTML document when the load state of the page's content has changed.

import {useState, useEffect, useRef} from 'react';
const ref = useRef();
useEffect(() => {
    document.onreadystatechange = () => {
      console.log(ref.current.clientHeight);
    };
  }, []);

I was trying to work with a youtube video player embedding whose dimensions may change after loading.

"â€™" showing on page instead of " ' "

So what's the problem,

It's a ’ (RIGHT SINGLE QUOTATION MARK - U+2019) character which is being decoded as CP-1252 instead of UTF-8. If you check the encodings table, then you see that this character is in UTF-8 composed of bytes 0xE2, 0x80 and 0x99. If you check the CP-1252 code page layout, then you'll see that each of those bytes stand for the individual characters â, € and ™.

and how can I fix it?

Use UTF-8 instead of CP-1252 to read, write, store, and display the characters.

I have the Content-Type set to UTF-8 in both my <head> tag and my HTTP headers:
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />

This only instructs the client which encoding to use to interpret and display the characters. This doesn't instruct your own program which encoding to use to read, write, store, and display the characters in. The exact answer depends on the server side platform / database / programming language used. Do note that the one set in HTTP response header has precedence over the HTML meta tag. The HTML meta tag would only be used when the page is opened from local disk file system instead of from HTTP.

In addition, my browser is set to Unicode (UTF-8):

This only forces the client which encoding to use to interpret and display the characters. But the actual problem is that you're already sending â€™ (encoded in UTF-8) to the client instead of ’. The client is correctly displaying â€™ using the UTF-8 encoding. If the client was misinstructed to use, for example ISO-8859-1, you would likely have seen Ã¢â¬â¢ instead.

I am using ASP.NET 2.0 with a database.

This is most likely where your problem lies. You need to verify with an independent database tool what the data looks like.

If the ’ character is there, then you aren't connecting to the database correctly. You need to tell the database connector to use UTF-8.

If your database contains â€™, then it's your database that's messed up. Most probably the tables aren't configured to use UTF-8. Instead, they use the database's default encoding, which varies depending on the configuration. If this is your issue, then usually just altering the table to use UTF-8 is sufficient. If your database doesn't support that, you'll need to recreate the tables. It is good practice to set the encoding of the table when you create it.

You're most likely using SQL Server, but here is some MySQL code (copied from this article):

CREATE DATABASE db_name CHARACTER SET utf8;
CREATE TABLE tbl_name (...) CHARACTER SET utf8;

If your table is however already UTF-8, then you need to take a step back. Who or what put the data there. That's where the problem is. One example would be HTML form submitted values which are incorrectly encoded/decoded.

Here are some more links to learn more about the problem:

The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!), from our own Joel.
Unicode - How to get the characters right?, with more concise and practical information, solutions are targeted on Java environments.
How to setup your PHP site to use UTF8, targeted on PHP environments.

Datagrid binding in WPF

Without seeing said object list, I believe you should be binding to the DataGrid's ItemsSource property, not its DataContext.

<DataGrid x:Name="Imported" VerticalAlignment="Top" ItemsSource="{Binding Source=list}"  AutoGenerateColumns="False" CanUserResizeColumns="True">
    <DataGrid.Columns>                
        <DataGridTextColumn Header="ID" Binding="{Binding ID}"/>
        <DataGridTextColumn Header="Date" Binding="{Binding Date}"/>
   </DataGrid.Columns>
</DataGrid>

(This assumes that the element [UserControl, etc.] that contains the DataGrid has its DataContext bound to an object that contains the list collection. The DataGrid is derived from ItemsControl, which relies on its ItemsSource property to define the collection it binds its rows to. Hence, if list isn't a property of an object bound to your control's DataContext, you might need to set both DataContext={Binding list} and ItemsSource={Binding list} on the DataGrid...)

What is the best way to implement constants in Java?

Just avoid using an interface:

public interface MyConstants {
    String CONSTANT_ONE = "foo";
}

public class NeddsConstant implements MyConstants {

}

It is tempting, but violates encapsulation and blurs the distinction of class definitions.

Check if application is installed - Android

Faster solution:

private boolean isPackageInstalled(String packagename, PackageManager packageManager) {
    try {
        packageManager.getPackageGids(packagename);
        return true;
    } catch (NameNotFoundException e) {
        return false;
    }
}

getPackageGids is less expensive from getPackageInfo, so it work faster.

Run 10000 on API 15
Exists pkg:
getPackageInfo: nanoTime = 930000000
getPackageGids: nanoTime = 350000000
Not exists pkg:
getPackageInfo: nanoTime = 420000000
getPackageGids: nanoTime = 380000000

Run 10000 on API 17
Exists pkg:
getPackageInfo: nanoTime = 2942745517
getPackageGids: nanoTime = 2443716170
Not exists pkg:
getPackageInfo: nanoTime = 2467565849
getPackageGids: nanoTime = 2479833890

Run 10000 on API 22
Exists pkg:
getPackageInfo: nanoTime = 4596551615
getPackageGids: nanoTime = 1864970154
Not exists pkg:
getPackageInfo: nanoTime = 3830033616
getPackageGids: nanoTime = 3789230769

Run 10000 on API 25
Exists pkg:
getPackageInfo: nanoTime = 3436647394
getPackageGids: nanoTime = 2876970397
Not exists pkg:
getPackageInfo: nanoTime = 3252946114
getPackageGids: nanoTime = 3117544269

Note: This will not work in some virtual spaces. They can violate the Android API and always return an array, even if there is no application with that package name.
In this case, use getPackageInfo.

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