Programs & Examples On #Modified preorder tree t

What are the options for storing hierarchical data in a relational database?

I am using PostgreSQL with closure tables for my hierarchies. I have one universal stored procedure for the whole database:

CREATE FUNCTION nomen_tree() RETURNS trigger
    LANGUAGE plpgsql
    AS $_$
DECLARE
  old_parent INTEGER;
  new_parent INTEGER;
  id_nom INTEGER;
  txt_name TEXT;
BEGIN
-- TG_ARGV[0] = name of table with entities with PARENT-CHILD relationships (TBL_ORIG)
-- TG_ARGV[1] = name of helper table with ANCESTOR, CHILD, DEPTH information (TBL_TREE)
-- TG_ARGV[2] = name of the field in TBL_ORIG which is used for the PARENT-CHILD relationship (FLD_PARENT)
    IF TG_OP = 'INSERT' THEN
    EXECUTE 'INSERT INTO ' || TG_ARGV[1] || ' (child_id,ancestor_id,depth) 
        SELECT $1.id,$1.id,0 UNION ALL
      SELECT $1.id,ancestor_id,depth+1 FROM ' || TG_ARGV[1] || ' WHERE child_id=$1.' || TG_ARGV[2] USING NEW;
    ELSE                                                           
    -- EXECUTE does not support conditional statements inside
    EXECUTE 'SELECT $1.' || TG_ARGV[2] || ',$2.' || TG_ARGV[2] INTO old_parent,new_parent USING OLD,NEW;
    IF COALESCE(old_parent,0) <> COALESCE(new_parent,0) THEN
      EXECUTE '
      -- prevent cycles in the tree
      UPDATE ' || TG_ARGV[0] || ' SET ' || TG_ARGV[2] || ' = $1.' || TG_ARGV[2]
        || ' WHERE id=$2.' || TG_ARGV[2] || ' AND EXISTS(SELECT 1 FROM '
        || TG_ARGV[1] || ' WHERE child_id=$2.' || TG_ARGV[2] || ' AND ancestor_id=$2.id);
      -- first remove edges between all old parents of node and its descendants
      DELETE FROM ' || TG_ARGV[1] || ' WHERE child_id IN
        (SELECT child_id FROM ' || TG_ARGV[1] || ' WHERE ancestor_id = $1.id)
        AND ancestor_id IN
        (SELECT ancestor_id FROM ' || TG_ARGV[1] || ' WHERE child_id = $1.id AND ancestor_id <> $1.id);
      -- then add edges for all new parents ...
      INSERT INTO ' || TG_ARGV[1] || ' (child_id,ancestor_id,depth) 
        SELECT child_id,ancestor_id,d_c+d_a FROM
        (SELECT child_id,depth AS d_c FROM ' || TG_ARGV[1] || ' WHERE ancestor_id=$2.id) AS child
        CROSS JOIN
        (SELECT ancestor_id,depth+1 AS d_a FROM ' || TG_ARGV[1] || ' WHERE child_id=$2.' 
        || TG_ARGV[2] || ') AS parent;' USING OLD, NEW;
    END IF;
  END IF;
  RETURN NULL;
END;
$_$;

Then for each table where I have a hierarchy, I create a trigger

CREATE TRIGGER nomenclature_tree_tr AFTER INSERT OR UPDATE ON nomenclature FOR EACH ROW EXECUTE PROCEDURE nomen_tree('my_db.nomenclature', 'my_db.nom_helper', 'parent_id');

For populating a closure table from existing hierarchy I use this stored procedure:

CREATE FUNCTION rebuild_tree(tbl_base text, tbl_closure text, fld_parent text) RETURNS void
    LANGUAGE plpgsql
    AS $$
BEGIN
    EXECUTE 'TRUNCATE ' || tbl_closure || ';
    INSERT INTO ' || tbl_closure || ' (child_id,ancestor_id,depth) 
        WITH RECURSIVE tree AS
      (
        SELECT id AS child_id,id AS ancestor_id,0 AS depth FROM ' || tbl_base || '
        UNION ALL 
        SELECT t.id,ancestor_id,depth+1 FROM ' || tbl_base || ' AS t
        JOIN tree ON child_id = ' || fld_parent || '
      )
      SELECT * FROM tree;';
END;
$$;

Closure tables are defined with 3 columns - ANCESTOR_ID, DESCENDANT_ID, DEPTH. It is possible (and I even advice) to store records with same value for ANCESTOR and DESCENDANT, and a value of zero for DEPTH. This will simplify the queries for retrieval of the hierarchy. And they are very simple indeed:

-- get all descendants
SELECT tbl_orig.*,depth FROM tbl_closure LEFT JOIN tbl_orig ON descendant_id = tbl_orig.id WHERE ancestor_id = XXX AND depth <> 0;
-- get only direct descendants
SELECT tbl_orig.* FROM tbl_closure LEFT JOIN tbl_orig ON descendant_id = tbl_orig.id WHERE ancestor_id = XXX AND depth = 1;
-- get all ancestors
SELECT tbl_orig.* FROM tbl_closure LEFT JOIN tbl_orig ON ancestor_id = tbl_orig.id WHERE descendant_id = XXX AND depth <> 0;
-- find the deepest level of children
SELECT MAX(depth) FROM tbl_closure WHERE ancestor_id = XXX;

Customize UITableView header section

call this delegate method

-(NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section{

return @"Some Title";
}

this will give a chance to automatically add a default header with dynamic title .

You may use reusable and customizable header / footer .

https://github.com/sourov2008/UITableViewCustomHeaderFooterSection

Correct format specifier for double in printf

"%f" is the (or at least one) correct format for a double. There is no format for a float, because if you attempt to pass a float to printf, it'll be promoted to double before printf receives it1. "%lf" is also acceptable under the current standard -- the l is specified as having no effect if followed by the f conversion specifier (among others).

Note that this is one place that printf format strings differ substantially from scanf (and fscanf, etc.) format strings. For output, you're passing a value, which will be promoted from float to double when passed as a variadic parameter. For input you're passing a pointer, which is not promoted, so you have to tell scanf whether you want to read a float or a double, so for scanf, %f means you want to read a float and %lf means you want to read a double (and, for what it's worth, for a long double, you use %Lf for either printf or scanf).


1. C99, §6.5.2.2/6: "If the expression that denotes the called function has a type that does not include a prototype, the integer promotions are performed on each argument, and arguments that have type float are promoted to double. These are called the default argument promotions." In C++ the wording is somewhat different (e.g., it doesn't use the word "prototype") but the effect is the same: all the variadic parameters undergo default promotions before they're received by the function.

how to get date of yesterday using php?

You can also do this using Carbon library:

Carbon::yesterday()->format('d.m.Y');         // '26.03.2019'

In other formats:

Carbon::yesterday()->toDateString();          // '2019-03-26'
Carbon::yesterday()->toDateTimeString();      // '2019-03-26 00:00:00'

Carbon::yesterday()->toFormattedDateString(); // 'Mar 26, 2019'
Carbon::yesterday()->toDayDateTimeString();   // 'Tue, Mar 26, 2019 12:00 AM'

Module is not available, misspelled or forgot to load (but I didn't)

I had the same error and fixed it. It turned out to be a silly reason.

This was the culprit: <script src="app.js"/>

Fix: <script src="app.js"></script>

Make sure your script tag is ended properly!

how to set font size based on container size?

If you want to scale it depending on the element width, you can use this web component:
https://github.com/pomber/full-width-text

Check the demo here:
https://pomber.github.io/full-width-text/

The usage is like this:

<full-width-text>Lorem Ipsum</full-width-text>

In C++, what is a virtual base class?

Virtual base classes, used in virtual inheritance, is a way of preventing multiple "instances" of a given class appearing in an inheritance hierarchy when using multiple inheritance.

Consider the following scenario:

class A { public: void Foo() {} };
class B : public A {};
class C : public A {};
class D : public B, public C {};

The above class hierarchy results in the "dreaded diamond" which looks like this:

  A
 / \
B   C
 \ /
  D

An instance of D will be made up of B, which includes A, and C which also includes A. So you have two "instances" (for want of a better expression) of A.

When you have this scenario, you have the possibility of ambiguity. What happens when you do this:

D d;
d.Foo(); // is this B's Foo() or C's Foo() ??

Virtual inheritance is there to solve this problem. When you specify virtual when inheriting your classes, you're telling the compiler that you only want a single instance.

class A { public: void Foo() {} };
class B : public virtual A {};
class C : public virtual A {};
class D : public B, public C {};

This means that there is only one "instance" of A included in the hierarchy. Hence

D d;
d.Foo(); // no longer ambiguous

This is a mini summary. For more information, have a read of this and this. A good example is also available here.

NSURLErrorDomain error codes description

I was unable to find name of an error for given code when developing in Swift. For that reason I paste minus codes for NSURLErrorDomain taken from NSURLError.h

/*!
    @enum NSURL-related Error Codes
    @abstract Constants used by NSError to indicate errors in the NSURL domain
*/
NS_ENUM(NSInteger)
{
    NSURLErrorUnknown =             -1,
    NSURLErrorCancelled =           -999,
    NSURLErrorBadURL =              -1000,
    NSURLErrorTimedOut =            -1001,
    NSURLErrorUnsupportedURL =          -1002,
    NSURLErrorCannotFindHost =          -1003,
    NSURLErrorCannotConnectToHost =         -1004,
    NSURLErrorNetworkConnectionLost =       -1005,
    NSURLErrorDNSLookupFailed =         -1006,
    NSURLErrorHTTPTooManyRedirects =        -1007,
    NSURLErrorResourceUnavailable =         -1008,
    NSURLErrorNotConnectedToInternet =      -1009,
    NSURLErrorRedirectToNonExistentLocation =   -1010,
    NSURLErrorBadServerResponse =       -1011,
    NSURLErrorUserCancelledAuthentication =     -1012,
    NSURLErrorUserAuthenticationRequired =  -1013,
    NSURLErrorZeroByteResource =        -1014,
    NSURLErrorCannotDecodeRawData =             -1015,
    NSURLErrorCannotDecodeContentData =         -1016,
    NSURLErrorCannotParseResponse =             -1017,
    NSURLErrorAppTransportSecurityRequiresSecureConnection NS_ENUM_AVAILABLE(10_11, 9_0) = -1022,
    NSURLErrorFileDoesNotExist =        -1100,
    NSURLErrorFileIsDirectory =         -1101,
    NSURLErrorNoPermissionsToReadFile =     -1102,
    NSURLErrorDataLengthExceedsMaximum NS_ENUM_AVAILABLE(10_5, 2_0) =   -1103,

    // SSL errors
    NSURLErrorSecureConnectionFailed =      -1200,
    NSURLErrorServerCertificateHasBadDate =     -1201,
    NSURLErrorServerCertificateUntrusted =  -1202,
    NSURLErrorServerCertificateHasUnknownRoot = -1203,
    NSURLErrorServerCertificateNotYetValid =    -1204,
    NSURLErrorClientCertificateRejected =   -1205,
    NSURLErrorClientCertificateRequired =   -1206,
    NSURLErrorCannotLoadFromNetwork =       -2000,

    // Download and file I/O errors
    NSURLErrorCannotCreateFile =        -3000,
    NSURLErrorCannotOpenFile =          -3001,
    NSURLErrorCannotCloseFile =         -3002,
    NSURLErrorCannotWriteToFile =       -3003,
    NSURLErrorCannotRemoveFile =        -3004,
    NSURLErrorCannotMoveFile =          -3005,
    NSURLErrorDownloadDecodingFailedMidStream = -3006,
    NSURLErrorDownloadDecodingFailedToComplete =-3007,

    NSURLErrorInternationalRoamingOff NS_ENUM_AVAILABLE(10_7, 3_0) =         -1018,
    NSURLErrorCallIsActive NS_ENUM_AVAILABLE(10_7, 3_0) =                    -1019,
    NSURLErrorDataNotAllowed NS_ENUM_AVAILABLE(10_7, 3_0) =                  -1020,
    NSURLErrorRequestBodyStreamExhausted NS_ENUM_AVAILABLE(10_7, 3_0) =      -1021,

    NSURLErrorBackgroundSessionRequiresSharedContainer NS_ENUM_AVAILABLE(10_10, 8_0) = -995,
    NSURLErrorBackgroundSessionInUseByAnotherProcess NS_ENUM_AVAILABLE(10_10, 8_0) = -996,
    NSURLErrorBackgroundSessionWasDisconnected NS_ENUM_AVAILABLE(10_10, 8_0)= -997,
};

What is the difference between print and puts?

The API docs give some good hints:

print() ? nil

print(obj, ...) ? nil

Writes the given object(s) to ios. Returns nil.

The stream must be opened for writing. Each given object that isn't a string will be converted by calling its to_s method. When called without arguments, prints the contents of $_.

If the output field separator ($,) is not nil, it is inserted between objects. If the output record separator ($\) is not nil, it is appended to the output.

...

puts(obj, ...) ? nil

Writes the given object(s) to ios. Writes a newline after any that do not already end with a newline sequence. Returns nil.

The stream must be opened for writing. If called with an array argument, writes each element on a new line. Each given object that isn't a string or array will be converted by calling its to_s method. If called without arguments, outputs a single newline.

Experimenting a little with the points given above, the differences seem to be:

  • Called with multiple arguments, print separates them by the 'output field separator' $, (which defaults to nothing) while puts separates them by newlines. puts also puts a newline after the final argument, while print does not.

    2.1.3 :001 > print 'hello', 'world'
    helloworld => nil 
    2.1.3 :002 > puts 'hello', 'world'
    hello
    world
     => nil
    2.1.3 :003 > $, = 'fanodd'
     => "fanodd" 
    2.1.3 :004 > print 'hello', 'world'
    hellofanoddworld => nil 
    2.1.3 :005 > puts 'hello', 'world'
    hello
    world
     => nil
  • puts automatically unpacks arrays, while print does not:

    2.1.3 :001 > print [1, [2, 3]], [4]
    [1, [2, 3]][4] => nil 
    2.1.3 :002 > puts [1, [2, 3]], [4]
    1
    2
    3
    4
     => nil
  • print with no arguments prints $_ (the last thing read by gets), while puts prints a newline:

    2.1.3 :001 > gets
    hello world
     => "hello world\n" 
    2.1.3 :002 > puts
    
     => nil 
    2.1.3 :003 > print
    hello world
     => nil
  • print writes the output record separator $\ after whatever it prints, while puts ignores this variable:

    mark@lunchbox:~$ irb
    2.1.3 :001 > $\ = 'MOOOOOOO!'
     => "MOOOOOOO!" 
    2.1.3 :002 > puts "Oink! Baa! Cluck! "
    Oink! Baa! Cluck! 
     => nil 
    2.1.3 :003 > print "Oink! Baa! Cluck! "
    Oink! Baa! Cluck! MOOOOOOO! => nil

Eclipse error ... cannot be resolved to a type

For many new users don't forget to add an asterisk (*) after your import statements if you wanna use all the classes in a package....for example

import java.io.*;

public class Learning 
{
    public static void main(String[] args) 
    {
        BufferedInputStream sd = new BufferedInputStream(System.in);
            // no error
    }
}

================================================================

import java.io;

public class Learning 
{
    public static void main(String[] args) 
    {
        BufferedInputStream sd = new BufferedInputStream(System.in);
            // BufferedInputStream cannot be resolved to a type error
    }
}

Difference between subprocess.Popen and os.system

When running python (cpython) on windows the <built-in function system> os.system will execute under the curtains _wsystem while if you're using a non-windows os, it'll use system.

On contrary, Popen should use CreateProcess on windows and _posixsubprocess.fork_exec in posix-based operating-systems.

That said, an important piece of advice comes from os.system docs, which says:

The subprocess module provides more powerful facilities for spawning new processes and retrieving their results; using that module is preferable to using this function. See the Replacing Older Functions with the subprocess Module section in the subprocess documentation for some helpful recipes.

NSUserDefaults - How to tell if a key exists

Swift 3 / 4:

Here is a simple extension for Int/Double/Float/Bool key-value types that mimic the Optional-return behavior of the other types accessed through UserDefaults.

(Edit Aug 30 2018: Updated with more efficient syntax from Leo's suggestion.)

extension UserDefaults {
    /// Convenience method to wrap the built-in .integer(forKey:) method in an optional returning nil if the key doesn't exist.
    func integerOptional(forKey: String) -> Int? {
        return self.object(forKey: forKey) as? Int
    }
    /// Convenience method to wrap the built-in .double(forKey:) method in an optional returning nil if the key doesn't exist.
    func doubleOptional(forKey: String) -> Double? {
        return self.object(forKey: forKey) as? Double
    }
    /// Convenience method to wrap the built-in .float(forKey:) method in an optional returning nil if the key doesn't exist.
    func floatOptional(forKey: String) -> Float? {
        return self.object(forKey: forKey) as? Float
    }
    /// Convenience method to wrap the built-in .bool(forKey:) method in an optional returning nil if the key doesn't exist.
    func boolOptional(forKey: String) -> Bool? {
        return self.object(forKey: forKey) as? Bool
    }
}

They are now more consistent alongside the other built-in get methods (string, data, etc.). Just use the get methods in place of the old ones.

let AppDefaults = UserDefaults.standard

// assuming the key "Test" does not exist...

// old:
print(AppDefaults.integer(forKey: "Test")) // == 0
// new:
print(AppDefaults.integerOptional(forKey: "Test")) // == nil

How to append data to div using JavaScript?

If you want to do it fast and don't want to lose references and listeners use: .insertAdjacentHTML();

"It does not reparse the element it is being used on and thus it does not corrupt the existing elements inside the element. This, and avoiding the extra step of serialization make it much faster than direct innerHTML manipulation."

Supported on all mainline browsers (IE6+, FF8+,All Others and Mobile): http://caniuse.com/#feat=insertadjacenthtml

Example from https://developer.mozilla.org/en-US/docs/Web/API/Element/insertAdjacentHTML

// <div id="one">one</div>
var d1 = document.getElementById('one');
d1.insertAdjacentHTML('afterend', '<div id="two">two</div>');

// At this point, the new structure is:
// <div id="one">one</div><div id="two">two</div>

How can I access getSupportFragmentManager() in a fragment?

getFragmentManager() has been deprecated in favor of getParentFragmentManager() to make it clear that you want to access the fragment manager of the parent instead of any child fragments.

Simply use getParentFragmentManager() in Java or parentFragmentManager in Kotlin.

Imshow: extent and aspect

You can do it by setting the aspect of the image manually (or by letting it auto-scale to fill up the extent of the figure).

By default, imshow sets the aspect of the plot to 1, as this is often what people want for image data.

In your case, you can do something like:

import matplotlib.pyplot as plt
import numpy as np

grid = np.random.random((10,10))

fig, (ax1, ax2, ax3) = plt.subplots(nrows=3, figsize=(6,10))

ax1.imshow(grid, extent=[0,100,0,1])
ax1.set_title('Default')

ax2.imshow(grid, extent=[0,100,0,1], aspect='auto')
ax2.set_title('Auto-scaled Aspect')

ax3.imshow(grid, extent=[0,100,0,1], aspect=100)
ax3.set_title('Manually Set Aspect')

plt.tight_layout()
plt.show()

enter image description here

How do I implement IEnumerable<T>

If you choose to use a generic collection, such as List<MyObject> instead of ArrayList, you'll find that the List<MyObject> will provide both generic and non-generic enumerators that you can use.

using System.Collections;

class MyObjects : IEnumerable<MyObject>
{
    List<MyObject> mylist = new List<MyObject>();

    public MyObject this[int index]  
    {  
        get { return mylist[index]; }  
        set { mylist.Insert(index, value); }  
    } 

    public IEnumerator<MyObject> GetEnumerator()
    {
        return mylist.GetEnumerator();
    }

    IEnumerator IEnumerable.GetEnumerator()
    {
        return this.GetEnumerator();
    }
}

Detect click outside element

I create a div at the end of the body like that:

<div v-if="isPopup" class="outside" v-on:click="away()"></div>

Where .outside is :

.outside {
  width: 100vw;
  height: 100vh;
  position: fixed;
  top: 0px;
  left: 0px;
}

And away() is a method in Vue instance :

away() {
 this.isPopup = false;
}

Easy, works well.

How to manually update datatables table with new JSON data

Here is solution for legacy datatable 1.9.4

    var myData = [
      {
        "id": 1,
        "first_name": "Andy",
        "last_name": "Anderson"
      }
   ];
    var myData2 = [
      {
        "id": 2,
        "first_name": "Bob",
        "last_name": "Benson"
      }
    ];

  $('#table').dataTable({
  //  data: myData,
       aoColumns: [
         { mData: 'id' },
         { mData: 'first_name' },
         { mData: 'last_name' }
      ]
  });

 $('#table').dataTable().fnClearTable();
 $('#table').dataTable().fnAddData(myData2);

Minimal web server using netcat

Donno how or why but i manage to find this around and it works for me, i had the problem I wanted to return the result of executing a bash

$ while true; do { echo -e 'HTTP/1.1 200 OK\r\n'; sh test; } | nc -l 8080; done

NOTE: This command was taken from: http://www.razvantudorica.com/08/web-server-in-one-line-of-bash

this executes bash script test and return the result to a browser client connecting to the server running this command on port 8080

My script does this ATM

$ nano test

#!/bin/bash

echo "************PRINT SOME TEXT***************\n"
echo "Hello World!!!"
echo "\n"

echo "Resources:"
vmstat -S M
echo "\n"

echo "Addresses:"
echo "$(ifconfig)"
echo "\n"


echo "$(gpio readall)"

and my web browser is showing

************PRINT SOME TEXT***************

Hello World!!!


Resources:
procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa
 0  0      0    314     18     78    0    0     2     1  306   31  0  0 100  0


Addresses:
eth0      Link encap:Ethernet  HWaddr b8:27:eb:86:e8:c5  
          inet addr:192.168.1.83  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:27734 errors:0 dropped:0 overruns:0 frame:0
          TX packets:26393 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:1924720 (1.8 MiB)  TX bytes:3841998 (3.6 MiB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)


GPIOs:
+----------+-Rev2-+------+--------+------+-------+
| wiringPi | GPIO | Phys | Name   | Mode | Value |
+----------+------+------+--------+------+-------+
|      0   |  17  |  11  | GPIO 0 | IN   | Low   |
|      1   |  18  |  12  | GPIO 1 | IN   | Low   |
|      2   |  27  |  13  | GPIO 2 | IN   | Low   |
|      3   |  22  |  15  | GPIO 3 | IN   | Low   |
|      4   |  23  |  16  | GPIO 4 | IN   | Low   |
|      5   |  24  |  18  | GPIO 5 | IN   | Low   |
|      6   |  25  |  22  | GPIO 6 | IN   | Low   |
|      7   |   4  |   7  | GPIO 7 | IN   | Low   |
|      8   |   2  |   3  | SDA    | IN   | High  |
|      9   |   3  |   5  | SCL    | IN   | High  |
|     10   |   8  |  24  | CE0    | IN   | Low   |
|     11   |   7  |  26  | CE1    | IN   | Low   |
|     12   |  10  |  19  | MOSI   | IN   | Low   |
|     13   |   9  |  21  | MISO   | IN   | Low   |
|     14   |  11  |  23  | SCLK   | IN   | Low   |
|     15   |  14  |   8  | TxD    | ALT0 | High  |
|     16   |  15  |  10  | RxD    | ALT0 | High  |
|     17   |  28  |   3  | GPIO 8 | ALT2 | Low   |
|     18   |  29  |   4  | GPIO 9 | ALT2 | Low   |
|     19   |  30  |   5  | GPIO10 | ALT2 | Low   |
|     20   |  31  |   6  | GPIO11 | ALT2 | Low   |
+----------+------+------+--------+------+-------+

simply amazing!

"Undefined reference to" template class constructor

This link explains where you're going wrong:

[35.12] Why can't I separate the definition of my templates class from its declaration and put it inside a .cpp file?

Place the definition of your constructors, destructors methods and whatnot in your header file, and that will correct the problem.

This offers another solution:

How can I avoid linker errors with my template functions?

However this requires you to anticipate how your template will be used and, as a general solution, is counter-intuitive. It does solve the corner case though where you develop a template to be used by some internal mechanism, and you want to police the manner in which it is used.

How to decrypt an encrypted Apple iTunes iPhone backup?

Sorry, but it might even be more complicated, involving pbkdf2, or even a variation of it. Listen to the WWDC 2010 session #209, which mainly talks about the security measures in iOS 4, but also mentions briefly the separate encryption of backups and how they're related.

You can be pretty sure that without knowing the password, there's no way you can decrypt it, even by brute force.

Let's just assume you want to try to enable people who KNOW the password to get to the data of their backups.

I fear there's no way around looking at the actual code in iTunes in order to figure out which algos are employed.

Back in the Newton days, I had to decrypt data from a program and was able to call its decryption function directly (knowing the password, of course) without the need to even undersand its algorithm. It's not that easy anymore, unfortunately.

I'm sure there are skilled people around who could reverse engineer that iTunes code - you just have to get them interested.

In theory, Apple's algos should be designed in a way that makes the data still safe (i.e. practically unbreakable by brute force methods) to any attacker knowing the exact encryption method. And in WWDC session 209 they went pretty deep into details about what they do to accomplish this. Maybe you can actually get answers directly from Apple's security team if you tell them your good intentions. After all, even they should know that security by obfuscation is not really efficient. Try their security mailing list. Even if they do not repond, maybe someone else silently on the list will respond with some help.

Good luck!

Delete item from state array in react

You forgot to use setState. Example:

removePeople(e){
  var array = this.state.people;
  var index = array.indexOf(e.target.value); // Let's say it's Bob.
  delete array[index];
  this.setState({
    people: array
  })
},

But it's better to use filter because it does not mutate array. Example:

removePeople(e){
  var array = this.state.people.filter(function(item) {
    return item !== e.target.value
  });
  this.setState({
    people: array
  })
},

How to set text color to a text view programmatically

Great answers. Adding one that loads the color from an Android resources xml but still sets it programmatically:

textView.setTextColor(getResources().getColor(R.color.some_color));

Please note that from API 23, getResources().getColor() is deprecated. Use instead:

textView.setTextColor(ContextCompat.getColor(context, R.color.some_color));

where the required color is defined in an xml as:

<resources>
  <color name="some_color">#bdbdbd</color>
</resources>

Update:

This method was deprecated in API level 23. Use getColor(int, Theme) instead.

Check this.

Best way to format multiple 'or' conditions in an if statement (Java)

Use a collection of some sort - this will make the code more readable and hide away all those constants. A simple way would be with a list:

// Declared with constants
private static List<Integer> myConstants = new ArrayList<Integer>(){{
    add(12);
    add(16);
    add(19);
}};

// Wherever you are checking for presence of the constant
if(myConstants.contains(x)){
    // ETC
}

As Bohemian points out the list of constants can be static so it's accessible in more than one place.

For anyone interested, the list in my example is using double brace initialization. Since I ran into it recently I've found it nice for writing quick & dirty list initializations.

Adding calculated column(s) to a dataframe in pandas

You could have is_hammer in terms of row["Open"] etc. as follows

def is_hammer(rOpen,rLow,rClose,rHigh):
    return lower_wick_at_least_twice_real_body(rOpen,rLow,rClose) \
       and closed_in_top_half_of_range(rHigh,rLow,rClose)

Then you can use map:

df["isHammer"] = map(is_hammer, df["Open"], df["Low"], df["Close"], df["High"])

How to write :hover condition for a:before and a:after?

Try to use .card-listing:hover::after hover and after using :: it wil work

Why are empty catch blocks a bad idea?

I find the most annoying with empty catch statements is when some other programmer did it. What I mean is when you need to debug code from somebody else any empty catch statements makes such an undertaking more difficult then it need to be. IMHO catch statements should always show some kind of error message - even if the error is not handled it should at least detect it (alt. on only in debug mode)

Laravel migration: unique key is too long, even if specified

You will not have this problem if you're using MySQL 5.7.7+ or MariaDB 10.2.2+.

To update MariaDB on your Mac using Brew first unlink the current one: brew unlink mariadb and then install a dev one using brew install mariadb --devel

After installation is done stop/start the service running: brew services stop mariadb brew services start mariadb

Current dev version is 10.2.3. After the installation is finished you won't have to worry about this anymore and you can use utf8mb4 (that is now a default in Laravel 5.4) without switching back to utf8 nor editing AppServiceProvider as proposed in the Laravel documentation: https://laravel.com/docs/master/releases#laravel-5.4 (scroll down to: Migration Default String Length)

Getting IPV4 address from a sockaddr structure

inet_ntoa() works for IPv4; inet_ntop() works for both IPv4 and IPv6.

Given an input struct sockaddr *res, here are two snippets of code (tested on macOS):

Using inet_ntoa()

#include <arpa/inet.h>

struct sockaddr_in *addr_in = (struct sockaddr_in *)res;
char *s = inet_ntoa(addr_in->sin_addr);
printf("IP address: %s\n", s);

Using inet_ntop()

#include <arpa/inet.h>
#include <stdlib.h>

char *s = NULL;
switch(res->sa_family) {
    case AF_INET: {
        struct sockaddr_in *addr_in = (struct sockaddr_in *)res;
        s = malloc(INET_ADDRSTRLEN);
        inet_ntop(AF_INET, &(addr_in->sin_addr), s, INET_ADDRSTRLEN);
        break;
    }
    case AF_INET6: {
        struct sockaddr_in6 *addr_in6 = (struct sockaddr_in6 *)res;
        s = malloc(INET6_ADDRSTRLEN);
        inet_ntop(AF_INET6, &(addr_in6->sin6_addr), s, INET6_ADDRSTRLEN);
        break;
    }
    default:
        break;
}
printf("IP address: %s\n", s);
free(s);

How do you add PostgreSQL Driver as a dependency in Maven?

Depending on your PostgreSQL version you would need to add the postgresql driver to your pom.xml file.

For PostgreSQL 9.1 this would be:

<project xmlns="http://maven.apache.org/POM/4.0.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

    <name>Your project name.</name>
    <dependencies>
        <dependency>
            <groupId>postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>9.1-901-1.jdbc4</version>
        </dependency>
    </dependencies>
</project>

You can get the code for the dependency (as well as any other dependency) from maven's central repository

If you are using postgresql 9.2+:

<project xmlns="http://maven.apache.org/POM/4.0.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

    <name>Your project name.</name>
    <dependencies>
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>42.2.1</version>
        </dependency>
    </dependencies>
</project>

You can check the latest versions and dependency snippets from:

Initializing select with AngularJS and ng-repeat

Thanks to TheSharpieOne for pointing out the ng-selected option. If that had been posted as an answer rather than as a comment, I would have made that the correct answer.

Here's a working JSFiddle: http://jsfiddle.net/coverbeck/FxM3B/5/.

I also updated the fiddle to use the title attribute, which I had left out in my original post, since it wasn't the cause of the problem (but it is the reason I want to use ng-repeat instead of ng-options).

HTML:

<body ng-app ng-controller="AppCtrl">
<div>Operator is: {{filterCondition.operator}}</div>
<select ng-model="filterCondition.operator">
   <option ng-repeat="operator in operators" title="{{operator.title}}" ng-selected="{{operator.value == filterCondition.operator}}" value="{{operator.value}}">{{operator.displayName}}</option>
</select>
</body>

JS:

function AppCtrl($scope) {

    $scope.filterCondition={
        operator: 'eq'
    }

    $scope.operators = [
        {value: 'eq', displayName: 'equals', title: 'The equals operator does blah, blah'},
        {value: 'neq', displayName: 'not equal', title: 'The not equals operator does yada yada'}
     ]
}

dll missing in JDBC

Set java.library.path to a directory containing this DLL which Java uses to find native libraries. Specify -D switch on the command line

java -Djava.library.path=C:\Java\native\libs YourProgram

C:\Java\native\libs should contain sqljdbc_auth.dll

Look at this SO post if you are using Eclipse or at this blog if you want to set programatically.

how to upload file using curl with php

Use:

if (function_exists('curl_file_create')) { // php 5.5+
  $cFile = curl_file_create($file_name_with_full_path);
} else { // 
  $cFile = '@' . realpath($file_name_with_full_path);
}
$post = array('extra_info' => '123456','file_contents'=> $cFile);
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$target_url);
curl_setopt($ch, CURLOPT_POST,1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post);
$result=curl_exec ($ch);
curl_close ($ch);

You can also refer:

http://blog.derakkilgo.com/2009/06/07/send-a-file-via-post-with-curl-and-php/

Important hint for PHP 5.5+:

Now we should use https://wiki.php.net/rfc/curl-file-upload but if you still want to use this deprecated approach then you need to set curl_setopt($ch, CURLOPT_SAFE_UPLOAD, false);

Change marker size in Google maps V3

This answer expounds on John Black's helpful answer, so I will repeat some of his answer content in my answer.

The easiest way to resize a marker seems to be leaving argument 2, 3, and 4 null and scaling the size in argument 5.

var pinIcon = new google.maps.MarkerImage(
    "http://chart.apis.google.com/chart?chst=d_map_pin_letter&chld=%E2%80%A2|FFFF00",
    null, /* size is determined at runtime */
    null, /* origin is 0,0 */
    null, /* anchor is bottom center of the scaled image */
    new google.maps.Size(42, 68)
);  

As an aside, this answer to a similar question asserts that defining marker size in the 2nd argument is better than scaling in the 5th argument. I don't know if this is true.

Leaving arguments 2-4 null works great for the default google pin image, but you must set an anchor explicitly for the default google pin shadow image, or it will look like this:

what happens when you leave anchor null on an enlarged shadow

The bottom center of the pin image happens to be collocated with the tip of the pin when you view the graphic on the map. This is important, because the marker's position property (marker's LatLng position on the map) will automatically be collocated with the visual tip of the pin when you leave the anchor (4th argument) null. In other words, leaving the anchor null ensures the tip points where it is supposed to point.

However, the tip of the shadow is not located at the bottom center. So you need to set the 4th argument explicitly to offset the tip of the pin shadow so the shadow's tip will be colocated with the pin image's tip.

By experimenting I found the tip of the shadow should be set like this: x is 1/3 of size and y is 100% of size.

var pinShadow = new google.maps.MarkerImage(
    "http://chart.apis.google.com/chart?chst=d_map_pin_shadow",
    null,
    null,
    /* Offset x axis 33% of overall size, Offset y axis 100% of overall size */
    new google.maps.Point(40, 110), 
    new google.maps.Size(120, 110)); 

to give this:

offset the enlarged shadow anchor explicitly

CSS3 gradient background set on body doesn't stretch but instead repeats?

There is a lot of partial information on this page, but not a complete one. Here is what I do:

  1. Create a gradient here: http://www.colorzilla.com/gradient-editor/
  2. Set gradient on HTML instead of BODY.
  3. Fix the background on HTML with "background-attachment: fixed;"
  4. Turn off the top and bottom margins on BODY
  5. (optional) I usually create a <DIV id='container'> that I put all of my content in

Here is an example:

html {  
  background: #a9e4f7; /* Old browsers */
  background: -moz-linear-gradient(-45deg,  #a9e4f7 0%, #0fb4e7 100%); /* FF3.6+ */
  background: -webkit-gradient(linear, left top, right bottom, color-stop(0%,#a9e4f7), color-stop(100%,#0fb4e7)); /* Chrome,Safari4+ */ 
  background: -webkit-linear-gradient(-45deg,  #a9e4f7 0%,#0fb4e7 100%); /* Chrome10+,Safari5.1+ */
  background: -o-linear-gradient(-45deg,  #a9e4f7 0%,#0fb4e7 100%); /* Opera 11.10+ */
  background: -ms-linear-gradient(-45deg,  #a9e4f7 0%,#0fb4e7 100%); /* IE10+ */
  background: linear-gradient(135deg,  #a9e4f7 0%,#0fb4e7 100%); /* W3C */ 
  filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#a9e4f7', endColorstr='#0fb4e7',GradientType=1 ); /* IE6-9 fallback on horizontal gradient */

  background-attachment: fixed;
}

body {
  margin-top: 0px;
  margin-bottom: 0px;
}

/* OPTIONAL: div to store content.  Many of these attributes should be changed to suit your needs */
#container
{
  width: 800px;
  margin: auto;
  background-color: white;
  border: 1px solid gray;
  border-top: none;
  border-bottom: none;
  box-shadow: 3px 0px 20px #333;
  padding: 10px;
}

This has been tested with IE, Chrome, and Firefox on pages of various sizes and scrolling needs.

The difference in months between dates in MySQL

As many of the answers here show, the 'right' answer depends on exactly what you need. In my case, I need to round to the closest whole number.

Consider these examples: 1st January -> 31st January: It's 0 whole months, and almost 1 month long. 1st January -> 1st February? It's 1 whole month, and exactly 1 month long.

To get the number of whole (complete) months, use:

SELECT TIMESTAMPDIFF(MONTH, '2018-01-01', '2018-01-31');  => 0
SELECT TIMESTAMPDIFF(MONTH, '2018-01-01', '2018-02-01');  => 1

To get a rounded duration in months, you could use:

SELECT ROUND(TIMESTAMPDIFF(DAY, '2018-01-01', '2018-01-31')*12/365.24); => 1
SELECT ROUND(TIMESTAMPDIFF(DAY, '2018-01-01', '2018-01-31')*12/365.24); => 1

This is accurate to +/- 5 days and for ranges over 1000 years. Zane's answer is obviously more accurate, but it's too verbose for my liking.

How can I change the value of the elements in a vector?

Your code works fine. When I ran it I got the output:

The values in the file input.txt are:
1
2
3
4
5
6
7
8
9
10
The sum of the values is: 55
The mean value is: 5.5

But it could still be improved.

You are iterating over the vector using indexes. This is not the "STL Way" -- you should be using iterators, to wit:

typedef vector<double> doubles;
for( doubles::const_iterator it = v.begin(), it_end = v.end(); it != it_end; ++it )
{
    total += *it;
    mean = total / v.size();
}

This is better for a number of reasons discussed here and elsewhere, but here are two main reasons:

  1. Every container provides the iterator concept. Not every container provides random-access (eg, indexed access).
  2. You can generalize your iteration code.

Point number 2 brings up another way you can improve your code. Another thing about your code that isn't very STL-ish is the use of a hand-written loop. <algorithm>s were designed for this purpose, and the best code is the code you never write. You can use a loop to compute the total and mean of the vector, through the use of an accumulator:

#include <numeric>
#include <functional>
struct my_totals : public std::binary_function<my_totals, double, my_totals>
{
    my_totals() : total_(0), count_(0) {};
    my_totals operator+(double v) const
    {
        my_totals ret = *this;
        ret.total_ += v;
        ++ret.count_;
        return ret;
    }
    double mean() const { return total_/count_; }
    double total_;
    unsigned count_;
};

...and then:

my_totals ttls = std::accumulate(v.begin(), v.end(), my_totals());
cout << "The sum of the values is: " << ttls.total_ << endl;
cout << "The mean value is: " << ttls.mean() << endl;

EDIT:

If you have the benefit of a C++0x-compliant compiler, this can be made even simpler using std::for_each (within #include <algorithm>) and a lambda expression:

double total = 0;
for_each( v.begin(), v.end(), [&total](double  v) { total += v; });
cout << "The sum of the values is: " << total << endl;
cout << "The mean value is: " << total/v.size() << endl;

"Can't find Project or Library" for standard VBA functions

Even when all references are fine the prefix problem causes compile errors.

What about creating a find and replace sub for all 'built-in VBA functions' in all modules, like this:

replace text in code module

e.g. "= Date" will be replaced with "= VBA.Date".

e.g. " Date(" will be replaced with " VBA.Date(" .

(excluding "dim t As Date" or "mydate")

All vba functions for find and replace are written here :

vba functions list

How to decrypt the password generated by wordpress

You will not be able to retrieve a plain text password from wordpress.

Wordpress use a 1 way encryption to store the passwords using a variation of md5. There is no way to reverse this.

See this article for more info http://wordpress.org/support/topic/how-is-the-user-password-encrypted-wp_hash_password

Regex remove all special characters except numbers?

to remove symbol use tag [ ]

step:1

[]

step 2:place what symbol u want to remove eg:@ like [@]

[@]

step 3:

var name = name.replace(/[@]/g, "");

thats it

_x000D_
_x000D_
var name="ggggggg@fffff"
var result = name.replace(/[@]/g, "");
console .log(result)
_x000D_
_x000D_
_x000D_

Extra Tips

To remove space (give one space into square bracket like []=>[ ])

[@ ]

It Remove Everything (using except)

[^place u dont want to remove]

eg:i remove everyting except alphabet (small and caps)

[^a-zA-Z ]

_x000D_
_x000D_
var name="ggggg33333@#$%^&**I(((**gg@fffff"
var result = name.replace(/[^a-zA-Z]/g, "");
console .log(result)
_x000D_
_x000D_
_x000D_

Getters \ setters for dummies

What's so confusing about it... getters are functions that are called when you get a property, setters, when you set it. example, if you do

obj.prop = "abc";

You're setting the property prop, if you're using getters/setters, then the setter function will be called, with "abc" as an argument. The setter function definition inside the object would ideally look something like this:

set prop(var) {
   // do stuff with var...
}

I'm not sure how well that is implemented across browsers. It seems Firefox also has an alternative syntax, with double-underscored special ("magic") methods. As usual Internet Explorer does not support any of this.

How to use C++ in Go

You might need to add -lc++ to the LDFlags for Golang/CGo to recognize the need for the standard library.

Software Design vs. Software Architecture

Architecture is design, but not all design is architectural. Therefore, strictly speaking, it would make more sense to try to differentiate between architectural design and non-architectural design. And what is the difference? It depends! Each software architect may have a different answer (ymmv!). We develop our heuristics to come up with an answer, such as 'class diagrams are architecture and sequence diagrams are design'. See DSA book for more.

It's common to say that architecture is at a higher abstraction level than design, or architecture is logical and design is physical. But this notion, albeit commonly accepted, is in practice useless. Where do you draw the line between high or low abstraction, between logical and physical? It depends!

So, my suggestion is:

  • create a single design document.
  • name this design document the way you want or, better, the way the readers are more accustomed to. Examples: "Software Architecture", "Software Design Specification".
  • break this document into views and keep in mind you can create a view as a refinement of another view.
  • make the views in the document navigable by adding cross-references or hyperlinks
  • then you'll have higher level views showing broad but shallow overview of the design, and closer-to-implementation views showing narrow but deeper design details.
  • you may want to take a look at an example of multi-view architecture document (here).

Having said all that... a more relevant question we need to ask is: how much design is enough? That is, when should I stop describing the design (in diagrams or prose) and should move on to coding?

Vue.js data-bind style backgroundImage not working

The accepted answer didn't seem to solve the problem for me, but this did

Ensure your backgroundImage declarations are wrapped in url( and quotes so the style works correctly, no matter the file name.

ES2015 Style:

<div :style="{ backgroundImage: `url('${image}')` }"></div>

Or without ES2015:

<div :style="{ backgroundImage: 'url(\'' + image + '\')' }"></div>

Source: vuejs/vue-loader issue #646

How to take off line numbers in Vi?

If you are talking about show line number command in vi/vim

you could use

set nu

in commandline mode to turn on and

set nonu

will turn off the line number display or

set nu!

to toggle off display of line numbers

Intersect Two Lists in C#

You need to first transform data1, in your case by calling ToString() on each element.

Use this if you want to return strings.

List<int> data1 = new List<int> {1,2,3,4,5};
List<string> data2 = new List<string>{"6","3"};

var newData = data1.Select(i => i.ToString()).Intersect(data2);

Use this if you want to return integers.

List<int> data1 = new List<int> {1,2,3,4,5};
List<string> data2 = new List<string>{"6","3"};

var newData = data1.Intersect(data2.Select(s => int.Parse(s));

Note that this will throw an exception if not all strings are numbers. So you could do the following first to check:

int temp;
if(data2.All(s => int.TryParse(s, out temp)))
{
    // All data2 strings are int's
}

Git undo changes in some files

git add B # Add it to the index
git reset A # Remove it from the index
git commit # Commit the index

Error: invalid operands of types ‘const char [35]’ and ‘const char [2]’ to binary ‘operator+’

Consider this:

std::string str = "Hello " + "world"; // bad!

Both the rhs and the lhs for operator + are char*s. There is no definition of operator + that takes two char*s (in fact, the language doesn't permit you to write one). As a result, on my compiler this produces a "cannot add two pointers" error (yours apparently phrases things in terms of arrays, but it's the same problem).

Now consider this:

std::string str = "Hello " + std::string("world"); // ok

There is a definition of operator + that takes a const char* as the lhs and a std::string as the rhs, so now everyone is happy.

You can extend this to as long a concatenation chain as you like. It can get messy, though. For example:

std::string str = "Hello " + "there " + std::string("world"); // no good!

This doesn't work because you are trying to + two char*s before the lhs has been converted to std::string. But this is fine:

std::string str = std::string("Hello ") + "there " + "world"; // ok

Because once you've converted to std::string, you can + as many additional char*s as you want.

If that's still confusing, it may help to add some brackets to highlight the associativity rules and then replace the variable names with their types:

((std::string("Hello ") + "there ") + "world");
((string + char*) + char*)

The first step is to call string operator+(string, char*), which is defined in the standard library. Replacing those two operands with their result gives:

((string) + char*)

Which is exactly what we just did, and which is still legal. But try the same thing with:

((char* + char*) + string)

And you're stuck, because the first operation tries to add two char*s.

Moral of the story: If you want to be sure a concatenation chain will work, just make sure one of the first two arguments is explicitly of type std::string.

How to render string with html tags in Angular 4+?

Use one way flow syntax property binding:

<div [innerHTML]="comment"></div>

From angular docs: "Angular recognizes the value as unsafe and automatically sanitizes it, which removes the <script> tag but keeps safe content such as the <b> element."

document.getElementById("test").style.display="hidden" not working

its a block element, and you need to use none

document.getElementById("test").style.display="none"

hidden is used for visibility

Android JSONObject - How can I loop through a flat JSON object to get each key and value

You shold use the keys() or names() method. keys() will give you an iterator containing all the String property names in the object while names() will give you an array of all key String names.

You can get the JSONObject documentation here

http://developer.android.com/reference/org/json/JSONObject.html

Change onClick attribute with javascript

Well, just do this and your problem is solved :

document.getElementById('buttonLED'+id).setAttribute('onclick','writeLED(1,1)')

Have a nice day XD

Laravel blank white screen

Other problem with the same behavior is use Laravel 3 with PHP 5.5.x. You have to change some laravel function's name "yield() because is a reserved word in php 5.5

How do I clone a generic list in C#?

public class CloneableList<T> : List<T>, ICloneable where T : ICloneable
{
  public object Clone()
  {
    var clone = new List<T>();
    ForEach(item => clone.Add((T)item.Clone()));
    return clone;
  }
}

How to set username and password for SmtpClient object in .NET?

The SmtpClient can be used by code:

SmtpClient mailer = new SmtpClient();
mailer.Host = "mail.youroutgoingsmtpserver.com";
mailer.Credentials = new System.Net.NetworkCredential("yourusername", "yourpassword");

Why is $$ returning the same id as the parent process?

If you were asking how to get the PID of a known command it would resemble something like this:

If you had issued the command below #The command issued was ***

dd if=/dev/diskx of=/dev/disky


Then you would use:

PIDs=$(ps | grep dd | grep if | cut -b 1-5)

What happens here is it pipes all needed unique characters to a field and that field can be echoed using

echo $PIDs

ggplot geom_text font size control

Here are a few options for changing text / label sizes

library(ggplot2)

# Example data using mtcars

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

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

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

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

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

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


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

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

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

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

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

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

Vue 2 - Mutating props vue-warn

For when TypeScript is your preferred lang. of development

<template>
<span class="someClassName">
      {{feesInLocale}}
</span>
</template>  



@Prop({default: 0}) fees: any;

// computed are declared with get before a function
get feesInLocale() {
    return this.fees;
}

and not

<template>
<span class="someClassName">
      {{feesInLocale}}
</span>
</template>  



@Prop() fees: any = 0;
get feesInLocale() {
    return this.fees;
}

Windows batch: echo without new line

Using set and the /p parameter you can echo without newline:

C:\> echo Hello World
Hello World

C:\> echo|set /p="Hello World"
Hello World
C:\>

Source

MVC Razor @foreach

I'm using @foreach when I send an entity that contains a list of entities ( for example to display 2 grids in 1 view )

For example if I'm sending as model the entity Foo that contains Foo1(List<Foo1>) and Foo2(List<Foo2>)

I can refer to the first List with:

@foreach (var item in Model.Foo.Foo1)
{
    @Html.DisplayFor(modelItem=> item.fooName)
}

How to set a dropdownlist item as selected in ASP.NET?

Set dropdown property

selected="true"

How to remove all namespaces from XML with C#?

The tagged most useful answer has two flaws:

  • It ignores attributes
  • It doesn't work with "mixed mode" elements

Here is my take on this:

 public static XElement RemoveAllNamespaces(XElement e)
 {
    return new XElement(e.Name.LocalName,
      (from n in e.Nodes()
        select ((n is XElement) ? RemoveAllNamespaces(n as XElement) : n)),
          (e.HasAttributes) ? 
            (from a in e.Attributes() 
               where (!a.IsNamespaceDeclaration)  
               select new XAttribute(a.Name.LocalName, a.Value)) : null);
  }          

Sample code here.

Restrict SQL Server Login access to only one database

I think this is what we like to do very much.

--Step 1: (create a new user)
create LOGIN hello WITH PASSWORD='foo', CHECK_POLICY = OFF;


-- Step 2:(deny view to any database)
USE master;
GO
DENY VIEW ANY DATABASE TO hello; 


 -- step 3 (then authorized the user for that specific database , you have to use the  master by doing use master as below)
USE master;
GO
ALTER AUTHORIZATION ON DATABASE::yourDB TO hello;
GO

If you already created a user and assigned to that database before by doing

USE [yourDB] 
CREATE USER hello FOR LOGIN hello WITH DEFAULT_SCHEMA=[dbo] 
GO

then kindly delete it by doing below and follow the steps

   USE yourDB;
   GO
   DROP USER newlogin;
   GO

For more information please follow the links:

Hiding databases for a login on Microsoft Sql Server 2008R2 and above

break out of if and foreach

For those of you landing here but searching how to break out of a loop that contains an include statement use return instead of break or continue.

<?php

for ($i=0; $i < 100; $i++) { 
    if (i%2 == 0) {
        include(do_this_for_even.php);
    }
    else {
        include(do_this_for_odd.php);
    }
}

?>

If you want to break when being inside do_this_for_even.php you need to use return. Using break or continue will return this error: Cannot break/continue 1 level. I found more details here

Debugging in Maven?

If you are using Maven 2.0.8+, run the mvnDebug command in place of mvn and attach a debugger on port 8000.

For Maven <2.0.8, uncomment the following line in your %M2_HOME%/bin/mvn.bat (and maybe save the modified version as mvnDebug.bat):

@REM set MAVEN_OPTS=-Xdebug -Xnoagent -Djava.compiler=NONE -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000

More details in MNG-2105 and Dealing with Eclipse-based IDE.

Label python data points on plot

How about print (x, y) at once.

from matplotlib import pyplot as plt

fig = plt.figure()
ax = fig.add_subplot(111)

A = -0.75, -0.25, 0, 0.25, 0.5, 0.75, 1.0
B = 0.73, 0.97, 1.0, 0.97, 0.88, 0.73, 0.54

plt.plot(A,B)
for xy in zip(A, B):                                       # <--
    ax.annotate('(%s, %s)' % xy, xy=xy, textcoords='data') # <--

plt.grid()
plt.show()

enter image description here

How to change background color of cell in table using java script

document.getElementById('id1').bgColor = '#00FF00';

seems to work. I don't think .style.backgroundColor does.

Error: TypeError: $(...).dialog is not a function

Here are the complete list of scripts required to get rid of this problem. (Make sure the file exists at the given file path)

   <script src="@Url.Content("~/Scripts/jquery-1.8.2.js")" type="text/javascript">
    </script>
    <script src="@Url.Content("~/Scripts/jquery-ui-1.8.24.js")" type="text/javascript">
    </script>
    <script src="@Url.Content("~/Scripts/jquery.validate.js")" type="text/javascript">
    </script>
    <script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.js")" type="text/javascript">
    </script>
    <script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.js")" type="text/javascript">
    </script>

and also include the below css link in _Layout.cshtml for a stylish popup.

<link rel="stylesheet" type="text/css" href="../../Content/themes/base/jquery-ui.css" />

vertical divider between two columns in bootstrap

To fix the ugly look of a divider being too short when the content of one column is taller, add borders to all columns. Give every other column a negative margin to compensate for position differences.

For example, my three column classes:

.border-right {
    border-right: 1px solid #ddd;
}
.borders {
    border-left: 1px solid #ddd;
    border-right: 1px solid #ddd;
    margin: -1px;
}
.border-left {
    border-left: 1px solid #ddd;
}

And the HTML:

<div class="col-sm-4 border-right">First</div>
<div class="col-sm-4 borders">Second</div>
<div class="col-sm-4 border-left">Third</div>

Make sure you use #ddd if you want the same color as Bootstrap's horizontal dividers.

GIT clone repo across local file system in windows

After clone, for me push wasn't working.

Solution: Where repo is cloned open .git folder and config file.

For remote origin url set value:

[remote "origin"]
    url = file:///C:/Documentation/git_server/kurmisoftware

python-How to set global variables in Flask?

With:

global index_add_counter

You are not defining, just declaring so it's like saying there is a global index_add_counter variable elsewhere, and not create a global called index_add_counter. As you name don't exists, Python is telling you it can not import that name. So you need to simply remove the global keyword and initialize your variable:

index_add_counter = 0

Now you can import it with:

from app import index_add_counter

The construction:

global index_add_counter

is used inside modules' definitions to force the interpreter to look for that name in the modules' scope, not in the definition one:

index_add_counter = 0
def test():
  global index_add_counter # means: in this scope, use the global name
  print(index_add_counter)

Scp command syntax for copying a folder from local machine to a remote server

In stall PuTTY in our system and set the environment variable PATH Pointing to putty path. open the command prompt and move to putty folder. Using PSCP command

Please check this

How to determine the installed webpack version

Put webpack -v into your package.json:

{
  "name": "js",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "build": "webpack -v",
    "dev": "webpack --watch"
  }
}

Then enter in the console:

npm run build

Expected output should look like:

> npm run build

> [email protected] build /home/user/repositories/myproject/js
> webpack -v

4.42.0

How can I check if an ip is in a network in Python?

Using ipaddress (in the stdlib since 3.3, at PyPi for 2.6/2.7):

>>> import ipaddress
>>> ipaddress.ip_address('192.168.0.1') in ipaddress.ip_network('192.168.0.0/24')
True

If you want to evaluate a lot of IP addresses this way, you'll probably want to calculate the netmask upfront, like

n = ipaddress.ip_network('192.0.0.0/16')
netw = int(n.network_address)
mask = int(n.netmask)

Then, for each address, calculate the binary representation with one of

a = int(ipaddress.ip_address('192.0.43.10'))
a = struct.unpack('!I', socket.inet_pton(socket.AF_INET, '192.0.43.10'))[0]
a = struct.unpack('!I', socket.inet_aton('192.0.43.10'))[0]  # IPv4 only

Finally, you can simply check:

in_network = (a & mask) == netw

RuntimeWarning: invalid value encountered in divide

You are dividing by rr which may be 0.0. Check if rr is zero and do something reasonable other than using it in the denominator.

List all virtualenv

If you are using virtualenv or Python 3's built in venv the above answers might not work.

If you are on Linux, just locate the activate script that is always present inside a env.

locate -b '\activate' | grep "/home"

This will grab all Python virtual environments present inside your home directory.

See Demo Here

Oracle client and networking components were not found

1.Go to My Computer Properties
2.Then click on Advance setting.
3.Go to Environment variable
4.Set the path to

 F:\oracle\product\10.2.0\db_2\perl\5.8.3\lib\MSWin32-x86;F:\oracle\product\10.2.0\db_2\perl\5.8.3\lib;F:\oracle\product\10.2.0\db_2\perl\5.8.3\lib\MSWin32-x86;F:\oracle\product\10.2.0\db_2\perl\site\5.8.3;F:\oracle\product\10.2.0\db_2\perl\site\5.8.3\lib;F:\oracle\product\10.2.0\db_2\sysman\admin\scripts;

change your drive and folder depending on your requirement...

cursor.fetchall() vs list(cursor) in Python

You could use list comprehensions to bring the item in your tuple into a list:

conn = mysql.connector.connect()
cursor = conn.cursor()
sql = "SELECT column_name FROM db.table_name;"
cursor.execute(sql)

results = cursor.fetchall()
# bring the first item of the tuple in your results here
item_0_in_result = [_[0] for _ in results]

jQuery: Scroll down page a set increment (in pixels) on click?

You might be after something that the scrollTo plugin from Ariel Flesler does really well.

http://demos.flesler.com/jquery/scrollTo/

Mathematical functions in Swift

For the Swift way of doing things, you can try and make use of the tools available in the Swift Standard Library. These should work on any platform that is able to run Swift.

Instead of floor(), round() and the rest of the rounding routines you can use rounded(_:):

let x = 6.5

// Equivalent to the C 'round' function:
print(x.rounded(.toNearestOrAwayFromZero))
// Prints "7.0"

// Equivalent to the C 'trunc' function:
print(x.rounded(.towardZero))
// Prints "6.0"

// Equivalent to the C 'ceil' function:
print(x.rounded(.up))
// Prints "7.0"

// Equivalent to the C 'floor' function:
print(x.rounded(.down))
// Prints "6.0"

These are currently available on Float and Double and it should be easy enough to convert to a CGFloat for example.

Instead of sqrt() there's the squareRoot() method on the FloatingPoint protocol. Again, both Float and Double conform to the FloatingPoint protocol:

let x = 4.0
let y = x.squareRoot()

For the trigonometric functions, the standard library can't help, so you're best off importing Darwin on the Apple platforms or Glibc on Linux. Fingers-crossed they'll be a neater way in the future.

#if os(OSX) || os(iOS)
import Darwin
#elseif os(Linux)
import Glibc
#endif

let x = 1.571
print(sin(x))
// Prints "~1.0"

Could not open input file: composer.phar

This is how it worked for me:

  • Make sure composer is installed without no errors.

  • Open "System Properties" on windows and go to the "Advanced" tab. (You can just press the windows button on your keyboard and type in "Edit the system environment variables`

  • "Environment variables"

  • Under "System variables" Edit "PATH"

  • Click on "New".

  • Type in: C:\ProgramData\ComposerSetup\bin\composer.phar

  • Close all folders & CMDs + restart you WAMP server.

  • Go to whatever directory you want to install a package in and type in

    composer.phar create-project slim/slim-skeleton

for example.

Class has no initializers Swift

simply provide the init block for HomeCell class

it's work in my case

Storyboard - refer to ViewController in AppDelegate

If you use XCode 5 you should do it in a different way.

  • Select your UIViewController in UIStoryboard
  • Go to the Identity Inspector on the right top pane
  • Check the Use Storyboard ID checkbox
  • Write a unique id to the Storyboard ID field

Then write your code.

// Override point for customization after application launch.

if (<your implementation>) {
    UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:@"Main" 
                                                             bundle: nil];
    YourViewController *yourController = (YourViewController *)[mainStoryboard 
      instantiateViewControllerWithIdentifier:@"YourViewControllerID"];
    self.window.rootViewController = yourController;
}

return YES;

Select values of checkbox group with jQuery

I just shortened the answer I selected a bit:

var selectedGroups  = new Array();
$("input[@name='user_group[]']:checked").each(function() {
    selectedGroups.push($(this).val());
});

and it works like a charm, thanks!

How can I check if character in a string is a letter? (Python)

This works:

word = str(input("Enter string:"))
notChar = 0
isChar = 0
for char in word:
    if not char.isalpha():
        notChar += 1
    else:
        isChar += 1
print(isChar, " were letters; ", notChar, " were not letters.")

Append value to empty vector in R?

You have a few options:

  • c(vector, values)

  • append(vector, values)

  • vector[(length(vector) + 1):(length(vector) + length(values))] <- values

The first one is the standard approach. The second one gives you the option to append someplace other than the end. The last one is a bit contorted but has the advantage of modifying vector (though really, you could just as easily do vector <- c(vector, values).

Notice that in R you don't need to cycle through vectors. You can just operate on them in whole.

Also, this is fairly basic stuff, so you should go through some of the references.

Some more options based on OP feedback:

for(i in values) vector <- c(vector, i)

C# static class why use?

Making a class static just prevents people from trying to make an instance of it. If all your class has are static members it is a good practice to make the class itself static.

Referencing a string in a string array resource with xml

Maybe this would help:

String[] some_array = getResources().getStringArray(R.array.your_string_array)

So you get the array-list as a String[] and then choose any i, some_array[i].

Android check null or empty string in Android

Yo can check it with this:

if(userEmail != null && !userEmail .isEmpty())

And remember you must use from exact above code with that order. Because that ensuring you will not get a null pointer exception from userEmail.isEmpty() if userEmail is null.

Above description, it's only available since Java SE 1.6. Check userEmail.length() == 0 on previous versions.


UPDATE:

Use from isEmpty(stringVal) method from TextUtils class:

if (TextUtils.isEmpty(userEmail))

Kotlin:

Use from isNullOrEmpty for null or empty values OR isNullOrBlank for null or empty or consists solely of whitespace characters.

if (userEmail.isNullOrEmpty())
...
if (userEmail.isNullOrBlank())

How to convert "0" and "1" to false and true

If you want the conversion to always succeed, probably the best way to convert the string would be to consider "1" as true and anything else as false (as Kevin does). If you wanted the conversion to fail if anything other than "1" or "0" is returned, then the following would suffice (you could put it in a helper method):

if (returnValue == "1")
{
    return true;
}
else if (returnValue == "0")
{
    return false;
}
else
{
    throw new FormatException("The string is not a recognized as a valid boolean value.");
}

XmlWriter to Write to a String Instead of to a File

I know this is old and answered, but here is another way to do it. Particularly if you don't want the UTF8 BOM at the start of your string and you want the text indented:

using (var ms = new MemoryStream())
using (var x = new XmlTextWriter(ms, new UTF8Encoding(false)) 
                   { Formatting = Formatting.Indented })
{
     // ...
     return Encoding.UTF8.GetString(ms.ToArray());
}

Set focus to field in dynamically loaded DIV

$("#display").load("?control=msgs", {}, function() { 
  $('#header').focus();
});

i tried it but it doesn't work, please give me more advice to resolve this problem. thanks for your help

Jquery mouseenter() vs mouseover()

See the example code and demo at the bottom of the jquery documentation page:

http://api.jquery.com/mouseenter/

... mouseover fires when the pointer moves into the child element as well, while mouseenter fires only when the pointer moves into the bound element.

Rebuild or regenerate 'ic_launcher.png' from images in Android Studio

No, but you can do this almost as easily.

Go here:

https://romannurik.github.io/AndroidAssetStudio/

Build your icons using that page, and then download the zip package. Unzip it into the right directory and it'll overwrite all the drawable-*/ic_launcher.png correctly.

Javascript : get <img> src and set as variable?

var youtubeimgsrc = document.getElementById('youtubeimg').src;
document.write(youtubeimgsrc);

Here's a fiddle for you http://jsfiddle.net/cruxst/dvrEN/

jQuery get value of select onChange

only with JS

 let select=document.querySelectorAll('select') 
  select.forEach(function(el) {
    el.onchange =  function(){
     alert(this.value);
      
  }}
  )

How to save MySQL query output to excel or .txt file?

From Save MySQL query results into a text or CSV file:

MySQL provides an easy mechanism for writing the results of a select statement into a text file on the server. Using extended options of the INTO OUTFILE nomenclature, it is possible to create a comma separated value (CSV) which can be imported into a spreadsheet application such as OpenOffice or Excel or any other application which accepts data in CSV format.

Given a query such as

SELECT order_id,product_name,qty FROM orders

which returns three columns of data, the results can be placed into the file /tmp/orders.txt using the query:

SELECT order_id,product_name,qty FROM orders
INTO OUTFILE '/tmp/orders.txt'

This will create a tab-separated file, each row on its own line. To alter this behavior, it is possible to add modifiers to the query:

SELECT order_id,product_name,qty FROM orders
INTO OUTFILE '/tmp/orders.csv'
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n'

In this example, each field will be enclosed in double quotes, the fields will be separated by commas, and each row will be output on a new line separated by a newline (\n). Sample output of this command would look like:

"1","Tech-Recipes sock puppet","14.95" "2","Tech-Recipes chef's hat","18.95"

Keep in mind that the output file must not already exist and that the user MySQL is running as has write permissions to the directory MySQL is attempting to write the file to.

Syntax

   SELECT Your_Column_Name
    FROM Your_Table_Name
    INTO OUTFILE 'Filename.csv'
    FIELDS TERMINATED BY ','
    ENCLOSED BY '"'
    LINES TERMINATED BY '\n'

Or you could try to grab the output via the client:

You could try executing the query from the your local client and redirect the output to a local file destination:

mysql -user -pass -e "select cols from table where cols not null" > /tmp/output

Hint: If you don't specify an absoulte path but use something like INTO OUTFILE 'output.csv' or INTO OUTFILE './output.csv', it will store the output file to the directory specified by show variables like 'datadir';.

How to do a non-greedy match in grep?

Actualy the .*? only works in perl. I am not sure what the equivalent grep extended regexp syntax would be. Fortunately you can use perl syntax with grep so grep -P would work but grep -E which is same as egrep would not work (it would be greedy).

See also: http://blog.vinceliu.com/2008/02/non-greedy-regular-expression-matching.html

How do you send a Firebase Notification to all devices via CURL?

Your can send notification to all devices using "/topics/all"

https://fcm.googleapis.com/fcm/send
Content-Type:application/json
Authorization:key=AIzaSyZ-1u...0GBYzPu7Udno5aA

{
  "to": "/topics/all",
  "notification":{ "title":"Notification title", "body":"Notification body", "sound":"default", "click_action":"FCM_PLUGIN_ACTIVITY", "icon":"fcm_push_icon" },
  "data": {
    "message": "This is a Firebase Cloud Messaging Topic Message!",
   }
}

Setting up PostgreSQL ODBC on Windows

Please note that you must install the driver for the version of your software client(MS access) not the version of the OS. that's mean that if your MS Access is a 32-bits version,you must install a 32-bit odbc driver. regards

How to check if X server is running?

$DISPLAY is the standard way. That's how users communicate with programs about which X server to use, if any.

C# convert int to string with padding zeros?

int p = 3; // fixed length padding
int n = 55; // number to test

string t = n.ToString("D" + p); // magic     

Console.WriteLine("Hello, world! >> {0}", t);

// outputs: 
// Hello, world! >> 055

Generating random strings with T-SQL

Similar to the first example, but with more flexibility:

-- min_length = 8, max_length = 12
SET @Length = RAND() * 5 + 8
-- SET @Length = RAND() * (max_length - min_length + 1) + min_length

-- define allowable character explicitly - easy to read this way an easy to 
-- omit easily confused chars like l (ell) and 1 (one) or 0 (zero) and O (oh)
SET @CharPool = 
    'abcdefghijkmnopqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ23456789.,-_!$@#%^&*'
SET @PoolLength = Len(@CharPool)

SET @LoopCount = 0
SET @RandomString = ''

WHILE (@LoopCount < @Length) BEGIN
    SELECT @RandomString = @RandomString + 
        SUBSTRING(@Charpool, CONVERT(int, RAND() * @PoolLength) + 1, 1)
    SELECT @LoopCount = @LoopCount + 1
END

I forgot to mention one of the other features that makes this more flexible. By repeating blocks of characters in @CharPool, you can increase the weighting on certain characters so that they are more likely to be chosen.

I lose my data when the container exits

When you use docker run to start a container, it actually creates a new container based on the image you have specified.

Besides the other useful answers here, note that you can restart an existing container after it exited and your changes are still there.

docker start f357e2faab77 # restart it in the background
docker attach f357e2faab77 # reattach the terminal & stdin

Multi-line bash commands in makefile

The ONESHELL directive allows to write multiple line recipes to be executed in the same shell invocation.

all: foo

SOURCE_FILES = $(shell find . -name '*.c')

.ONESHELL:
foo: ${SOURCE_FILES}
    FILES=()
    for F in $^; do
        FILES+=($${F})
    done
    gcc "$${FILES[@]}" -o $@

There is a drawback though : special prefix characters (‘@’, ‘-’, and ‘+’) are interpreted differently.

https://www.gnu.org/software/make/manual/html_node/One-Shell.html

android TextView: setting the background color dynamically doesn't work

here is in little detail,

if you are in activity use this

textview.setBackground(ContextCompat.getColor(this,R.color.yourcolor));

if you are in fragment use below code

textview.setBackground(ContextCompat.getColor(getActivity(),R.color.yourcolor));

if you are in recyclerview adapter use below code

textview.setBackground(ContextCompat.getColor(context,R.color.yourcolor));

// use holder.textview if you are in onBindviewholder
//here context is passed from fragment

How do the PHP equality (== double equals) and identity (=== triple equals) comparison operators differ?

All of the answers so far ignore a dangerous problem with ===. It has been noted in passing, but not stressed, that integer and double are different types, so the following code:

$n = 1000;
$d = $n + 0.0e0;
echo '<br/>'. ( ($n ==  $d)?'equal' :'not equal' );
echo '<br/>'. ( ($n === $d)?'equal' :'not equal' );

gives:

 equal
 not equal

Note that this is NOT a case of a "rounding error". The two numbers are exactly equal down to the last bit, but they have different types.

This is a nasty problem because a program using === can run happily for years if all of the numbers are small enough (where "small enough" depends on the hardware and OS you are running on). However, if by chance, an integer happens to be large enough to be converted to a double, its type is changed "forever" even though a subsequent operation, or many operations, might bring it back to a small integer in value. And, it gets worse. It can spread - double-ness infection can be passed along to anything it touches, one calculation at a time.

In the real world, this is likely to be a problem in programs that handle dates beyond the year 2038, for example. At this time, UNIX timestamps (number of seconds since 1970-01-01 00:00:00 UTC) will require more than 32-bits, so their representation will "magically" switch to double on some systems. Therefore, if you calculate the difference between two times you might end up with a couple of seconds, but as a double, rather than the integer result that occurs in the year 2017.

I think this is much worse than conversions between strings and numbers because it is subtle. I find it easy to keep track of what is a string and what is a number, but keeping track of the number of bits in a number is beyond me.

So, in the above answers there are some nice tables, but no distinction between 1 (as an integer) and 1 (subtle double) and 1.0 (obvious double). Also, advice that you should always use === and never == is not great because === will sometimes fail where == works properly. Also, JavaScript is not equivalent in this regard because it has only one number type (internally it may have different bit-wise representations, but it does not cause problems for ===).

My advice - use neither. You need to write your own comparison function to really fix this mess.

What is a raw type and why shouldn't we use it?

What is saying is that your list is a List of unespecified objects. That is that Java does not know what kind of objects are inside the list. Then when you want to iterate the list you have to cast every element, to be able to access the properties of that element (in this case, String).

In general is a better idea to parametrize the collections, so you don't have conversion problems, you will only be able to add elements of the parametrized type and your editor will offer you the appropiate methods to select.

private static List<String> list = new ArrayList<String>();

Delete a single record from Entity Framework?

The best way is to check and then delete

        if (ctx.Employ.Any(r=>r.Id == entity.Id))
        {
            Employ rec = new Employ() { Id = entity.Id };
            ctx.Entry(rec).State = EntityState.Deleted;
            ctx.SaveChanges();
        }

How to set encoding in .getJSON jQuery

Use this function to regain the utf-8 characters

function decode_utf8(s) { 
  return decodeURIComponent(escape(s)); 
}

Example: var new_Str=decode_utf8(str);

Import / Export database with SQL Server Server Management Studio

for Microsoft SQL Server Management Studio 2012,2008.. First Copy your database file .mdf and log file .ldf & Paste in your sql server install file in Programs Files->Microsoft SQL Server->MSSQL10.SQLEXPRESS->MSSQL->DATA. Then open Microsoft Sql Server . Right Click on Databases -> Select Attach...option.

Pass a PHP variable value through an HTML form

EDIT: After your comments, I understand that you want to pass variable through your form.

You can do this using hidden field:

<input type='hidden' name='var' value='<?php echo "$var";?>'/> 

In PHP action File:

<?php 
   if(isset($_POST['var'])) $var=$_POST['var'];
?>

Or using sessions: In your first page:

 $_SESSION['var']=$var;

start_session(); should be placed at the beginning of your php page.

In PHP action File:

if(isset($_SESSION['var'])) $var=$_SESSION['var'];

First Answer:

You can also use $GLOBALS :

if (isset($_POST['save_exit']))
{

   echo $GLOBALS['var']; 

}

Check this documentation for more informations.

What is the difference between "screen" and "only screen" in media queries?

@media screen and (max-width:480px) { … } 

screen here is to set the screen size of the media query. E.g the maximum width of the display area is 480px. So it is specifying the screen as opposed to the other available media types.

@media only screen and (max-width: 480px;) { … } 

only screen here is used to prevent older browsers that do not support media queries with media features from applying the specified styles.

Set line spacing

lineSpacing is used in React Native (or native mobile apps).

For web you can use letterSpacing (or letter-spacing)

web.xml is missing and <failOnMissingWebXml> is set to true

I encountered this issue in eclipse only, everything worked fine in Maven command line, and my web.xml file existed. It was a mature project (already deployed out in production) that was impacted. My problem was tied to the eclipse metadata. There was an issue with one of the files in my .settings/ folder, specifically org.eclipse.wst.common.component had been changed. I was able to restore this file to its prior version, which resolved the issue in my case.

Note that Yuci's answer did not work for me, when I tried to click on Deployment Assembly in the eclipse properties, I got an error that said "the currently displayed page contains invalid values."

CSS table-cell equal width

this will work for everyone

_x000D_
_x000D_
<table border="your val" cellspacing="your val" cellpadding="your val" role="grid" style="width=100%; table-layout=fixed">_x000D_
<!-- set the table td element roll attr to gridcell -->_x000D_
<tr>_x000D_
<td roll="gridcell"></td>_x000D_
</tr>_x000D_
</table>
_x000D_
_x000D_
_x000D_

This will also work for table data created by iteration

Merge some list items in a Python List

On what basis should the merging take place? Your question is rather vague. Also, I assume a, b, ..., f are supposed to be strings, that is, 'a', 'b', ..., 'f'.

>>> x = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
>>> x[3:6] = [''.join(x[3:6])]
>>> x
['a', 'b', 'c', 'def', 'g']

Check out the documentation on sequence types, specifically on mutable sequence types. And perhaps also on string methods.

What exactly is a Context in Java?

since you capitalized the word, I assume you are referring to the interface javax.naming.Context. A few classes implement this interface, and at its simplest description, it (generically) is a set of name/object pairs.

How to add 20 minutes to a current date?

Use .getMinutes() to get the current minutes, then add 20 and use .setMinutes() to update the date object.

var twentyMinutesLater = new Date();
twentyMinutesLater.setMinutes(twentyMinutesLater.getMinutes() + 20);

Why doesn't catching Exception catch RuntimeException?

catch (Exception ex) { ... }

WILL catch RuntimeException.

Whatever you put in catch block will be caught as well as the subclasses of it.

What is the significance of load factor in HashMap?

For HashMap DEFAULT_INITIAL_CAPACITY = 16 and DEFAULT_LOAD_FACTOR = 0.75f it means that MAX number of ALL Entries in the HashMap = 16 * 0.75 = 12. When the thirteenth element will be added capacity (array size) of HashMap will be doubled! Perfect illustration answered this question: enter image description here image is taken from here:

https://javabypatel.blogspot.com/2015/10/what-is-load-factor-and-rehashing-in-hashmap.html

selecting unique values from a column

Use the DISTINCT operator in MySQL:

SELECT DISTINCT(Date) AS Date FROM buy ORDER BY Date DESC;

How to fix java.lang.UnsupportedClassVersionError: Unsupported major.minor version

In Eclipse, I just went to menu command Window -> Preferences -> Java -> Compiler and then set "Compiler compliance level" to 1.6.

Printing an int list in a single line python3

You want to say

for i in array:
    print(i, end=" ")

The syntax i in array iterates over each member of the list. So, array[i] was trying to access array[1], array[2], and array[3], but the last of these is out of bounds (array has indices 0, 1, and 2).

You can get the same effect with print(" ".join(map(str,array))).

Replace words in a string - Ruby

If you're dealing with natural language text and need to replace a word, not just part of a string, you have to add a pinch of regular expressions to your gsub as a plain text substitution can lead to disastrous results:

'mislocated cat, vindicating'.gsub('cat', 'dog')
=> "mislodoged dog, vindidoging"

Regular expressions have word boundaries, such as \b which matches start or end of a word. Thus,

'mislocated cat, vindicating'.gsub(/\bcat\b/, 'dog')
=> "mislocated dog, vindicating"

In Ruby, unlike some other languages like Javascript, word boundaries are UTF-8-compatible, so you can use it for languages with non-Latin or extended Latin alphabets:

'???? ? ??????, ??? ??????'.gsub(/\b????\b/, '?????')
=> "????? ? ??????, ??? ??????"

How do I compile C++ with Clang?

I do not know why there is no answer directly addressing the problem. When you want to compile C++ program, it is best to use clang++. For example, the following works for me:

clang++ -Wall -std=c++11 test.cc -o test

If compiled correctly, it will produce the executable file test, and you can run the file by using ./test.

Or you can just use clang++ test.cc to compile the program. It will produce a default executable file named a.out. Use ./a.out to run the file.

The whole process is a lot like g++ if you are familiar with g++. See this post to check which warnings are included with -Wall option. This page shows a list of diagnostic flags supported by Clang.

A note on using clang -x c++: Kim Gräsman says that you can also use clang -x c++ to compile cpp programs, but that may not be true. For example, I am having a simple program below:

#include <iostream>
#include <vector>

int main() {
    /* std::vector<int> v = {1, 2, 3, 4, 5}; */
    std::vector<int> v(10, 5);
    int sum = 0;
    for (int i = 0; i < v.size(); i++){
        sum += v[i]*2;
    }
    std::cout << "sum is " << sum << std::endl;
    return 0;
}                                                      

clang++ test.cc -o test will compile successfully, but clang -x c++ will not, showing a lot undefined references errors. So I guess they are not exactly equivalent. It is best to use clang++ instead of clang -x c++ when compiling c++ programs to avoid extra troubles.

  • clang version: 11.0.0
  • Platform: Ubuntu 16.04

How to retrieve the last autoincremented ID from a SQLite table?

I've had issues with using SELECT last_insert_rowid() in a multithreaded environment. If another thread inserts into another table that has an autoinc, last_insert_rowid will return the autoinc value from the new table.

Here's where they state that in the doco:

If a separate thread performs a new INSERT on the same database connection while the sqlite3_last_insert_rowid() function is running and thus changes the last insert rowid, then the value returned by sqlite3_last_insert_rowid() is unpredictable and might not equal either the old or the new last insert rowid.

That's from sqlite.org doco

How to compute the similarity between two text documents?

To find sentence similarity with very less dataset and to get high accuracy you can use below python package which is using pre-trained BERT models,

pip install similar-sentences

Laravel Eloquent ORM Transactions

You can do this:

DB::transaction(function() {
      //
});

Everything inside the Closure executes within a transaction. If an exception occurs it will rollback automatically.

How do I get the max ID with Linq to Entity?

try this

int intIdt = db.Users.Max(u => u.UserId);

Update:

If no record then generate exception using above code try this

int? intIdt = db.Users.Max(u => (int?)u.UserId);

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

Just wanted to share a pure C++ 98 work around:

#include <map>

std::map<std::string, std::string> aka;

struct akaInit
{
    akaInit()
    {
        aka[ "George" ] = "John";
        aka[ "Joe" ] = "Al";
        aka[ "Phil" ] = "Sue";
        aka[ "Smitty" ] = "Yando";
    }
} AkaInit;

How to show full object in Chrome console?

To output obj:

console.log(obj, null, 4)

What static analysis tools are available for C#?

Code violation detection Tools:

  • Fxcop, excellent tool by Microsoft. Check compliance with .net framework guidelines.

    Edit October 2010: No longer available as a standalone download. It is now included in the Windows SDK and after installation can be found in Program Files\Microsoft SDKs\Windows\ [v7.1] \Bin\FXCop\FxCopSetup.exe

    Edit February 2018: This functionality has now been integrated into Visual Studio 2012 and later as Code Analysis

  • Clocksharp, based on code source analysis (to C# 2.0)

  • Mono.Gendarme, similar to Fxcop but with an opensource licence (based on Mono.Cecil)

  • Smokey, similar to Fxcop and Gendarme, based on Mono.Cecil. No longer on development, the main developer works with Gendarme team now.

  • Coverity Prevent™ for C#, commercial product

  • PRQA QA·C#, commercial product

  • PVS-Studio, commercial product

  • CAT.NET, visual studio addin that helps identification of security flaws Edit November 2019: Link is dead.

  • CodeIt.Right

  • Spec#

  • Pex

  • SonarQube, FOSS & Commercial options to support writing cleaner and safer code.

Quality Metric Tools:

  • NDepend, great visual tool. Useful for code metrics, rules, diff, coupling and dependency studies.
  • Nitriq, free, can easily write your own metrics/constraints, nice visualizations. Edit February 2018: download links now dead. Edit June 17, 2019: Links not dead.
  • RSM Squared, based on code source analysis
  • C# Metrics, using a full parse of C#
  • SourceMonitor, an old tool that occasionally gets updates
  • Code Metrics, a Reflector add-in
  • Vil, old tool that doesn't support .NET 2.0. Edit January 2018: Link now dead

Checking Style Tools:

  • StyleCop, Microsoft tool ( run from inside of Visual Studio or integrated into an MSBuild project). Also available as an extension for Visual Studio 2015 and C#6.0
  • Agent Smith, code style validation plugin for ReSharper

Duplication Detection:

  • Simian, based on source code. Works with plenty languages.
  • CloneDR, detects parameterized clones only on language boundaries (also handles many languages other than C#)
  • Clone Detective a Visual Studio plugin. (It uses ConQAT internally)
  • Atomiq, based on source code, plenty of languages, cool "wheel" visualization

General Refactoring tools

  • ReSharper - Majorly cool C# code analysis and refactoring features

Defining and using a variable in batch file

input location.bat

@echo off
cls

set /p "location"="bob"
echo We're working with %location%
pause

output

We're working with bob

(mistakes u done : space and " ")

Closing Bootstrap modal onclick

You can hide the modal and popup the window to review the carts in validateShipping() function itself.

function validateShipping(){
...
...
$('#product-options').modal('hide');
//pop the window to select items
}

How to check all checkboxes using jQuery?

html :

    <div class="col-md-3 general-sidebar" id="CategoryGrid">
                                                    <h5>Category &amp; Sub Category <span style="color: red;">* </span></h5>
                                                    <div class="checkbox">
                                                        <label>
                                                            <input onclick="checkUncheckAll(this)" type="checkbox">
                                                            All
                                                        </label>
                                                    </div>
                                                <div class="checkbox"><label><input class="cat" type="checkbox" value="Quality">Quality</label></div>
<div class="checkbox"><label><input class="subcat" type="checkbox" value="Planning process and execution">Planning process and execution</label></div>

javascript:

function checkUncheckAll(ele) {
    if (ele.checked) {
        $('.cat').prop('checked', ele.checked);
        $('.subcat').prop('checked', ele.checked);
    }
    else {
        $('.cat').prop('checked', ele.checked);
        $('.subcat').prop('checked', ele.checked);
    }
}

Writing to a file in a for loop

The main problem was that you were opening/closing files repeatedly inside your loop.

Try this approach:

with open('new.txt') as text_file, open('xyz.txt', 'w') as myfile:  
    for line in text_file:
        var1, var2 = line.split(",");
        myfile.write(var1+'\n')

We open both files at once and because we are using with they will be automatically closed when we are done (or an exception occurs). Previously your output file was repeatedly openend inside your loop.

We are also processing the file line-by-line, rather than reading all of it into memory at once (which can be a problem when you deal with really big files).

Note that write() doesn't append a newline ('\n') so you'll have to do that yourself if you need it (I replaced your writelines() with write() as you are writing a single item, not a list of items).

When opening a file for rread, the 'r' is optional since it's the default mode.

Pandas : compute mean or std (standard deviation) over entire dataframe

You could convert the dataframe to be a single column with stack (this changes the shape from 5x3 to 15x1) and then take the standard deviation:

df.stack().std()         # pandas default degrees of freedom is one

Alternatively, you can use values to convert from a pandas dataframe to a numpy array before taking the standard deviation:

df.values.std(ddof=1)    # numpy default degrees of freedom is zero

Unlike pandas, numpy will give the standard deviation of the entire array by default, so there is no need to reshape before taking the standard deviation.

A couple of additional notes:

  • The numpy approach here is a bit faster than the pandas one, which is generally true when you have the option to accomplish the same thing with either numpy or pandas. The speed difference will depend on the size of your data, but numpy was roughly 10x faster when I tested a few different sized dataframes on my laptop (numpy version 1.15.4 and pandas version 0.23.4).

  • The numpy and pandas approaches here will not give exactly the same answers, but will be extremely close (identical at several digits of precision). The discrepancy is due to slight differences in implementation behind the scenes that affect how the floating point values get rounded.

Send json post using php

use CURL luke :) seriously, thats one of the best ways to do it AND you get the response.

Default value for field in Django model

You can set the default like this:

b = models.CharField(max_length=7,default="foobar")

and then you can hide the field with your model's Admin class like this:

class SomeModelAdmin(admin.ModelAdmin):
    exclude = ("b")

Android: Expand/collapse animation

This was my solution, my ImageView grows from 100% to 200% and return to his original size, using two animation files inside res/anim/ folder

anim_grow.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
 android:interpolator="@android:anim/accelerate_interpolator">
 <scale
  android:fromXScale="1.0"
  android:toXScale="2.0"
  android:fromYScale="1.0"
  android:toYScale="2.0"
  android:duration="3000"
  android:pivotX="50%"
  android:pivotY="50%"
  android:startOffset="2000" />
</set>

anim_shrink.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
 android:interpolator="@android:anim/accelerate_interpolator">
 <scale
  android:fromXScale="2.0"
  android:toXScale="1.0"
  android:fromYScale="2.0"
  android:toYScale="1.0"
  android:duration="3000"
  android:pivotX="50%"
  android:pivotY="50%"
  android:startOffset="2000" />
</set>

Send an ImageView to my method setAnimationGrowShrink()

ImageView img1 = (ImageView)findViewById(R.id.image1);
setAnimationGrowShrink(img1);

setAnimationGrowShrink() method:

private void setAnimationGrowShrink(final ImageView imgV){
    final Animation animationEnlarge = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.anim_grow);
    final Animation animationShrink = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.anim_shrink);

    imgV.startAnimation(animationEnlarge);

    animationEnlarge.setAnimationListener(new AnimationListener() {         
        @Override
        public void onAnimationStart(Animation animation) {}

        @Override
        public void onAnimationRepeat(Animation animation) {}

        @Override
        public void onAnimationEnd(Animation animation) {
            imgV.startAnimation(animationShrink);
        }
    });

    animationShrink.setAnimationListener(new AnimationListener() {          
        @Override
        public void onAnimationStart(Animation animation) {}

        @Override
        public void onAnimationRepeat(Animation animation) {}

        @Override
        public void onAnimationEnd(Animation animation) {
            imgV.startAnimation(animationEnlarge);
        }
    });

}

In C - check if a char exists in a char array

Assuming your input is a standard null-terminated C string, you want to use strchr:

#include <string.h>

char* foo = "abcdefghijkl";
if (strchr(foo, 'a') != NULL)
{
  // do stuff
}

If on the other hand your array is not null-terminated (i.e. just raw data), you'll need to use memchr and provide a size:

#include <string.h>

char foo[] = { 'a', 'b', 'c', 'd', 'e' }; // note last element isn't '\0'
if (memchr(foo, 'a', sizeof(foo)))
{
  // do stuff
}

Pygame mouse clicking detection

The MOUSEBUTTONDOWN event occurs once when you click the mouse button and the MOUSEBUTTONUP event occurs once when the mouse button is released. The pygame.event.Event() object has two attributes that provide information about the mouse event. pos is a tuple that stores the position that was clicked. button stores the button that was clicked. Each mouse button is associated a value. For instance the value of the attributes is 1, 2, 3, 4, 5 for the left mouse button, middle mouse button, right mouse button, mouse wheel up respectively mouse wheel down. When multiple keys are pressed, multiple mouse button events occur. Further explanations can be found in the documentation of the module pygame.event.

Use the rect attribute of the pygame.sprite.Sprite object and the collidepoint method to see if the Sprite was clicked. Pass the list of events to the update method of the pygame.sprite.Group so that you can process the events in the Sprite class:

class SpriteObject(pygame.sprite.Sprite):
    # [...]

    def update(self, event_list):

        for event in event_list:
            if event.type == pygame.MOUSEBUTTONDOWN:
                if self.rect.collidepoint(event.pos):
                    # [...]

my_sprite = SpriteObject()
group = pygame.sprite.Group(my_sprite)

# [...]

run = True
while run:
    event_list = pygame.event.get()
    for event in event_list:
        if event.type == pygame.QUIT:
            run = False 

    group.update(event_list)

    # [...]

Minimal example: repl.it/@Rabbid76/PyGame-MouseClick

import pygame

class SpriteObject(pygame.sprite.Sprite):
    def __init__(self, x, y, color):
        super().__init__() 
        self.original_image = pygame.Surface((50, 50), pygame.SRCALPHA)
        pygame.draw.circle(self.original_image, color, (25, 25), 25)
        self.click_image = pygame.Surface((50, 50), pygame.SRCALPHA)
        pygame.draw.circle(self.click_image, color, (25, 25), 25)
        pygame.draw.circle(self.click_image, (255, 255, 255), (25, 25), 25, 4)
        self.image = self.original_image 
        self.rect = self.image.get_rect(center = (x, y))
        self.clicked = False

    def update(self, event_list):
        for event in event_list:
            if event.type == pygame.MOUSEBUTTONDOWN:
                if self.rect.collidepoint(event.pos):
                    self.clicked = not self.clicked

        self.image = self.click_image if self.clicked else self.original_image

pygame.init()
window = pygame.display.set_mode((300, 300))
clock = pygame.time.Clock()

sprite_object = SpriteObject(*window.get_rect().center, (128, 128, 0))
group = pygame.sprite.Group([
    SpriteObject(window.get_width() // 3, window.get_height() // 3, (128, 0, 0)),
    SpriteObject(window.get_width() * 2 // 3, window.get_height() // 3, (0, 128, 0)),
    SpriteObject(window.get_width() // 3, window.get_height() * 2 // 3, (0, 0, 128)),
    SpriteObject(window.get_width() * 2// 3, window.get_height() * 2 // 3, (128, 128, 0)),
])

run = True
while run:
    clock.tick(60)
    event_list = pygame.event.get()
    for event in event_list:
        if event.type == pygame.QUIT:
            run = False 

    group.update(event_list)

    window.fill(0)
    group.draw(window)
    pygame.display.flip()

pygame.quit()
exit()

See further Creating multiple sprites with different update()'s from the same sprite class in Pygame


The current position of the mouse can be determined via pygame.mouse.get_pos(). The return value is a tuple that represents the x and y coordinates of the mouse cursor. pygame.mouse.get_pressed() returns a list of Boolean values ??that represent the state (True or False) of all mouse buttons. The state of a button is True as long as a button is held down. When multiple buttons are pressed, multiple items in the list are True. The 1st, 2nd and 3rd elements in the list represent the left, middle and right mouse buttons.

Detect evaluate the mouse states in the Update method of the pygame.sprite.Sprite object:

class SpriteObject(pygame.sprite.Sprite):
    # [...]

    def update(self, event_list):

        mouse_pos = pygame.mouse.get_pos()
        mouse_buttons = pygame.mouse.get_pressed()

        if  self.rect.collidepoint(mouse_pos) and any(mouse_buttons):
            # [...]

my_sprite = SpriteObject()
group = pygame.sprite.Group(my_sprite)

# [...]

run = True
while run:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False

    group.update(event_list)

    # [...]

Minimal example: repl.it/@Rabbid76/PyGame-MouseHover

import pygame

class SpriteObject(pygame.sprite.Sprite):
    def __init__(self, x, y, color):
        super().__init__() 
        self.original_image = pygame.Surface((50, 50), pygame.SRCALPHA)
        pygame.draw.circle(self.original_image, color, (25, 25), 25)
        self.hover_image = pygame.Surface((50, 50), pygame.SRCALPHA)
        pygame.draw.circle(self.hover_image, color, (25, 25), 25)
        pygame.draw.circle(self.hover_image, (255, 255, 255), (25, 25), 25, 4)
        self.image = self.original_image 
        self.rect = self.image.get_rect(center = (x, y))
        self.hover = False

    def update(self):
        mouse_pos = pygame.mouse.get_pos()
        mouse_buttons = pygame.mouse.get_pressed()

        #self.hover = self.rect.collidepoint(mouse_pos)
        self.hover = self.rect.collidepoint(mouse_pos) and any(mouse_buttons)

        self.image = self.hover_image if self.hover else self.original_image

pygame.init()
window = pygame.display.set_mode((300, 300))
clock = pygame.time.Clock()

sprite_object = SpriteObject(*window.get_rect().center, (128, 128, 0))
group = pygame.sprite.Group([
    SpriteObject(window.get_width() // 3, window.get_height() // 3, (128, 0, 0)),
    SpriteObject(window.get_width() * 2 // 3, window.get_height() // 3, (0, 128, 0)),
    SpriteObject(window.get_width() // 3, window.get_height() * 2 // 3, (0, 0, 128)),
    SpriteObject(window.get_width() * 2// 3, window.get_height() * 2 // 3, (128, 128, 0)),
])

run = True
while run:
    clock.tick(60)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False 

    group.update()

    window.fill(0)
    group.draw(window)
    pygame.display.flip()

pygame.quit()
exit()

How to use ES6 Fat Arrow to .filter() an array of objects

return arrayname.filter((rec) => rec.age > 18)

Write this in the method and call it

Could not calculate build plan: Plugin org.apache.maven.plugins:maven-resources-plugin:2.5 or one of its dependencies could not be resolved

It appears that there can be a lot of different causes for this issue. I experienced it after installing a new version of Eclipse (Luna). Command-line maven worked fine, but Eclipse had build issues.

I use a Certificate Authority in my JRE. This is important because this provides my authentication when downloading Maven resources. Even though my project was pointing to the appropriate JRE inside of Eclipse - Eclipse was running using a different JRE (this is apparent looking at the Java process properties in Windows task manager). My solution was to add the following in my eclipse.ini and explicitly define the JRE I want to use.

-vm
C:\Program Files\Java\jdk1.7.0_51\bin\javaw.exe 

How to make a Python script run like a service or daemon in Linux

You can also make the python script run as a service using a shell script. First create a shell script to run the python script like this (scriptname arbitary name)

#!/bin/sh
script='/home/.. full path to script'
/usr/bin/python $script &

now make a file in /etc/init.d/scriptname

#! /bin/sh

PATH=/bin:/usr/bin:/sbin:/usr/sbin
DAEMON=/home/.. path to shell script scriptname created to run python script
PIDFILE=/var/run/scriptname.pid

test -x $DAEMON || exit 0

. /lib/lsb/init-functions

case "$1" in
  start)
     log_daemon_msg "Starting feedparser"
     start_daemon -p $PIDFILE $DAEMON
     log_end_msg $?
   ;;
  stop)
     log_daemon_msg "Stopping feedparser"
     killproc -p $PIDFILE $DAEMON
     PID=`ps x |grep feed | head -1 | awk '{print $1}'`
     kill -9 $PID       
     log_end_msg $?
   ;;
  force-reload|restart)
     $0 stop
     $0 start
   ;;
  status)
     status_of_proc -p $PIDFILE $DAEMON atd && exit 0 || exit $?
   ;;
 *)
   echo "Usage: /etc/init.d/atd {start|stop|restart|force-reload|status}"
   exit 1
  ;;
esac

exit 0

Now you can start and stop your python script using the command /etc/init.d/scriptname start or stop.

Center div on the middle of screen

2018: CSS3

div{
    position: absolute;
    top: 50%;
    left: 50%;
    margin-right: -50%;
    transform: translate(-50%, -50%);
}

This is even shorter. For more information see this: CSS: Centering Things

How to control size of list-style-type disc in CSS?

If you choose to use inline SVG to render your bullets, you can use width and height properties to control their size:

_x000D_
_x000D_
ul {_x000D_
  list-style-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='10' height='10' viewBox='-1 -1 2 2'><circle r='1' /></svg>");_x000D_
}_x000D_
_x000D_
.x {_x000D_
  list-style-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='10' height='10' viewBox='-1 -1 2 2'><circle r='0.5' /></svg>");_x000D_
}_x000D_
_x000D_
.x_alternative {_x000D_
  list-style-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='10' height='10' viewBox='-2.2 -2.4 4 4'><circle r='1' /></svg>");_x000D_
}
_x000D_
<ul>_x000D_
  <li>foo</li>_x000D_
  <li>bar</li>_x000D_
  <li>baz</li>_x000D_
</ul>_x000D_
_x000D_
<ul class="x">_x000D_
  <li>foo</li>_x000D_
  <li>bar</li>_x000D_
  <li>baz</li>_x000D_
</ul>_x000D_
_x000D_
<ul class="x_alternative">_x000D_
  <li>foo</li>_x000D_
  <li>bar</li>_x000D_
  <li>baz</li>_x000D_
</ul>
_x000D_
_x000D_
_x000D_

Click here for an easy explanation of the viewBox.

Java reading a file into an ArrayList?

This Java code reads in each word and puts it into the ArrayList:

Scanner s = new Scanner(new File("filepath"));
ArrayList<String> list = new ArrayList<String>();
while (s.hasNext()){
    list.add(s.next());
}
s.close();

Use s.hasNextLine() and s.nextLine() if you want to read in line by line instead of word by word.

Cross-browser custom styling for file upload button

The best example is this one, No hiding, No jQuery, It's completely pure CSS

http://css-tricks.com/snippets/css/custom-file-input-styling-webkitblink/

_x000D_
_x000D_
.custom-file-input::-webkit-file-upload-button {_x000D_
    visibility: hidden;_x000D_
}_x000D_
_x000D_
.custom-file-input::before {_x000D_
    content: 'Select some files';_x000D_
    display: inline-block;_x000D_
    background: -webkit-linear-gradient(top, #f9f9f9, #e3e3e3);_x000D_
    border: 1px solid #999;_x000D_
    border-radius: 3px;_x000D_
    padding: 5px 8px;_x000D_
    outline: none;_x000D_
    white-space: nowrap;_x000D_
    -webkit-user-select: none;_x000D_
    cursor: pointer;_x000D_
    text-shadow: 1px 1px #fff;_x000D_
    font-weight: 700;_x000D_
    font-size: 10pt;_x000D_
}_x000D_
_x000D_
.custom-file-input:hover::before {_x000D_
    border-color: black;_x000D_
}_x000D_
_x000D_
.custom-file-input:active::before {_x000D_
    background: -webkit-linear-gradient(top, #e3e3e3, #f9f9f9);_x000D_
}
_x000D_
<input type="file" class="custom-file-input">
_x000D_
_x000D_
_x000D_

Iterating over a numpy array

If you only need the indices, you could try numpy.ndindex:

>>> a = numpy.arange(9).reshape(3, 3)
>>> [(x, y) for x, y in numpy.ndindex(a.shape)]
[(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2)]

How do I include the string header?

You want to include <string> and use std::string:

#include <string>
#include <iostream>

int main()
{
    std::string s = "a string";
    std::cout << s << std::endl;
}

But what you really need to do is get an introductory level book. You aren't going to learn properly any other way, certainly not scrapping for information online.

PHP PDO returning single row

Just fetch. only gets one row. So no foreach loop needed :D

$row  = $STH -> fetch();

example (ty northkildonan):

$dbh = new PDO(" --- connection string --- "); 
$stmt = $dbh->prepare("SELECT name FROM mytable WHERE id=4 LIMIT 1"); 
$stmt->execute(); 
$row = $stmt->fetch();

How do I get current URL in Selenium Webdriver 2 Python?

Use current_url element for Python 2:

print browser.current_url

For Python 3 and later versions of selenium:

print(driver.current_url)

SQL Server: Make all UPPER case to Proper Case/Title Case

This function:

  • "Proper Cases" all "UPPER CASE" words that are delimited by white space
  • leaves "lower case words" alone
  • works properly even for non-English alphabets
  • is portable in that it does not use fancy features of recent SQL server versions
  • can be easily changed to use NCHAR and NVARCHAR for unicode support,as well as any parameter length you see fit
  • white space definition can be configured
CREATE FUNCTION ToProperCase(@string VARCHAR(255)) RETURNS VARCHAR(255)
AS
BEGIN
  DECLARE @i INT           -- index
  DECLARE @l INT           -- input length
  DECLARE @c NCHAR(1)      -- current char
  DECLARE @f INT           -- first letter flag (1/0)
  DECLARE @o VARCHAR(255)  -- output string
  DECLARE @w VARCHAR(10)   -- characters considered as white space

  SET @w = '[' + CHAR(13) + CHAR(10) + CHAR(9) + CHAR(160) + ' ' + ']'
  SET @i = 1
  SET @l = LEN(@string)
  SET @f = 1
  SET @o = ''

  WHILE @i <= @l
  BEGIN
    SET @c = SUBSTRING(@string, @i, 1)
    IF @f = 1 
    BEGIN
     SET @o = @o + @c
     SET @f = 0
    END
    ELSE
    BEGIN
     SET @o = @o + LOWER(@c)
    END

    IF @c LIKE @w SET @f = 1

    SET @i = @i + 1
  END

  RETURN @o
END

Result:

dbo.ToProperCase('ALL UPPER CASE and    SOME lower ÄÄ ÖÖ ÜÜ ÉÉ ØØ CC ÆÆ')
-----------------------------------------------------------------
All Upper Case and      Some lower Ää Öö Üü Éé Øø Cc Ææ

How to detect READ_COMMITTED_SNAPSHOT is enabled?

Neither on SQL2005 nor 2012 does DBCC USEROPTIONS show is_read_committed_snapshot_on:

Set Option  Value
textsize    2147483647
language    us_english
dateformat  mdy
datefirst   7
lock_timeout    -1
quoted_identifier   SET
arithabort  SET
ansi_null_dflt_on   SET
ansi_warnings   SET
ansi_padding    SET
ansi_nulls  SET
concat_null_yields_null SET
isolation level read committed

jQuery delete confirmation box

Try with this JSFiddle DEMO : http://jsfiddle.net/2yEtK/3/

Jquery Code:

$("a.removeRecord").live("click",function(event){
   event.stopPropagation();
   if(confirm("Do you want to delete?")) {
    this.click;
       alert("Ok");
   }
   else
   {
       alert("Cancel");
   }       
   event.preventDefault();

});

Change priorityQueue to max priorityqueue

Using lamda, just multiple the result with -1 to get max priority queue.

PriorityQueue<> q = new PriorityQueue<Integer>(
                       (a,b) ->  -1 * Integer.compare(a, b)
                    );

Replace "\\" with "\" in a string in C#

Regex.Unescape(string) method converts any escaped characters in the input string.

The Unescape method performs one of the following two transformations:

  1. It reverses the transformation performed by the Escape method by removing the escape character ("\") from each character escaped by the method. These include the \, *, +, ?, |, {, [, (,), ^, $, ., #, and white space characters. In addition, the Unescape method unescapes the closing bracket (]) and closing brace (}) characters.

  2. It replaces the hexadecimal values in verbatim string literals with the actual printable characters. For example, it replaces @"\x07" with "\a", or @"\x0A" with "\n". It converts to supported escape characters such as \a, \b, \e, \n, \r, \f, \t, \v, and alphanumeric characters.

string str = @"a\\b\\c";
var output = System.Text.RegularExpressions.Regex.Unescape(str);

Reference:

https://docs.microsoft.com/en-us/dotnet/api/system.text.regularexpressions.regex.unescape?view=netframework-4.8

Align div with fixed position on the right side

With position fixed, you need to provide values to set where the div will be placed, since it's a fixed position.

Something like....

.test
{
   position:fixed;
   left:100px;
   top:150px;
}

Fixed - Generates an absolutely positioned element, positioned relative to the browser window. The element's position is specified with the "left", "top", "right", and "bottom" properties

More on position here.

How to make a page redirect using JavaScript?

You can append the values in the query string for the next page to see and process. You can wrap them inside the link tags:

<a href="your_page.php?var1=value1&var2=value2">

You separate each of those values with the & sign.

Or you can create this on a button click like this:

<input type="button" onclick="document.location.href = 'your_page.php?var1=value1&var2=value2';">

Window vs Page vs UserControl for WPF navigation?

A Window object is just what it sounds like: its a new Window for your application. You should use it when you want to pop up an entirely new window. I don't often use more than one Window in WPF because I prefer to put dynamic content in my main Window that changes based on user action.

A Page is a page inside your Window. It is mostly used for web-based systems like an XBAP, where you have a single browser window and different pages can be hosted in that window. It can also be used in Navigation Applications like sellmeadog said.

A UserControl is a reusable user-created control that you can add to your UI the same way you would add any other control. Usually I create a UserControl when I want to build in some custom functionality (for example, a CalendarControl), or when I have a large amount of related XAML code, such as a View when using the MVVM design pattern.

When navigating between windows, you could simply create a new Window object and show it

var NewWindow = new MyWindow();
newWindow.Show();

but like I said at the beginning of this answer, I prefer not to manage multiple windows if possible.

My preferred method of navigation is to create some dynamic content area using a ContentControl, and populate that with a UserControl containing whatever the current view is.

<Window x:Class="MyNamespace.MainWindow" ...>
    <DockPanel>
        <ContentControl x:Name="ContentArea" />
    </DockPanel>
</Window>

and in your navigate event you can simply set it using

ContentArea.Content = new MyUserControl();

But if you're working with WPF, I'd highly recommend the MVVM design pattern. I have a very basic example on my blog that illustrates how you'd navigate using MVVM, using this pattern:

<Window x:Class="SimpleMVVMExample.ApplicationView"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:SimpleMVVMExample"
        Title="Simple MVVM Example" Height="350" Width="525">

   <Window.Resources>
      <DataTemplate DataType="{x:Type local:HomeViewModel}">
         <local:HomeView /> <!-- This is a UserControl -->
      </DataTemplate>
      <DataTemplate DataType="{x:Type local:ProductsViewModel}">
         <local:ProductsView /> <!-- This is a UserControl -->
      </DataTemplate>
   </Window.Resources>

   <DockPanel>
      <!-- Navigation Buttons -->
      <Border DockPanel.Dock="Left" BorderBrush="Black"
                                    BorderThickness="0,0,1,0">
         <ItemsControl ItemsSource="{Binding PageViewModels}">
            <ItemsControl.ItemTemplate>
               <DataTemplate>
                  <Button Content="{Binding Name}"
                          Command="{Binding DataContext.ChangePageCommand,
                             RelativeSource={RelativeSource AncestorType={x:Type Window}}}"
                          CommandParameter="{Binding }"
                          Margin="2,5"/>
               </DataTemplate>
            </ItemsControl.ItemTemplate>
         </ItemsControl>
      </Border>

      <!-- Content Area -->
      <ContentControl Content="{Binding CurrentPageViewModel}" />
   </DockPanel>
</Window>

Screenshot1 Screenshot2

How do I count the number of occurrences of a char in a String?

While methods can hide it, there is no way to count without a loop (or recursion). You want to use a char[] for performance reasons though.

public static int count( final String s, final char c ) {
  final char[] chars = s.toCharArray();
  int count = 0;
  for(int i=0; i<chars.length; i++) {
    if (chars[i] == c) {
      count++;
    }
  }
  return count;
}

Using replaceAll (that is RE) does not sound like the best way to go.

how to add script inside a php code?

You mean you want to show a javascript alert when a button is clicked on a PHP generated page?

echo('<button type="button" onclick="alert(\'Alrt Text!\');">My Button</button>');

Would do that

Virtual Serial Port for Linux

Using the links posted in the previous answers, I coded a little example in C++ using a Virtual Serial Port. I pushed the code into GitHub: https://github.com/cymait/virtual-serial-port-example .

The code is pretty self explanatory. First, you create the master process by running ./main master and it will print to stderr the device is using. After that, you invoke ./main slave device, where device is the device printed in the first command.

And that's it. You have a bidirectional link between the two process.

Using this example you can test you the application by sending all kind of data, and see if it works correctly.

Also, you can always symlink the device, so you don't need to re-compile the application you are testing.

Multi-key dictionary in c#?

Tuples will be (are) in .Net 4.0 Until then, you can also use a

 Dictionary<key1, Dictionary<key2, TypeObject>> 

or, creating a custom collection class to represent this...

 public class TwoKeyDictionary<K1, K2, T>: 
        Dictionary<K1, Dictionary<K2, T>> { }

or, with three keys...

public class ThreeKeyDictionary<K1, K2, K3, T> :
    Dictionary<K1, Dictionary<K2, Dictionary<K3, T>>> { }

Removing items from a list

You can't and shouldn't modify a list while iterating over it. You can solve this by temporarely saving the objects to remove:

List<Object> toRemove = new ArrayList<Object>();
for(Object a: list){
    if(a.getXXX().equalsIgnoreCase("AAA")){
        toRemove.add(a);
    }
}
list.removeAll(toRemove);

Check if returned value is not null and if so assign it, in one line, with one method call

If you're not on java 1.8 yet and you don't mind to use commons-lang you can use org.apache.commons.lang3.ObjectUtils#defaultIfNull

Your code would be:

dinner = ObjectUtils.defaultIfNull(cage.getChicken(),getFreeRangeChicken())

Counting the occurrences / frequency of array elements

Here's just something light and easy for the eyes...

function count(a,i){
 var result = 0;
 for(var o in a)
  if(a[o] == i)
   result++;
 return result;
}

Edit: And since you want all the occurences...

function count(a){
 var result = {};
 for(var i in a){
  if(result[a[i]] == undefined) result[a[i]] = 0;
  result[a[i]]++;
 }
 return result;
}

How do you declare string constants in C?

If you want a "const string" like your question says, I would really go for the version you stated in your question:

/* first version */
const char *HELLO2 = "Howdy";

Particularly, I would avoid:

/* second version */
const char HELLO2[] = "Howdy";

Reason: The problem with second version is that compiler will make a copy of the entire string "Howdy", PLUS that string is modifiable (so not really const).

On the other hand, first version is a const string accessible by const pointer HELLO2, and there is no way anybody can modify it.

How to order citations by appearance using BibTeX?

If you happen to be using amsrefs they will override all the above - so comment out:

\usepackage{amsrefs}

Convert `List<string>` to comma-separated string

To expand on Jon Skeets answer the code for this in .Net 4 is:

string myCommaSeperatedString = string.Join(",",ls);

Increasing the maximum number of TCP/IP connections in Linux

There are a couple of variables to set the max number of connections. Most likely, you're running out of file numbers first. Check ulimit -n. After that, there are settings in /proc, but those default to the tens of thousands.

More importantly, it sounds like you're doing something wrong. A single TCP connection ought to be able to use all of the bandwidth between two parties; if it isn't:

  • Check if your TCP window setting is large enough. Linux defaults are good for everything except really fast inet link (hundreds of mbps) or fast satellite links. What is your bandwidth*delay product?
  • Check for packet loss using ping with large packets (ping -s 1472 ...)
  • Check for rate limiting. On Linux, this is configured with tc
  • Confirm that the bandwidth you think exists actually exists using e.g., iperf
  • Confirm that your protocol is sane. Remember latency.
  • If this is a gigabit+ LAN, can you use jumbo packets? Are you?

Possibly I have misunderstood. Maybe you're doing something like Bittorrent, where you need lots of connections. If so, you need to figure out how many connections you're actually using (try netstat or lsof). If that number is substantial, you might:

  • Have a lot of bandwidth, e.g., 100mbps+. In this case, you may actually need to up the ulimit -n. Still, ~1000 connections (default on my system) is quite a few.
  • Have network problems which are slowing down your connections (e.g., packet loss)
  • Have something else slowing you down, e.g., IO bandwidth, especially if you're seeking. Have you checked iostat -x?

Also, if you are using a consumer-grade NAT router (Linksys, Netgear, DLink, etc.), beware that you may exceed its abilities with thousands of connections.

I hope this provides some help. You're really asking a networking question.

Opening a .ipynb.txt File

These steps work for me:

  • Open the file in Jupyter Notebook.
  • Rename the file: Click File > Rename, change the name so that it ends with '.ipynb' behind, and click OK
  • Close the file.
  • From the Jupyter Notebook's directory tree, click the filename to open it.

Hide password with "•••••••" in a textField

You can achieve this directly in Xcode:

enter image description here

The very last checkbox, make sure secure is checked .

Or you can do it using code:

Identifies whether the text object should hide the text being entered.

Declaration

optional var secureTextEntry: Bool { get set }

Discussion

This property is set to false by default. Setting this property to true creates a password-style text object, which hides the text being entered.

example:

texfield.secureTextEntry = true

How to skip the OPTIONS preflight request?

Preflight is a web security feature implemented by the browser. For Chrome you can disable all web security by adding the --disable-web-security flag.

For example: "C:\Program Files\Google\Chrome\Application\chrome.exe" --disable-web-security --user-data-dir="C:\newChromeSettingsWithoutSecurity" . You can first create a new shortcut of chrome, go to its properties and change the target as above. This should help!

How to correctly use "section" tag in HTML5?

My understanding is that SECTION holds a section with a heading which is an important part of the "flow" of the page (not an aside). SECTIONs would be chapters, numbered parts of documents and so on.

ARTICLE is for syndicated content -- e.g. posts, news stories etc. ARTICLE and SECTION are completely separate -- you can have one without the other as they are very different use cases.

Another thing about SECTION is that you shouldn't use it if your page has only the one section. Also, each section must have a heading (H1-6, HGROUP, HEADING). Headings are "scoped" withing the SECTION, so e.g. if you use a H1 in the main page (outside a SECTION) and then a H1 inside the section, the latter will be treated as an H2.

The examples in the spec are pretty good at time of writing.

So in your first example would be correct if you had several sections of content which couldn't be described as ARTICLEs. (With a minor point that you wouldn't need the #primary DIV unless you wanted it for a style hook - P tags would be better).

The second example would be correct if you removed all the SECTION tags -- the data in that document would be articles, posts or something like this.

SECTIONs should not be used as containers -- DIV is still the correct use for that, and any other custom box you might come up with.

Keyboard shortcut to comment lines in Sublime Text 2

In my keyboard (Swedish) it´s the key to the right of "ä": "*".

ctrl+*

How do I calculate a trendline for a graph?

This is the way i calculated the slope: Source: http://classroom.synonym.com/calculate-trendline-2709.html

class Program
    {
        public double CalculateTrendlineSlope(List<Point> graph)
        {
            int n = graph.Count;
            double a = 0;
            double b = 0;
            double bx = 0;
            double by = 0;
            double c = 0;
            double d = 0;
            double slope = 0;

            foreach (Point point in graph)
            {
                a += point.x * point.y;
                bx = point.x;
                by = point.y;
                c += Math.Pow(point.x, 2);
                d += point.x;
            }
            a *= n;
            b = bx * by;
            c *= n;
            d = Math.Pow(d, 2);

            slope = (a - b) / (c - d);
            return slope;
        }
    }

    class Point
    {
        public double x;
        public double y;
    }

Set cookies for cross origin requests

What you need to do

To allow receiving & sending cookies by a CORS request successfully, do the following.

Back-end (server): Set the HTTP header Access-Control-Allow-Credentials value to true. Also, make sure the HTTP headers Access-Control-Allow-Origin and Access-Control-Allow-Headers are set and not with a wildcard *.

Recommended Cookie settings per Chrome and Firefox update in 2021: SameSite=None and Secure. See MDN documentation

For more info on setting CORS in express js read the docs here

Front-end (client): Set the XMLHttpRequest.withCredentials flag to true, this can be achieved in different ways depending on the request-response library used:

Or

Avoid having to use CORS in combination with cookies. You can achieve this with a proxy.

If you for whatever reason don't avoid it. The solution is above.

It turned out that Chrome won't set the cookie if the domain contains a port. Setting it for localhost (without port) is not a problem. Many thanks to Erwin for this tip!

How to increase Java heap space for a tomcat app

For Windows Service, you need to run tomcat9w.exe (or 6w/7w/8w) depending on your version of tomcat. First, make sure tomcat is stopped. Then double click on tomcat9w.exe. Navigate to the Java tab. If you know you have 64 bit Windows with 64 bit Java and 64 bit Tomcat, then feel free to set the memory higher than 512. You'll need to do some task manager monitoring to determine how high to set it. For most apps developed in 2019... I'd recommend an initial memory pool of 1024, and the maximum memory pool of 2048. Of course if your computer has tons of RAM... feel free to go as high as you want. Also, see this answer: How to increase Maximum Memory Pool Size? Apache Tomcat 9

Get json value from response

var results = {"id":"2231f87c-a62c-4c2c-8f5d-b76d11942301"}
console.log(results.id)
=>2231f87c-a62c-4c2c-8f5d-b76d11942301

results is now an object.

Highcharts - how to have a chart with dynamic height?

Alternatively, you can directly use javascript's window.onresize

As example, my code (using scriptaculos) is :

window.onresize = function (){
    var w = $("form").getWidth() + "px";
    $('gfx').setStyle( { width : w } );
}

Where form is an html form on my webpage and gfx the highchart graphics.

Do I need a content-type header for HTTP GET requests?

Get requests should not have content-type because they do not have request entity (that is, a body)

Python pandas: fill a dataframe row by row

df['y'] will set a column

since you want to set a row, use .loc

Note that .ix is equivalent here, yours failed because you tried to assign a dictionary to each element of the row y probably not what you want; converting to a Series tells pandas that you want to align the input (for example you then don't have to to specify all of the elements)

In [7]: df = pandas.DataFrame(columns=['a','b','c','d'], index=['x','y','z'])

In [8]: df.loc['y'] = pandas.Series({'a':1, 'b':5, 'c':2, 'd':3})

In [9]: df
Out[9]: 
     a    b    c    d
x  NaN  NaN  NaN  NaN
y    1    5    2    3
z  NaN  NaN  NaN  NaN

ggplot2 plot area margins?

You can adjust the plot margins with plot.margin in theme() and then move your axis labels and title with the vjust argument of element_text(). For example :

library(ggplot2)
library(grid)
qplot(rnorm(100)) +
    ggtitle("Title") +
    theme(axis.title.x=element_text(vjust=-2)) +
    theme(axis.title.y=element_text(angle=90, vjust=-0.5)) +
    theme(plot.title=element_text(size=15, vjust=3)) +
    theme(plot.margin = unit(c(1,1,1,1), "cm"))

will give you something like this :

enter image description here

If you want more informations about the different theme() parameters and their arguments, you can just enter ?theme at the R prompt.

What is an OS kernel ? How does it differ from an operating system?

The kernel might be the operating system or it might be a part of the operating system. In Linux, the kernel is loaded and executed first. Then it starts up other bits of the OS (like init) to make the system useful.

This is especially true in a micro-kernel environment. The kernel has minimal functionality. Everything else, like file systems and TCP/IP, run as a user process.

Add multiple items to a list

Code check:

This is offtopic here but the people over at CodeReview are more than happy to help you.

I strongly suggest you to do so, there are several things that need attention in your code. Likewise I suggest that you do start reading tutorials since there is really no good reason not to do so.

Lists:

As you said yourself: you need a list of items. The way it is now you only store a reference to one item. Lucky there is exactly that to hold a group of related objects: a List.

Lists are very straightforward to use but take a look at the related documentation anyway.

A very simple example to keep multiple bikes in a list:

List<Motorbike> bikes = new List<Motorbike>();

bikes.add(new Bike { make = "Honda", color = "brown" });
bikes.add(new Bike { make = "Vroom", color = "red" });

And to iterate over the list you can use the foreach statement:

foreach(var bike in bikes) {
     Console.WriteLine(bike.make);
}

What's the difference between F5 refresh and Shift+F5 in Google Chrome browser?

The difference is not just for Chrome but for most of the web browsers.

enter image description here

F5 refreshes the web page and often reloads the same page from the cached contents of the web browser. However, reloading from cache every time is not guaranteed and it also depends upon the cache expiry.

Shift + F5 forces the web browser to ignore its cached contents and retrieve a fresh copy of the web page into the browser.

Shift + F5 guarantees loading of latest contents of the web page.
However, depending upon the size of page, it is usually slower than F5.

You may want to refer to: What requests do browsers' "F5" and "Ctrl + F5" refreshes generate?

Getting the last element of a list

You can also do:

alist.pop()

It depends on what you want to do with your list because the pop() method will delete the last element.

What is the best way to iterate over multiple lists at once?

The usual way is to use zip():

for x, y in zip(a, b):
    # x is from a, y is from b

This will stop when the shorter of the two iterables a and b is exhausted. Also worth noting: itertools.izip() (Python 2 only) and itertools.izip_longest() (itertools.zip_longest() in Python 3).

How to compress a String in Java?

Huffman encoding is a sensible option here. Gzip and friends do this, but the way they work is to build a Huffman tree for the input, send that, then send the data encoded with the tree. If the tree is large relative to the data, there may be no not saving in size.

However, it is possible to avoid sending a tree: instead, you arrange for the sender and receiver to already have one. It can't be built specifically for every string, but you can have a single global tree used to encode all strings. If you build it from the same language as the input strings (English or whatever), you should still get good compression, although not as good as with a custom tree for every input.

What does the NS prefix mean?

When NeXT were defining the NextStep API (as opposed to the NEXTSTEP operating system), they used the prefix NX, as in NXConstantString. When they were writing the OpenStep specification with Sun (not to be confused with the OPENSTEP operating system) they used the NS prefix, as in NSObject.

RS256 vs HS256: What's the difference?

Both choices refer to what algorithm the identity provider uses to sign the JWT. Signing is a cryptographic operation that generates a "signature" (part of the JWT) that the recipient of the token can validate to ensure that the token has not been tampered with.

  • RS256 (RSA Signature with SHA-256) is an asymmetric algorithm, and it uses a public/private key pair: the identity provider has a private (secret) key used to generate the signature, and the consumer of the JWT gets a public key to validate the signature. Since the public key, as opposed to the private key, doesn't need to be kept secured, most identity providers make it easily available for consumers to obtain and use (usually through a metadata URL).

  • HS256 (HMAC with SHA-256), on the other hand, involves a combination of a hashing function and one (secret) key that is shared between the two parties used to generate the hash that will serve as the signature. Since the same key is used both to generate the signature and to validate it, care must be taken to ensure that the key is not compromised.

If you will be developing the application consuming the JWTs, you can safely use HS256, because you will have control on who uses the secret keys. If, on the other hand, you don't have control over the client, or you have no way of securing a secret key, RS256 will be a better fit, since the consumer only needs to know the public (shared) key.

Since the public key is usually made available from metadata endpoints, clients can be programmed to retrieve the public key automatically. If this is the case (as it is with the .Net Core libraries), you will have less work to do on configuration (the libraries will fetch the public key from the server). Symmetric keys, on the other hand, need to be exchanged out of band (ensuring a secure communication channel), and manually updated if there is a signing key rollover.

Auth0 provides metadata endpoints for the OIDC, SAML and WS-Fed protocols, where the public keys can be retrieved. You can see those endpoints under the "Advanced Settings" of a client.

The OIDC metadata endpoint, for example, takes the form of https://{account domain}/.well-known/openid-configuration. If you browse to that URL, you will see a JSON object with a reference to https://{account domain}/.well-known/jwks.json, which contains the public key (or keys) of the account.

If you look at the RS256 samples, you will see that you don't need to configure the public key anywhere: it's retrieved automatically by the framework.

How to upload a project to Github

Probably the most useful thing you could do is to peruse the online book [http://git-scm.com/book/en/]. It's really a pretty decent read and gives you the conceptual context with which to execute things properly.

Add a link to an image in a css style sheet

You can not do that...

via css the URL you put on the background-image is just for the image.

Via HTML you have to add the href for your hyperlink in this way:

<a href="http://home.com" id="logo">Your logo</a>

With text-indent and some other css you can adjust your a element to show just the image and clicking on it you will go to your link.


EDIT:

I'm here again to show you and explain why my solution is much better:

<a href="http://home.com" id="logo">Your logo name</a>

This block of HTML is SEO friendly because you have some text inside your link!

How to style it with css:

#logo {
  background-image: url(images/logo.png);
  display: block;
  margin: 0 auto;
  text-indent: -9999px;
  width: 981px;
  height: 180px;
}

Then if you don't care about SEO good to choose the other answer.