Programs & Examples On #Macvim

MacVim is a version of the Vim text editor for Mac OS X.

What are the most-used vim commands/keypresses?

I can't imagine everyone uses all 20 different keypresses to navigate text, 10 or so keys to start adding text, and 18 ways to visually select an inner block. Or do you!?

I do.

In theory, once I have that and start becoming as proficient in VIM as I am in Textmate, then I can start learning the thousands of other VIM commands that will make me more efficient.

That's the right way to do it. Start with basic commands and then pick up ones that improve your productivity. I like following this blog for tips on how to improve my productivity with vim.

Highlight all occurrence of a selected word?

I know than it's a really old question, but if someone is interested in this feature, can check this code http://vim.wikia.com/wiki/Auto_highlight_current_word_when_idle

" Highlight all instances of word under cursor, when idle.
" Useful when studying strange source code.
" Type z/ to toggle highlighting on/off.
nnoremap z/ :if AutoHighlightToggle()<Bar>set hls<Bar>endif<CR>
function! AutoHighlightToggle()
   let @/ = ''
   if exists('#auto_highlight')
     au! auto_highlight
     augroup! auto_highlight
     setl updatetime=4000
     echo 'Highlight current word: off'
     return 0
  else
    augroup auto_highlight
    au!
    au CursorHold * let @/ = '\V\<'.escape(expand('<cword>'), '\').'\>'
    augroup end
    setl updatetime=500
    echo 'Highlight current word: ON'
  return 1
 endif
endfunction

How can I install MacVim on OS X?

  1. Download the latest build from https://github.com/macvim-dev/macvim/releases

  2. Expand the archive.

  3. Put MacVim.app into /Applications/.

Done.

What is the <leader> in a .vimrc file?

The <Leader> key is mapped to \ by default. So if you have a map of <Leader>t, you can execute it by default with \+t. For more detail or re-assigning it using the mapleader variable, see

:help leader

To define a mapping which uses the "mapleader" variable, the special string
"<Leader>" can be used.  It is replaced with the string value of "mapleader".
If "mapleader" is not set or empty, a backslash is used instead.  
Example:
    :map <Leader>A  oanother line <Esc>
Works like:
    :map \A  oanother line <Esc>
But after:
    :let mapleader = ","
It works like:
    :map ,A  oanother line <Esc>

Note that the value of "mapleader" is used at the moment the mapping is
defined.  Changing "mapleader" after that has no effect for already defined
mappings.


How to run mvim (MacVim) from Terminal?

There should be a script named mvim in the root of the .bz2 file. Copy this somewhere into your $PATH ( /usr/local/bin would be good ) and you should be sorted.

What is the difference between MacVim and regular Vim?

The one reason I have which made switching to MacVim worth it: Yank uses the system clipboard.

I can finally copy paste between MacVim on my terminal and the rest of my applications.

Autocompletion in Vim

Use Ctrl-N to get a list of word suggestions while in insert mode. Type :help i_CTRL-N to see Vim's documentation on this functionality.

Here is an example of importing the Python dictionary into Vim.

How to transform numpy.matrix or array to scipy sparse matrix

There are several sparse matrix classes in scipy.

bsr_matrix(arg1[, shape, dtype, copy, blocksize]) Block Sparse Row matrix
coo_matrix(arg1[, shape, dtype, copy]) A sparse matrix in COOrdinate format.
csc_matrix(arg1[, shape, dtype, copy]) Compressed Sparse Column matrix
csr_matrix(arg1[, shape, dtype, copy]) Compressed Sparse Row matrix
dia_matrix(arg1[, shape, dtype, copy]) Sparse matrix with DIAgonal storage
dok_matrix(arg1[, shape, dtype, copy]) Dictionary Of Keys based sparse matrix.
lil_matrix(arg1[, shape, dtype, copy]) Row-based linked list sparse matrix

Any of them can do the conversion.

import numpy as np
from scipy import sparse
a=np.array([[1,0,1],[0,0,1]])
b=sparse.csr_matrix(a)
print(b)

(0, 0)  1
(0, 2)  1
(1, 2)  1

See http://docs.scipy.org/doc/scipy/reference/sparse.html#usage-information .

How do I call a dynamically-named method in Javascript?

A simple function to call a function dynamically with parameters:

this.callFunction = this.call_function = function(name) {
    var args = Array.prototype.slice.call(arguments, 1);
    return window[name].call(this, ...args);
};

function sayHello(name, age) {
    console.log('hello ' + name + ', your\'e age is ' + age);
    return some;
}

console.log(call_function('sayHello', 'john', 30)); // hello john, your'e age is 30

Python virtualenv questions

Yes basically this is what virtualenv do , and this is what the activate command is for, from the doc here:

activate script

In a newly created virtualenv there will be a bin/activate shell script, or a Scripts/activate.bat batch file on Windows.

This will change your $PATH to point to the virtualenv bin/ directory. Unlike workingenv, this is all it does; it's a convenience. But if you use the complete path like /path/to/env/bin/python script.py you do not need to activate the environment first. You have to use source because it changes the environment in-place. After activating an environment you can use the function deactivate to undo the changes.

The activate script will also modify your shell prompt to indicate which environment is currently active.

so you should just use activate command which will do all that for you:

> \path\to\env\bin\activate.bat

ImportError: No module named PyQt4

After brew install pyqt, you can brew test pyqt which will use the python you have got in your PATH in oder to do the test (show a Qt window).

For non-brewed Python, you'll have to set your PYTHONPATH as brew info pyqt will tell.

Sometimes it is necessary to open a new shell or tap in order to use the freshly brewed binaries.

I frequently check these issues by printing the sys.path from inside of python: python -c "import sys; print(sys.path)" The $(brew --prefix)/lib/pythonX.Y/site-packages have to be in the sys.path in order to be able to import stuff. As said, for brewed python, this is default but for any other python, you will have to set the PYTHONPATH.

wamp server mysql user id and password

Use http://localhost/sqlbuddy --> users interface.

You can find it at the localhost main page at Your Aliases section.

CMD what does /im (taskkill)?

im is "image process name" example /f /im notepad.exe is specified to kill image process name (program) notepad.exe

JQuery - Get select value

val() returns the value of the <select> element, i.e. the value attribute of the selected <option> element.

Since you actually want the inner text of the selected <option> element, you should match that element and use text() instead:

var nationality = $("#dancerCountry option:selected").text();

List file names based on a filename pattern and file content?

It can be done without find as well by using grep's "--include" option.

grep man page says:

--include=GLOB
Search only files whose base name matches GLOB (using wildcard matching as described under --exclude).

So to do a recursive search for a string in a file matching a specific pattern, it will look something like this:

grep -r --include=<pattern> <string> <directory>

For example, to recursively search for string "mytarget" in all Makefiles:

grep -r --include="Makefile" "mytarget" ./

Or to search in all files starting with "Make" in filename:

grep -r --include="Make*" "mytarget" ./

Detect if the app was launched/opened from a push notification

There is only one reliable way, and it works only for iOS 10+ :

Using UNUserNotificationCenter implement UNUserNotificationCenterDelegate method:

- (void) userNotificationCenter:(UNUserNotificationCenter *)center didReceiveNotificationResponse:(UNNotificationResponse *)response withCompletionHandler:(void (^)(void))completionHandler {

    //Here you can get your original push if you need to
    NSDictionary* pusDict = response.notification.request.content.userInfo;

    if ([response.actionIdentifier isEqualToString: UNNotificationDefaultActionIdentifier]) {
        //User tapped the notification
    } else if ([response.actionIdentifier isEqualToString: UNNotificationDismissActionIdentifier]) {
        //User dismissed the notification 
    } else if ([response.actionIdentifier isEqualToString: MYCustomActionId]) {
        //User chose my custom defined action
    }
    ...
}

Finding duplicate integers in an array and display how many times they occurred

int copt = 1;
int element = 0;
int[] array = { 1, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 5 };
for (int i = 0; i < array.Length; i++)
{
   for (int j = i + 1; j < array.Length - 1; j++)
   {
       if (array[i] == array[j])
       {
          element = array[i];
          copt++;
          break;
       }
   }
}

Console.WriteLine("the repeat element is {0} and it's appears {1} times ", element, copt);
Console.ReadKey();

// the output is the element is 3 and appears 9 times

Python Requests - No connection adapters

You need to include the protocol scheme:

'http://192.168.1.61:8080/api/call'

Without the http:// part, requests has no idea how to connect to the remote server.

Note that the protocol scheme must be all lowercase; if your URL starts with HTTP:// for example, it won’t find the http:// connection adapter either.

Convert a String of Hex into ASCII in Java

Just use a for loop to go through each couple of characters in the string, convert them to a character and then whack the character on the end of a string builder:

String hex = "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";
StringBuilder output = new StringBuilder();
for (int i = 0; i < hex.length(); i+=2) {
    String str = hex.substring(i, i+2);
    output.append((char)Integer.parseInt(str, 16));
}
System.out.println(output);

Or (Java 8+) if you're feeling particularly uncouth, use the infamous "fixed width string split" hack to enable you to do a one-liner with streams instead:

System.out.println(Arrays
        .stream(hex.split("(?<=\\G..)")) //https://stackoverflow.com/questions/2297347/splitting-a-string-at-every-n-th-character
        .map(s -> Character.toString((char)Integer.parseInt(s, 16)))
        .collect(Collectors.joining()));

Either way, this gives a few lines starting with the following:

uTorrent\Completed\nfsuc_ost_by_mustang\Pendulum-9,000 Miles.mp3

Hmmm... :-)

MySQL: How to reset or change the MySQL root password?

You can try these some steps to reset mysql 5.7 root password :

Stop Mysql Service 1st

sudo /etc/init.d/mysql stop 

Login as root without password sudo mysqld_safe --skip-grant-tables &

After login mysql terminal you should need execute commands more:

use mysql;




UPDATE mysql.user SET authentication_string=PASSWORD('solutionclub3@*^G'), plugin='mysql_native_password' WHERE User='root';


flush privileges;


sudo mysqladmin -S /var/run/mysqld/mysqld.sock shutdown

After you restart your mysql server If you still facing error you must visit : Reset MySQL 5.7 root password Ubuntu 16.04

How to check if a python module exists without importing it

After use yarbelk's response, I've made this for don't have to import ìmp.

try:
    __import__('imp').find_module('eggs')
    # Make things with supposed existing module
except ImportError:
    pass

Useful in Django's settings.pyfor example.

Ansible: create a user with sudo privileges

Sometimes it's knowing what to ask. I didn't know as I am a developer who has taken on some DevOps work.

Apparently 'passwordless' or NOPASSWD login is a thing which you need to put in the /etc/sudoers file.

The answer to my question is at Ansible: best practice for maintaining list of sudoers.

The Ansible playbook code fragment looks like this from my problem:

- name: Make sure we have a 'wheel' group
  group:
    name: wheel
    state: present

- name: Allow 'wheel' group to have passwordless sudo
  lineinfile:
    dest: /etc/sudoers
    state: present
    regexp: '^%wheel'
    line: '%wheel ALL=(ALL) NOPASSWD: ALL'
    validate: 'visudo -cf %s'

- name: Add sudoers users to wheel group
  user:
    name=deployer
    groups=wheel
    append=yes
    state=present
    createhome=yes

- name: Set up authorized keys for the deployer user
  authorized_key: user=deployer key="{{item}}"
  with_file:
    - /home/railsdev/.ssh/id_rsa.pub

And the best part is that the solution is idempotent. It doesn't add the line

%wheel ALL=(ALL) NOPASSWD: ALL

to /etc/sudoers when the playbook is run a subsequent time. And yes...I was able to ssh into the server as "deployer" and run sudo commands without having to give a password.

Extracting numbers from vectors of strings

Or simply:

as.numeric(gsub("\\D", "", years))
# [1] 20  1

A SQL Query to select a string between two known strings

I had a similar need to parse out a set of parameters stored within an IIS logs' csUriQuery field, which looked like this: id=3598308&user=AD\user&parameter=1&listing=No needed in this format.

I ended up creating a User-defined function to accomplish a string between, with the following assumptions:

  1. If the starting occurrence is not found, a NULL is returned, and
  2. If the ending occurrence is not found, the rest of the string is returned

Here's the code:

CREATE FUNCTION dbo.str_between(@col varchar(max), @start varchar(50), @end varchar(50))  
  RETURNS varchar(max)  
  WITH EXECUTE AS CALLER  
AS  
BEGIN  
  RETURN substring(@col, charindex(@start, @col) + len(@start), 
         isnull(nullif(charindex(@end, stuff(@col, 1, charindex(@start, @col)-1, '')),0),
         len(stuff(@col, 1, charindex(@start, @col)-1, ''))+1) - len(@start)-1);
END;  
GO

For the above question, the usage is as follows:

DECLARE @a VARCHAR(MAX) = 'All I knew was that the dog had been very bad and required harsh punishment immediately regardless of what anyone else thought.'
SELECT dbo.str_between(@a, 'the dog', 'immediately')
-- Yields' had been very bad and required harsh punishment '

What is the difference between "INNER JOIN" and "OUTER JOIN"?

Simplest Definitions

Inner Join: Returns matched records from both tables.

Full Outer Join: Returns matched and unmatched records from both tables with null for unmatched records from Both Tables.

Left Outer Join: Returns matched and unmatched records only from table on Left Side.

Right Outer Join: Returns matched and unmatched records only from table on Right Side.

In-Short

Matched + Left Unmatched + Right Unmatched = Full Outer Join

Matched + Left Unmatched = Left Outer Join

Matched + Right Unmatched = Right Outer Join

Matched = Inner Join

getSupportActionBar() The method getSupportActionBar() is undefined for the type TaskActivity. Why?

If you are already extending from ActionBarActivity and you are trying to get the action bar from a fragment:

ActionBar mActionBar = (ActionBarActivity)getActivity()).getSupportActionBar();

Project Links do not work on Wamp Server

Re: Wampserver LocalHost links not working correctly
This is as of June 2014 with Wampserver2.5 (maybe they'll fix this in later builds).
Note: to use LocalHost:8080 instead of LocalHost just make the appropriate changes in the edits mentioned below.

There are 2 aspects of this issue -
The first is to be able to access items under "Your Projects" from the Wamp localhost homepage.
The second is to be able to correctly access items listed in the Wampserver Icon Taskbar's "My Projects" list.

To fix the first (to be able to access items under "Your Projects" from the Wamp localhost homepage) you will need to do the following...

There are 2 edits that you must make in the index.php file located in your wamp\www folder (usually C:\wamp\www)

1) on Line 30 change

  $suppress_localhost = true;

to

  $suppress_localhost = false;

2) on line 338 change

  $projectContents .= '<li><a href="'.($suppress_localhost ? 'http://' : '').$file.'">'.$file.'</a></li>';

to

  $projectContents .= '<li><a href="'.($suppress_localhost ? 'http://' : 'http://localhost//').$file.'">'.$file.'</a></li>';

After you've made the above edits - if the Wampserver is running just refresh the local host page and the changes become immediately effective.

To fix the 2nd item (the Wampserver Icon Taskbar's "My Projects" list): You need to edit C:\wamp\scripts\refresh.php

Locate line 651 and change the section of the line that reads

   Parameters: "http://'.$projectContents[$i].'/"; Glyph: 5

to

   Parameters: "http://localhost//'.$projectContents[$i].'/"; Glyph: 5

After you make these 2nd set of changes you may have to force Wampserver to refresh the "My Projects" list by toggling the Put Online/Offline option at the bottom of the Wamp Icon Tray App.

Filter rows which contain a certain string

The answer to the question was already posted by the @latemail in the comments above. You can use regular expressions for the second and subsequent arguments of filter like this:

dplyr::filter(df, !grepl("RTB",TrackingPixel))

Since you have not provided the original data, I will add a toy example using the mtcars data set. Imagine you are only interested in cars produced by Mazda or Toyota.

mtcars$type <- rownames(mtcars)
dplyr::filter(mtcars, grepl('Toyota|Mazda', type))

   mpg cyl  disp  hp drat    wt  qsec vs am gear carb           type
1 21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4      Mazda RX4
2 21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4  Mazda RX4 Wag
3 33.9   4  71.1  65 4.22 1.835 19.90  1  1    4    1 Toyota Corolla
4 21.5   4 120.1  97 3.70 2.465 20.01  1  0    3    1  Toyota Corona

If you would like to do it the other way round, namely excluding Toyota and Mazda cars, the filter command looks like this:

dplyr::filter(mtcars, !grepl('Toyota|Mazda', type))

SQL/mysql - Select distinct/UNIQUE but return all columns?

It can be done by inner query

$query = "SELECT * 
            FROM (SELECT field
                FROM table
                ORDER BY id DESC) as rows               
            GROUP BY field";

Github Windows 'Failed to sync this branch'

I had the same problem when I tried from inside Visual Studio and "git status" in shell showed no problem. But I managed to push the local changes with "git push" via shell.

How to get Map data using JDBCTemplate.queryForMap

To add to @BrianBeech's answer, this is even more trimmed down in java 8:

jdbcTemplate.query("select string1,string2 from table where x=1", (ResultSet rs) -> {
    HashMap<String,String> results = new HashMap<>();
    while (rs.next()) {
        results.put(rs.getString("string1"), rs.getString("string2"));
    }
    return results;
});

How to bind inverse boolean properties in WPF?

Don't know if this is relevant to XAML, but in my simple Windows app I created the binding manually and added a Format event handler.

public FormMain() {
  InitializeComponent();

  Binding argBinding = new Binding("Enabled", uxCheckBoxArgsNull, "Checked", false, DataSourceUpdateMode.OnPropertyChanged);
  argBinding.Format += new ConvertEventHandler(Binding_Format_BooleanInverse);
  uxTextBoxArgs.DataBindings.Add(argBinding);
}

void Binding_Format_BooleanInverse(object sender, ConvertEventArgs e) {
  bool boolValue = (bool)e.Value;
  e.Value = !boolValue;
}

Is there a way to get a <button> element to link to a location without wrapping it in an <a href ... tag?

<form action="portfolio.html">
 <button type="link" class="btn btn-primary btn-lg">View Work</button>
</form>

I just figured this out, and it links perfectly to another page without having my default link settings over ride my button classes! :)

How can I display two div in one line via css inline property

use inline-block instead of inline. Read more information here about the difference between inline and inline-block.

.inline { 
display: inline-block; 
border: 1px solid red; 
margin:10px;
}

DEMO

Why can't Python find shared objects that are in directories in sys.path?

You can also set LD_RUN_PATH to /usr/local/lib in your user environment when you compile pycurl in the first place. This will embed /usr/local/lib in the RPATH attribute of the C extension module .so so that it automatically knows where to find the library at run time without having to have LD_LIBRARY_PATH set at run time.

Insert, on duplicate update in PostgreSQL?

There is no simple command to do it.

The most correct approach is to use function, like the one from docs.

Another solution (although not that safe) is to do update with returning, check which rows were updates, and insert the rest of them

Something along the lines of:

update table
set column = x.column
from (values (1,'aa'),(2,'bb'),(3,'cc')) as x (id, column)
where table.id = x.id
returning id;

assuming id:2 was returned:

insert into table (id, column) values (1, 'aa'), (3, 'cc');

Of course it will bail out sooner or later (in concurrent environment), as there is clear race condition in here, but usually it will work.

Here's a longer and more comprehensive article on the topic.

Rails - How to use a Helper Inside a Controller

In general, if the helper is to be used in (just) controllers, I prefer to declare it as an instance method of class ApplicationController.

How to join multiple collections with $lookup in mongodb

You can actually chain multiple $lookup stages. Based on the names of the collections shared by profesor79, you can do this :

db.sivaUserInfo.aggregate([
    {
        $lookup: {
           from: "sivaUserRole",
           localField: "userId",
           foreignField: "userId",
           as: "userRole"
        }
    },
    {
        $unwind: "$userRole"
    },
    {
        $lookup: {
            from: "sivaUserInfo",
            localField: "userId",
            foreignField: "userId",
            as: "userInfo"
        }
    },
    {
        $unwind: "$userInfo"
    }
])

This will return the following structure :

{
    "_id" : ObjectId("56d82612b63f1c31cf906003"),
    "userId" : "AD",
    "phone" : "0000000000",
    "userRole" : {
        "_id" : ObjectId("56d82612b63f1c31cf906003"),
        "userId" : "AD",
        "role" : "admin"
    },
    "userInfo" : {
        "_id" : ObjectId("56d82612b63f1c31cf906003"),
        "userId" : "AD",
        "phone" : "0000000000"
    }
}

Maybe this could be considered an anti-pattern because MongoDB wasn't meant to be relational but it is useful.

Editing specific line in text file in Python

I have been practising working on files this evening and realised that I can build on Jochen's answer to provide greater functionality for repeated/multiple use. Unfortunately my answer does not address issue of dealing with large files but does make life easier in smaller files.

with open('filetochange.txt', 'r+') as foo:
    data = foo.readlines()                  #reads file as list
    pos = int(input("Which position in list to edit? "))-1  #list position to edit
    data.insert(pos, "more foo"+"\n")           #inserts before item to edit
    x = data[pos+1]
    data.remove(x)                      #removes item to edit
    foo.seek(0)                     #seeks beginning of file
    for i in data:
        i.strip()                   #strips "\n" from list items
        foo.write(str(i))

Replace words in a string - Ruby

First, you don't declare the type in Ruby, so you don't need the first string.

To replace a word in string, you do: sentence.gsub(/match/, "replacement").

Set the layout weight of a TextView programmatically

I had a fair amount of difficulty with a solution something very similar to this: trying to have two buttons in a TableRow, with each being half the screen width. For whatever reason, the left button would always be about 70% of the width, and the right button 30%. Calling table_layout.setStretchAllColumns(true) had no effect, nor did setting the button's width to half the screen, nor setting their layout weight.

The solution I ended up with was nesting a LinearLayout in the TableRows, which did take into account the value of the buttons' width.

    TableLayout layout = new TableLayout(this);
    TableRow top_row = new TableRow(this);
    left_button = styleButton();
    right_button = styleButton();
    LinearLayout toprow_layout = new LinearLayout (this);
    toprow_layout.setOrientation(LinearLayout.HORIZONTAL);
    toprow_layout.addView (left_button);
    toprow_layout.addView(right_button);
    toprow.addView(top_layout);
    layout.addView(top_row)

    private Button styleButton() {
            Button btn = new Button (this);
            android.view.Display display = ((android.view.WindowManager)getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();      
            btn.setWidth((int)(display.getWidth()/2));    // set width to half
            btn.setHeight(((int)display.getHeight()/6));  // set height to whatevs
            btn.setText("foo");
            return btn;
        }

How can I check if a jQuery plugin is loaded?

for the plugins that doesn't use fn namespace (for example pnotify), this works:

if($.pluginname) {
    alert("plugin loaded");
} else {
    alert("plugin not loaded");
}

This doesn't work:

if($.fn.pluginname)

How do I delete rows in a data frame?

Create id column in your data frame or use any column name to identify the row. Using index is not fair to delete.

Use subset function to create new frame.

updated_myData <- subset(myData, id!= 6)
print (updated_myData)

updated_myData <- subset(myData, id %in% c(1, 3, 5, 7))
print (updated_myData)

Using HTML5/Canvas/JavaScript to take in-browser screenshots

Here is a complete screenshot example that works with chrome in 2021. The end result is a blob ready to be transmitted. Flow is: request media > grab frame > draw to canvas > transfer to blob. If you want to do it more memory efficient explore OffscreenCanvas or possibly ImageBitmapRenderingContext

https://jsfiddle.net/v24hyd3q/1/

// Request media
navigator.mediaDevices.getDisplayMedia().then(stream => 
{
  // Grab frame from stream
  let track = stream.getVideoTracks()[0];
  let capture = new ImageCapture(track);
  capture.grabFrame().then(bitmap => 
  {
    // Stop sharing
    track.stop();
      
    // Draw the bitmap to canvas
    canvas.width = bitmap.width;
    canvas.height = bitmap.height;
    canvas.getContext('2d').drawImage(bitmap, 0, 0);
      
    // Grab blob from canvas
    canvas.toBlob(blob => {
        // Do things with blob here
        console.log('output blob:', blob);
    });
  });
})
.catch(e => console.log(e));

How do I request a file but not save it with Wget?

Curl does that by default without any parameters or flags, I would use it for your purposes:

curl $url > /dev/null 2>&1

Curl is more about streams and wget is more about copying sites based on this comparison.

NPM: npm-cli.js not found when running npm

I run into this problem when installing node9.0.0 on windows7 at the end the solution was to just remove npm npm.cmd npx npx.cmd from C:\Program Files\nodejs\node_modules\npm\bin before doing this a workaround was to run C:\Program Files\nodejs\npm so that is one way so see if you have the same problem I had.

adding multiple event listeners to one element

//catch volume update
var volEvents = "change,input";
var volEventsArr = volEvents.split(",");
for(var i = 0;i<volknob.length;i++) {
    for(var k=0;k<volEventsArr.length;k++) {
    volknob[i].addEventListener(volEventsArr[k], function() {
        var cfa = document.getElementsByClassName('watch_televised');
        for (var j = 0; j<cfa.length; j++) {
            cfa[j].volume = this.value / 100;
        }
    });
}
}

How to trigger HTML button when you press Enter in textbox?

This should do it, I am using jQuery you can write plain javascript.
Replace sendMessage() with your functionality.

$('#addLinks').keypress(function(e) {
    if (e.which == 13) {
        sendMessage();
        e.preventDefault();
    }
});

Reference - What does this error mean in PHP?

Fatal error: Using $this when not in object context

$this is a special variable in PHP which can not be assigned. If it is accessed in a context where it does not exist, this fatal error is given.

This error can occur:

  1. If a non-static method is called statically. Example:

    class Foo {
       protected $var;
       public function __construct($var) {
           $this->var = $var;
       }
    
       public static function bar () {
           // ^^^^^^
           echo $this->var;
           //   ^^^^^
       }
    }
    
    Foo::bar();
    

    How to fix: review your code again, $this can only be used in an object context, and should never be used in a static method. Also, a static method should not access the non-static property. Use self::$static_property to access the static property.

  2. If code from a class method has been copied over into a normal function or just the global scope and keeping the $this special variable.
    How to fix: Review the code and replace $this with a different substitution variable.

Related Questions:

  1. Call non-static method as static: PHP Fatal error: Using $this when not in object context
  2. Copy over code: Fatal error: Using $this when not in object context
  3. All "Using $this when not in object context" Questions on Stackoverflow

How to convert a string to an integer in JavaScript?

_x000D_
_x000D_
function doSth(){_x000D_
  var a = document.getElementById('input').value;_x000D_
  document.getElementById('number').innerHTML = toNumber(a) + 1;_x000D_
}_x000D_
function toNumber(str){_x000D_
  return +str;_x000D_
}
_x000D_
<input id="input" type="text">_x000D_
<input onclick="doSth()" type="submit">_x000D_
<span id="number"></span>
_x000D_
_x000D_
_x000D_

C++ printing boolean, what is displayed?

0 will get printed.

As in C++ true refers to 1 and false refers to 0.

In case, you want to print false instead of 0,then you have to sets the boolalpha format flag for the str stream.

When the boolalpha format flag is set, bool values are inserted/extracted by their textual representation: either true or false, instead of integral values.

#include <iostream>
int main()
{
  std::cout << std::boolalpha << false << std::endl;
}

output:

false

IDEONE

How to place a div below another div?

what about changing the position: relative on your #content #text div to position: absolute

#content #text {
   position:absolute;
   width:950px;
   height:215px;
   color:red;
}

http://jsfiddle.net/CaZY7/12/

then you can use the css properties left and top to position within the #content div

presentViewController and displaying navigation bar

If you use NavigationController in Swift 2.x

let storyboard = UIStoryboard(name: "Main", bundle: nil)
let targetViewController = storyboard.instantiateViewControllerWithIdentifier("targetViewControllerID") as? TargetViewController
self.navigationController?.pushViewController(targetViewController!, animated: true)

What is the difference between Visual Studio Express 2013 for Windows and Visual Studio Express 2013 for Windows Desktop?

More importantly, the 2013 versions of Visual Studio Express have all the languages that comes with the commercial versions. You can use the Windows desktop versions not only to program using Windows Forms, it is possible to write those windowed applications with any language that comes with the software, may it be C++ using the windows.h header if you want to actually learn how to create windows applications from scratch, or use Windows form to create windows in C# or visual Basic.

In the past, you had to download one version for each language or type of content. Or just download an all-in-one that still installed separate versions of the software for different languages. Now with 2013 you get all the languages needed in each content oriented version of the 2013 express.

You pick what matters the most to you.

Besides, it might be a good way to learn using notepad and the command line to write and compile, but I find that a bit tedious to use. While using an IDE might be overwhelming at first, you start small, learning how to create a project, write code, compile your code. They have gone way over their heads to ease up your day when you take it for the first time.

Have a div cling to top of screen if scrolled down past it

There was a previous question today (no answers) that gave a good example of this functionality. You can check the relevant source code for specifics (search for "toolbar"), but basically they use a combination of webdestroya's solution and a bit of JavaScript:

  1. Page loads and element is position: static
  2. On scroll, the position is measured, and if the element is position: static and it's off the page then the element is flipped to position: fixed.

I'd recommend checking the aforementioned source code though, because they do handle some "gotchas" that you might not immediately think of, such as adjusting scroll position when clicking on anchor links.

Click a button with XPath containing partial id and title in Selenium IDE

Now that you have provided your HTML sample, we're able to see that your XPath is slightly wrong. While it's valid XPath, it's logically wrong.

You've got:

//*[contains(@id, 'ctl00_btnAircraftMapCell')]//*[contains(@title, 'Select Seat')]

Which translates into:

Get me all the elements that have an ID that contains ctl00_btnAircraftMapCell. Out of these elements, get any child elements that have a title that contains Select Seat.

What you actually want is:

//a[contains(@id, 'ctl00_btnAircraftMapCell') and contains(@title, 'Select Seat')]

Which translates into:

Get me all the anchor elements that have both: an id that contains ctl00_btnAircraftMapCell and a title that contains Select Seat.

Double quotes within php script echo

use a HEREDOC, which eliminates any need to swap quote types and/or escape them:

echo <<<EOL
<script>$('#edit_errors').html('<h3><em><font color="red">Please Correct Errors Before Proceeding</font></em></h3>')</script>
EOL;

GIT: Checkout to a specific folder

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

You can use git checkout-index for that, this is a low level command, if you want to export everything, you can use -a,

git checkout-index -a -f --prefix=/destination/path/

To quote the man pages:

The final "/" [on the prefix] is important. The exported name is literally just prefixed with the specified string.

If you want to export a certain directory, there are some tricks involved. The command only takes files, not directories. To apply it to directories, use the 'find' command and pipe the output to git.

find dirname -print0 | git checkout-index --prefix=/path-to/dest/ -f -z --stdin

Also from the man pages:

Intuitiveness is not the goal here. Repeatability is.

SQL Update Multiple Fields FROM via a SELECT Statement

you can use update from...

something like:

update shipment set.... from shipment inner join ProfilerTest.dbo.BookingDetails on ...

How do I reverse a C++ vector?

There's a function std::reverse in the algorithm header for this purpose.

#include <vector>
#include <algorithm>

int main() {
  std::vector<int> a;
  std::reverse(a.begin(), a.end());
  return 0;
}

typedef fixed length array

The typedef would be

typedef char type24[3];

However, this is probably a very bad idea, because the resulting type is an array type, but users of it won't see that it's an array type. If used as a function argument, it will be passed by reference, not by value, and the sizeof for it will then be wrong.

A better solution would be

typedef struct type24 { char x[3]; } type24;

You probably also want to be using unsigned char instead of char, since the latter has implementation-defined signedness.

gzip: stdin: not in gzip format tar: Child returned status 1 tar: Error is not recoverable: exiting now

Sometimes the .gz extension is wrongfully appended to the filename.

  • Run file foo.csv.gz to know the actual file type.
  • Rename the file to foo.csv or whatever the actual file type is.

How to add a href link in PHP?

There is no need to invoke PHP for this. Just put it directly into the HTML:

<a href="http://www.example.com/">...

Example of a strong and weak entity types

Just to play with it, question is strong entity type and answer is weak. Question is always there, but an answer requires a question to exist.

Example: Don't ask 'Why?' if Your Dad's a Chemistry Professor

Get input value from TextField in iOS alert in Swift

In Swift5 ans Xcode 10

Add two textfields with Save and Cancel actions and read TextFields text data

func alertWithTF() {
    //Step : 1
    let alert = UIAlertController(title: "Great Title", message: "Please input something", preferredStyle: UIAlertController.Style.alert )
    //Step : 2
    let save = UIAlertAction(title: "Save", style: .default) { (alertAction) in
        let textField = alert.textFields![0] as UITextField
        let textField2 = alert.textFields![1] as UITextField
        if textField.text != "" {
            //Read TextFields text data
            print(textField.text!)
            print("TF 1 : \(textField.text!)")
        } else {
            print("TF 1 is Empty...")
        }

        if textField2.text != "" {
            print(textField2.text!)
            print("TF 2 : \(textField2.text!)")
        } else {
            print("TF 2 is Empty...")
        }
    }

    //Step : 3
    //For first TF
    alert.addTextField { (textField) in
        textField.placeholder = "Enter your first name"
        textField.textColor = .red
    }
    //For second TF
    alert.addTextField { (textField) in
        textField.placeholder = "Enter your last name"
        textField.textColor = .blue
    }

    //Step : 4
    alert.addAction(save)
    //Cancel action
    let cancel = UIAlertAction(title: "Cancel", style: .default) { (alertAction) in }
    alert.addAction(cancel)
    //OR single line action
    //alert.addAction(UIAlertAction(title: "Cancel", style: .default) { (alertAction) in })

    self.present(alert, animated:true, completion: nil)

}

For more explanation https://medium.com/@chan.henryk/alert-controller-with-text-field-in-swift-3-bda7ac06026c

How to place div side by side

CSS3 introduced flexible boxes (aka. flex box) which can also achieve this behavior.

Simply define the width of the first div, and then give the second a flex-grow value of 1 which will allow it to fill the remaining width of the parent.

.container{
    display: flex;
}
.fixed{
    width: 200px;
}
.flex-item{
    flex-grow: 1;
}
<div class="container">
  <div class="fixed"></div>
  <div class="flex-item"></div>
</div>

Demo:

_x000D_
_x000D_
div {
    color: #fff;
    font-family: Tahoma, Verdana, Segoe, sans-serif;
    padding: 10px;
}
.container {
    background-color:#2E4272;
    display:flex;
}
.fixed {
    background-color:#4F628E;
    width: 200px;
}
.flex-item {
    background-color:#7887AB;
    flex-grow: 1;
}
_x000D_
<div class="container">
    <div class="fixed">Fixed width</div>
    <div class="flex-item">Dynamically sized content</div>
</div>
_x000D_
_x000D_
_x000D_

Note that flex boxes are not backwards compatible with old browsers, but is a great option for targeting modern browsers (see also Caniuse and MDN). A great comprehensive guide on how to use flex boxes is available on CSS Tricks.

Executors.newCachedThreadPool() versus Executors.newFixedThreadPool()

If you are not worried about an unbounded queue of Callable/Runnable tasks, you can use one of them. As suggested by bruno, I too prefer newFixedThreadPool to newCachedThreadPool over these two.

But ThreadPoolExecutor provides more flexible features compared to either newFixedThreadPool or newCachedThreadPool

ThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, 
TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory,
RejectedExecutionHandler handler)

Advantages:

  1. You have full control of BlockingQueue size. It's not un-bounded, unlike the earlier two options. I won't get an out of memory error due to a huge pile-up of pending Callable/Runnable tasks when there is unexpected turbulence in the system.

  2. You can implement custom Rejection handling policy OR use one of the policies:

    1. In the default ThreadPoolExecutor.AbortPolicy, the handler throws a runtime RejectedExecutionException upon rejection.

    2. In ThreadPoolExecutor.CallerRunsPolicy, the thread that invokes execute itself runs the task. This provides a simple feedback control mechanism that will slow down the rate that new tasks are submitted.

    3. In ThreadPoolExecutor.DiscardPolicy, a task that cannot be executed is simply dropped.

    4. In ThreadPoolExecutor.DiscardOldestPolicy, if the executor is not shut down, the task at the head of the work queue is dropped, and then execution is retried (which can fail again, causing this to be repeated.)

  3. You can implement a custom Thread factory for the below use cases:

    1. To set a more descriptive thread name
    2. To set thread daemon status
    3. To set thread priority

How do I concatenate strings and variables in PowerShell?

One way is:

Write-Host "$($assoc.Id)  -  $($assoc.Name)  -  $($assoc.Owner)"

Another one is:

Write-Host  ("{0}  -  {1}  -  {2}" -f $assoc.Id,$assoc.Name,$assoc.Owner )

Or just (but I don't like it ;) ):

Write-Host $assoc.Id  "  -  "   $assoc.Name  "  -  "  $assoc.Owner

LDAP root query syntax to search more than one specific OU

I don't think this is possible with AD. The distinguishedName attribute is the only thing I know of that contains the OU piece on which you're trying to search, so you'd need a wildcard to get results for objects under those OUs. Unfortunately, the wildcard character isn't supported on DNs.

If at all possible, I'd really look at doing this in 2 queries using OU=Staff... and OU=Vendors... as the base DNs.

How to enable bulk permission in SQL Server

USE Master GO

ALTER Server Role [bulkadmin] ADD MEMBER [username] GO Command failed even tried several command parameters

master..sp_addsrvrolemember @loginame = N'username', @rolename = N'bulkadmin' GO Command was successful..

Email Address Validation for ASP.NET

Preventing XSS is a different issue from validating input.

Regarding XSS: You should not try to check input for XSS or related exploits. You should prevent XSS exploits, SQL injection and so on by escaping correctly when inserting strings into a different language where some characters are "magic", eg, when inserting strings in HTML or SQL. For example a name like O'Reilly is perfectly valid input, but could cause a crash or worse if inserted unescaped into SQL. You cannot prevent that kind of problems by validating input.

Validation of user input makes sense to prevent missing or malformed data, eg. a user writing "asdf" in the zip-code field and so on. Wrt. e-mail adresses, the syntax is so complex though, that it doesnt provide much benefit to validate it using a regex. Just check that it contains a "@".

Uploading Files in ASP.net without using the FileUpload server control

The Request.Files collection contains any files uploaded with your form, regardless of whether they came from a FileUpload control or a manually written <input type="file">.

So you can just write a plain old file input tag in the middle of your WebForm, and then read the file uploaded from the Request.Files collection.

Test if a variable is a list or tuple

>>> l = []
>>> l.__class__.__name__ in ('list', 'tuple')
True

How to access JSON decoded array in PHP

As you're passing true as the second parameter to json_decode, in the above example you can retrieve data doing something similar to:

$myArray = json_decode($data, true);
echo $myArray[0]['id']; // Fetches the first ID
echo $myArray[0]['c_name']; // Fetches the first c_name
// ...
echo $myArray[2]['id']; // Fetches the third ID
// etc..

If you do NOT pass true as the second parameter to json_decode it would instead return it as an object:

echo $myArray[0]->id;

How to fix: Error device not found with ADB.exe

How about:

Settings -> System -> Developer options -> Debugging -> turn on toggle for Wireless ADB debugging

or:

Revoke USB debugging authorizations

and try from the scratch.

Why Maven uses JDK 1.6 but my java -version is 1.7

Please check the compatibility. I struggled with mvn 3.2.1 and jdk 1.6.0_37 for many hours. All variables were set but was not working. Finally I upgraded jdk to 1.8.0_60 and mvn 3.3.3 and that worked. Environment Variables as following:

JAVA_HOME=C:\ProgramFiles\Java\jdk1.8.0_60 
MVN_HOME=C:\ProgramFiles\apache-maven\apache-maven-3.3.3 
M2=%MVN_HOME%\bin extend system level Path- ;%M2%;%JAVA_HOME%\bin;

enable or disable checkbox in html

According the W3Schools you might use JavaScript for disabled checkbox.

<!-- Checkbox who determine if the other checkbox must be disabled -->
<input type="checkbox" id="checkboxDetermine">
<!-- The other checkbox conditionned by the first checkbox -->
<input type="checkbox" id="checkboxConditioned">
<!-- JS Script -->
<script type="text/javascript">
    // Get your checkbox who determine the condition
    var determine = document.getElementById("checkboxDetermine");
    // Make a function who disabled or enabled your conditioned checkbox
    var disableCheckboxConditioned = function () {
        if(determine.checked) {
            document.getElementById("checkboxConditioned").disabled = true;
        }
        else {
            document.getElementById("checkboxConditioned").disabled = false;
        }
    }
    // On click active your function
    determine.onclick = disableCheckboxConditioned;
    disableCheckboxConditioned();
</script>

You can see the demo working here : http://jsfiddle.net/antoinesubit/vptk0nh6/

Transfer data from one database to another database

if both databases are on same server and you want to transfer entire table (make copy of it) then use simple select into statement ...

select * into anotherDatabase..copyOfTable from oneDatabase..tableName

You can then write cursor top of sysobjects and copy entire set of tables that way.

If you want more complex data extraction & transformation, then use SSIS and build appropriate ETL in it.

mappedBy reference an unknown target entity property

I know the answer by @Pascal Thivent has solved the issue. I would like to add a bit more to his answer to others who might be surfing this thread.

If you are like me in the initial days of learning and wrapping your head around the concept of using the @OneToMany annotation with the 'mappedBy' property, it also means that the other side holding the @ManyToOne annotation with the @JoinColumn is the 'owner' of this bi-directional relationship.

Also, mappedBy takes in the instance name (mCustomer in this example) of the Class variable as an input and not the Class-Type (ex:Customer) or the entity name(Ex:customer).

BONUS : Also, look into the orphanRemoval property of @OneToMany annotation. If it is set to true, then if a parent is deleted in a bi-directional relationship, Hibernate automatically deletes it's children.

Javascript setInterval not working

That's because you should pass a function, not a string:

function funcName() {
    alert("test");
}

setInterval(funcName, 10000);

Your code has two problems:

  • var func = funcName(); calls the function immediately and assigns the return value.
  • Just "func" is invalid even if you use the bad and deprecated eval-like syntax of setInterval. It would be setInterval("func()", 10000) to call the function eval-like.

How do I programmatically "restart" an Android app?

Directly start the initial screen with FLAG_ACTIVITY_CLEAR_TASK and FLAG_ACTIVITY_NEW_TASK.

How can I detect if this dictionary key exists in C#?

You can use ContainsKey:

if (dict.ContainsKey(key)) { ... }

or TryGetValue:

dict.TryGetValue(key, out value);

Update: according to a comment the actual class here is not an IDictionary but a PhysicalAddressDictionary, so the methods are Contains and TryGetValue but they work in the same way.

Example usage:

PhysicalAddressEntry entry;
PhysicalAddressKey key = c.PhysicalAddresses[PhysicalAddressKey.Home].Street;
if (c.PhysicalAddresses.TryGetValue(key, out entry))
{
    row["HomeStreet"] = entry;
}

Update 2: here is the working code (compiled by question asker)

PhysicalAddressEntry entry;
PhysicalAddressKey key = PhysicalAddressKey.Home;
if (c.PhysicalAddresses.TryGetValue(key, out entry))
{
    if (entry.Street != null)
    {
        row["HomeStreet"] = entry.Street.ToString();
    }
}

...with the inner conditional repeated as necessary for each key required. The TryGetValue is only done once per PhysicalAddressKey (Home, Work, etc).

Is it possible to assign numeric value to an enum in Java?

public enum EXIT_CODE {
    A(104), B(203);

    private int numVal;

    EXIT_CODE(int numVal) {
        this.numVal = numVal;
    }

    public int getNumVal() {
        return numVal;
    }
}

where is create-react-app webpack config and files?

The files are located in your node_modules/react-scripts folder:

Webpack config:

https://github.com/facebook/create-react-app/blob/master/packages/react-scripts/config/webpack.config.js

Start Script:

https://github.com/facebook/create-react-app/blob/master/packages/react-scripts/scripts/start.js

Build Script:

https://github.com/facebook/create-react-app/blob/master/packages/react-scripts/scripts/build.js

Test Script:

https://github.com/facebook/create-react-app/blob/master/packages/react-scripts/scripts/test.js

and so on ...

Now, the purpose of CRA is not to worry about these.

From the documentation:

You don’t need to install or configure tools like Webpack or Babel. They are preconfigured and hidden so that you can focus on the code.

If you want to have access to the config files, you need to eject by running:

npm run eject

Note: this is a one-way operation. Once you eject, you can’t go back!

In most scenarios, it is best not to eject and try to find a way to make it work for you in another way.

If you need to override some of the config options, you can have a look at https://github.com/gsoft-inc/craco

How to get unique device hardware id in Android?

Update: 19 -11-2019

The below answer is no more relevant to present day.

So for any one looking for answers you should look at the documentation linked below

https://developer.android.com/training/articles/user-data-ids


Old Answer - Not relevant now. You check this blog in the link below

http://android-developers.blogspot.in/2011/03/identifying-app-installations.html

ANDROID_ID

import android.provider.Settings.Secure;

private String android_id = Secure.getString(getContext().getContentResolver(),
                                                    Secure.ANDROID_ID); 

The above is from the link @ Is there a unique Android device ID?

More specifically, Settings.Secure.ANDROID_ID. This is a 64-bit quantity that is generated and stored when the device first boots. It is reset when the device is wiped.

ANDROID_ID seems a good choice for a unique device identifier. There are downsides: First, it is not 100% reliable on releases of Android prior to 2.2 (“Froyo”). Also, there has been at least one widely-observed bug in a popular handset from a major manufacturer, where every instance has the same ANDROID_ID.

The below solution is not a good one coz the value survives device wipes (“Factory resets”) and thus you could end up making a nasty mistake when one of your customers wipes their device and passes it on to another person.

You get the imei number of the device using the below

  TelephonyManager telephonyManager = (TelephonyManager)getSystemService(Context.TELEPHONY_SERVICE);
  telephonyManager.getDeviceId();

http://developer.android.com/reference/android/telephony/TelephonyManager.html#getDeviceId%28%29

Add this is manifest

<uses-permission android:name="android.permission.READ_PHONE_STATE"/>

Find closing HTML tag in Sublime Text

There is a shortcut (Ctrl+Shift+A for Windows and Linux users, Command+Shift+A for Mac users) to select the whole block within the currently selected tag.

For example, if you pressed this while your text cursor was within the outer div tag in the code below, all the divs with class selected would be selected.

<div class='current_tag_block'>
  <div class='selected'></div>
  <div class='selected'></div>
  <div class='selected'></div>
  <div class='selected'></div>
</div>

Best way to find if an item is in a JavaScript array?

A robust way to check if an object is an array in javascript is detailed here:

Here are two functions from the xa.js framework which I attach to a utils = {} ‘container’. These should help you properly detect arrays.

var utils = {};

/**
 * utils.isArray
 *
 * Best guess if object is an array.
 */
utils.isArray = function(obj) {
     // do an instanceof check first
     if (obj instanceof Array) {
         return true;
     }
     // then check for obvious falses
     if (typeof obj !== 'object') {
         return false;
     }
     if (utils.type(obj) === 'array') {
         return true;
     }
     return false;
 };

/**
 * utils.type
 *
 * Attempt to ascertain actual object type.
 */
utils.type = function(obj) {
    if (obj === null || typeof obj === 'undefined') {
        return String (obj);
    }
    return Object.prototype.toString.call(obj)
        .replace(/\[object ([a-zA-Z]+)\]/, '$1').toLowerCase();
};

If you then want to check if an object is in an array, I would also include this code:

/**
 * Adding hasOwnProperty method if needed.
 */
if (typeof Object.prototype.hasOwnProperty !== 'function') {
    Object.prototype.hasOwnProperty = function (prop) {
        var type = utils.type(this);
        type = type.charAt(0).toUpperCase() + type.substr(1);
        return this[prop] !== undefined
            && this[prop] !== window[type].prototype[prop];
    };
}

And finally this in_array function:

function in_array (needle, haystack, strict) {
    var key;

    if (strict) {
        for (key in haystack) {
            if (!haystack.hasOwnProperty[key]) continue;

            if (haystack[key] === needle) {
                return true;
            }
        }
    } else {
        for (key in haystack) {
            if (!haystack.hasOwnProperty[key]) continue;

            if (haystack[key] == needle) {
                return true;
            }
        }
    }

    return false;
}

jQuery checkbox check/uncheck

Use prop() instead of attr() to set the value of checked. Also use :checkbox in find method instead of input and be specific.

Live Demo

$("#news_list tr").click(function() {
    var ele = $(this).find('input');
    if(ele.is(':checked')){
        ele.prop('checked', false);
        $(this).removeClass('admin_checked');
    }else{
        ele.prop('checked', true);
        $(this).addClass('admin_checked');
    }
});

Use prop instead of attr for properties like checked

As of jQuery 1.6, the .attr() method returns undefined for attributes that have not been set. To retrieve and change DOM properties such as the checked, selected, or disabled state of form elements, use the .prop() method

copy-item With Alternate Credentials

You should be able to pass whatever credentials you want to the -Credential parameter. So something like:

$cred = Get-Credential

[Enter the credentials]

Copy-Item -Path $from -Destination $to -Credential $cred

How to apply a patch generated with git format-patch?

Or, if you're kicking it old school:

cd /path/to/other/repository
patch -p1 < 0001-whatever.patch

Run a PHP file in a cron job using CPanel

This is the easiest way:

php -f /home/your_username/public_html/script.php

And if you want to log the script output to a file, add this to the end of the command:

>> /home/your_username/logs/someFile.txt 2>&1

A CSS selector to get last visible div

in other way, you can do it with javascript , in Jquery you can use something like:

$('div:visible').last()

*reedited

Attempted to read or write protected memory. This is often an indication that other memory is corrupt

I got this error message on lambda expression that was using Linq to filter a collection of objects. When I inspected the collection I noticed that its members weren't populated - in the Locals window, expanding them just showed "...". Ultimately the problem was in the repository method that initially populated the collection - Dapper was trying to automatically map a property of a nested object. I fixed the Dapper query to handle the multi-mapping and that fixed the memory error.

Pick images of root folder from sub-folder

../ takes you one folder up the directory tree. Then, select the appropriate folder and its contents.

../images/logo.png

turn typescript object into json string

TS gets compiled to JS which then executed. Therefore you have access to all of the objects in the JS runtime. One of those objects is the JSON object. This contains the following methods:

  • JSON.parse() method parses a JSON string, constructing the JavaScript value or object described by the string.
  • JSON.stringify() method converts a JavaScript object or value to a JSON string.

Example:

_x000D_
_x000D_
const jsonString = '{"employee":{ "name":"John", "age":30, "city":"New York" }}';_x000D_
_x000D_
_x000D_
const JSobj = JSON.parse(jsonString);_x000D_
_x000D_
console.log(JSobj);_x000D_
console.log(typeof JSobj);_x000D_
_x000D_
const JSON_string = JSON.stringify(JSobj);_x000D_
_x000D_
console.log(JSON_string);_x000D_
console.log(typeof JSON_string);
_x000D_
_x000D_
_x000D_

Pad a number with leading zeros in JavaScript

You could do something like this:

function pad ( num, size ) {
  return ( Math.pow( 10, size ) + ~~num ).toString().substring( 1 );
}

Edit: This was just a basic idea for a function, but to add support for larger numbers (as well as invalid input), this would probably be better:

function pad ( num, size ) {
  if (num.toString().length >= size) return num;
  return ( Math.pow( 10, size ) + Math.floor(num) ).toString().substring( 1 );
}

This does 2 things:

  1. If the number is larger than the specified size, it will simply return the number.
  2. Using Math.floor(num) in place of ~~num will support larger numbers.

Why and when to use angular.copy? (Deep Copy)

I know its already answered, still i am just trying to make it simple. So angular.copy(data) you can use in case where you want to modify/change your received object by keeping its original values unmodified/unchanged.

For example: suppose i have made api call and got my originalObj, now i want to change the values of api originalObj for some case but i want the original values too so what i can do is, i can make a copy of my api originalObj in duplicateObj and modify duplicateObj this way my originalObj values will not change. In simple words duplicateObj modification will not reflect in originalObj unlike how js obj behave.

 $scope.originalObj={
            fname:'sudarshan',
            country:'India'
        }
        $scope.duplicateObj=angular.copy($scope.originalObj);
        console.log('----------originalObj--------------');
        console.log($scope.originalObj);
        console.log('-----------duplicateObj---------------');
        console.log($scope.duplicateObj);

        $scope.duplicateObj.fname='SUD';
        $scope.duplicateObj.country='USA';
        console.log('---------After update-------')
        console.log('----------originalObj--------------');
        console.log($scope.originalObj);
        console.log('-----------duplicateObj---------------');
        console.log($scope.duplicateObj);

Result is like....

    ----------originalObj--------------
manageProfileController.js:1183 {fname: "sudarshan", country: "India"}
manageProfileController.js:1184 -----------duplicateObj---------------
manageProfileController.js:1185 {fname: "sudarshan", country: "India"}
manageProfileController.js:1189 ---------After update-------
manageProfileController.js:1190 ----------originalObj--------------
manageProfileController.js:1191 {fname: "sudarshan", country: "India"}
manageProfileController.js:1192 -----------duplicateObj---------------
manageProfileController.js:1193 {fname: "SUD", country: "USA"}

How to configure postgresql for the first time?

You probably need to update your pg_hba.conf file. This file controls what users can log in from what IP addresses. I think that the postgres user is pretty locked-down by default.

Apply CSS rules if browser is IE

In browsers up to and including IE9, this is done through conditional comments.

<!--[if IE]>
<style type="text/css">
  IE specific CSS rules go here
</style>
<![endif]-->

How to convert jsonString to JSONObject in Java

Codehaus Jackson - I have been this awesome API since 2012 for my RESTful webservice and JUnit tests. With their API, you can:

(1) Convert JSON String to Java bean

public static String beanToJSONString(Object myJavaBean) throws Exception {
    ObjectMapper jacksonObjMapper = new ObjectMapper();
    return jacksonObjMapper.writeValueAsString(myJavaBean);
}

(2) Convert JSON String to JSON object (JsonNode)

public static JsonNode stringToJSONObject(String jsonString) throws Exception {
    ObjectMapper jacksonObjMapper = new ObjectMapper();
    return jacksonObjMapper.readTree(jsonString);
}

//Example:
String jsonString = "{\"phonetype\":\"N95\",\"cat\":\"WP\"}";   
JsonNode jsonNode = stringToJSONObject(jsonString);
Assert.assertEquals("Phonetype value not legit!", "N95", jsonNode.get("phonetype").getTextValue());
Assert.assertEquals("Cat value is tragic!", "WP", jsonNode.get("cat").getTextValue());

(3) Convert Java bean to JSON String

    public static Object JSONStringToBean(Class myBeanClass, String JSONString) throws Exception {
    ObjectMapper jacksonObjMapper = new ObjectMapper();
    return jacksonObjMapper.readValue(JSONString, beanClass);
}

REFS:

  1. Codehaus Jackson

  2. JsonNode API - How to use, navigate, parse and evaluate values from a JsonNode object

  3. Tutorial - Simple tutorial how to use Jackson to convert JSON string to JsonNode

NSURLConnection Using iOS Swift

An abbreviated version of your code worked for me,

class Remote: NSObject {

    var data = NSMutableData()

    func connect(query:NSString) {
        var url =  NSURL.URLWithString("http://www.google.com")
        var request = NSURLRequest(URL: url)
        var conn = NSURLConnection(request: request, delegate: self, startImmediately: true)
    }


     func connection(didReceiveResponse: NSURLConnection!, didReceiveResponse response: NSURLResponse!) {
        println("didReceiveResponse")
    }

    func connection(connection: NSURLConnection!, didReceiveData conData: NSData!) {
        self.data.appendData(conData)
    }

    func connectionDidFinishLoading(connection: NSURLConnection!) {
        println(self.data)
    }


    deinit {
        println("deiniting")
    }
}

This is the code I used in the calling class,

class ViewController: UIViewController {

    var remote = Remote()


    @IBAction func downloadTest(sender : UIButton) {
        remote.connect("/apis")
    }

}

You didn't specify in your question where you had this code,

var remote = Remote()
remote.connect("/apis")

If var is a local variable, then the Remote class will be deallocated right after the connect(query:NSString) method finishes, but before the data returns. As you can see by my code, I usually implement reinit (or dealloc up to now) just to make sure when my instances go away. You should add that to your Remote class to see if that's your problem.

Watching variables contents in Eclipse IDE

You can use Expressions windows: while debugging, menu window -> Show View -> Expressions, then it has place to type variables of which you need to see contents

How do I make a https post in Node Js without any third party module?

For example, like this:

const querystring = require('querystring');
const https = require('https');

var postData = querystring.stringify({
    'msg' : 'Hello World!'
});

var options = {
  hostname: 'posttestserver.com',
  port: 443,
  path: '/post.php',
  method: 'POST',
  headers: {
       'Content-Type': 'application/x-www-form-urlencoded',
       'Content-Length': postData.length
     }
};

var req = https.request(options, (res) => {
  console.log('statusCode:', res.statusCode);
  console.log('headers:', res.headers);

  res.on('data', (d) => {
    process.stdout.write(d);
  });
});

req.on('error', (e) => {
  console.error(e);
});

req.write(postData);
req.end();

Primitive type 'short' - casting in Java

As explained in short C# (but also for other language compilers as well, like Java)

There is a predefined implicit conversion from short to int, long, float, double, or decimal.

You cannot implicitly convert nonliteral numeric types of larger storage size to short (see Integral Types Table for the storage sizes of integral types). Consider, for example, the following two short variables x and y:

short x = 5, y = 12;

The following assignment statement will produce a compilation error, because the arithmetic expression on the right-hand side of the assignment operator evaluates to int by default.

short z = x + y;   // Error: no conversion from int to short

To fix this problem, use a cast:

short z = (short)(x + y);   // OK: explicit conversion

It is possible though to use the following statements, where the destination variable has the same storage size or a larger storage size:

int m = x + y;
long n = x + y;

A good follow-up question is:

"why arithmetic expression on the right-hand side of the assignment operator evaluates to int by default" ?

A first answer can be found in:

Classifying and Formally Verifying Integer Constant Folding

The Java language specification defines exactly how integer numbers are represented and how integer arithmetic expressions are to be evaluated. This is an important property of Java as this programming language has been designed to be used in distributed applications on the Internet. A Java program is required to produce the same result independently of the target machine executing it.

In contrast, C (and the majority of widely-used imperative and object-oriented programming languages) is more sloppy and leaves many important characteristics open. The intention behind this inaccurate language specification is clear. The same C programs are supposed to run on a 16-bit, 32-bit, or even 64-bit architecture by instantiating the integer arithmetics of the source programs with the arithmetic operations built-in in the target processor. This leads to much more e?cient code because it can use the available machine operations directly. As long as the integer computations deal only with numbers being “sufficiently small”, no inconsistencies will arise.

In this sense, the C integer arithmetic is a placeholder which is not defined exactly by the programming language specification but is only completely instantiated by determining the target machine.

Java precisely defines how integers are represented and how integer arithmetic is to be computed.

      Java Integers
--------------------------
Signed         |  Unsigned
--------------------------
long  (64-bit) |
int   (32-bit) |
short (16-bit) |  char (16-bit)
byte  (8-bit)  |

Char is the only unsigned integer type. Its values represent Unicode characters, from \u0000 to \uffff, i.e. from 0 to 216-1.

If an integer operator has an operand of type long, then the other operand is also converted to type long. Otherwise the operation is performed on operands of type int, if necessary shorter operands are converted into int. The conversion rules are exactly specified.

[From Electronic Notes in Theoretical Computer Science 82 No. 2 (2003)
Blesner-Blech-COCV 2003: Sabine GLESNER, Jan Olaf BLECH,
Fakultät für Informatik,
Universität Karlsruhe
Karlsruhe, Germany]

Session state can only be used when enableSessionState is set to true either in a configuration

I want to let everyone know that sometimes this error just is a result of some weird memory error. Restart your pc and go back into visual studio and it will be gone!! Bizarre! Try that before you start playing around with your web config file etc like I did!!!! ;-)

How do I format date and time on ssrs report?

hi friend please try this expression your report

="Page " + Globals!PageNumber.ToString() + " of " + Globals!OverallTotalPages.ToString() + vbcrlf + "Generated: " + Globals!ExecutionTime.ToString()

Disable back button in react navigation

In Latest Version (v2) works headerLeft:null. you can add in controller's navigationOptions as bellow

static navigationOptions = {
    headerLeft: null,
};

why numpy.ndarray is object is not callable in my simple for python loop

The error TypeError: 'numpy.ndarray' object is not callable means that you tried to call a numpy array as a function.

Use

Z=XY[0]+XY[1]

Instead of

Z=XY(i,0)+XY(i,1)

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

You do not need to use ORDER BY in inner query after WHERE clause because you have already used it in ROW_NUMBER() OVER (ORDER BY VRDATE DESC).

SELECT 
    * 
FROM (
    SELECT 
        Stockmain.VRNOA, 
        item.description as item_description, 
        party.name as party_name, 
        stockmain.vrdate, 
        stockdetail.qty, 
        stockdetail.rate, 
        stockdetail.amount, 
        ROW_NUMBER() OVER (ORDER BY VRDATE DESC) AS RowNum  --< ORDER BY
    FROM StockMain 
    INNER JOIN StockDetail 
        ON StockMain.stid = StockDetail.stid 
    INNER JOIN party 
        ON party.party_id = stockmain.party_id 
    INNER JOIN item 
        ON item.item_id = stockdetail.item_id 
    WHERE stockmain.etype='purchase' 
) AS MyDerivedTable
WHERE 
    MyDerivedTable.RowNum BETWEEN 1 and 5 

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

That's the way I'd prefer to see if I was maintaining your code. If you manage to find a faster solution, it's going to be very esoteric, and you should really bury it inside of a method that describes what it does.

(does it still work without the ToArray)?

Windows XP or later Windows: How can I run a batch file in the background with no window displayed?

Run it under a different user name, using "runas" or by scheduling it under a different user in Windows Scheduled Tasks.

How to convert a pymongo.cursor.Cursor into a dict?

The find method returns a Cursor instance, which allows you to iterate over all matching documents.

To get the first document that matches the given criteria you need to use find_one. The result of find_one is a dictionary.

You can always use the list constructor to return a list of all the documents in the collection but bear in mind that this will load all the data in memory and may not be what you want.

You should do that if you need to reuse the cursor and have a good reason not to use rewind()


Demo using find:

>>> import pymongo
>>> conn = pymongo.MongoClient()
>>> db = conn.test #test is my database
>>> col = db.spam #Here spam is my collection
>>> cur = col.find()  
>>> cur
<pymongo.cursor.Cursor object at 0xb6d447ec>
>>> for doc in cur:
...     print(doc)  # or do something with the document
... 
{'a': 1, '_id': ObjectId('54ff30faadd8f30feb90268f'), 'b': 2}
{'a': 1, 'c': 3, '_id': ObjectId('54ff32a2add8f30feb902690'), 'b': 2}

Demo using find_one:

>>> col.find_one()
{'a': 1, '_id': ObjectId('54ff30faadd8f30feb90268f'), 'b': 2}

addEventListener vs onclick

Using inline handlers is incompatible with Content Security Policy so the addEventListener approach is more secure from that point of view. Of course you can enable the inline handlers with unsafe-inline but, as the name suggests, it's not safe as it brings back the whole hordes of JavaScript exploits that CSP prevents.

Selecting empty text input using jQuery

Since creating an JQuery object for every comparison is not efficient, just use:

$.expr[":"].blank = function(element) {
    return element.value == "";
};

Then you can do:

$(":input:blank")

PHP cURL vs file_get_contents

file_get_contents() is a simple screwdriver. Great for simple GET requests where the header, HTTP request method, timeout, cookiejar, redirects, and other important things do not matter.

fopen() with a stream context or cURL with setopt are powerdrills with every bit and option you can think of.

What is the benefit of zerofill in MySQL?

When you select a column with type ZEROFILL it pads the displayed value of the field with zeros up to the display width specified in the column definition. Values longer than the display width are not truncated. Note that usage of ZEROFILL also implies UNSIGNED.

Using ZEROFILL and a display width has no effect on how the data is stored. It affects only how it is displayed.

Here is some example SQL that demonstrates the use of ZEROFILL:

CREATE TABLE yourtable (x INT(8) ZEROFILL NOT NULL, y INT(8) NOT NULL);
INSERT INTO yourtable (x,y) VALUES
(1, 1),
(12, 12),
(123, 123),
(123456789, 123456789);
SELECT x, y FROM yourtable;

Result:

        x          y
 00000001          1
 00000012         12
 00000123        123
123456789  123456789

Formatting ISODate from Mongodb

// from MongoDate object to Javascript Date object

var MongoDate = {sec: 1493016016, usec: 650000};
var dt = new Date("1970-01-01T00:00:00+00:00");
    dt.setSeconds(MongoDate.sec);

How to convert string to integer in PowerShell

Example:

2.032 MB (2,131,022 bytes)

$u=($mbox.TotalItemSize.value).tostring()

$u=$u.trimend(" bytes)") #yields 2.032 MB (2,131,022

$u=$u.Split("(") #yields `$u[1]` as 2,131,022

$uI=[int]$u[1]

The result is 2131022 in integer form.

Log4net rolling daily filename with date in the file name

In your Log4net config file, use the following parameter with the RollingFileAppender:

<param name="DatePattern" value="dd.MM.yyyy'.log'" />

Populate one dropdown based on selection in another

Setup mine within a closure and with straight JavaScript, explanation provided in comments

_x000D_
_x000D_
(function() {_x000D_
_x000D_
  //setup an object fully of arrays_x000D_
  //alternativly it could be something like_x000D_
  //{"yes":[{value:sweet, text:Sweet}.....]}_x000D_
  //so you could set the label of the option tag something different than the name_x000D_
  var bOptions = {_x000D_
    "yes": ["sweet", "wohoo", "yay"],_x000D_
    "no": ["you suck!", "common son"]_x000D_
  };_x000D_
_x000D_
  var A = document.getElementById('A');_x000D_
  var B = document.getElementById('B');_x000D_
_x000D_
  //on change is a good event for this because you are guarenteed the value is different_x000D_
  A.onchange = function() {_x000D_
    //clear out B_x000D_
    B.length = 0;_x000D_
    //get the selected value from A_x000D_
    var _val = this.options[this.selectedIndex].value;_x000D_
    //loop through bOption at the selected value_x000D_
    for (var i in bOptions[_val]) {_x000D_
      //create option tag_x000D_
      var op = document.createElement('option');_x000D_
      //set its value_x000D_
      op.value = bOptions[_val][i];_x000D_
      //set the display label_x000D_
      op.text = bOptions[_val][i];_x000D_
      //append it to B_x000D_
      B.appendChild(op);_x000D_
    }_x000D_
  };_x000D_
  //fire this to update B on load_x000D_
  A.onchange();_x000D_
_x000D_
})();
_x000D_
<select id='A' name='A'>_x000D_
  <option value='yes' selected='selected'>yes_x000D_
  <option value='no'> no_x000D_
</select>_x000D_
<select id='B' name='B'>_x000D_
</select>
_x000D_
_x000D_
_x000D_

Swift - how to make custom header for UITableView?

If you are using custom cell as header, add the following.

func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {

        let headerView = UIView()
        let headerCell = tableView.dequeueReusableCell(withIdentifier: "customTableCell") as! CustomTableCell
        headerView.addSubview(headerCell)
        return headerView
    }

If you want to have simple view, add the following.

func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let headerView:UIView =  UIView()
    return headerView
}

CSS to select/style first word

There isn't a plain CSS method for this. You might have to go with JavaScript + Regex to pop in a span.

Ideally, there would be a pseudo-element for first-word, but you're out of luck as that doesn't appear to work. We do have :first-letter and :first-line.

You might be able to use a combination of :after or :before to get at it without using a span.

Convert char array to single int?

I'll just leave this here for people interested in an implementation with no dependencies.

inline int
stringLength (char *String)
    {
    int Count = 0;
    while (*String ++) ++ Count;
    return Count;
    }

inline int
stringToInt (char *String)
    {
    int Integer = 0;
    int Length = stringLength(String);
    for (int Caret = Length - 1, Digit = 1; Caret >= 0; -- Caret, Digit *= 10)
        {
        if (String[Caret] == '-') return Integer * -1;
        Integer += (String[Caret] - '0') * Digit;
        }

    return Integer;
    }

Works with negative values, but can't handle non-numeric characters mixed in between (should be easy to add though). Integers only.

Can I access variables from another file?

As Fermin said, a variable in the global scope should be accessible to all scripts loaded after it is declared. You could also use a property of window or (in the global scope) this to get the same effect.

// first.js
var colorCodes = {

  back  : "#fff",
  front : "#888",
  side  : "#369"

};

... in another file ...

// second.js
alert (colorCodes.back); // alerts `#fff`

... in your html file ...

<script type="text/javascript" src="first.js"></script> 
<script type="text/javascript" src="second.js"></script> 

How to list active connections on PostgreSQL?

SELECT * FROM pg_stat_activity WHERE datname = 'dbname' and state = 'active';

Since pg_stat_activity contains connection statistics of all databases having any state, either idle or active, database name and connection state should be included in the query to get the desired output.

Copy directory contents into a directory with python

The python libs are obsolete with this function. I've done one that works correctly:

import os
import shutil

def copydirectorykut(src, dst):
    os.chdir(dst)
    list=os.listdir(src)
    nom= src+'.txt'
    fitx= open(nom, 'w')

    for item in list:
        fitx.write("%s\n" % item)

    fitx.close()

    f = open(nom,'r')
    for line in f.readlines():
        if "." in line:
            shutil.copy(src+'/'+line[:-1],dst+'/'+line[:-1])
        else:
            if not os.path.exists(dst+'/'+line[:-1]):
                os.makedirs(dst+'/'+line[:-1])
                copydirectorykut(src+'/'+line[:-1],dst+'/'+line[:-1])
            copydirectorykut(src+'/'+line[:-1],dst+'/'+line[:-1])
    f.close()
    os.remove(nom)
    os.chdir('..')

adding noise to a signal in python

In real life you wish to simulate a signal with white noise. You should add to your signal random points that have Normal Gaussian distribution. If we speak about a device that have sensitivity given in unit/SQRT(Hz) then you need to devise standard deviation of your points from it. Here I give function "white_noise" that does this for you, an the rest of a code is demonstration and check if it does what it should.

%matplotlib inline
import numpy as np
import matplotlib.pyplot as plt
from scipy import signal

"""
parameters: 
rhp - spectral noise density unit/SQRT(Hz)
sr  - sample rate
n   - no of points
mu  - mean value, optional

returns:
n points of noise signal with spectral noise density of rho
"""
def white_noise(rho, sr, n, mu=0):
    sigma = rho * np.sqrt(sr/2)
    noise = np.random.normal(mu, sigma, n)
    return noise

rho = 1 
sr = 1000
n = 1000
period = n/sr
time = np.linspace(0, period, n)
signal_pure = 100*np.sin(2*np.pi*13*time)
noise = white_noise(rho, sr, n)
signal_with_noise = signal_pure + noise

f, psd = signal.periodogram(signal_with_noise, sr)

print("Mean spectral noise density = ",np.sqrt(np.mean(psd[50:])), "arb.u/SQRT(Hz)")

plt.plot(time, signal_with_noise)
plt.plot(time, signal_pure)
plt.xlabel("time (s)")
plt.ylabel("signal (arb.u.)")
plt.show()

plt.semilogy(f[1:], np.sqrt(psd[1:]))
plt.xlabel("frequency (Hz)")
plt.ylabel("psd (arb.u./SQRT(Hz))")
#plt.axvline(13, ls="dashed", color="g")
plt.axhline(rho, ls="dashed", color="r")
plt.show()

Signal with noise

PSD

Disable button in angular with two conditions?

It sounds like you need an OR instead:

<button type="submit" [disabled]="!validate || !SAForm.valid">Add</button>

This will disable the button if not validate or if not SAForm.valid.

What is difference between MVC, MVP & MVVM design pattern in terms of coding c#

MVC, MVP, MVVM

MVC (old one)

MVP (more modular because of its low-coupling. Presenter is a mediator between the View and Model)

MVVM (You already have two-way binding between VM and UI component, so it is more automated than MVP) enter image description here

Another image: enter image description here

how to select rows based on distinct values of A COLUMN only

use this(assume that your table name is emails):

select * from emails as a 
inner join  
(select EmailAddress, min(Id) as id from emails 
group by EmailAddress ) as b 
on a.EmailAddress = b.EmailAddress 
and a.Id = b.id

hope this help..

grep output to show only matching file

grep -l 

(That's a lowercase L)

The most accurate way to check JS object's type?

Accepted answer is correct, but I like to define this little utility in most projects I build.

var types = {
   'get': function(prop) {
      return Object.prototype.toString.call(prop);
   },
   'null': '[object Null]',
   'object': '[object Object]',
   'array': '[object Array]',
   'string': '[object String]',
   'boolean': '[object Boolean]',
   'number': '[object Number]',
   'date': '[object Date]',
}

Used like this:

if(types.get(prop) == types.number) {

}

If you're using angular you can even have it cleanly injected:

angular.constant('types', types);

How to expand and compute log(a + b)?

In general, one doesn't expand out log(a + b); you just deal with it as is. That said, there are occasionally circumstances where it makes sense to use the following identity:

log(a + b) = log(a * (1 + b/a)) = log a + log(1 + b/a)

(In fact, this identity is often used when implementing log in math libraries).

Catch an exception thrown by an async void method

The exception can be caught in the async function.

public async void Foo()
{
    try
    {
        var x = await DoSomethingAsync();
        /* Handle the result, but sometimes an exception might be thrown
           For example, DoSomethingAsync get's data from the network
           and the data is invalid... a ProtocolException might be thrown */
    }
    catch (ProtocolException ex)
    {
          /* The exception will be caught here */
    }
}

public void DoFoo()
{
    Foo();
}

How to run (not only install) an android application using .apk file?

if you're looking for the equivalent of "adb run myapp.apk"

you can use the script shown in this answer

(linux and mac only - maybe with cygwin on windows)

linux/mac users can also create a script to run an apk with something like the following:

create a file named "adb-run.sh" with these 3 lines:

pkg=$(aapt dump badging $1|awk -F" " '/package/ {print $2}'|awk -F"'" '/name=/ {print $2}')
act=$(aapt dump badging $1|awk -F" " '/launchable-activity/ {print $2}'|awk -F"'" '/name=/ {print $2}')
adb shell am start -n $pkg/$act

then "chmod +x adb-run.sh" to make it executable.

now you can simply:

adb-run.sh myapp.apk

The benefit here is that you don't need to know the package name or launchable activity name. Similarly, you can create "adb-uninstall.sh myapp.apk"

Note: This requires that you have aapt in your path. You can find it under the new build tools folder in the SDK

How to use 'git pull' from the command line?

One more option is to add the path of the privatekey file like this in terminal:

ssh-add "path to the privatekeyfile"

and then execute the pull command

Package structure for a Java project?

You could follow maven's standard project layout. You don't have to actually use maven, but it would make the transition easier in the future (if necessary). Plus, other developers will be used to seeing that layout, since many open source projects are layed out this way,

Creating a dynamic choice field

Underneath working solution with normal choice field. my problem was that each user have their own CUSTOM choicefield options based on few conditions.

class SupportForm(BaseForm):

    affiliated = ChoiceField(required=False, label='Fieldname', choices=[], widget=Select(attrs={'onchange': 'sysAdminCheck();'}))

    def __init__(self, *args, **kwargs):

        self.request = kwargs.pop('request', None)
        grid_id = get_user_from_request(self.request)
        for l in get_all_choices().filter(user=user_id):
            admin = 'y' if l in self.core else 'n'
            choice = (('%s_%s' % (l.name, admin)), ('%s' % l.name))
            self.affiliated_choices.append(choice)
        super(SupportForm, self).__init__(*args, **kwargs)
        self.fields['affiliated'].choices = self.affiliated_choice

When to use a View instead of a Table?

First of all as the name suggests a view is immutable. thats because a view is nothing other than a virtual table created from a stored query in the DB. Because of this you have some characteristics of views:

  • you can show only a subset of the data
  • you can join multiple tables into a single view
  • you can aggregate data in a view (select count)
  • view dont actually hold data, they dont need any tablespace since they are virtual aggregations of underlying tables

so there are a gazillion of use cases for which views are better fitted than tables, just think about only displaying active users on a website. a view would be better because you operate only on a subset of the data which actually is in your DB (active and inactive users)

check out this article

hope this helped..

Invoke-WebRequest, POST with parameters

Single command without ps variables when using JSON as body {lastName:"doe"} for POST api call:

Invoke-WebRequest -Headers @{"Authorization" = "Bearer N-1234ulmMGhsDsCAEAzmo1tChSsq323sIkk4Zq9"} `
                  -Method POST `
                  -Body (@{"lastName"="doe";}|ConvertTo-Json) `
                  -Uri https://api.dummy.com/getUsers `
                  -ContentType application/json

Best practices with STDIN in Ruby?

Quick and simple:

STDIN.gets.chomp == 'YES'

How to compare variables to undefined, if I don’t know whether they exist?

!undefined is true in javascript, so if you want to know whether your variable or object is undefined and want to take actions, you could do something like this:

if(<object or variable>) {
     //take actions if object is not undefined
} else {
     //take actions if object is undefined
}

java.lang.ClassNotFoundException: org.apache.log4j.Level

In my environment, I just added the two files to class path. And is work fine.

slf4j-jdk14-1.7.25.jar
slf4j-api-1.7.25.jar

How to synchronize or lock upon variables in Java?

Use the synchronized keyword.

class sample {
    private String msg=null;

    public synchronized void newmsg(String x){
        msg=x;
    }

    public synchronized string getmsg(){
        String temp=msg;
        msg=null;
        return msg;
    }
}

Using the synchronized keyword on the methods will require threads to obtain a lock on the instance of sample. Thus, if any one thread is in newmsg(), no other thread will be able to get a lock on the instance of sample, even if it were trying to invoke getmsg().

On the other hand, using synchronized methods can become a bottleneck if your methods perform long-running operations - all threads, even if they want to invoke other methods in that object that could be interleaved, will still have to wait.

IMO, in your simple example, it's ok to use synchronized methods since you actually have two methods that should not be interleaved. However, under different circumstances, it might make more sense to have a lock object to synchronize on, as shown in Joh Skeet's answer.

Fastest way to determine if an integer's square root is an integer

I'm not sure if it would be faster, or even accurate, but you could use John Carmack's Magical Square Root, algorithm to solve the square root faster. You could probably easily test this for all possible 32 bit integers, and validate that you actually got correct results, as it's only an appoximation. However, now that I think about it, using doubles is approximating also, so I'm not sure how that would come into play.

How do I fix the indentation of selected lines in Visual Studio

I like Ctrl+K, Ctrl+D, which indents the whole document.

How to add browse file button to Windows Form using C#

These links explain it with examples

http://dotnetperls.com/openfiledialog

http://www.geekpedia.com/tutorial67_Using-OpenFileDialog-to-open-files.html

private void button1_Click(object sender, EventArgs e)
{
    int size = -1;
    DialogResult result = openFileDialog1.ShowDialog(); // Show the dialog.
    if (result == DialogResult.OK) // Test result.
    {
       string file = openFileDialog1.FileName;
       try
       {
          string text = File.ReadAllText(file);
          size = text.Length;
       }
       catch (IOException)
       {
       }
    }
    Console.WriteLine(size); // <-- Shows file size in debugging mode.
    Console.WriteLine(result); // <-- For debugging use.
}

Regular Expressions- Match Anything

Normally the dot matches any character except newlines.

So if .* isn't working, set the "dot matches newlines, too" option (or use (?s).*).

If you're using JavaScript, which doesn't have a "dotall" option, try [\s\S]*. This means "match any number of characters that are either whitespace or non-whitespace" - effectively "match any string".

Another option that only works for JavaScript (and is not recognized by any other regex flavor) is [^]* which also matches any string. But [\s\S]* seems to be more widely used, perhaps because it's more portable.

How to fit Windows Form to any screen resolution?

Set the form property to open in maximized state.

this.WindowState = FormWindowState.Maximized;

c++ and opencv get and set pixel color to Mat

I would not use .at for performance reasons.

Define a struct:

//#pragma pack(push, 2) //not useful (see comments below)
struct RGB {
    uchar blue;
    uchar green;
    uchar red;  };

And then use it like this on your cv::Mat image:

RGB& rgb = image.ptr<RGB>(y)[x];

image.ptr(y) gives you a pointer to the scanline y. And iterate through the pixels with loops of x and y

#1025 - Error on rename of './database/#sql-2e0f_1254ba7' to './database/table' (errno: 150)

For those who are getting to this question via google... this error can also happen if you try to rename a field that is acting as a foreign key.

How to make lists contain only distinct element in Python?

From http://www.peterbe.com/plog/uniqifiers-benchmark:

def f5(seq, idfun=None):  
    # order preserving
    if idfun is None:
        def idfun(x): return x
    seen = {}
    result = []
    for item in seq:
        marker = idfun(item)
        # in old Python versions:
        # if seen.has_key(marker)
        # but in new ones:
        if marker in seen: continue
        seen[marker] = 1
        result.append(item)
    return result

Getting Image from API in Angular 4/5+?

There is no need to use angular http, you can get with js native functions

_x000D_
_x000D_
// you will ned this function to fetch the image blob._x000D_
async function getImage(url, fileName) {_x000D_
     // on the first then you will return blob from response_x000D_
    return await fetch(url).then(r => r.blob())_x000D_
    .then((blob) => { // on the second, you just create a file from that blob, getting the type and name that intend to inform_x000D_
         _x000D_
        return new File([blob], fileName+'.'+   blob.type.split('/')[1]) ;_x000D_
    });_x000D_
}_x000D_
_x000D_
// example url_x000D_
var url = 'https://img.freepik.com/vetores-gratis/icone-realista-quebrado-vidro-fosco_1284-12125.jpg';_x000D_
_x000D_
// calling the function_x000D_
getImage(url, 'your-name-image').then(function(file) {_x000D_
_x000D_
    // with file reader you will transform the file in a data url file;_x000D_
    var reader = new FileReader();_x000D_
    reader.readAsDataURL(file);_x000D_
    reader.onloadend = () => {_x000D_
    _x000D_
    // just putting the data url to img element_x000D_
        document.querySelector('#image').src = reader.result ;_x000D_
    }_x000D_
})
_x000D_
<img src="" id="image"/>
_x000D_
_x000D_
_x000D_

what is the differences between sql server authentication and windows authentication..?

I don't know SQLServer as well as other DBMS' but I imagine the benefit is the same as with DB2 and Oracle. If you use Windows authentication, you only have to maintain one set of users and/or passwords, that of Windows, which is already done for you.

DBMS authentication means having a separate set of users and/or passwords which must be maintained.

In addition, Windows passwords allow them to be configured centrally for the enterprise (Active Directory) whereas SQLServer has to maintain one set for each DBMS instance.

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

It can also happen when your parameters are wrong in the request. In my case I was working with a API that sent me the message

"No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. The response had HTTP status code 401."

when I send wrong username or password with the POST request to login.

Calling ASP.NET MVC Action Methods from JavaScript

If you want to call an action from your JavaScript, one way is to embed your JavaScript code, inside your view (.cshtml file for example), and then, use Razor, to create a URL of that action:

$(function(){
    $('#sampleDiv').click(function(){
        /*
         While this code is JavaScript, but because it's embedded inside
         a cshtml file, we can use Razor, and create the URL of the action

         Don't forget to add '' around the url because it has to become a     
         valid string in the final webpage
        */

        var url = '@Url.Action("ActionName", "Controller")';
    });
});

Setting focus to a textbox control

create a textbox:

 <TextBox Name="tb">
 ..hello..
</TextBox>

focus() ---> it is used to set input focus to the textbox control

tb.focus()

Why does the PHP json_encode function convert UTF-8 strings to hexadecimal entities?

Is this the expected behavior?

the json_encode() only works with UTF-8 encoded data.

maybe you can get an answer to convert it here: cyrillic-characters-in-phps-json-encode

Why use #ifndef CLASS_H and #define CLASS_H in .h file but not in .cpp?

.cpp files are not included (using #include) into other files. Therefore they don't need include guarding. Main.cpp will know the names and signatures of the class that you have implemented in class.cpp only because you have specified all that in class.h - this is the purpose of a header file. (It is up to you to make sure that class.h accurately describes the code you implement in class.cpp.) The executable code in class.cpp will be made available to the executable code in main.cpp thanks to the efforts of the linker.

Check mySQL version on Mac 10.8.5

To check your MySQL version on your mac, navigate to the directory where you installed it (default is usr/local/mysql/bin) and issue this command:

./mysql --version

Alternatively, to avoid needing to navigate to that specific dir to run the command, add its location to your path ($PATH). There's more than one way to add a dir to your $PATH (with explanations on stackoverflow and other places on how to do so), such as adding it to your ./bash_profile.

After adding the mysql bin dir to your $PATH, verify it's there by executing:

echo $PATH

Thereafter you can check your mysql version from anywhere by running (note no "./"):

mysql --version

Get form data in ReactJS

This might help Meteor (v1.3) users:

render: function() {
    return (
        <form onSubmit={this.submitForm.bind(this)}>
            <input type="text" ref="email" placeholder="Email" />
            <input type="password" ref="password" placeholder="Password" />
            <button type="submit">Login</button>
        </form>
    );
},
submitForm: function(e) {
    e.preventDefault();
    console.log( this.refs.email.value );
    console.log( this.refs.password.value );
}

Get an image extension from an uploaded file in Laravel

If you just want the extension, you can use pathinfo:

$ext = pathinfo($file_path, PATHINFO_EXTENSION);

How can I list all collections in the MongoDB shell?

First you need to use a database to show all collection/tables inside it.

>show dbs
users 0.56787GB
test (empty)
>db.test.help() // this will give you all the function which can be used with this db
>use users
>show tables //will show all the collection in the db

Entity Framework - Include Multiple Levels of Properties

The EFCore examples on MSDN show that you can do some quite complex things with Include and ThenInclude.

This is a good example of how complex you can get (this is all one chained statement!):

viewModel.Instructors = await _context.Instructors

      .Include(i => i.OfficeAssignment)

      .Include(i => i.CourseAssignments)
        .ThenInclude(i => i.Course)
            .ThenInclude(i => i.Enrollments)
                .ThenInclude(i => i.Student)

      .Include(i => i.CourseAssignments)
        .ThenInclude(i => i.Course)
            .ThenInclude(i => i.Department)

      .AsNoTracking()
      .OrderBy(i => i.LastName)
      .ToListAsync();

You can have multiple Include calls - even after ThenInclude and it kind of 'resets' you back to the level of the top level entity (Instructors).

You can even repeat the same 'first level' collection (CourseAssignments) multiple times followed by separate ThenIncludes commands to get to different child entities.

Note your actual query must be tagged onto the end of the Include or ThenIncludes chain. The following does NOT work:

var query = _context.Instructors.AsQueryable();
query.Include(i => i.OfficeAssignment);

var first10Instructors = query.Take(10).ToArray();

Would strongly recommend you set up logging and make sure your queries aren't out of control if you're including more than one or two things. It's important to see how it actually works - and you'll notice each separate 'include' is typically a new query to avoid massive joins returning redundant data.

AsNoTracking can greatly speed things up if you're not intending on actually editing the entities and resaving.


EFCore 5 made some changes to the way queries for multiple sets of entities are sent to the server. There are new options for Split Queries which can make certain queries of this type far more efficient with fewer joins, but make sure to understand the limitations.

SQL update fields of one table from fields of another one

Try Following

Update A a, B b, SET a.column1=b.column1 where b.id=1

EDITED:- Update more than one column

Update A a, B b, SET a.column1=b.column1, a.column2=b.column2 where b.id=1

How to create a inset box-shadow only on one side?

This might not be the exact thing you are looking for, but you can create a very similar effect by using rgba in combination with linear-gradient:

  background: linear-gradient(rgba(0,0,0,.5) 0%, rgba(0,0,0,0) 30%);

This creates a linear-gradient from black with 50% opacity (rgba(0,0,0,.5)) to transparent (rgba(0,0,0,0)) which starts being competently transparent 30% from the top. You can play with those values to create your desired effect. You can have it on a different side by adding a deg-value (linear-gradient(90deg, rgba(0,0,0,.5) 0%, rgba(0,0,0,0) 30%)) or switching the colors around. If you want really complex shadows like different angles on different sides you could even start layering linear-gradient.

Here is a snippet to see it in action:

_x000D_
_x000D_
.box {_x000D_
  background: linear-gradient(rgba(0,0,0,.5) 0%, rgba(0,0,0,0) 30%);_x000D_
}_x000D_
_x000D_
.text {_x000D_
  padding: 20px;_x000D_
}
_x000D_
<div class="box">_x000D_
  <div class="text">_x000D_
    Lorem ipsum ...._x000D_
  </div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

How can I add NSAppTransportSecurity to my info.plist file?

Open your info.plist file of your project with any editor of your preference, then add this code at the end of the file before the last

<key>NSAppTransportSecurity</key>
<dict>
   <key>NSAllowsArbitraryLoads</key>
<true/>
</dict>

FFT in a single C-file

You could start converting this java snippet to C the author states he has converted it from C based on the book numerical recipies which you find online! here

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

Since I don't know how to control only the list marker size with CSS and no one's offered this yet, you can use :before content to generate the bullets:

li {
    list-style: none;
    font-size: 20px;
}

li:before {
    content:"·";
    font-size:120px;
    vertical-align:middle;
    line-height:20px;
}

Demo: http://jsfiddle.net/4wDL5/

The markers are limited to appearing "inside" with this particular CSS, although you could change it. It's definitely not the best option (browser must support generated content, so no IE6 or 7), but it might be the easiest - plus you can choose any character you want for the marker.

If you go the image route, see list-style-image.

Find a value in an array of objects in Javascript

Finding the array element:

_x000D_
_x000D_
let arr = [_x000D_
    { name:"string 1", value:"this", other: "that" },_x000D_
    { name:"string 2", value:"this", other: "that" }_x000D_
];_x000D_
_x000D_
let obj = arr.find(o => o.name === 'string 1');_x000D_
_x000D_
console.log(obj);
_x000D_
_x000D_
_x000D_


Replacing the array element:

_x000D_
_x000D_
let arr = [_x000D_
    { name:"string 1", value:"this", other: "that" },_x000D_
    { name:"string 2", value:"this", other: "that" }_x000D_
];_x000D_
_x000D_
let obj = arr.find((o, i) => {_x000D_
    if (o.name === 'string 1') {_x000D_
        arr[i] = { name: 'new string', value: 'this', other: 'that' };_x000D_
        return true; // stop searching_x000D_
    }_x000D_
});_x000D_
_x000D_
console.log(arr);
_x000D_
_x000D_
_x000D_

Export JAR with Netbeans

It does this by default, you just need to look into the project's /dist folder.

How to clear react-native cache?

For React Native Init approach (without expo) use:

npm start -- --reset-cache

pgadmin4 : postgresql application server could not be contacted.

I use the cmd prompt on Windows 10 with psql postgres postgres.

Then I launch pgAdmin4 and it works.

specifying goal in pom.xml

I've bumped into this question because I actually wanted to define a default goal in pom.xml. You can define a default goal under build:

<build>
    <defaultGoal>install</defaultGoal>
...
</build>

After that change, you can then simply run mvn which will do exactly the same as mvn install.

Note: I don't favor this as a default approach. My use case was to define a profile that downloaded a previous version of that project from Artifactory and wanted to tie that profile to a given phase. For convenience, I can run mvn -Pdownload-jar -Dversion=0.0.9 and don't need to specify a goal/phase there. I think it's reasonable to define a defaultGoal in a profile which has a very specific function for a particular phase.

Git on Bitbucket: Always asked for password, even after uploading my public SSH key

With me, although I ran 'git clone ssh://[email protected]:7999/projName/projA.git' I was still being prompted for password for this new repo that I cloned, so by comparing its .git/config file to other repos that work, It turned out to be the url under the [remote "origin"] section, it was set to the ssh path above for the new repo, but was set to https:xxx for the working one.

Posting a File and Associated Data to a RESTful WebService preferably as JSON

@RequestMapping(value = "/uploadImageJson", method = RequestMethod.POST)
    public @ResponseBody Object jsongStrImage(@RequestParam(value="image") MultipartFile image, @RequestParam String jsonStr) {
-- use  com.fasterxml.jackson.databind.ObjectMapper convert Json String to Object
}

Nodejs - Redirect url

You have to use the following code:

response.writeHead(302 , {
           'Location' : '/view/index.html' // This is your url which you want
        });
response.end();

How to find the array index with a value?

Use indexOf

imageList.indexOf(200)

How to declare array of zeros in python (or an array of a certain size)

Depending on what you're actually going to do with the data after it's collected, collections.defaultdict(int) might be useful.

How to find encoding of a file via script on Linux?

In Debian you can also use: encguess:

$ encguess test.txt
test.txt  US-ASCII

android: data binding error: cannot find symbol class

I consistently run into this problem. I believe it has to do with android studio not being aware of dynamically generated files. If you have everything else right for databinding try to File > Invalidate Caches/Restart... and select Invalidate Caches and Restart. Then try and import the BR file... it should import fine.

You may have to throw in a Clean and Rebuild.

Set the text in a span

You need to fix your selector. Although CSS syntax requires multiple classes to be space separated, selector syntax would require them to be directly concatenated, and dot prefixed:

$(".ui-icon.ui-icon-circle-triangle-w").text(...);

or better:

$(".ui-datepicker-prev > span").text(...);

New line in Sql Query

use CHAR(10) for New Line in SQL
char(9) for Tab
and Char(13) for Carriage Return

Replace values in list using Python

Build a new list with a list comprehension:

new_items = [x if x % 2 else None for x in items]

You can modify the original list in-place if you want, but it doesn't actually save time:

items = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
for index, item in enumerate(items):
    if not (item % 2):
        items[index] = None

Here are (Python 3.6.3) timings demonstrating the non-timesave:

In [1]: %%timeit
   ...: items = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
   ...: for index, item in enumerate(items):
   ...:     if not (item % 2):
   ...:         items[index] = None
   ...:
1.06 µs ± 33.7 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

In [2]: %%timeit
   ...: items = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
   ...: new_items = [x if x % 2 else None for x in items]
   ...:
891 ns ± 13.6 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

And Python 2.7.6 timings:

In [1]: %%timeit
   ...: items = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
   ...: for index, item in enumerate(items):
   ...:     if not (item % 2):
   ...:         items[index] = None
   ...: 
1000000 loops, best of 3: 1.27 µs per loop
In [2]: %%timeit
   ...: items = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
   ...: new_items = [x if x % 2 else None for x in items]
   ...: 
1000000 loops, best of 3: 1.14 µs per loop

format a Date column in a Data Frame

This should do it (where df is your dataframe)

df$JoiningDate <- as.Date(df$JoiningDate , format = "%m/%d/%y")

df[order(df$JoiningDate ),]

Set left margin for a paragraph in html

<p style="margin-left:5em;">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut lacinia vestibulum quam sit amet aliquet. Phasellus tempor nisi eget tellus venenatis tempus. Aliquam dapibus porttitor convallis. Praesent pretium luctus orci, quis ullamcorper lacus lacinia a. Integer eget molestie purus. Vestibulum porta mollis tempus. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. </p>

That'll do it, there's a few improvements obviously, but that's the basics. And I use 'em' as the measurement, you may want to use other units, like 'px'.

EDIT: What they're describing above is a way of associating groups of styles, or classes, with elements on a web page. You can implement that in a few ways, here's one which may suit you:

In your HTML page, containing the <p> tagged content from your DB add in a new 'style' node and wrap the styles you want to declare in a class like so:

<head>
  <style type="text/css">
    p { margin-left:5em; /* Or another measurement unit, like px */ }
  </style>
</head>
<body>
  <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut lacinia vestibulum quam sit amet aliquet.</p>
</body>

So above, all <p> elements in your document will have that style rule applied. Perhaps you are pumping your paragraph content into a container of some sort? Try this:

<head>
  <style type="text/css">
    .container p { margin-left:5em; /* Or another measurement unit, like px */ }
  </style>
</head>
<body>
  <div class="container">
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut lacinia vestibulum quam sit amet aliquet.</p>
  </div>
  <p>Vestibulum porta mollis tempus. Class aptent taciti sociosqu ad litora torquent per conubia nostra.</p>
</body>

In the example above, only the <p> element inside the div, whose class name is 'container', will have the styles applied - and not the <p> element outside the container.

In addition to the above, you can collect your styles together and remove the style element from the <head> tag, replacing it with a <link> tag, which points to an external CSS file. This external file is where you'd now put your <p> tag styles. This concept is known as 'seperating content from style' and is considered good practice, and is also an extendible way to create styles, and can help with low maintenance.

Longer object length is not a multiple of shorter object length?

Yes, this is something that you should worry about. Check the length of your objects with nrow(). R can auto-replicate objects so that they're the same length if they differ, which means you might be performing operations on mismatched data.

In this case you have an obvious flaw in that your subtracting aggregated data from raw data. These will definitely be of different lengths. I suggest that you merge them as time series (using the dates), then locf(), then do your subtraction. Otherwise merge them by truncating the original dates to the same interval as the aggregated series. Just be very careful that you don't drop observations.

Lastly, as some general advice as you get started: look at the result of your computations to see if they make sense. You might even pull them into a spreadsheet and replicate the results.

Converting HTML to PDF using PHP?

If you wish to create a pdf from php, pdflib will help you (as some others suggested).

Else, if you want to convert an HTML page to PDF via PHP, you'll find a little trouble outta here.. For 3 years I've been trying to do it as best as I can.

So, the options I know are:

DOMPDF : php class that wraps the html and builds the pdf. Works good, customizable (if you know php), based on pdflib, if I remember right it takes even some CSS. Bad news: slow when the html is big or complex.

HTML2PS: same as DOMPDF, but this one converts first to a .ps (ghostscript) file, then, to whatever format you need (pdf, jpg, png). For me is little better than dompdf, but has the same speed problem.. but, better compatibility with CSS.

Those two are php classes, but if you can install some software on the server, and access it throught passthru() or system(), give a look to these too:

wkhtmltopdf: based on webkit (safari's wrapper), is really fast and powerful.. seems like this is the best one (atm) for converting html pages to pdf on the fly; taking only 2 seconds for a 3 page xHTML document with CSS2. It is a recent project, anyway, the google.code page is often updated.

htmldoc : This one is a tank, it never really stops/crashes.. the project looks dead since 2007, but anyway if you don't need CSS compatibility this can be nice for you.

Concatenate two char* strings in a C program

strcat concats str2 onto str1

You'll get runtime errors because str1 is not being properly allocated for concatenation

How can I exclude all "permission denied" messages from "find"?

You can also use the -perm and -prune predicates to avoid descending into unreadable directories (see also How do I remove "permission denied" printout statements from the find program? - Unix & Linux Stack Exchange):

find . -type d ! -perm -g+r,u+r,o+r -prune -o -print > files_and_folders

How to compare objects by multiple fields

Following blog given good chained Comparator example

http://www.codejava.net/java-core/collections/sorting-a-list-by-multiple-attributes-example

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;

/**
 * This is a chained comparator that is used to sort a list by multiple
 * attributes by chaining a sequence of comparators of individual fields
 * together.
 *
 */
public class EmployeeChainedComparator implements Comparator<Employee> {

    private List<Comparator<Employee>> listComparators;

    @SafeVarargs
    public EmployeeChainedComparator(Comparator<Employee>... comparators) {
        this.listComparators = Arrays.asList(comparators);
    }

    @Override
    public int compare(Employee emp1, Employee emp2) {
        for (Comparator<Employee> comparator : listComparators) {
            int result = comparator.compare(emp1, emp2);
            if (result != 0) {
                return result;
            }
        }
        return 0;
    }
}

Calling Comparator:

Collections.sort(listEmployees, new EmployeeChainedComparator(
                new EmployeeJobTitleComparator(),
                new EmployeeAgeComparator(),
                new EmployeeSalaryComparator())
        );

Python Error: "ValueError: need more than 1 value to unpack"

You have to pass the arguments in the terminal in order to store them in 'argv'. This variable holds the arguments you pass to your Python script when you run it. It later unpacks the arguments and store them in different variables you specify in the program e.g.

script, first, second = argv
print "Your file is:", script
print "Your first entry is:", first
print "Your second entry is:" second

Then in your command line you have to run your code like this,

$python ex14.py Hamburger Pizza

Your output will look like this:

Your file is: ex14.py
Your first entry is: Hamburger
Your second entry is: Pizza

What does git push -u mean?

This is no longer up-to-date!

Push.default is unset; its implicit value has changed in
Git 2.0 from 'matching' to 'simple'. To squelch this message
and maintain the traditional behavior, use:

  git config --global push.default matching

To squelch this message and adopt the new behavior now, use:

  git config --global push.default simple

When push.default is set to 'matching', git will push local branches
to the remote branches that already exist with the same name.

Since Git 2.0, Git defaults to the more conservative 'simple'
behavior, which only pushes the current branch to the corresponding
remote branch that 'git pull' uses to update the current branch.

How to extract the file name from URI returned from Intent.ACTION_GET_CONTENT?

Stefan Haustein function for xamarin/c#:

public string GetFilenameFromURI(Android.Net.Uri uri)
        {
            string result = null;
            if (uri.Scheme == "content")
            {
                using (var cursor = Application.Context.ContentResolver.Query(uri, null, null, null, null))
                {
                    try
                    {
                        if (cursor != null && cursor.MoveToFirst())
                        {
                            result = cursor.GetString(cursor.GetColumnIndex(OpenableColumns.DisplayName));
                        }
                    }
                    finally
                    {
                        cursor.Close();
                    }
                }
            }
            if (result == null)
            {
                result = uri.Path;
                int cut = result.LastIndexOf('/');
                if (cut != -1)
                {
                    result = result.Substring(cut + 1);
                }
            }
            return result;
        }

VB.net: Date without time

Or, if for some reason you don't like any of the more sensible answers, just discard everything to the right of (and including) the space.

How to run a shell script on a Unix console or Mac terminal?

For the bourne shell:

sh myscript.sh

For bash:

bash myscript.sh

How to click a browser button with JavaScript automatically?

You can use

setInterval(function(){ 
    document.getElementById("yourbutton").click();
}, 1000);

Get Time from Getdate()

To get the format you want:

SELECT (substring(CONVERT(VARCHAR,GETDATE(),22),10,8) + ' ' + SUBSTRING(CONVERT(VARCHAR,getdate(),22), 19,2))

Why are you pulling this from sql?

Drop rows with all zeros in pandas data frame

df = df [~( df [ ['kt'  'b'   'tt'  'mky' 'depth', ] ] == 0).all(axis=1) ]

Try this command its perfectly working.

How to define optional methods in Swift protocol?

1. Using default implementations (preferred).

protocol MyProtocol {
    func doSomething()
}

extension MyProtocol {
    func doSomething() {
        /* return a default value or just leave empty */
    }
}

struct MyStruct: MyProtocol {
    /* no compile error */
}

Advantages

  • No Objective-C runtime is involved (well, no explicitly at least). This means you can conform structs, enums and non-NSObject classes to it. Also, this means you can take advantage of powerful generics system.

  • You can always be sure that all requirements are met when encountering types that conform to such protocol. It's always either concrete implementation or default one. This is how "interfaces" or "contracts" behave in other languages.

Disadvantages

  • For non-Void requirements, you need to have a reasonable default value, which is not always possible. However, when you encounter this problem, it means that either such requirement should really have no default implementation, or that your you made a mistake during API design.

  • You can't distinguish between a default implementation and no implementation at all, at least without addressing that problem with special return values. Consider the following example:

    protocol SomeParserDelegate {
        func validate(value: Any) -> Bool
    }
    

    If you provide a default implementation which just returns true — it's fine at the first glance. Now, consider the following pseudo code:

    final class SomeParser {
        func parse(data: Data) -> [Any] {
            if /* delegate.validate(value:) is not implemented */ {
                /* parse very fast without validating */
            } else {
                /* parse and validate every value */
            }
        }
    }
    

    There's no way to implement such an optimization — you can't know if your delegate implements a method or not.

    Although there's a number of different ways to overcome this problem (using optional closures, different delegate objects for different operations to name a few), that example presents the problem clearly.


2. Using @objc optional.

@objc protocol MyProtocol {
    @objc optional func doSomething()
}

class MyClass: NSObject, MyProtocol {
    /* no compile error */
}

Advantages

  • No default implementation is needed. You just declare an optional method or a variable and you're ready to go.

Disadvantages

  • It severely limits your protocol's capabilities by requiring all conforming types to be Objective-C compatible. This means, only classes that inherit from NSObject can conform to such protocol. No structs, no enums, no associated types.

  • You must always check if an optional method is implemented by either optionally calling or checking if the conforming type implements it. This might introduce a lot of boilerplate if you're calling optional methods often.

insert/delete/update trigger in SQL server

I agree with @Vishnu's answer. I would like to add that if you want to use the application user in your trigger you can use "context_info" to pass the info to the trigger.

I found following very helpful in doing that: http://jasondentler.com/blog/2010/01/exploiting-context_info-for-fun-and-audit

Rename master branch for both local and remote Git repositories

OK, renaming a branch both locally and on the remote is pretty easy!...

If you on the branch, you can easily do:

git branch -m <branch>

or if not, you need to do:

git branch -m <your_old_branch> <your_new_branch>

Then, push deletion to the remote like this:

git push origin <your_old_branch>

Now you done, if you get upstream error while you trying to push, simply do:

git push --set-upstream origin <your_new_branch>

I also create the image below to show the steps in real command line, just follow the steps and you would be good:

enter image description here

Easy interview question got harder: given numbers 1..100, find the missing number(s) given exactly k are missing

We can do the Q1 and Q2 in O(log n) most of the time.

Suppose our memory chip consists of array of n number of test tubes. And a number x in the the test tube is represented by x milliliter of chemical-liquid.

Suppose our processor is a laser light. When we light up the laser it traverses all the tubes perpendicularly to it's length. Every-time it passes through the chemical liquid, the luminosity is reduced by 1. And passing the light at certain milliliter mark is an operation of O(1).

Now if we light our laser at the middle of the test-tube and get the output of luminosity

  • equals to a pre-calculated value(calculated when no numbers were missing), then the missing numbers are greater than n/2 .
  • If our output is smaller, then there is at least one missing number that is smaller than n/2 . We can also check if the luminosity is reduced by 1 or 2. if it is reduced by 1 then one missing number is smaller than n/2 and other is bigger than n/2 . If it is reduced by 2 then both numbers are smaller than n/2 .

We can repeat the above process again and again narrowing down our problem domain. In each step, we make the domain smaller by half. And finally we can get to our result.

Parallel algorithms that are worth mentioning(because they are interesting),

  • sorting by some parallel algorithm, for example, parallel merge can be done in O(log^3 n) time. And then the missing number can be found by binary search in O(log n) time.
  • Theoretically, if we have n processors then each process can check one of the inputs and set some flag that identifies the number(conveniently in an array). And in the next step each process can check each flag and finally output the number that is not flagged. The whole process will take O(1) time. It has additional O(n) space/memory requirement.

Note, that the two parallel algorithms provided above may need additional space as mentioned in the comment.

Change bundle identifier in Xcode when submitting my first app in IOS

View this picture to see how you can change the bundle identifier

Explanation:

  1. Select your project form the leftmost project navigator
  2. Under the General Tab, there is a section called Targets inside where you will see the name of your project. Click on the name.
  3. Then you will be able to see the bundle identifier which you can change as below:

As you can see in the picture, the name of my App is PracticeApp. And my bundle identifier is: com.hello500.PracticeApp

In this case, You can change hello500 to change the bundle identifier of the app.