Programs & Examples On #Boolean expression

A boolean expression is an expression in a programming language that produces a boolean value when evaluated, i.e. one of true or false.

Is this the proper way to do boolean test in SQL?

MS SQL 2008 can also use the string version of true or false...

select * from users where active = 'true'
-- or --
select * from users where active = 'false'

Any good boolean expression simplifiers out there?

I found that The Boolean Expression Reducer is much easier to use than Logic Friday. Plus it doesn't require installation and is multi-platform (Java).

Also in Logic Friday the expression A | B just returns 3 entries in truth table; I expected 4.

Python `if x is not None` or `if not x is None`?

if not x is None is more similar to other programming languages, but if x is not None definitely sounds more clear (and is more grammatically correct in English) to me.

That said it seems like it's more of a preference thing to me.

How can I express that two values are not equal to eachother?

"Not equals" can be expressed with the "not" operator ! and the standard .equals.

if (a.equals(b)) // a equals b
if (!a.equals(b)) // a not equal to b

How to make "if not true condition"?

What am I doing wrong?

$(...) holds the value, not the exit status, that is why this approach is wrong. However, in this specific case, it does indeed work because sysa will be printed which makes the test statement come true. However, if ! [ $(true) ]; then echo false; fi would always print false because the true command does not write anything to stdout (even though the exit code is 0). That is why it needs to be rephrased to if ! grep ...; then.

An alternative would be cat /etc/passwd | grep "sysa" || echo error. Edit: As Alex pointed out, cat is useless here: grep "sysa" /etc/passwd || echo error.

Found the other answers rather confusing, hope this helps someone.

'and' (boolean) vs '&' (bitwise) - Why difference in behavior with lists vs numpy arrays?

For the first example and base on the django's doc
It will always return the second list, indeed a non empty list is see as a True value for Python thus python return the 'last' True value so the second list

In [74]: mylist1 = [False]
In [75]: mylist2 = [False, True, False,  True, False]
In [76]: mylist1 and mylist2
Out[76]: [False, True, False, True, False]
In [77]: mylist2 and mylist1
Out[77]: [False]

if (boolean == false) vs. if (!boolean)

No. I don't see any advantage. Second one is more straitforward.

btw: Second style is found in every corners of JDK source.

set gvim font in .vimrc file

I use the following (Uses Consolas size 11 on Windows, Menlo Regular size 14 on Mac OS X and Inconsolata size 12 everywhere else):

if has("gui_running")
  if has("gui_gtk2")
    set guifont=Inconsolata\ 12
  elseif has("gui_macvim")
    set guifont=Menlo\ Regular:h14
  elseif has("gui_win32")
    set guifont=Consolas:h11:cANSI
  endif
endif

Edit: And while you're at it, you could take a look at Coding Horror's Programming Fonts blog post.

Edit²: Added MacVim.

Twitter Bootstrap - add top space between rows

I added these classes to my bootstrap stylesheet

.voffset  { margin-top: 2px; }
.voffset1 { margin-top: 5px; }
.voffset2 { margin-top: 10px; }
.voffset3 { margin-top: 15px; }
.voffset4 { margin-top: 30px; }
.voffset5 { margin-top: 40px; }
.voffset6 { margin-top: 60px; }
.voffset7 { margin-top: 80px; }
.voffset8 { margin-top: 100px; }
.voffset9 { margin-top: 150px; }

Example

<div class="container">
  <div class="row voffset2">
    <div class="col-lg-12">
      <p>
        Vertically offset text.
      </p>
    </div>
  </div>
</div>

Using NotNull Annotation in method argument

To test your method validation in a test, you have to wrap it a proxy in the @Before method.

@Before
public void setUp() {
    this.classAutowiredWithFindStuffMethod = MethodValidationProxyFactory.createProxy(this.classAutowiredWithFindStuffMethod);
}

With MethodValidationProxyFactory as :

import org.springframework.context.support.StaticApplicationContext;
import org.springframework.validation.beanvalidation.MethodValidationPostProcessor;

public class MethodValidationProxyFactory {

private static final StaticApplicationContext ctx = new StaticApplicationContext();

static {
    MethodValidationPostProcessor processor = new MethodValidationPostProcessor();
    processor.afterPropertiesSet(); // init advisor
    ctx.getBeanFactory()
            .addBeanPostProcessor(processor);
}

@SuppressWarnings("unchecked")
public static <T> T createProxy(T instance) {

    return (T) ctx.getAutowireCapableBeanFactory()
            .applyBeanPostProcessorsAfterInitialization(instance, instance.getClass()
                    .getName());
}

}

And then, add your test :

@Test
public void findingNullStuff() {
 assertThatExceptionOfType(ConstraintViolationException.class).isThrownBy(() -> this.classAutowiredWithFindStuffMethod.findStuff(null));

}

Class method decorator with self arguments?

A more concise example might be as follows:

#/usr/bin/env python3
from functools import wraps

def wrapper(method):
    @wraps(method)
    def _impl(self, *method_args, **method_kwargs):
        method_output = method(self, *method_args, **method_kwargs)
        return method_output + "!"
    return _impl

class Foo:
    @wrapper
    def bar(self, word):
        return word

f = Foo()
result = f.bar("kitty")
print(result)

Which will print:

kitty!

Creating the checkbox dynamically using JavaScript?

   /* worked for me  */
     <div id="divid"> </div>
     <script type="text/javascript">
         var hold = document.getElementById("divid");
         var checkbox = document.createElement('input');
         checkbox.type = "checkbox";
         checkbox.name = "chkbox1";
         checkbox.id = "cbid";
         var label = document.createElement('label');
         var tn = document.createTextNode("Not A RoBot");
         label.htmlFor="cbid";
         label.appendChild(tn); 
         hold.appendChild(label);
         hold.appendChild(checkbox);
      </script>  

Clip/Crop background-image with CSS

may be you can write like this:

#graphic { 
 background-image: url(image.jpg); 
 background-position: 0 -50px; 
 width: 200px; 
 height: 100px;
}

Eloquent ->first() if ->exists()

An answer has already been accepted, but in these situations, a more elegant solution in my opinion would be to use error handling.

    try {
        $user = User::where('mobile', Input::get('mobile'))->first();
    } catch (ErrorException $e) {
        // Do stuff here that you need to do if it doesn't exist.
        return View::make('some.view')->with('msg', $e->getMessage());
    }

Spring Hibernate - Could not obtain transaction-synchronized Session for current thread

In your xyz.DAOImpl.java

Do the following steps:

//Step-1: Set session factory

@Resource(name="sessionFactory")
private SessionFactory sessionFactory;

public void setSessionFactory(SessionFactory sf)
{
    this.sessionFactory = sf;
}

//Step-2: Try to get the current session, and catch the HibernateException exception.


//Step-3: If there are any HibernateException exception, then true to get openSession.

try 
{
    //Step-2: Implementation
    session = sessionFactory.getCurrentSession();
} 
catch (HibernateException e) 
{
    //Step-3: Implementation
    session = sessionFactory.openSession();
}

How can I read input from the console using the Scanner class in Java?

When the user enters his/her username, check for valid entry also.

java.util.Scanner input = new java.util.Scanner(System.in);
String userName;
final int validLength = 6; // This is the valid length of an user name

System.out.print("Please enter the username: ");
userName = input.nextLine();

while(userName.length() < validLength) {

    // If the user enters less than validLength characters
    // ask for entering again
    System.out.println(
        "\nUsername needs to be " + validLength + " character long");

    System.out.print("\nPlease enter the username again: ");
    userName = input.nextLine();
}

System.out.println("Username is: " + userName);

What is the difference between dynamic programming and greedy approach?

Based on Wikipedia's articles.

Greedy Approach

A greedy algorithm is an algorithm that follows the problem solving heuristic of making the locally optimal choice at each stage with the hope of finding a global optimum. In many problems, a greedy strategy does not in general produce an optimal solution, but nonetheless a greedy heuristic may yield locally optimal solutions that approximate a global optimal solution in a reasonable time.

We can make whatever choice seems best at the moment and then solve the subproblems that arise later. The choice made by a greedy algorithm may depend on choices made so far but not on future choices or all the solutions to the subproblem. It iteratively makes one greedy choice after another, reducing each given problem into a smaller one.

Dynamic programming

The idea behind dynamic programming is quite simple. In general, to solve a given problem, we need to solve different parts of the problem (subproblems), then combine the solutions of the subproblems to reach an overall solution. Often when using a more naive method, many of the subproblems are generated and solved many times. The dynamic programming approach seeks to solve each subproblem only once, thus reducing the number of computations: once the solution to a given subproblem has been computed, it is stored or "memo-ized": the next time the same solution is needed, it is simply looked up. This approach is especially useful when the number of repeating subproblems grows exponentially as a function of the size of the input.

Difference

Greedy choice property

We can make whatever choice seems best at the moment and then solve the subproblems that arise later. The choice made by a greedy algorithm may depend on choices made so far but not on future choices or all the solutions to the subproblem. It iteratively makes one greedy choice after another, reducing each given problem into a smaller one. In other words, a greedy algorithm never reconsiders its choices.

This is the main difference from dynamic programming, which is exhaustive and is guaranteed to find the solution. After every stage, dynamic programming makes decisions based on all the decisions made in the previous stage, and may reconsider the previous stage's algorithmic path to solution.

For example, let's say that you have to get from point A to point B as fast as possible, in a given city, during rush hour. A dynamic programming algorithm will look into the entire traffic report, looking into all possible combinations of roads you might take, and will only then tell you which way is the fastest. Of course, you might have to wait for a while until the algorithm finishes, and only then can you start driving. The path you will take will be the fastest one (assuming that nothing changed in the external environment).

On the other hand, a greedy algorithm will start you driving immediately and will pick the road that looks the fastest at every intersection. As you can imagine, this strategy might not lead to the fastest arrival time, since you might take some "easy" streets and then find yourself hopelessly stuck in a traffic jam.

Some other details...

In mathematical optimization, greedy algorithms solve combinatorial problems having the properties of matroids.

Dynamic programming is applicable to problems exhibiting the properties of overlapping subproblems and optimal substructure.

How can I remove the outline around hyperlinks images?

For Remove outline for anchor tag

a {outline : none;}

Remove outline from image link

a img {outline : none;}

Remove border from image link

img {border : 0;}

How to install sklearn?

You didn't provide us which operating system are you on? If it is a Linux, make sure you have scipy installed as well, after that just do

pip install -U scikit-learn

If you are on windows you might want to check out these pages.

Get connection status on Socket.io client

Track the state of the connection yourself. With a boolean. Set it to false at declaration. Use the various events (connect, disconnect, reconnect, etc.) to reassign the current boolean value. Note: Using undocumented API features (e.g., socket.connected), is not a good idea; the feature could get removed in a subsequent version without the removal being mentioned.

Python using enumerate inside list comprehension

All great answer guys. I know the question here is specific to enumeration but how about something like this, just another perspective

from itertools import izip, count
a = ["5", "6", "1", "2"]
tupleList = list( izip( count(), a ) )
print(tupleList)

It becomes more powerful, if one has to iterate multiple lists in parallel in terms of performance. Just a thought

a = ["5", "6", "1", "2"]
b = ["a", "b", "c", "d"]
tupleList = list( izip( count(), a, b ) )
print(tupleList)

Show/hide forms using buttons and JavaScript

There's the global attribute called hidden. But I'm green to all this and maybe there was a reason it wasn't mentioned yet?

_x000D_
_x000D_
var someCondition = true;_x000D_
_x000D_
if (someCondition == true){_x000D_
    document.getElementById('hidden div').hidden = false;_x000D_
}
_x000D_
<div id="hidden div" hidden>_x000D_
    stuff hidden by default_x000D_
</div>
_x000D_
_x000D_
_x000D_

https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/hidden

CSS3 Transition not working

Transition is more like an animation.

div.sicon a {
    background:-moz-radial-gradient(left, #ffffff 24%, #cba334 88%);
    transition: background 0.5s linear;
    -moz-transition: background 0.5s linear; /* Firefox 4 */
    -webkit-transition: background 0.5s linear; /* Safari and Chrome */
    -o-transition: background 0.5s linear; /* Opera */
    -ms-transition: background 0.5s linear; /* Explorer 10 */
}

So you need to invoke that animation with an action.

div.sicon a:hover {
    background:-moz-radial-gradient(left, #cba334 24%, #ffffff 88%);
}

Also check for browser support and if you still have some problem with whatever you're trying to do! Check css-overrides in your stylesheet and also check out for behavior: ***.htc css hacks.. there may be something overriding your transition!

You should check this out: http://www.w3schools.com/css/css3_transitions.asp

How to inject a Map using the @Value Spring Annotation?

You can inject .properties as a map in your class using @Resource annotation.

If you are working with XML based configuration, then add below bean in your spring configuration file:

 <bean id="myProperties" class="org.springframework.beans.factory.config.PropertiesFactoryBean">
      <property name="location" value="classpath:your.properties"/>
 </bean>

For, Annotation based:

@Bean(name = "myProperties")
public static PropertiesFactoryBean mapper() {
        PropertiesFactoryBean bean = new PropertiesFactoryBean();
        bean.setLocation(new ClassPathResource(
                "your.properties"));
        return bean;
}

Then you can pick them up in your application as a Map:

@Resource(name = "myProperties")
private Map<String, String> myProperties;

Android TextView Justify Text

Android does not yet support full justification. We can use Webview and justify HTML instead of using textview. It works so fine. If you guys not clear, feel free to ask me :)

Spark: Add column to dataframe conditionally

Try withColumn with the function when as follows:

val sqlContext = new SQLContext(sc)
import sqlContext.implicits._ // for `toDF` and $""
import org.apache.spark.sql.functions._ // for `when`

val df = sc.parallelize(Seq((4, "blah", 2), (2, "", 3), (56, "foo", 3), (100, null, 5)))
    .toDF("A", "B", "C")

val newDf = df.withColumn("D", when($"B".isNull or $"B" === "", 0).otherwise(1))

newDf.show() shows

+---+----+---+---+
|  A|   B|  C|  D|
+---+----+---+---+
|  4|blah|  2|  1|
|  2|    |  3|  0|
| 56| foo|  3|  1|
|100|null|  5|  0|
+---+----+---+---+

I added the (100, null, 5) row for testing the isNull case.

I tried this code with Spark 1.6.0 but as commented in the code of when, it works on the versions after 1.4.0.

Is it possible to add an array or object to SharedPreferences on Android

I loaded an array of waist sizes (already created in my array.xml) into my preferences.xml file with the code below. @array/pant_inch_size is the id of the entire array.

 <ListPreference 
 android:title="choosepantsize"
 android:summary="Choose Pant Size"
 android:key="pantSizePref" 
 android:defaultValue="34" 
 android:entries="@array/pant_inch_size"
 android:entryValues="@array/pant_inch_size" /> 

This populated the menu with choices from the array. I set the default size as 34, so when the menu pops up, they see size 34 is pre-selected.

Why does an SSH remote command get fewer environment variables then when run manually?

Shell environment does not load when running remote ssh command. You can edit ssh environment file:

vi ~/.ssh/environment

Its format is:

VAR1=VALUE1
VAR2=VALUE2

Also, check sshd configuration for PermitUserEnvironment=yes option.

Moving from JDK 1.7 to JDK 1.8 on Ubuntu

You can do the following to install java 8 on your machine. First get the link of tar that you want to install. You can do this by:

  1. go to java downloads page and find the appropriate download.
  2. Accept the license agreement and download it.
  3. In the download page in your browser right click and copy link address.

Then in your terminal:

$ cd /tmp
$ wget http://download.oracle.com/otn-pub/java/jdk/8u74-b02/jdk-8u74-linux-x64.tar.gz\?AuthParam\=1458001079_a6c78c74b34d63befd53037da604746c
$ tar xzf jdk-8u74-linux-x64.tar.gz?AuthParam=1458001079_a6c78c74b34d63befd53037da604746c
$ sudo mv jdk1.8.0_74 /opt
$ cd /opt/jdk1.8.0_74/
$ sudo update-alternatives --install /usr/bin/java java /opt/jdk1.8.0_91/bin/java 2
$ sudo update-alternatives --config java // select version
$ sudo update-alternatives --install /usr/bin/jar jar /opt/jdk1.8.0_91/bin/jar 2
$ sudo update-alternatives --install /usr/bin/javac javac /opt/jdk1.8.0_91/bin/javac 2
$ sudo update-alternatives --set jar /opt/jdk1.8.0_91/bin/jar
$ sudo update-alternatives --set javac /opt/jdk1.8.0_74/bin/javac
$ java -version // you should have the updated java

How do I view 'git diff' output with my preferred diff tool/ viewer?

Here's a batch file that works for Windows - assumes DiffMerge installed in default location, handles x64, handles forward to backslash replacement as necessary and has ability to install itself. Should be easy to replace DiffMerge with your favourite diff program.

To install:

gitvdiff --install 

gitvdiff.bat:

@echo off

REM ---- Install? ----
REM To install, run gitvdiff --install

if %1==--install goto install



REM ---- Find DiffMerge ----

if DEFINED ProgramFiles^(x86^) (
    Set DIFF="%ProgramFiles(x86)%\SourceGear\DiffMerge\DiffMerge.exe"
) else (
    Set DIFF="%ProgramFiles%\SourceGear\DiffMerge\DiffMerge.exe"
)



REM ---- Switch forward slashes to back slashes ----

set oldW=%2
set oldW=%oldW:/=\%
set newW=%5
set newW=%newW:/=\%


REM ---- Launch DiffMerge ----

%DIFF% /title1="Old Version" %oldW% /title2="New Version" %newW%

goto :EOF



REM ---- Install ----
:install
set selfL=%~dpnx0
set selfL=%selfL:\=/%
@echo on
git config --global diff.external %selfL%
@echo off


:EOF

Git checkout - switching back to HEAD

You can stash (save the changes in temporary box) then, back to master branch HEAD.

$ git add .
$ git stash
$ git checkout master

Jump Over Commits Back and Forth:

  • Go to a specific commit-sha.

      $ git checkout <commit-sha>
    
  • If you have uncommitted changes here then, you can checkout to a new branch | Add | Commit | Push the current branch to the remote.

      # checkout a new branch, add, commit, push
      $ git checkout -b <branch-name>
      $ git add .
      $ git commit -m 'Commit message'
      $ git push origin HEAD          # push the current branch to remote 
    
      $ git checkout master           # back to master branch now
    
  • If you have changes in the specific commit and don't want to keep the changes, you can do stash or reset then checkout to master (or, any other branch).

      # stash
      $ git add -A
      $ git stash
      $ git checkout master
    
      # reset
      $ git reset --hard HEAD
      $ git checkout master
    
  • After checking out a specific commit if you have no uncommitted change(s) then, just back to master or other branch.

      $ git status          # see the changes
      $ git checkout master
    
      # or, shortcut
      $ git checkout -      # back to the previous state
    

Execute ssh with password authentication via windows command prompt

The sshpass utility is meant for exactly this. First, install sshpass by typing this command:

sudo apt-get install sshpass

Then prepend your ssh/scp command with

sshpass -p '<password>' <ssh/scp command>

This program is easiest to install when using Linux.

User should consider using SSH's more secure public key authentication (with the ssh command) instead.

Find and replace in file and overwrite file doesn't work, it empties the file

And the ed answer:

printf "%s\n" '1,$s/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g' w q | ed index.html

To reiterate what codaddict answered, the shell handles the redirection first, wiping out the "input.html" file, and then the shell invokes the "sed" command passing it a now empty file.

In Django, how do I check if a user is in a certain group?

If you don't need the user instance on site (as I did), you can do it with

User.objects.filter(pk=userId, groups__name='Editor').exists()

This will produce only one request to the database and return a boolean.

how to evenly distribute elements in a div next to each other?

Make all spans used inline-block elements. Create an empty stretch span with a 100% width beneath the list of spans containing the menu items. Next make the div containing the spans text-align: justified. This would then force the inline-block elements [your menu items] to evenly distribute.

https://jsfiddle.net/freedawirl/bh0eadzz/3/

  <div id="container">

          <div class="social">
            <a href="#" target="_blank" aria-label="facebook-link">
            <img src="http://placehold.it/40x40">
            </a>
            <a href="#" target="_blank" aria-label="twitter-link">
                <img src="http://placehold.it/40x40">
            </a>
            <a href="#" target="_blank" aria-label="youtube-link">
                <img src="http://placehold.it/40x40">
            </a>
            <a href="#" target="_blank" aria-label="pinterest-link">
                 <img src="http://placehold.it/40x40">
            </a>
            <a href="#" target="_blank" aria-label="snapchat-link">
                <img src="http://placehold.it/40x40">
            </a>
            <a href="#" target="_blank" aria-label="blog-link">
                 <img src="http://placehold.it/40x40">
            </a>

            <a href="#" aria-label="phone-link">
                 <img src="http://placehold.it/40x40">
            </a>
            <span class="stretch"></span>
          </div>
             </div>

Very simple C# CSV reader

This is what I used in a project, parses a single line of data.

    private string[] csvParser(string csv, char separator = ',')
    {
        List <string> = new <string>();
        string[] temp = csv.Split(separator);
        int counter = 0;
        string data = string.Empty;
        while (counter < temp.Length)
        {
            data = temp[counter].Trim();
            if (data.Trim().StartsWith("\""))
            {
                bool isLast = false;
                while (!isLast && counter < temp.Length)
                {
                    data += separator.ToString() + temp[counter + 1];
                    counter++;
                    isLast = (temp[counter].Trim().EndsWith("\""));
                }
            }
            parsed.Add(data);
            counter++;
        }

        return parsed.ToArray();

    }

http://zamirsblog.blogspot.com/2013/09/c-csv-parser-csvparser.html

Windows Forms ProgressBar: Easiest way to start/stop marquee?

you can use a Timer (System.Windows.Forms.Timer).

Hook it's Tick event, advance then progress bar until it reaches the max value. when it does (hit the max) and you didn't finish the job, reset the progress bar value back to minimum.

...just like Windows Explorer :-)

Regular Expression for alphanumeric and underscores

Try these multi-lingual extensions I have made for string.

IsAlphaNumeric - String must contain atleast 1 alpha (letter in Unicode range, specified in charSet) and atleast 1 number (specified in numSet). Also, the string should comprise only of alpha and numbers.

IsAlpha - String should contain atleast 1 alpha (in the language charSet specified) and comprise only of alpha.

IsNumeric - String should contain atleast 1 number (in the language numSet specified) and comprise only of numbers.

The charSet/numSet range for the desired language can be specified. The Unicode ranges are available on below link:

http://www.ssec.wisc.edu/~tomw/java/unicode.html

API :

    public static bool IsAlphaNumeric(this string stringToTest)
    {
        //English
        const string charSet = "a-zA-Z";
        const string numSet = @"0-9";

        //Greek
        //const string charSet = @"\u0388-\u03EF";            
        //const string numSet = @"0-9";

        //Bengali
        //const string charSet = @"\u0985-\u09E3";
        //const string numSet = @"\u09E6-\u09EF";

        //Hindi
        //const string charSet = @"\u0905-\u0963";
        //const string numSet = @"\u0966-\u096F";

        return Regex.Match(stringToTest, @"^(?=[" + numSet + @"]*?[" + charSet + @"]+)(?=[" + charSet + @"]*?[" + numSet + @"]+)[" + charSet + numSet +@"]+$").Success;
    }

    public static bool IsNumeric(this string stringToTest)
    {
        //English
        const string numSet = @"0-9";

        //Hindi
        //const string numSet = @"\u0966-\u096F";

        return Regex.Match(stringToTest, @"^[" + numSet + @"]+$").Success;
    }

    public static bool IsAlpha(this string stringToTest)
    {
        //English
        const string charSet = "a-zA-Z";

        return Regex.Match(stringToTest, @"^[" + charSet + @"]+$").Success;
    }

Usage :

        //English
        string test = "AASD121asf";

        //Greek
        //string test = "??ß123";

        //Bengali
        //string test = "????";

        //Hindi
        //string test = @"??????";

        bool isAlphaNum = test.IsAlphaNumeric();

The given key was not present in the dictionary. Which key?

You can try this code

Dictionary<string,string> AllFields = new Dictionary<string,string>();  
string value = (AllFields.TryGetValue(key, out index) ? AllFields[key] : null);

If the key is not present, it simply returns a null value.

An exception of type 'System.NullReferenceException' occurred in myproject.DLL but was not handled in user code

It means you have a null reference somewhere in there. Can you debug the app and stop the debugger when it gets here and investigate? Probably img1 is null or ConfigurationManager.AppSettings.Get("Url") is returning null.

How to set a session variable when clicking a <a> link

In HTML:

<a href="index.php?link=home" name="home">home</a>

Then in PHP:

if(isset($_GET['link'])){$_SESSION['link'] = $_GET['link'];}

selenium get current url after loading a page

It's been a little while since I coded with selenium, but your code looks ok to me. One thing to note is that if the element is not found, but the timeout is passed, I think the code will continue to execute. So you can do something like this:

boolean exists = driver.findElements(By.xpath("//*[@id='someID']")).size() != 0

What does the above boolean return? And are you sure selenium actually navigates to the expected page? (That may sound like a silly question but are you actually watching the pages change... selenium can be run remotely you know...)

How to frame two for loops in list comprehension python

return=[entry for tag in tags for entry in entries if tag in entry for entry in entry]

powershell is missing the terminator: "

Look closely at the two dashes in

unzipRelease –Src '$ReleaseFile' -Dst '$Destination'

This first one is not a normal dash but an en-dash (&ndash; in HTML). Replace that with the dash found before Dst.

Does .NET provide an easy way convert bytes to KB, MB, GB, etc.?

I recently needed this and required to convert the in bytes to a number in long.

Usage: Byte.Kb.ToLong(1) should give 1024.

public enum Byte
{
    Kb,
    Mb,
    Gb,
    Tb
}

public static class ByteSize
{
    private const long OneKb = 1024;
    private const long OneMb = OneKb * 1024;
    private const long OneGb = OneMb * 1024;
    private const long OneTb = OneGb * 1024;

    public static long ToLong(this Byte size, int value)
    {
        return size switch
        {
            Byte.Kb => value * OneKb,
            Byte.Mb => value * OneMb,
            Byte.Gb => value * OneGb,
            Byte.Tb => value * OneTb,
            _ => throw new NotImplementedException("This should never be hit.")
        };
    }
}

Tests using xunit:

[Theory]
[InlineData(Byte.Kb, 1, 1024)]
[InlineData(Byte.Kb, 2, 2048)]
[InlineData(Byte.Mb, 1, 1048576)]
[InlineData(Byte.Mb, 2, 2097152)]
[InlineData(Byte.Gb, 1, 1073741824)]
[InlineData(Byte.Gb, 2, 2147483648)]
[InlineData(Byte.Tb, 1, 1099511627776)]
[InlineData(Byte.Tb, 2, 2199023255552)]
public void ToLong_WhenConverting_ShouldMatchExpected(Byte size, int value, long expected)
{
    var result = size.ToLong(value);

    result.Should().Be(expected);
}

Python Pandas: Get index of rows which column matches certain value

First you may check query when the target column is type bool (PS: about how to use it please check link )

df.query('BoolCol')
Out[123]: 
    BoolCol
10     True
40     True
50     True

After we filter the original df by the Boolean column we can pick the index .

df=df.query('BoolCol')
df.index
Out[125]: Int64Index([10, 40, 50], dtype='int64')

Also pandas have nonzero, we just select the position of True row and using it slice the DataFrame or index

df.index[df.BoolCol.nonzero()[0]]
Out[128]: Int64Index([10, 40, 50], dtype='int64')

How to connect Bitbucket to Jenkins properly

I am not familiar with this plugin, but we quite successfully use Bitbucket and Jenkins together, however we poll for changes instead of having them pushed from BitBucket (due to the fact our build server is hidden behind a company firewall). This approach may work for you if you are still having problems with the current approach.

This document on Setting up SSH for Git & Mercurial on Linux covers the details of what you need to do to be able to communicate between your build server and Bitbucket over SSH. Once this is done, with the Git Plugin installed, go to your build configuration and select 'Git' under Source Code Management, and enter the ssh URL of your repository as the repository URL. Finally, in the Build Triggers section, select Poll SCM and set the poll frequency to whatever you require.

How to wait 5 seconds with jQuery?

$( "#foo" ).slideUp( 300 ).delay( 5000 ).fadeIn( 400 );

How to clear the text of all textBoxes in the form?

You can try this code

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
    {


        if(keyData==Keys.C)
        {
            RefreshControl();
            return true;
        }


        return base.ProcessCmdKey(ref msg, keyData);
    }

What method in the String class returns only the first N characters?

string.Substring(0,n); // 0 - start index and n - number of characters

Removing border from table cells

Just collapse the table borders and remove the borders from table cells (td elements).

table {
    border: 1px solid #CCC;
    border-collapse: collapse;
}

td {
    border: none;
}

Without explicitly setting border-collapse cross-browser removal of table cell borders is not guaranteed.

How can I reorder my divs using only CSS?

This can be done with CSS only!

Please check my answer to this similar question:

https://stackoverflow.com/a/25462829/1077230

I don't want to double post my answer but the short of it is that the parent needs to become a flexbox element. Eg:

(only using the webkit vendor prefix here.)

#main {
    display: -webkit-box;
    display: -webkit-flex;
    display: flex;
    -webkit-box-orient: vertical;
    -webkit-flex-direction: column;
    flex-direction: column;
    -webkit-box-align: start;
    -webkit-align-items: flex-start;
    align-items: flex-start;
}

Then, swap divs around by indicating their order with:

#main > div#one{
    -webkit-box-ordinal-group: 2;
    -moz-box-ordinal-group: 2;
    -ms-flex-order: 2;
    -webkit-order: 2;
    order: 2;
    overflow:visible;
}

#main > div#two{
    -webkit-box-ordinal-group: 1;
    -moz-box-ordinal-group: 1;
    -ms-flex-order: 1;
    -webkit-order: 1;
    order: 1;
}

How to get a value of an element by name instead of ID

//name directly given
<input type="text" name="MeetingDateFrom">
var meetingDateFrom = $("input[name=MeetingDateFrom]").val();

//Handle name array
<select multiple="multiple" name="Roles[]"></select>
 var selectedValues = $('select[name="Roles[]"] option:selected').map(function() {
    arr.push(this.value);
  });

Create a folder and sub folder in Excel VBA

Another simple version working on PC:

Sub CreateDir(strPath As String)
    Dim elm As Variant
    Dim strCheckPath As String

    strCheckPath = ""
    For Each elm In Split(strPath, "\")
        strCheckPath = strCheckPath & elm & "\"
        If Len(Dir(strCheckPath, vbDirectory)) = 0 Then MkDir strCheckPath
    Next
End Sub

Change default global installation directory for node.js modules in Windows?

Building on the installation concept of chocolatey and the idea suggested by @Tracker, what worked for me was to do the following and all users on windows were then happy working with nodejs and npm.

Choose C:\ProgramData\nodejs as installation directory for nodejs and install nodejs with any user that is a member of the administrator group.

This can be done with chocolatey as: choco install nodejs.install -ia "'INSTALLDIR=C:\ProgramData\nodejs'"

Then create a folder called npm-cache at the root of the installation directory, which after following above would be C:\ProgramData\nodejs\npm-cache.

Create a folder called etc at the root of the installation directory, which after following above would be C:\ProgramData\nodejs\etc.

Set NODE environment variable as C:\ProgramData\nodejs.

Set NODE_PATH environment variable as C:\ProgramData\nodejs\node_modules.

Ensure %NODE% environment variable previously created above is added (or its path) is added to %PATH% environment variable.

Edit %NODE_PATH%\npm\npmrc with the following content prefix=C:\ProgramData\nodejs

From command prompt, set the global config like so...

npm config --global set prefix "C:\ProgramData\nodejs"

npm config --global set cache "C:\ProgramData\nodejs\npm-cache"

It is important the steps above are carried out preferably in sequence and before updating npm (npm -g install npm@latest) or attempting to install any npm module.

Performing the above steps helped us running nodejs as system wide installation, easily available to all users with proper permissions. Each user can then run node and npm as required.

How do I set environment variables from Java?

For use in scenarios where you need to set specific environment values for unit tests, you might find the following hack useful. It will change the environment variables throughout the JVM (so make sure you reset any changes after your test), but will not alter your system environment.

I found that a combination of the two dirty hacks by Edward Campbell and anonymous works best, as one of the does not work under linux, one does not work under windows 7. So to get a multiplatform evil hack I combined them:

protected static void setEnv(Map<String, String> newenv) throws Exception {
  try {
    Class<?> processEnvironmentClass = Class.forName("java.lang.ProcessEnvironment");
    Field theEnvironmentField = processEnvironmentClass.getDeclaredField("theEnvironment");
    theEnvironmentField.setAccessible(true);
    Map<String, String> env = (Map<String, String>) theEnvironmentField.get(null);
    env.putAll(newenv);
    Field theCaseInsensitiveEnvironmentField = processEnvironmentClass.getDeclaredField("theCaseInsensitiveEnvironment");
    theCaseInsensitiveEnvironmentField.setAccessible(true);
    Map<String, String> cienv = (Map<String, String>)     theCaseInsensitiveEnvironmentField.get(null);
    cienv.putAll(newenv);
  } catch (NoSuchFieldException e) {
    Class[] classes = Collections.class.getDeclaredClasses();
    Map<String, String> env = System.getenv();
    for(Class cl : classes) {
      if("java.util.Collections$UnmodifiableMap".equals(cl.getName())) {
        Field field = cl.getDeclaredField("m");
        field.setAccessible(true);
        Object obj = field.get(env);
        Map<String, String> map = (Map<String, String>) obj;
        map.clear();
        map.putAll(newenv);
      }
    }
  }
}

This Works like a charm. Full credits to the two authors of these hacks.

What is http multipart request?

As the official specification says, "one or more different sets of data are combined in a single body". So when photos and music are handled as multipart messages as mentioned in the question, probably there is some plain text metadata associated as well, thus making the request containing different types of data (binary, text), which implies the usage of multipart.

How to get current url in view in asp.net core 1.0

There is a clean way to get the current URL from a Razor page or PageModel class. That is:

Url.PageLink()

Please note that I meant, the "ASP.NET Core Razor Pages", not the MVC.

I use this method when I want to print the canonical URL meta tag in the ASP.NET Core razor pages. But there is a catch. It will give you the URL which is supposed to be the right URL for that page. Let me explain.

Say, you have defined a route named "id" for your page and therefore, your URL should look like

http://example.com/product?id=34

The Url.PageLink() will give you exactly that URL as shown above.

Now, if the user adds anything extra on that URL, say,

http://example.com/product?id=34&somethingElse

Then, you will not get that "somethingElse" from this method. And that is why it is exactly good for printing canonical URL meta tag in the HTML page.

"Input string was not in a correct format."

Please change your code like below.

  int QuestionID;

  bool IsIntValue = Int32.TryParse("YOUR-VARIABLE", out QuestionID);

  if (IsIntValue)
  {
      // YOUR CODE HERE  
  }

Hope i will be help.

"Register" an .exe so you can run it from any command line in Windows

You can add the following registry key:

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\myexe.exe

In this key, add the default string value containing the path to the exe file.

Spark - load CSV file as DataFrame?

In case you are building a jar with scala 2.11 and Apache 2.0 or higher.

There is no need to create a sqlContext or sparkContext object. Just a SparkSession object suffices the requirement for all needs.

Following is mycode which works fine:

import org.apache.spark.sql.{DataFrame, Row, SQLContext, SparkSession}
import org.apache.log4j.{Level, LogManager, Logger}

object driver {

  def main(args: Array[String]) {

    val log = LogManager.getRootLogger

    log.info("**********JAR EXECUTION STARTED**********")

    val spark = SparkSession.builder().master("local").appName("ValidationFrameWork").getOrCreate()
    val df = spark.read.format("csv")
      .option("header", "true")
      .option("delimiter","|")
      .option("inferSchema","true")
      .load("d:/small_projects/spark/test.pos")
    df.show()
  }
}

In case you are running in cluster just change .master("local") to .master("yarn") while defining the sparkBuilder object

The Spark Doc covers this: https://spark.apache.org/docs/2.2.0/sql-programming-guide.html

An item with the same key has already been added

I had 2 model properties like this

public int LinkId {get;set;}
public int LinkID {get;set;}

it is strange that it threw this error for these 2 haha..

canvas.toDataURL() SecurityError

In my case I was using the WebBrowser control (forcing IE 11) and I could not get past the error. Switching to CefSharp which uses Chrome solved it for me.

AngularJS Dropdown required validation

You need to add a name attribute to your dropdown list, then you need to add a required attribute, and then you can reference the error using myForm.[input name].$error.required:

HTML:

        <form name="myForm" ng-controller="Ctrl" ng-submit="save(myForm)" novalidate>
        <input type="text" name="txtServiceName" ng-model="ServiceName" required>
<span ng-show="myForm.txtServiceName.$error.required">Enter Service Name</span>
<br/>
          <select name="service_id" class="Sitedropdown" style="width: 220px;"          
                  ng-model="ServiceID" 
                  ng-options="service.ServiceID as service.ServiceName for service in services"
                  required> 
            <option value="">Select Service</option> 
          </select> 
          <span ng-show="myForm.service_id.$error.required">Select service</span>

        </form>

    Controller:

        function Ctrl($scope) {
          $scope.services = [
            {ServiceID: 1, ServiceName: 'Service1'},
            {ServiceID: 2, ServiceName: 'Service2'},
            {ServiceID: 3, ServiceName: 'Service3'}
          ];

    $scope.save = function(myForm) {
    console.log('Selected Value: '+ myForm.service_id.$modelValue);
    alert('Data Saved! without validate');
    };
        }

Here's a working plunker.

Preventing multiple clicks on button

using count,

 clickcount++;
    if (clickcount == 1) {}

After coming back again clickcount set to zero.

how to return a char array from a function in C

Lazy notes in comments.

#include <stdio.h>
// for malloc
#include <stdlib.h>

// you need the prototype
char *substring(int i,int j,char *ch);


int main(void /* std compliance */)
{
  int i=0,j=2;
  char s[]="String";
  char *test;
  // s points to the first char, S
  // *s "is" the first char, S
  test=substring(i,j,s); // so s only is ok
  // if test == NULL, failed, give up
  printf("%s",test);
  free(test); // you should free it
  return 0;
}


char *substring(int i,int j,char *ch)
{
  int k=0;
  // avoid calc same things several time
  int n = j-i+1; 
  char *ch1;
  // you can omit casting - and sizeof(char) := 1
  ch1=malloc(n*sizeof(char));
  // if (!ch1) error...; return NULL;

  // any kind of check missing:
  // are i, j ok? 
  // is n > 0... ch[i] is "inside" the string?...
  while(k<n)
    {   
      ch1[k]=ch[i];
      i++;k++;
    }   

  return ch1;
}

asynchronous vs non-blocking

  • Asynchronous refers to something done in parallel, say is another thread.
  • Non-blocking often refers to polling, i.e. checking whether given condition holds (socket is readable, device has more data, etc.)

Best method for reading newline delimited files and discarding the newlines?

I use this

def cleaned( aFile ):
    for line in aFile:
        yield line.strip()

Then I can do things like this.

lines = list( cleaned( open("file","r") ) )

Or, I can extend cleaned with extra functions to, for example, drop blank lines or skip comment lines or whatever.

NOT IN vs NOT EXISTS

I always default to NOT EXISTS.

The execution plans may be the same at the moment but if either column is altered in the future to allow NULLs the NOT IN version will need to do more work (even if no NULLs are actually present in the data) and the semantics of NOT IN if NULLs are present are unlikely to be the ones you want anyway.

When neither Products.ProductID or [Order Details].ProductID allow NULLs the NOT IN will be treated identically to the following query.

SELECT ProductID,
       ProductName
FROM   Products p
WHERE  NOT EXISTS (SELECT *
                   FROM   [Order Details] od
                   WHERE  p.ProductId = od.ProductId) 

The exact plan may vary but for my example data I get the following.

Neither NULL

A reasonably common misconception seems to be that correlated sub queries are always "bad" compared to joins. They certainly can be when they force a nested loops plan (sub query evaluated row by row) but this plan includes an anti semi join logical operator. Anti semi joins are not restricted to nested loops but can use hash or merge (as in this example) joins too.

/*Not valid syntax but better reflects the plan*/ 
SELECT p.ProductID,
       p.ProductName
FROM   Products p
       LEFT ANTI SEMI JOIN [Order Details] od
         ON p.ProductId = od.ProductId 

If [Order Details].ProductID is NULL-able the query then becomes

SELECT ProductID,
       ProductName
FROM   Products p
WHERE  NOT EXISTS (SELECT *
                   FROM   [Order Details] od
                   WHERE  p.ProductId = od.ProductId)
       AND NOT EXISTS (SELECT *
                       FROM   [Order Details]
                       WHERE  ProductId IS NULL) 

The reason for this is that the correct semantics if [Order Details] contains any NULL ProductIds is to return no results. See the extra anti semi join and row count spool to verify this that is added to the plan.

One NULL

If Products.ProductID is also changed to become NULL-able the query then becomes

SELECT ProductID,
       ProductName
FROM   Products p
WHERE  NOT EXISTS (SELECT *
                   FROM   [Order Details] od
                   WHERE  p.ProductId = od.ProductId)
       AND NOT EXISTS (SELECT *
                       FROM   [Order Details]
                       WHERE  ProductId IS NULL)
       AND NOT EXISTS (SELECT *
                       FROM   (SELECT TOP 1 *
                               FROM   [Order Details]) S
                       WHERE  p.ProductID IS NULL) 

The reason for that one is because a NULL Products.ProductId should not be returned in the results except if the NOT IN sub query were to return no results at all (i.e. the [Order Details] table is empty). In which case it should. In the plan for my sample data this is implemented by adding another anti semi join as below.

Both NULL

The effect of this is shown in the blog post already linked by Buckley. In the example there the number of logical reads increase from around 400 to 500,000.

Additionally the fact that a single NULL can reduce the row count to zero makes cardinality estimation very difficult. If SQL Server assumes that this will happen but in fact there were no NULL rows in the data the rest of the execution plan may be catastrophically worse, if this is just part of a larger query, with inappropriate nested loops causing repeated execution of an expensive sub tree for example.

This is not the only possible execution plan for a NOT IN on a NULL-able column however. This article shows another one for a query against the AdventureWorks2008 database.

For the NOT IN on a NOT NULL column or the NOT EXISTS against either a nullable or non nullable column it gives the following plan.

Not EXists

When the column changes to NULL-able the NOT IN plan now looks like

Not In - Null

It adds an extra inner join operator to the plan. This apparatus is explained here. It is all there to convert the previous single correlated index seek on Sales.SalesOrderDetail.ProductID = <correlated_product_id> to two seeks per outer row. The additional one is on WHERE Sales.SalesOrderDetail.ProductID IS NULL.

As this is under an anti semi join if that one returns any rows the second seek will not occur. However if Sales.SalesOrderDetail does not contain any NULL ProductIDs it will double the number of seek operations required.

Install numpy on python3.3 - Install pip for python3

In the solution below I used python3.4 as binary, but it's safe to use with any version or binary of python. it works fine on windows too (except the downloading pip with wget obviously but just save the file locally and run it with python).

This is great if you have multiple versions of python installed, so you can manage external libraries per python version.

So first, I'd recommend get-pip.py, it's great to install pip :

wget https://bootstrap.pypa.io/get-pip.py

Then you need to install pip for your version of python, I have python3.4 so for me this is the command :

python3.4 get-pip.py

Now pip is installed for python3.4 and in order to get libraries for python3.4 one need to call it within this version, like this :

python3.4 -m pip

So if you want to install numpy you would use :

python3.4 -m pip install numpy

Note that numpy is quite the heavy library. I thought my system was hanging and failing. But using the verbose option, you can see that the system is fine :

python3.4 -m pip install numpy -v

This may tell you that you lack python.h but you can easily get it :

On RHEL (Red hat, CentOS, Fedora) it would be something like this :

yum install python34-devel

On debian-like (Debian, Ubuntu, Kali, ...) :

apt-get install python34-dev

Then rerun this :

python3.4 -m pip install numpy -v

How to use router.navigateByUrl and router.navigate in Angular

navigateByUrl

routerLink directive as used like this:

<a [routerLink]="/inbox/33/messages/44">Open Message 44</a>

is just a wrapper around imperative navigation using router and its navigateByUrl method:

router.navigateByUrl('/inbox/33/messages/44')

as can be seen from the sources:

export class RouterLink {
  ...

  @HostListener('click')
  onClick(): boolean {
    ...
    this.router.navigateByUrl(this.urlTree, extras);
    return true;
  }

So wherever you need to navigate a user to another route, just inject the router and use navigateByUrl method:

class MyComponent {
   constructor(router: Router) {
      this.router.navigateByUrl(...);
   }
}

navigate

There's another method on the router that you can use - navigate:

router.navigate(['/inbox/33/messages/44'])

difference between the two

Using router.navigateByUrl is similar to changing the location bar directly–we are providing the “whole” new URL. Whereas router.navigate creates a new URL by applying an array of passed-in commands, a patch, to the current URL.

To see the difference clearly, imagine that the current URL is '/inbox/11/messages/22(popup:compose)'.

With this URL, calling router.navigateByUrl('/inbox/33/messages/44') will result in '/inbox/33/messages/44'. But calling it with router.navigate(['/inbox/33/messages/44']) will result in '/inbox/33/messages/44(popup:compose)'.

Read more in the official docs.

How do you add an image?

In order to add attributes, XSL wants

<xsl:element name="img">
     (attributes)
</xsl:element>

instead of just

<img>
     (attributes)
</img>

Although, yes, if you're just copying the element as-is, you don't need any of that.

How to create a DateTime equal to 15 minutes ago?

 datetime.datetime.now() - datetime.timedelta(minutes=15)

Differences between Oracle JDK and OpenJDK

A list of the few remaining cosmetic and packaging differences between Oracle JDK 11 and OpenJDK 11 can be found in this blog post:

https://blogs.oracle.com/java-platform-group/oracle-jdk-releases-for-java-11-and-later

In short:

  • Oracle JDK 11 emits a warning when using the -XX:+UnlockCommercialFeatures option,
  • it can be configured to provide usage log data to the “Advanced Management Console” tool,
  • it has always required third party cryptographic providers to be signed by a known certificate,
  • it will continue to include installers, branding and JRE packaging,
  • while the javac --release command behaves slightly differently for the Java 9 and Java 10 targets, and
  • the output of the java --version and java -fullversion commands will distinguish Oracle JDK builds from OpenJDK builds.

How to remove files that are listed in the .gitignore but still on the repository?

I can't say it's an appropriate solution but you can try this.

Steps

  • I am hoping that you have already cloned your repo.
  • Now copy the file somewhere outside of your project.
  • Add that filename with a location in gitigonre file.
  • Remove that file from your local project.
  • Push your code to remote origin.
  • And now add that copied file into your project it'll be ignored.

This is just a hack solution if you want to maintain the history and don't to create mass in it.

If you don't want to use this solution please kindly ignore and try to avoid devote it. Because I am really trying to increase my score on this side

How to set RelativeLayout layout params in code not in xml?

Just a basic example:

RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
params.addRule(RelativeLayout.ALIGN_PARENT_LEFT, RelativeLayout.TRUE);
Button button1;
button1.setLayoutParams(params);

params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
params.addRule(RelativeLayout.RIGHT_OF, button1.getId());
Button button2;
button2.setLayoutParams(params);

As you can see, this is what you have to do:

  1. Create a RelativeLayout.LayoutParams object.
  2. Use addRule(int) or addRule(int, int) to set the rules. The first method is used to add rules that don't require values.
  3. Set the parameters to the view (in this case, to each button).

How do I declare an array with a custom class?

you just need to add a default constructor to your class to look like this:

class name {
  public:
    string first;
    string last;

  name() {
  }

  name(string a, string b){
    first = a;
    last = b;
  }
};

How to get attribute of element from Selenium?

As the recent developed Web Applications are using JavaScript, jQuery, AngularJS, ReactJS etc there is a possibility that to retrieve an attribute of an element through Selenium you have to induce WebDriverWait to synchronize the WebDriver instance with the lagging Web Client i.e. the Web Browser before trying to retrieve any of the attributes.

Some examples:

  • Python:

    • To retrieve any attribute form a visible element (e.g. <h1> tag) you need to use the expected_conditions as visibility_of_element_located(locator) as follows:

      attribute_value = WebDriverWait(driver, 20).until(EC.visibility_of_element_located((By.ID, "org"))).get_attribute("attribute_name")
      
    • To retrieve any attribute form an interactive element (e.g. <input> tag) you need to use the expected_conditions as element_to_be_clickable(locator) as follows:

      attribute_value = WebDriverWait(driver, 20).until(EC.element_to_be_clickable((By.ID, "org"))).get_attribute("attribute_name")
      

HTML Attributes

Below is a list of some attributes often used in HTML

HTML Attributes

Note: A complete list of all attributes for each HTML element, is listed in: HTML Attribute Reference

Create empty file using python

Of course there IS a way to create files without opening. It's as easy as calling os.mknod("newfile.txt"). The only drawback is that this call requires root privileges on OSX.

How to model type-safe enum types?

http://www.scala-lang.org/docu/files/api/scala/Enumeration.html

Example use

  object Main extends App {

    object WeekDay extends Enumeration {
      type WeekDay = Value
      val Mon, Tue, Wed, Thu, Fri, Sat, Sun = Value
    }
    import WeekDay._

    def isWorkingDay(d: WeekDay) = ! (d == Sat || d == Sun)

    WeekDay.values filter isWorkingDay foreach println
  }

Is it possible to listen to a "style change" event?

I think the best answer if from Mike in the case you can't launch your event because is not from your code. But I get some errors when I used it. So I write a new answer for show you the code that I use.

Extension

// Extends functionality of ".css()"
// This could be renamed if you'd like (i.e. "$.fn.cssWithListener = func ...")
(function() {
    orig = $.fn.css;
    $.fn.css = function() {
        var result = orig.apply(this, arguments);
        $(this).trigger('stylechanged');
        return result;
    }
})();

Usage

// Add listener
$('element').on('stylechanged', function () {
    console.log('css changed');
});

// Perform change
$('element').css('background', 'red');

I got error because var ev = new $.Event('style'); Something like style was not defined in HtmlDiv.. I removed it, and I launch now $(this).trigger("stylechanged"). Another problem was that Mike didn't return the resulto of $(css, ..) then It can make problems in some cases. So I get the result and return it. Now works ^^ In every css change include from some libs that I can't modify and trigger an event.

How to locate the git config file in Mac

The solution to the problem is:

  1. Find the .gitconfig file

  2. [user] name = 1wQasdTeedFrsweXcs234saS56Scxs5423 email = [email protected] [credential] helper = osxkeychain [url ""] insteadOf = git:// [url "https://"] [url "https://"] insteadOf = git://

there would be a blank url="" replace it with url="https://"

[user]
    name = 1wQasdTeedFrsweXcs234saS56Scxs5423
    email = [email protected]
[credential]
    helper = osxkeychain
[url "https://"]
    insteadOf = git://
[url "https://"]
[url "https://"]
    insteadOf = git://

This will work :)

Happy Bower-ing

How to obtain the last path segment of a URI

You can use getPathSegments() function. (Android Documentation)

Consider your example URI:

String uri = "http://base_path/some_segment/id"

You can get the last segment using:

List<String> pathSegments = uri.getPathSegments();
String lastSegment = pathSegments.get(pathSegments.size - 1);

lastSegment will be id.

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

You can add an extra exit command after the return statement/command so that it works for both, executing the script from the command line and sourcing from the terminal.

Example exit code in the script:

   if [ $# -lt 2 ]; then
     echo "Needs at least two arguments"
     return 1 2>/dev/null
     exit 1
   fi

The line with the exit command will not be called when you source the script after the return command.

When you execute the script, return command gives an error. So, we suppress the error message by forwarding it to /dev/null.

How to terminate a python subprocess launched with shell=True

what i feel like we could use:

import os
import signal
import subprocess
p = subprocess.Popen(cmd, stdout=subprocess.PIPE, shell=True)

os.killpg(os.getpgid(pro.pid), signal.SIGINT)

this will not kill all your task but the process with the p.pid

Delete all rows in a table based on another table

To Delete table records based on another table

     Delete From Table1 a,Table2 b where a.id=b.id

    Or

      DELETE FROM Table1
    WHERE Table1.id IN (SELECT Table2.id FROM Table2)

  Or

        DELETE Table1
     FROM Table1 t1 INNER JOIN Table2 t2 ON t1.ID = t2.ID;

How can I find all the subsets of a set, with exactly n elements?

>>>Set = ["A", "B","C","D"]
>>>n = 2
>>>Subsets=[[i for i,s in zip(Set, status) if int(s)  ] for status in [(format(bit,'b').zfill(len(Set))) for bit in range(2**len(Set))] if sum(map(int,status)) == n]
>>>Subsets
[['C', 'D'], ['B', 'D'], ['B', 'C'], ['A', 'D'], ['A', 'C'], ['A', 'B']]

How to use default Android drawables

Better to use android.R.drawable because it is public and documented.

"for line in..." results in UnicodeDecodeError: 'utf-8' codec can't decode byte

Your file doesn't actually contain UTF-8 encoded data; it contains some other encoding. Figure out what that encoding is and use it in the open call.

In Windows-1252 encoding, for example, the 0xe9 would be the character é.

Handling errors in Promise.all

As @jib said,

Promise.all is all or nothing.

Though, you can control certain promises that are "allowed" to fail and we would like to proceed to .then.

For example.

  Promise.all([
    doMustAsyncTask1,
    doMustAsyncTask2,
    doOptionalAsyncTask
    .catch(err => {
      if( /* err non-critical */) {
        return
      }
      // if critical then fail
      throw err
    })
  ])
  .then(([ mustRes1, mustRes2, optionalRes ]) => {
    // proceed to work with results
  })

How can I define an array of objects?

 var xxxx : { [key:number]: MyType };

How can you determine a point is between two other points on a line segment?

Using a more geometric approach, calculate the following distances:

ab = sqrt((a.x-b.x)**2 + (a.y-b.y)**2)
ac = sqrt((a.x-c.x)**2 + (a.y-c.y)**2)
bc = sqrt((b.x-c.x)**2 + (b.y-c.y)**2)

and test whether ac+bc equals ab:

is_on_segment = abs(ac + bc - ab) < EPSILON

That's because there are three possibilities:

  • The 3 points form a triangle => ac+bc > ab
  • They are collinear and c is outside the ab segment => ac+bc > ab
  • They are collinear and c is inside the ab segment => ac+bc = ab

How to import XML file into MySQL database table using XML_LOAD(); function

you can specify fields like this:

LOAD XML LOCAL INFILE '/pathtofile/file.xml' 
INTO TABLE my_tablename(personal_number, firstname, ...); 

IPython/Jupyter Problems saving notebook as PDF

2015-4-22: It looks like an IPython update means that --to pdf should be used instead of --to latex --post PDF. There is a related Github issue.

How to set the part of the text view is clickable

For those that are looking for a solution in Kotlin here is what worked for me:

private fun setupTermsAndConditions() {
    val termsAndConditions = resources.getString(R.string.terms_and_conditions)
    val spannableString = SpannableString(termsAndConditions)
    val clickableSpan = object : ClickableSpan() {
        override fun onClick(widget: View) {
            if (checkForWifiAndMobileInternet()) {
                // binding.viewModel!!.openTermsAndConditions()
                showToast("Good, open the link!!!")

            } else {
                showToast("Cannot open this file because of internet connection!")
            }

        }

        override fun updateDrawState(textPaint : TextPaint) {
            super.updateDrawState(textPaint)
            textPaint.color = resources.getColor(R.color.colorGrey)
            textPaint.isFakeBoldText = true
        }
    }

    spannableString.setSpan(clickableSpan, 34, 86, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
    binding.tvTermsAndConditions.text = spannableString
    binding.tvTermsAndConditions.movementMethod = LinkMovementMethod.getInstance()
    binding.tvTermsAndConditions.setHighlightColor(Color.TRANSPARENT);

}

How to get char from string by index?

I think this is more clear than describing it in words

s = 'python'
print(len(s))
6
print(s[5])
'n'
print(s[len(s) - 1])
'n'
print(s[-1])
'n'

How to check if a variable is equal to one string or another string?

for a in soup("p",{'id':'pagination'})[0]("a",{'href': True}):
        if createunicode(a.text) in ['<','<']:
            links.append(a.attrMap['href'])
        else:
            continue

It works for me.

Getting only 1 decimal place

Are you trying to represent it with only one digit:

print("{:.1f}".format(number)) # Python3
print "%.1f" % number          # Python2

or actually round off the other decimal places?

round(number,1)

or even round strictly down?

math.floor(number*10)/10

iPhone - Get Position of UIView within entire UIWindow

In Swift:

let globalPoint = aView.superview?.convertPoint(aView.frame.origin, toView: nil)

Difference between ProcessBuilder and Runtime.exec()

Look at how Runtime.getRuntime().exec() passes the String command to the ProcessBuilder. It uses a tokenizer and explodes the command into individual tokens, then invokes exec(String[] cmdarray, ......) which constructs a ProcessBuilder.

If you construct the ProcessBuilder with an array of strings instead of a single one, you'll get to the same result.

The ProcessBuilder constructor takes a String... vararg, so passing the whole command as a single String has the same effect as invoking that command in quotes in a terminal:

shell$ "command with args"

How to change permissions for a folder and its subfolders/files in one step?

The other answers are correct, in that chmod -R 755 will set these permissions to all files and subfolders in the tree. But why on earth would you want to? It might make sense for the directories, but why set the execute bit on all the files?

I suspect what you really want to do is set the directories to 755 and either leave the files alone or set them to 644. For this, you can use the find command. For example:

To change all the directories to 755 (drwxr-xr-x):

find /opt/lampp/htdocs -type d -exec chmod 755 {} \;

To change all the files to 644 (-rw-r--r--):

find /opt/lampp/htdocs -type f -exec chmod 644 {} \;

Does JavaScript have a built in stringbuilder class?

In C# you can do something like

 String.Format("hello {0}, your age is {1}.",  "John",  29) 

In JavaScript you could do something like

 var x = "hello {0}, your age is {1}";
 x = x.replace(/\{0\}/g, "John");
 x = x.replace(/\{1\}/g, 29);

Difference between web server, web container and application server

Web Server: It provides HTTP Request and HTTP response. It handles request from client only through HTTP protocol. It contains Web Container. Web Application mostly deployed on web Server. EX: Servlet JSP

Web Container: it maintains the life cycle for Servlet Object. Calls the service method for that servlet object. pass the HttpServletRequest and HttpServletResponse Object

Application Server: It holds big Enterprise application having big business logic. It is Heavy Weight or it holds Heavy weight Applications. Ex: EJB

Can I use CASE statement in a JOIN condition?

Here I have compared the difference in two different result sets:

SELECT main.ColumnName, compare.Value PreviousValue,  main.Value CurrentValue
FROM 
(
    SELECT 'Name' AS ColumnName, 'John' as Value UNION ALL
    SELECT 'UserName' AS ColumnName, 'jh001' as Value UNION ALL
    SELECT 'Department' AS ColumnName, 'HR' as Value UNION ALL
    SELECT 'Phone' AS ColumnName, NULL as Value UNION ALL
    SELECT 'DOB' AS ColumnName, '1993-01-01' as Value UNION ALL
    SELECT 'CreateDate' AS ColumnName, '2017-01-01' as Value UNION ALL
    SELECT 'IsActive' AS ColumnName, '1' as Value
) main
INNER JOIN
(
    SELECT 'Name' AS ColumnName, 'Rahul' as Value UNION ALL
    SELECT 'UserName' AS ColumnName, 'rh001' as Value UNION ALL
    SELECT 'Department' AS ColumnName, 'HR' as Value UNION ALL
    SELECT 'Phone' AS ColumnName, '01722112233' as Value UNION ALL
    SELECT 'DOB' AS ColumnName, '1993-01-01' as Value UNION ALL
    SELECT 'CreateDate' AS ColumnName, '2017-01-01' as Value UNION ALL
    SELECT 'IsActive' AS ColumnName, '1' as Value
) compare
ON main.ColumnName = compare.ColumnName AND
CASE 
    WHEN main.Value IS NULL AND compare.Value IS NULL THEN 0
    WHEN main.Value IS NULL AND compare.Value IS NOT NULL THEN 1
    WHEN main.Value IS NOT NULL AND compare.Value IS NULL THEN 1
    WHEN main.Value <> compare.Value THEN 1
END = 1 

Android custom dropdown/popup menu

The Kotlin Way

fun showPopupMenu(view: View) {
    PopupMenu(view.context, view).apply {
                menuInflater.inflate(R.menu.popup_men, menu)
                setOnMenuItemClickListener { item ->
                    Toast.makeText(view.context, "You Clicked : " + item.title, Toast.LENGTH_SHORT).show()
                    true
                }
            }.show()
}

UPDATE: In the above code, the apply function returns this which is not required, so we can use run which don't return anything and to make it even simpler we can also remove the curly braces of showPopupMenu method.

Even Simpler:

fun showPopupMenu(view: View) = PopupMenu(view.context, view).run {
            menuInflater.inflate(R.menu.popup_men, menu)
            setOnMenuItemClickListener { item ->
                Toast.makeText(view.context, "You Clicked : ${item.title}", Toast.LENGTH_SHORT).show()
                true
            }
            show()
        }

Anybody knows any knowledge base open source?

How about one of the many wikis?

Kenny: I've used FlexWiki & ScrewTurn (abandoned).

someone else with RepPower to edit my post added this.
Wikipedia is powered by MediaWiki.

A simple scenario using wait() and notify() in java

Example

public class myThread extends Thread{
     @override
     public void run(){
        while(true){
           threadCondWait();// Circle waiting...
           //bla bla bla bla
        }
     }
     public synchronized void threadCondWait(){
        while(myCondition){
           wait();//Comminucate with notify()
        }
     }

}
public class myAnotherThread extends Thread{
     @override
     public void run(){
        //Bla Bla bla
        notify();//Trigger wait() Next Step
     }

}

Mysql Compare two datetime fields

You can use the following SQL to compare both date and time -

Select * From temp where mydate > STR_TO_DATE('2009-06-29 04:00:44', '%Y-%m-%d %H:%i:%s');

Attached mysql output when I used same SQL on same kind of table and field that you mentioned in the problem-

enter image description here

It should work perfect.

Why does writeObject throw java.io.NotSerializableException and how do I fix it?

The fields of your object have in turn their fields, some of which do not implement Serializable. In your case the offending class is TransformGroup. How to solve it?

  • if the class is yours, make it Serializable
  • if the class is 3rd party, but you don't need it in the serialized form, mark the field as transient
  • if you need its data and it's third party, consider other means of serialization, like JSON, XML, BSON, MessagePack, etc. where you can get 3rd party objects serialized without modifying their definitions.

How to make a Bootstrap accordion collapse when clicking the header div?

Another way is make your <a> full fill all the space of the panel-heading. Use this style to do so:

.panel-title a {
    display: block;
    padding: 10px 15px;
    margin: -10px -15px;
}

Check this demo (http://jsfiddle.net/KbQyx/).

Then when you clicking on the heading, you are actually clicking on the <a>.

Create a hexadecimal colour based on a string with JavaScript

I find that generating random colors tends to create colors that do not have enough contrast for my taste. The easiest way I have found to get around that is to pre-populate a list of very different colors. For every new string, assign the next color in the list:

// Takes any string and converts it into a #RRGGBB color.
var StringToColor = (function(){
    var instance = null;

    return {
    next: function stringToColor(str) {
        if(instance === null) {
            instance = {};
            instance.stringToColorHash = {};
            instance.nextVeryDifferntColorIdx = 0;
            instance.veryDifferentColors = ["#000000","#00FF00","#0000FF","#FF0000","#01FFFE","#FFA6FE","#FFDB66","#006401","#010067","#95003A","#007DB5","#FF00F6","#FFEEE8","#774D00","#90FB92","#0076FF","#D5FF00","#FF937E","#6A826C","#FF029D","#FE8900","#7A4782","#7E2DD2","#85A900","#FF0056","#A42400","#00AE7E","#683D3B","#BDC6FF","#263400","#BDD393","#00B917","#9E008E","#001544","#C28C9F","#FF74A3","#01D0FF","#004754","#E56FFE","#788231","#0E4CA1","#91D0CB","#BE9970","#968AE8","#BB8800","#43002C","#DEFF74","#00FFC6","#FFE502","#620E00","#008F9C","#98FF52","#7544B1","#B500FF","#00FF78","#FF6E41","#005F39","#6B6882","#5FAD4E","#A75740","#A5FFD2","#FFB167","#009BFF","#E85EBE"];
        }

        if(!instance.stringToColorHash[str])
            instance.stringToColorHash[str] = instance.veryDifferentColors[instance.nextVeryDifferntColorIdx++];

            return instance.stringToColorHash[str];
        }
    }
})();

// Get a new color for each string
StringToColor.next("get first color");
StringToColor.next("get second color");

// Will return the same color as the first time
StringToColor.next("get first color");

While this has a limit to only 64 colors, I find most humans can't really tell the difference after that anyway. I suppose you could always add more colors.

While this code uses hard-coded colors, you are at least guaranteed to know during development exactly how much contrast you will see between colors in production.

Color list has been lifted from this SO answer, there are other lists with more colors.

How to select following sibling/xml tag using xpath

How would I accomplish the nextsibling and is there an easier way of doing this?

You may use:

tr/td[@class='name']/following-sibling::td

but I'd rather use directly:

tr[td[@class='name'] ='Brand']/td[@class='desc']

This assumes that:

  1. The context node, against which the XPath expression is evaluated is the parent of all tr elements -- not shown in your question.

  2. Each tr element has only one td with class attribute valued 'name' and only one td with class attribute valued 'desc'.

How can I call PHP functions by JavaScript?

I wrote some script for me its working .. I hope it may useful to you

<?php
if(@$_POST['add'])
{
function add()
{
   $a="You clicked on add fun";
   echo $a;
}
add();
}
else if (@$_POST['sub']) 
{
function sub()
{
   $a="You clicked on sub funn";
echo $a;  
}
sub();  
}
?>
<form action="<?php echo $_SERVER['PHP_SELF'];?>" method="POST">

<input type="submit" name="add" Value="Call Add fun">
<input type="submit" name="sub" Value="Call Sub funn">
<?php echo @$a; ?>

</form>

Move textfield when keyboard appears swift

    func registerForKeyboardNotifications(){
        //Keyboard
        NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(keyboardWasShown), name: UIKeyboardDidShowNotification, object: nil)
        NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(keyboardWillBeHidden), name: UIKeyboardDidHideNotification, object: nil)


    }
    func deregisterFromKeyboardNotifications(){

        NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillShowNotification, object: nil)
        NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillHideNotification, object: nil)

    }
    func keyboardWasShown(notification: NSNotification){

        let userInfo: NSDictionary = notification.userInfo!
        let keyboardInfoFrame = userInfo.objectForKey(UIKeyboardFrameEndUserInfoKey)?.CGRectValue()

        let windowFrame:CGRect = (UIApplication.sharedApplication().keyWindow!.convertRect(self.view.frame, fromView:self.view))

        let keyboardFrame = CGRectIntersection(windowFrame, keyboardInfoFrame!)

        let coveredFrame = UIApplication.sharedApplication().keyWindow!.convertRect(keyboardFrame, toView:self.view)

        let contentInsets = UIEdgeInsetsMake(0, 0, (coveredFrame.size.height), 0.0)
        self.scrollViewInAddCase .contentInset = contentInsets;
        self.scrollViewInAddCase.scrollIndicatorInsets = contentInsets;
        self.scrollViewInAddCase.contentSize = CGSizeMake((self.scrollViewInAddCase.contentSize.width), (self.scrollViewInAddCase.contentSize.height))

    }
    /**
     this method will fire when keyboard was hidden

     - parameter notification: contains keyboard details
     */
    func keyboardWillBeHidden (notification: NSNotification) {

        self.scrollViewInAddCase.contentInset = UIEdgeInsetsZero
        self.scrollViewInAddCase.scrollIndicatorInsets = UIEdgeInsetsZero

    }

The smallest difference between 2 Angles

There is no need to compute trigonometric functions. The simple code in C language is:

#include <math.h>
#define PIV2 M_PI+M_PI
#define C360 360.0000000000000000000
double difangrad(double x, double y)
{
double arg;

arg = fmod(y-x, PIV2);
if (arg < 0 )  arg  = arg + PIV2;
if (arg > M_PI) arg  = arg - PIV2;

return (-arg);
}
double difangdeg(double x, double y)
{
double arg;
arg = fmod(y-x, C360);
if (arg < 0 )  arg  = arg + C360;
if (arg > 180) arg  = arg - C360;
return (-arg);
}

let dif = a - b , in radians

dif = difangrad(a,b);

let dif = a - b , in degrees

dif = difangdeg(a,b);

difangdeg(180.000000 , -180.000000) = 0.000000
difangdeg(-180.000000 , 180.000000) = -0.000000
difangdeg(359.000000 , 1.000000) = -2.000000
difangdeg(1.000000 , 359.000000) = 2.000000

No sin, no cos, no tan,.... only geometry!!!!

JUnit 4 compare Sets

If you want to check whether a List or Set contains a set of specific values (instead of comparing it with an already existing collection), often the toString method of collections is handy:

String[] actualResult = calltestedmethod();
assertEquals("[foo, bar]", Arrays.asList(actualResult).toString());

List otherResult = callothertestedmethod();
assertEquals("[42, mice]", otherResult.toString());

This is a bit shorter than first constructing the expected collection and comparing it with the actual collection, and easier to write and correct.

(Admittedly, this is not a particularily clean method, and can't distinguish an element "foo, bar" from two elements "foo" and "bar". But in practice I think it's most important that it's easy and fast to write tests, otherwise many developers just won't without being pressed.)

Fixing npm path in Windows 8 and 10

If after installing your npm successfully, and you want to install VueJS then this is what you should do

after running the following command (as Admin)

npm install --global vue-cli

It will place the vue.cmd in the following directory C:\Users\YourUserName\AppData\Roaming\npm

you will see this in your directory.

Now to use vue as a command in cmd. Open the cmd as admin and run the following command.

setx /M path "%path%;%appdata%\npm"

Now restart the cmd and run the vue again. It should work just fine, and then you can begin to develop with VueJS.

I hope this helps.

Fastest way to duplicate an array in JavaScript - slice vs. 'for' loop

A simple solution:

original = [1,2,3]
cloned = original.map(x=>x)

Find nginx version?

In my case, I try to add sudo

sudo nginx -v

enter image description here

Android custom Row Item for ListView

create resource layout file list_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:orientation="vertical"
          android:layout_width="match_parent"
          android:layout_height="wrap_content">
<TextView
        android:id="@+id/header_text"
        android:layout_height="0dp"
        android:layout_width="fill_parent"
        android:layout_weight="1"
        android:text="Header"
        />
<TextView
        android:id="@+id/item_text"
        android:layout_height="0dp"
        android:layout_width="fill_parent"
        android:layout_weight="1"
        android:text="dynamic text"
        />
</LinearLayout>

and initialise adaptor like this

adapter = new ArrayAdapter<String>(this, R.layout.list_item,R.id.item_text,data_array);

Why is enum class preferred over plain enum?

C++11 FAQ mentions below points:

conventional enums implicitly convert to int, causing errors when someone does not want an enumeration to act as an integer.

enum color
{
    Red,
    Green,
    Yellow
};

enum class NewColor
{
    Red_1,
    Green_1,
    Yellow_1
};

int main()
{
    //! Implicit conversion is possible
    int i = Red;

    //! Need enum class name followed by access specifier. Ex: NewColor::Red_1
    int j = Red_1; // error C2065: 'Red_1': undeclared identifier

    //! Implicit converison is not possible. Solution Ex: int k = (int)NewColor::Red_1;
    int k = NewColor::Red_1; // error C2440: 'initializing': cannot convert from 'NewColor' to 'int'

    return 0;
}

conventional enums export their enumerators to the surrounding scope, causing name clashes.

// Header.h

enum vehicle
{
    Car,
    Bus,
    Bike,
    Autorickshow
};

enum FourWheeler
{
    Car,        // error C2365: 'Car': redefinition; previous definition was 'enumerator'
    SmallBus
};

enum class Editor
{
    vim,
    eclipes,
    VisualStudio
};

enum class CppEditor
{
    eclipes,       // No error of redefinitions
    VisualStudio,  // No error of redefinitions
    QtCreator
};

The underlying type of an enum cannot be specified, causing confusion, compatibility problems, and makes forward declaration impossible.

// Header1.h
#include <iostream>

using namespace std;

enum class Port : unsigned char; // Forward declare

class MyClass
{
public:
    void PrintPort(enum class Port p);
};

void MyClass::PrintPort(enum class Port p)
{
    cout << (int)p << endl;
}

.

// Header.h
enum class Port : unsigned char // Declare enum type explicitly
{
    PORT_1 = 0x01,
    PORT_2 = 0x02,
    PORT_3 = 0x04
};

.

// Source.cpp
#include "Header1.h"
#include "Header.h"

using namespace std;
int main()
{
    MyClass m;
    m.PrintPort(Port::PORT_1);

    return 0;
}

Get a filtered list of files in a directory

import glob

jpgFilenamesList = glob.glob('145592*.jpg')

See glob in python documenttion

How to install packages offline?

The pip download command lets you download packages without installing them:

pip download -r requirements.txt

(In previous versions of pip, this was spelled pip install --download -r requirements.txt.)

Then you can use pip install --no-index --find-links /path/to/download/dir/ -r requirements.txt to install those downloaded sdists, without accessing the network.

How can I do an UPDATE statement with JOIN in SQL Server?

Teradata Aster offers another interesting way how to achieve the goal:

MERGE INTO ud --what trable should be updated
USING sale -- from what table/relation update info should be taken
ON ud.id = sale.udid --join condition
WHEN MATCHED THEN 
    UPDATE SET ud.assid = sale.assid; -- how to update

React Router with optional path parameter

If you are looking to do an exact match, use the following syntax: (param)?.

Eg.

<Route path={`my/(exact)?/path`} component={MyComponent} />

The nice thing about this is that you'll have props.match to play with, and you don't need to worry about checking the value of the optional parameter:

{ props: { match: { "0": "exact" } } }

How to check if an integer is within a range of numbers in PHP?

You could whip up a little helper function to do this:

/**
 * Determines if $number is between $min and $max
 *
 * @param  integer  $number     The number to test
 * @param  integer  $min        The minimum value in the range
 * @param  integer  $max        The maximum value in the range
 * @param  boolean  $inclusive  Whether the range should be inclusive or not
 * @return boolean              Whether the number was in the range
 */
function in_range($number, $min, $max, $inclusive = FALSE)
{
    if (is_int($number) && is_int($min) && is_int($max))
    {
        return $inclusive
            ? ($number >= $min && $number <= $max)
            : ($number > $min && $number < $max) ;
    }

    return FALSE;
}

And you would use it like so:

var_dump(in_range(5, 0, 10));        // TRUE
var_dump(in_range(1, 0, 1));         // FALSE
var_dump(in_range(1, 0, 1, TRUE));   // TRUE
var_dump(in_range(11, 0, 10, TRUE)); // FALSE

// etc...

jquery/javascript convert date string to date

var stringDate = "Sunday, February 28, 2010";

var months = ["January", "February", "March"]; // You add the rest  :-)

var m = /(\w+) (\d+), (\d+)/.exec(stringDate);

var date = new Date(+m[3], months.indexOf(m[1]), +m[2]);

The indexOf method on arrays is only supported on newer browsers (i.e. not IE). You'll need to do the searching yourself or use one of the many libraries that provide the same functionality.

Also the code is lacking any error checking which should be added. (String not matching the regular expression, non existent months, etc.)

Calling stored procedure from another stored procedure SQL Server

You could add an OUTPUT parameter to test2, and set it to the new id straight after the INSERT using:

SELECT @NewIdOutputParam = SCOPE_IDENTITY()

Then in test1, retrieve it like so:

DECLARE @NewId INTEGER
EXECUTE test2 @NewId OUTPUT
-- Now use @NewId as needed

fatal: The current branch master has no upstream branch

Also you can use the following command:

git push -u origin master

This creates (-u) another branch in your remote repo. Once the authentication using ssh is done that is.

Counting Number of Letters in a string variable

What is wrong with using string.Length?

// len will be 5
int len = "Hello".Length;

Java: Convert a String (representing an IP) to InetAddress

Simply call InetAddress.getByName(String host) passing in your textual IP address.

From the javadoc: The host name can either be a machine name, such as "java.sun.com", or a textual representation of its IP address.

InetAddress javadoc

Ignore parent padding

If you have a parent container with vertical padding and you want something (e.g. an image) inside that container to ignore its vertical padding you can set a negative, but equal, margin for both 'top' and 'bottom':

margin-top: -100px;
margin-bottom: -100px;

The actual value doesn't appear to matter much. Haven't tried this for horizontal paddings.

for each loop in groovy

Your code works fine.

def list = [["c":"d"], ["e":"f"], ["g":"h"]]
Map tmpHM = [1:"second (e:f)", 0:"first (c:d)", 2:"third (g:h)"]

for (objKey in tmpHM.keySet()) {   
    HashMap objHM = (HashMap) list.get(objKey);
    print("objHM: ${objHM}  , ")
}

prints objHM: [e:f] , objHM: [c:d] , objHM: [g:h] ,

See https://groovyconsole.appspot.com/script/5135817529884672

Then click "edit in console", "execute script"

Select the first row by group

What about

DT <- data.table(test)
setkey(DT, id)

DT[J(unique(id)), mult = "first"]

Edit

There is also a unique method for data.tables which will return the the first row by key

jdtu <- function() unique(DT)

I think, if you are ordering test outside the benchmark, then you can removing the setkey and data.table conversion from the benchmark as well (as the setkey basically sorts by id, the same as order).

set.seed(21)
test <- data.frame(id=sample(1e3, 1e5, TRUE), string=sample(LETTERS, 1e5, TRUE))
test <- test[order(test$id), ]
DT <- data.table(DT, key = 'id')
ju <- function() test[!duplicated(test$id),]

jdt <- function() DT[J(unique(id)),mult = 'first']


 library(rbenchmark)
benchmark(ju(), jdt(), replications = 5)
##    test replications elapsed relative user.self sys.self 
## 2 jdt()            5    0.01        1      0.02        0        
## 1  ju()            5    0.05        5      0.05        0         

and with more data

** Edit with unique method**

set.seed(21)
test <- data.frame(id=sample(1e4, 1e6, TRUE), string=sample(LETTERS, 1e6, TRUE))
test <- test[order(test$id), ]
DT <- data.table(test, key = 'id')
       test replications elapsed relative user.self sys.self 
2  jdt()            5    0.09     2.25      0.09     0.00    
3 jdtu()            5    0.04     1.00      0.05     0.00      
1   ju()            5    0.22     5.50      0.19     0.03        

The unique method is fastest here.

What are the default access modifiers in C#?

I would like to add some documentation link. Check out more detail here.

enter image description here

Reset Windows Activation/Remove license key

On Windows XP -

  1. Reboot into "Safe mode with Command Prompt"
  2. Type "explorer" in the command prompt that comes up and push [Enter]
  3. Click on Start>Run, and type the following :

    rundll32.exe syssetup,SetupOobeBnk

Reboot, and login as normal.

This will reset the 30 day timer for activation back to 30 days so you can enter in the key normally.

How to align td elements in center

I personally didn't find any of these answers helpful. What worked in my case was giving the element float:none and position:relative. After that the element centered itself in the <td>.

What is the best way to merge mp3 files?

The time problem has to do with the ID3 headers of the MP3 files, which is something your method isn't taking into account as the entire file is copied.

Do you have a language of choice that you want to use or doesn't it matter? That will affect what libraries are available that support the operations you want.

Static link of shared library function in gcc

If you have the .a file of your shared library (.so) you can simply include it with its full path as if it was an object file, like this:

This generates main.o by just compiling:

gcc -c main.c

This links that object file with the corresponding static library and creates the executable (named "main"):

gcc main.o mylibrary.a -o main

Or in a single command:

gcc main.c mylibrary.a -o main

It could also be an absolute or relative path:

gcc main.c /usr/local/mylibs/mylibrary.a -o main

Check if an excel cell exists on another worksheet in a column - and return the contents of a different column

You can use following formulas.

For Excel 2007 or later:

=IFERROR(VLOOKUP(D3,List!A:C,3,FALSE),"No Match")

For Excel 2003:

=IF(ISERROR(MATCH(D3,List!A:A, 0)), "No Match", VLOOKUP(D3,List!A:C,3,FALSE))

Note, that

  • I'm using List!A:C in VLOOKUP and returns value from column ? 3
  • I'm using 4th argument for VLOOKUP equals to FALSE, in that case VLOOKUP will only find an exact match, and the values in the first column of List!A:C do not need to be sorted (opposite to case when you're using TRUE).

A TypeScript GUID class?

I found this https://typescriptbcl.codeplex.com/SourceControl/latest

here is the Guid version they have in case the link does not work later.

module System {
    export class Guid {
        constructor (public guid: string) {
            this._guid = guid;
        }

        private _guid: string;

        public ToString(): string {
            return this.guid;
        }

        // Static member
        static MakeNew(): Guid {
            var result: string;
            var i: string;
            var j: number;

            result = "";
            for (j = 0; j < 32; j++) {
                if (j == 8 || j == 12 || j == 16 || j == 20)
                    result = result + '-';
                i = Math.floor(Math.random() * 16).toString(16).toUpperCase();
                result = result + i;
            }
            return new Guid(result);
        }
    }
}

Create an Android GPS tracking application

The source code for the Android mobile application open-gpstracker which you appreciated is available here.

You can checkout the code using SVN client application or via Git:

Debugging the source code will surely help you.

How do I loop through a list by twos?

The simplest in my opinion is just this:

it = iter([1,2,3,4,5,6])
for x, y in zip(it, it):
    print x, y

Out: 1 2
     3 4
     5 6

No extra imports or anything. And very elegant, in my opinion.

Remote debugging a Java application

I'd like to emphasize that order of arguments is important.

For me java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000 -jar app.jar command opens debugger port,

but java -jar app.jar -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000 command doesn't.

Add inline style using Javascript

You can do it directly on the style:

var nFilter = document.createElement('div');
nFilter.className = 'well';
nFilter.innerHTML = '<label>'+sSearchStr+'</label>';

// Css styling
nFilter.style.width = "330px";
nFilter.style.float = "left";

// or
nFilter.setAttribute("style", "width:330px;float:left;");

Onclick javascript to make browser go back to previous page?

100% work

_x000D_
_x000D_
<a onclick="window.history.go(-1); return false;" style="cursor: pointer;">Go Back</a>
_x000D_
_x000D_
_x000D_

Sheet.getRange(1,1,1,12) what does the numbers in bracket specify?

Found these docu on the google docu pages:

  • row --- int --- top row of the range
  • column --- int--- leftmost column of the range
  • optNumRows --- int --- number of rows in the range.
  • optNumColumns --- int --- number of columns in the range

In your example, you would get (if you picked the 3rd row) "C3:O3", cause C --> O is 12 columns

edit

Using the example on the docu:

// The code below will get the number of columns for the range C2:G8
// in the active spreadsheet, which happens to be "4"
var count = SpreadsheetApp.getActiveSheet().getRange(2, 3, 6, 4).getNumColumns(); Browser.msgBox(count);

The values between brackets:
2: the starting row = 2
3: the starting col = C
6: the number of rows = 6 so from 2 to 8
4: the number of cols = 4 so from C to G

So you come to the range: C2:G8

How to get date and time from server

Try this -

<?php
date_default_timezone_set('Asia/Kolkata');

$timestamp = time();
$date_time = date("d-m-Y (D) H:i:s", $timestamp);
echo "Current date and local time on this server is $date_time";
?>

Get generic type of class at runtime

Here is my solution

public class GenericClass<T>
{
    private Class<T> realType;

    public GenericClass() {
        findTypeArguments(getClass());
    }

    private void findTypeArguments(Type t) {
        if (t instanceof ParameterizedType) {
            Type[] typeArgs = ((ParameterizedType) t).getActualTypeArguments();
            realType = (Class<T>) typeArgs[0];
        } else {
            Class c = (Class) t;
            findTypeArguments(c.getGenericSuperclass());
        }
    }

    public Type getMyType()
    {
        // How do I return the type of T? (your question)
        return realType;
    }
}

No matter how many level does your class hierarchy has, this solution still works, for example:

public class FirstLevelChild<T> extends GenericClass<T> {

}

public class SecondLevelChild extends FirstLevelChild<String> {

}

In this case, getMyType() = java.lang.String

How to check if a variable is empty in python?

See section 5.1:

http://docs.python.org/library/stdtypes.html

Any object can be tested for truth value, for use in an if or while condition or as operand of the Boolean operations below. The following values are considered false:

None

False

zero of any numeric type, for example, 0, 0L, 0.0, 0j.

any empty sequence, for example, '', (), [].

any empty mapping, for example, {}.

instances of user-defined classes, if the class defines a __nonzero__() or __len__() method, when that method returns the integer zero or bool value False. [1]

All other values are considered true — so objects of many types are always true.

Operations and built-in functions that have a Boolean result always return 0 or False for false and 1 or True for true, unless otherwise stated. (Important exception: the Boolean operations or and and always return one of their operands.)

What does the Java assert keyword do, and when should it be used?

Assertions are disabled by default. To enable them we must run the program with -ea options (granularity can be varied). For example, java -ea AssertionsDemo.

There are two formats for using assertions:

  1. Simple: eg. assert 1==2; // This will raise an AssertionError.
  2. Better: assert 1==2: "no way.. 1 is not equal to 2"; This will raise an AssertionError with the message given displayed too and is thus better. Although the actual syntax is assert expr1:expr2 where expr2 can be any expression returning a value, I have used it more often just to print a message.

SQL ROWNUM how to return rows between a specific range

SELECT * FROM
(SELECT ROW_NUMBER() OVER(ORDER BY Id) AS RowNum, * FROM maps006) AS DerivedTable
WHERE RowNum BETWEEN 49 AND 101

Twitter Bootstrap - how to center elements horizontally or vertically

You may directly write into your css file like this :

_x000D_
_x000D_
.content {_x000D_
  position: absolute;_x000D_
  top: 50%;_x000D_
  left:50%;_x000D_
  transform: translate(-50%,-50%);_x000D_
  }
_x000D_
<div class = "content" >_x000D_
  _x000D_
   <p> some text </p>_x000D_
  </div>
_x000D_
_x000D_
_x000D_

Failed to authenticate on SMTP server error using gmail

This is how I solved this issue:

  1. Change the .env file as follow

Screenshot Reference

  1. Never forget to restart the server after you change the .env file

How to parse XML using shellscript?

A rather new project is the xml-coreutils package featuring xml-cat, xml-cp, xml-cut, xml-grep, ...

http://xml-coreutils.sourceforge.net/contents.html

Override console.log(); for production

This will override console.log function when the url does not contain localhost. You can replace the localhost with your own development settings.

// overriding console.log in production
if(window.location.host.indexOf('localhost:9000') < 0) {
    console.log = function(){};
}

Steps to send a https request to a rest service in Node js

Note if you are using https.request do not directly use the body from res.on('data',... This will fail if you have a large data coming in chunks. So you need to concatenate all the data and then process the response in res.on('end'. Example -

  var options = {
    hostname: "www.google.com",
    port: 443,
    path: "/upload",
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Content-Length': Buffer.byteLength(post_data)
    }
  };

  //change to http for local testing
  var req = https.request(options, function (res) {
    res.setEncoding('utf8');

    var body = '';

    res.on('data', function (chunk) {
      body = body + chunk;
    });

    res.on('end',function(){
      console.log("Body :" + body);
      if (res.statusCode != 200) {
        callback("Api call failed with response code " + res.statusCode);
      } else {
        callback(null);
      }
    });

  });

  req.on('error', function (e) {
    console.log("Error : " + e.message);
    callback(e);
  });

  // write data to request body
  req.write(post_data);
  req.end();

Eclipse C++ : "Program "g++" not found in PATH"

Had this problem on windows 10, eclipse Neon Release (4.6.0) and MSYS2 installed. Eclipse kept complaining that "Program 'g++' not found in PATH” and "Program 'gcc' not found in PATH”, yet it was compiling and running my C++ code. From the command prompt, I could run g++.

Solution was to define the C++ Environmental variable for eclipse called 'PATH' to point to windows variable called 'path' also $(Path). Menus: Preferences>>C/C++>>Build>>Environment

Looks like eclipse is case sensitive with the name of this environmental, while windows doesn't care about the case.

How do you copy a record in a SQL table but swap out the unique id of the new row?

You can do like this:

INSERT INTO DENI/FRIEN01P 
SELECT 
   RCRDID+112,
   PROFESION,
   NAME,
   SURNAME,
   AGE, 
   RCRDTYP, 
   RCRDLCU, 
   RCRDLCT, 
   RCRDLCD 
FROM 
   FRIEN01P      

There instead of 112 you should put a number of the maximum id in table DENI/FRIEN01P.

Regular expression for first and last name

After going through all of these answers I found a way to build a tiny regex that supports most languages and only allows for word characters. It even supports some special characters like hyphens, spaces and apostrophes. I've tested in python and it supports the characters below:

^[\w'\-,.][^0-9_!¡?÷?¿/\\+=@#$%ˆ&*(){}|~<>;:[\]]{2,}$

Characters supported:

abcdefghijklmnopqrstwxyz
ABCDEFGHIJKLMNOPQRSTUVWXYZ
áéíóúäëïöüÄ'
???
lLoOuUZàáâäãåacceèéêëeiìíîïlnòóôöõøùúûüuu
ÿýzzñçcšžÀÁÂÄÃÅACCEEÈÉÊËÌÍÎÏIL
NÒÓÔÖÕØÙÚÛÜUUŸÝZZÑßÇŒÆCŠŽ.-
ñÑâê?????????????
????????? ?????? ??

How can I determine if a date is between two dates in Java?

Here's a couple ways to do this using the Joda-Time 2.3 library.

One way is to use the simple isBefore and isAfter methods on DateTime instances. By the way, DateTime in Joda-Time is similar in concept to a java.util.Date (a moment in time on the timeline of the Universe) but includes a time zone.

Another way is to build an Interval in Joda-Time. The contains method tests if a given DateTime occurs within the span of time covered by the Interval. The beginning of the Interval is inclusive, but the endpoint is exclusive. This approach is known as "Half-Open", symbolically [).

See both ways in the following code example.

Convert the java.util.Date instances to Joda-Time DateTime instances. Simply pass the Date instance to constructor of DateTime. In practice you should also pass a specific DateTimeZone object rather than rely on JVM’s default time zone.

DateTime dateTime1 = new DateTime( new java.util.Date() ).minusWeeks( 1 );
DateTime dateTime2 = new DateTime( new java.util.Date() );
DateTime dateTime3 = new DateTime( new java.util.Date() ).plusWeeks( 1 );

Compare by testing for before/after…

boolean is1After2 = dateTime1.isAfter( dateTime2 );
boolean is2Before3 = dateTime2.isBefore( dateTime3 );

boolean is2Between1And3 = ( ( dateTime2.isAfter( dateTime1 ) ) && ( dateTime2.isBefore( dateTime3 ) ) );

Using the Interval approach instead of isAfter/isBefore…

Interval interval = new Interval( dateTime1, dateTime3 );
boolean intervalContainsDateTime2 = interval.contains( dateTime2 );

Dump to console…

System.out.println( "DateTimes: " + dateTime1 + " " + dateTime1 + " " + dateTime1 );
System.out.println( "is1After2 " + is1After2 );
System.out.println( "is2Before3 " + is2Before3 );
System.out.println( "is2Between1And3 " + is2Between1And3 );
System.out.println( "intervalContainsDateTime2 " + intervalContainsDateTime2 );

When run…

DateTimes: 2014-01-22T20:26:14.955-08:00 2014-01-22T20:26:14.955-08:00 2014-01-22T20:26:14.955-08:00
is1After2 false
is2Before3 true
is2Between1And3 true
intervalContainsDateTime2 true

What is in your .vimrc?

I keep my vimrc file up on github. You can find it here:

http://github.com/developernotes/vim-setup/tree/master

How can I generate a 6 digit unique number?

Try this using uniqid and hexdec,

echo hexdec(uniqid());

What does the M stand for in C# Decimal literal notation?

Well, i guess M represent the mantissa. Decimal can be used to save money, but it doesn't mean, decimal only used for money.

LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup

Because it hasn't been mentioned yet, this was the solution for me:

I had this error with a DLL after creating a new configuration for my project. I had to go to Project Properties -> Configuration Properties -> General and change the Configuration Type to Dynamic Library (.dll).

So if you're still having trouble after trying everything else, it's worth checking to see if the configuration type is what you expect for your project. If it's not set correctly, the compiler will be looking for the wrong main symbol. In my case, it was looking for WinMain instead of DllMain.

Error: fix the version conflict (google-services plugin)

After All Working for 6 hours i got the solution...

Simple Just what ever the plugins you defined in the build.gradle file... for ex: google services plugins or firebase plugins or any third party plugins all the **version code** should be same..

Example: In my application i am using following plugins...

    // google services plugins
    implementation 'com.google.android.gms:play-services-analytics:10.0.1'
    implementation 'com.google.android.gms:play-services-gcm:10.0.1'
    implementation 'com.google.android.gms:play-services-base:11.6.1'
    implementation 'com.google.android.gms:play-services-auth-api-phone:11.6.0'

    //firebase plugin
    implementation 'com.google.firebase:firebase-ads:10.0.1'

    //Third Party plugin
    implementation 'com.google.android.gms:play-services-auth:16.0.0'

In the above plugins version code(ex:10.0.1, 16.0.0, 11.6.1) are different I was facing fix the version conflict (google-services plugin) issue

Below for all plugins i have given single version code(11.6.0) and the issue is resovled...

 // google services plugins
    implementation 'com.google.android.gms:play-services-analytics:11.6.0'
    implementation 'com.google.android.gms:play-services-gcm:11.6.0'
    implementation 'com.google.android.gms:play-services-base:11.6.0'
    implementation 'com.google.android.gms:play-services-auth-api-phone:11.6.0'

    //firebase plugin
    implementation 'com.google.firebase:firebase-ads:11.6.0'

    //Third Party plugin
    implementation 'com.google.android.gms:play-services-auth:11.6.0'


**Syn Gradle**...

Go to Build>>Rebuild Projcet...

Sure it will work....@Ambilpura

How can I run a directive after the dom has finished rendering?

Here is how I do it:

app.directive('example', function() {

    return function(scope, element, attrs) {
        angular.element(document).ready(function() {
                //MANIPULATE THE DOM
        });
    };

});

Uncompress tar.gz file

Try this:

tar -zxvf file.tar.gz

Get The Current Domain Name With Javascript (Not the path, etc.)

If you are not interested in the host name (for example www.beta.example.com) but in the domain name (for example example.com), this works for valid host names:

function getDomainName(hostName)
{
    return hostName.substring(hostName.lastIndexOf(".", hostName.lastIndexOf(".") - 1) + 1);
}

Convert varchar dd/mm/yyyy to dd/mm/yyyy datetime

Try this code:

CONVERT(varchar(15), date_started, 103)

How to terminate the script in JavaScript?

This is an example, that, if a condition exist, then terminate the script. I use this in my SSE client side javascript, if the

<script src="sse-clint.js" host="https://sse.host" query='["q1,"q2"]' ></script>

canot be parsed right from JSON parse ...

if( ! SSE_HOST  ) throw new Error(['[!] SSE.js: ERR_NOHOST - finished !']);

... anyway the general idea is:

if( error==true) throw new Error([ 'You have This error' ,  'At this file', 'At this line'  ]);

this will terminate/die your javasript script

What's a concise way to check that environment variables are set in a Unix shell script?

None of the above solutions worked for my purposes, in part because I checking the environment for an open-ended list of variables that need to be set before starting a lengthy process. I ended up with this:

mapfile -t arr < variables.txt

EXITCODE=0

for i in "${arr[@]}"
do
   ISSET=$(env | grep ^${i}= | wc -l)
   if [ "${ISSET}" = "0" ];
   then
      EXITCODE=-1
      echo "ENV variable $i is required."
   fi
done

exit ${EXITCODE}

Creating multiple log files of different content with log4j

I had this question, but with a twist - I was trying to log different content to different files. I had information for a LowLevel debug log, and a HighLevel user log. I wanted the LowLevel to go to only one file, and the HighLevel to go to both a file, and a syslogd.

My solution was to configure the 3 appenders, and then setup the logging like this:

log4j.threshold=ALL
log4j.rootLogger=,LowLogger

log4j.logger.HighLevel=ALL,Syslog,HighLogger
log4j.additivity.HighLevel=false

The part that was difficult for me to figure out was that the 'log4j.logger' could have multiple appenders listed. I was trying to do it one line at a time.

Hope this helps someone at some point!

keytool error Keystore was tampered with, or password was incorrect

I fixed this issue by deleting the output file and running the command again. It turns out it does NOT overwrite the previous file. I had this issue when renewing a let's encrypt cert with tomcat

Read/Parse text file line by line in VBA

For completeness; working with the data loaded into memory;

dim hf As integer: hf = freefile
dim lines() as string, i as long

open "c:\bla\bla.bla" for input as #hf
    lines = Split(input$(LOF(hf), #hf), vbnewline)
close #hf

for i = 0 to ubound(lines)
    debug.? "Line"; i; "="; lines(i)
next

python multithreading wait till all threads finished

Maybe, something like

for t in threading.enumerate():
    if t.daemon:
        t.join()

Cmake is not able to find Python-libraries

For me was helpful next:

> apt-get install python-dev python3-dev

HTML SELECT - Change selected option by VALUE using JavaScript

You can select the value using javascript:

document.getElementById('sel').value = 'bike';

DEMO

bad operand types for binary operator "&" java

Because & has a lesser priority than ==.

Your code is equivalent to a[0] & (1 == 0), and unless a[0] is a boolean this won't compile...

You need to:

(a[0] & 1) == 0

etc etc.

(yes, Java does hava a boolean & operator -- a non shortcut logical and)

Page scroll when soft keyboard popped up

well the simplest answer i tried is just remove your code which makes the activity go full screen .I had a code like this which was responsible for making my activity go fullscreen :

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {

        getWindow().setFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS,
                WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);
    }

i just removed my code and it works completely fine although if you want to achieve this with your fullscreen on then you'll have to try some other methods

Return string Input with parse.string

As you see in an error UseCalls.java:27: error: cannot find symbol return String.parseString(input); there is no method parseString in String class. There is no need to parse it as long as JOptionPane.showInputDialog(prompt); already returns a string.

How to highlight a selected row in ngRepeat?

I needed something similar, the ability to click on a set of icons to indicate a choice, or a text-based choice and have that update the model (2-way-binding) with the represented value and to also a way to indicate which was selected visually. I created an AngularJS directive for it, since it needed to be flexible enough to handle any HTML element being clicked on to indicate a choice.

<ul ng-repeat="vote in votes" ...>
    <li data-choice="selected" data-value="vote.id">...</li>
</ul>

Solution: http://jsfiddle.net/brandonmilleraz/5fr9V/

JQuery select2 set default value from an option in list?

Came from the future? Looking for the ajax source default value ?

// Set up the Select2 control
$('#mySelect2').select2({
    ajax: {
        url: '/api/students'
    }
});

// Fetch the preselected item, and add to the control
var studentSelect = $('#mySelect2');
$.ajax({
    type: 'GET',
    url: '/api/students/s/' + studentId
}).then(function (data) {
    // create the option and append to Select2
    var option = new Option(data.full_name, data.id, true, true);
    studentSelect.append(option).trigger('change');

    // manually trigger the `select2:select` event
    studentSelect.trigger({
        type: 'select2:select',
        params: {
            data: data
        }
    });
});

You're welcome.

Reference: https://select2.org/programmatic-control/add-select-clear-items#preselecting-options-in-an-remotely-sourced-ajax-select2

`node-pre-gyp install --fallback-to-build` failed during MeanJS installation on OSX

are you running the example from the node_modules folder?

They are not supposed to be ran from there.

Create the following file on your project instead:

post-data.js

var Curl = require( 'node-libcurl' ).Curl,
   querystring = require( 'querystring' );

var curl = new Curl(),
  url  = 'http://posttestserver.com/post.php',
data = { //Data to send, inputName : value
    'input-arr[0]' : 'input-arr-val0',
    'input-arr[1]' : 'input-arr-val1',
    'input-arr[2]' : 'input-arr-val2',
    'input-name' : 'input-val'
};

//You need to build the query string, 
// node has this helper function, but it's limited for real use cases (no support for 
array values for example)
data = querystring.stringify( data );

 curl.setOpt( Curl.option.URL, url );
 curl.setOpt( Curl.option.POSTFIELDS, data );
 curl.setOpt( Curl.option.HTTPHEADER, ['User-Agent: node-libcurl/1.0'] );
 curl.setOpt( Curl.option.VERBOSE, true );

 console.log( querystring.stringify( data ) );

 curl.perform();

 curl.on( 'end', function( statusCode, body ) {

console.log( body );

this.close();
});

curl.on( 'error', curl.close.bind( curl ) );

Run with node post-data.js

ref:https://github.com/JCMais/node-libcurl/issues/98

What is 'Currying'?

Curry can simplify your code. This is one of the main reasons to use this. Currying is a process of converting a function that accepts n arguments into n functions that accept only one argument.

The principle is to pass the arguments of the passed function, using the closure (closure) property, to store them in another function and treat it as a return value, and these functions form a chain, and the final arguments are passed in to complete the operation.

The benefit of this is that it can simplify the processing of parameters by dealing with one parameter at a time, which can also improve the flexibility and readability of the program. This also makes the program more manageable. Also dividing the code into smaller pieces would make it reuse-friendly.

For example:

function curryMinus(x) 
{
  return function(y) 
  {
    return x - y;
  }
}

var minus5 = curryMinus(1);
minus5(3);
minus5(5);

I can also do...

var minus7 = curryMinus(7);
minus7(3);
minus7(5);

This is very great for making complex code neat and handling of unsynchronized methods etc.

Saving and Reading Bitmaps/Images from Internal memory in Android

Make sure to use WEBP as your media format to save more space with same quality:

fun saveImage(context: Context, bitmap: Bitmap, name: String): String {
        context.openFileOutput(name, Context.MODE_PRIVATE).use { fos ->
            bitmap.compress(Bitmap.CompressFormat.WEBP, 25, fos)
        }
    return context.filesDir.absolutePath
 }

How to get $(this) selected option in jQuery?

Best and shortest way in my opinion for onchange events on the dropdown to get the selected option:

$('option:selected',this);

to get the value attribute:

$('option:selected',this).attr('value');

to get the shown part between the tags:

$('option:selected',this).text();

In your sample:

$("#select-id").change(function(){
  var cur_value = $('option:selected',this).text();
});

Pandas concat: ValueError: Shape of passed values is blah, indices imply blah2

Aus_lacy's post gave me the idea of trying related methods, of which join does work:

In [196]:

hl.name = 'hl'
Out[196]:
'hl'
In [199]:

df.join(hl).head(4)
Out[199]:
high    low loc_h   loc_l   hl
2014-01-01 17:00:00 1.376235    1.375945    1.376235    1.375945    1.376090
2014-01-01 17:01:00 1.376005    1.375775    NaN NaN NaN
2014-01-01 17:02:00 1.375795    1.375445    NaN 1.375445    1.375445
2014-01-01 17:03:00 1.375625    1.375515    NaN NaN NaN

Some insight into why concat works on the example but not this data would be nice though!

Easy login script without database

I would use a two file setup like this:

index.php

<?php 
session_start(); 

define('DS',  TRUE); // used to protect includes
define('USERNAME', $_SESSION['username']);
define('SELF',  $_SERVER['PHP_SELF'] );

if (!USERNAME or isset($_GET['logout']))
 include('login.php');

// everything below will show after correct login 
?>

login.php

<?php defined('DS') OR die('No direct access allowed.');

$users = array(
 "user" => "userpass"
);

if(isset($_GET['logout'])) {
    $_SESSION['username'] = '';
    header('Location:  ' . $_SERVER['PHP_SELF']);
}

if(isset($_POST['username'])) {
    if($users[$_POST['username']] !== NULL && $users[$_POST['username']] == $_POST['password']) {
  $_SESSION['username'] = $_POST['username'];
  header('Location:  ' . $_SERVER['PHP_SELF']);
    }else {
        //invalid login
  echo "<p>error logging in</p>";
    }
}

echo '<form method="post" action="'.SELF.'">
  <h2>Login</h2>
  <p><label for="username">Username</label> <input type="text" id="username" name="username" value="" /></p>
  <p><label for="password">Password</label> <input type="password" id="password" name="password" value="" /></p>
  <p><input type="submit" name="submit" value="Login" class="button"/></p>
  </form>';
exit; 
?>

Using a different font with twitter bootstrap

The easiest way I've seen is to use Google Fonts.

Go to Google Fonts and choose a font, then Google will give you a link to put in your HTML.

Google's link to your font

Then add this to your custom.css:

h1, h2, h3, h4, h5, h6 {
    font-family: 'Your Font' !important;
}
p, div {
    font-family: 'Your Font' !important;
}

or

body {
   font-family: 'Your Font' !important;
}

Quick way to clear all selections on a multiselect enabled <select> with jQuery?

I've tried many solutions and came up with this.

Options and selections of the dropdown are cleared using this only

$("#my-multi option:selected").prop("selected", false);
$("#my-multi option").remove();


But the interface is not updated. So you have to do this

$('#my-multi').multiselect('rebuild');


Hence, the final code is

$("#my-multi option:selected").prop("selected", false);
$("#my-multi option").remove();
$('#my-multi').multiselect('rebuild');


Suggestions and improvements are welcome.

Build and Install unsigned apk on device without the development server?

With me, in the project directory run the following commands.

For react native old version (you will see index.android.js in root):

mkdir -p android/app/src/main/assets && rm -rf android/app/build && react-native bundle --platform android --dev false --entry-file index.android.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res && cd android && ./gradlew clean assembleRelease && cd ../

For react native new version (you just see index.js in root):

mkdir -p android/app/src/main/assets && rm -rf android/app/build && react-native bundle --platform android --dev false --entry-file index.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res && cd android && ./gradlew clean assembleRelease && cd ../

The apk file will be generated at:

  • Gradle < 3.0: android/app/build/outputs/apk/
  • Gradle 3.0+: android/app/build/outputs/apk/release/

Progress during large file copy (Copy-Item & Write-Progress?)

I amended the code from stej (which was great, just what i needed!) to use larger buffer, [long] for larger files and used System.Diagnostics.Stopwatch class to track elapsed time and estimate time remaining.

Also added reporting of transfer rate during transfer and outputting overall elapsed time and overall transfer rate.

Using 4MB (4096*1024 bytes) buffer to get better than Win7 native throughput copying from NAS to USB stick on laptop over wifi.

On To-Do list:

  • add error handling (catch)
  • handle get-childitem file list as input
  • nested progress bars when copying multiple files (file x of y, % if total data copied etc)
  • input parameter for buffer size

Feel free to use/improve :-)

function Copy-File {
param( [string]$from, [string]$to)
$ffile = [io.file]::OpenRead($from)
$tofile = [io.file]::OpenWrite($to)
Write-Progress `
    -Activity "Copying file" `
    -status ($from.Split("\")|select -last 1) `
    -PercentComplete 0
try {
    $sw = [System.Diagnostics.Stopwatch]::StartNew();
    [byte[]]$buff = new-object byte[] (4096*1024)
    [long]$total = [long]$count = 0
    do {
        $count = $ffile.Read($buff, 0, $buff.Length)
        $tofile.Write($buff, 0, $count)
        $total += $count
        [int]$pctcomp = ([int]($total/$ffile.Length* 100));
        [int]$secselapsed = [int]($sw.elapsedmilliseconds.ToString())/1000;
        if ( $secselapsed -ne 0 ) {
            [single]$xferrate = (($total/$secselapsed)/1mb);
        } else {
            [single]$xferrate = 0.0
        }
        if ($total % 1mb -eq 0) {
            if($pctcomp -gt 0)`
                {[int]$secsleft = ((($secselapsed/$pctcomp)* 100)-$secselapsed);
                } else {
                [int]$secsleft = 0};
            Write-Progress `
                -Activity ($pctcomp.ToString() + "% Copying file @ " + "{0:n2}" -f $xferrate + " MB/s")`
                -status ($from.Split("\")|select -last 1) `
                -PercentComplete $pctcomp `
                -SecondsRemaining $secsleft;
        }
    } while ($count -gt 0)
$sw.Stop();
$sw.Reset();
}
finally {
    write-host (($from.Split("\")|select -last 1) + `
     " copied in " + $secselapsed + " seconds at " + `
     "{0:n2}" -f [int](($ffile.length/$secselapsed)/1mb) + " MB/s.");
     $ffile.Close();
     $tofile.Close();
    }
}

How to set max and min value for Y axis

_x000D_
_x000D_
var config = {_x000D_
            type: 'line',_x000D_
            data: {_x000D_
                labels: ["January", "February", "March", "April", "May", "June", "July"],_x000D_
                datasets: [{_x000D_
                        label: "My First dataset",_x000D_
                        data: [10, 80, 56, 60, 6, 45, 15],_x000D_
                        fill: false,_x000D_
                        backgroundColor: "#eebcde ",_x000D_
                        borderColor: "#eebcde",_x000D_
                        borderCapStyle: 'butt',_x000D_
                        borderDash: [5, 5],_x000D_
                    }]_x000D_
            },_x000D_
            options: {_x000D_
                responsive: true,_x000D_
                legend: {_x000D_
                    position: 'bottom',_x000D_
                },_x000D_
                hover: {_x000D_
                    mode: 'label'_x000D_
                },_x000D_
                scales: {_x000D_
                    xAxes: [{_x000D_
                            display: true,_x000D_
                            scaleLabel: {_x000D_
                                display: true,_x000D_
                                labelString: 'Month'_x000D_
                            }_x000D_
                        }],_x000D_
                    yAxes: [{_x000D_
                            display: true,_x000D_
                            ticks: {_x000D_
                                beginAtZero: true,_x000D_
                                steps: 10,_x000D_
                                stepValue: 5,_x000D_
                                max: 100_x000D_
                            }_x000D_
                        }]_x000D_
                },_x000D_
                title: {_x000D_
                    display: true,_x000D_
                    text: 'Chart.js Line Chart - Legend'_x000D_
                }_x000D_
            }_x000D_
        };_x000D_
_x000D_
        var ctx = document.getElementById("canvas").getContext("2d");_x000D_
       new Chart(ctx, config);
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.2.1/Chart.bundle.js"></script>_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<body>_x000D_
  <canvas id="canvas"></canvas>_x000D_
</body>
_x000D_
_x000D_
_x000D_

In Angular, how to pass JSON object/array into directive?

If you want to follow all the "best practices," there's a few things I'd recommend, some of which are touched on in other answers and comments to this question.


First, while it doesn't have too much of an affect on the specific question you asked, you did mention efficiency, and the best way to handle shared data in your application is to factor it out into a service.

I would personally recommend embracing AngularJS's promise system, which will make your asynchronous services more composable compared to raw callbacks. Luckily, Angular's $http service already uses them under the hood. Here's a service that will return a promise that resolves to the data from the JSON file; calling the service more than once will not cause a second HTTP request.

app.factory('locations', function($http) {
  var promise = null;

  return function() {
    if (promise) {
      // If we've already asked for this data once,
      // return the promise that already exists.
      return promise;
    } else {
      promise = $http.get('locations/locations.json');
      return promise;
    }
  };
});

As far as getting the data into your directive, it's important to remember that directives are designed to abstract generic DOM manipulation; you should not inject them with application-specific services. In this case, it would be tempting to simply inject the locations service into the directive, but this couples the directive to that service.

A brief aside on code modularity: a directive’s functions should almost never be responsible for getting or formatting their own data. There’s nothing to stop you from using the $http service from within a directive, but this is almost always the wrong thing to do. Writing a controller to use $http is the right way to do it. A directive already touches a DOM element, which is a very complex object and is difficult to stub out for testing. Adding network I/O to the mix makes your code that much more difficult to understand and that much more difficult to test. In addition, network I/O locks in the way that your directive will get its data – maybe in some other place you’ll want to have this directive receive data from a socket or take in preloaded data. Your directive should either take data in as an attribute through scope.$eval and/or have a controller to handle acquiring and storing the data.

- The 80/20 Guide to Writing AngularJS Directives

In this specific case, you should place the appropriate data on your controller's scope and share it with the directive via an attribute.

app.controller('SomeController', function($scope, locations) {
  locations().success(function(data) {
    $scope.locations = data;
  });
});
<ul class="list">
   <li ng-repeat="location in locations">
      <a href="#">{{location.id}}. {{location.name}}</a>
   </li>
</ul>
<map locations='locations'></map>
app.directive('map', function() {
  return {
    restrict: 'E',
    replace: true,
    template: '<div></div>',
    scope: {
      // creates a scope variable in your directive
      // called `locations` bound to whatever was passed
      // in via the `locations` attribute in the DOM
      locations: '=locations'
    },
    link: function(scope, element, attrs) {
      scope.$watch('locations', function(locations) {
        angular.forEach(locations, function(location, key) {
          // do something
        });
      });
    }
  };
});

In this way, the map directive can be used with any set of location data--the directive is not hard-coded to use a specific set of data, and simply linking the directive by including it in the DOM will not fire off random HTTP requests.

ORA-00979 not a group by expression

You must put all columns of the SELECT in the GROUP BY or use functions on them which compress the results to a single value (like MIN, MAX or SUM).

A simple example to understand why this happens: Imagine you have a database like this:

FOO BAR
0   A
0   B

and you run SELECT * FROM table GROUP BY foo. This means the database must return a single row as result with the first column 0 to fulfill the GROUP BY but there are now two values of bar to chose from. Which result would you expect - A or B? Or should the database return more than one row, violating the contract of GROUP BY?

Stop embedded youtube iframe?

Here is a codepen, it worked for me.

I was searching for the simplest solution for embedding the YT video within an iframe, and I feel this is it.

What I needed was to have the video appear in a modal window and stop playing when it was closed

Here is the code : (from: https://codepen.io/anon/pen/GBjqQr)

    <div><a href="#" class="play-video">Play Video</a></div>
    <div><a href="#" class="stop-video">Stop Video</a></div>
    <div><a href="#" class="pause-video">Pause Video</a></div>

    <iframe class="youtube-video" width="560" height="315" src="https://www.youtube.com/embed/glEiPXAYE-U?enablejsapi=1&version=3&playerapiid=ytplayer" frameborder="0" allowfullscreen></iframe>

$('a.play-video').click(function(){
    $('.youtube-video')[0].contentWindow.postMessage('{"event":"command","func":"' + 'playVideo' + '","args":""}', '*');
});

$('a.stop-video').click(function(){
    $('.youtube-video')[0].contentWindow.postMessage('{"event":"command","func":"' + 'stopVideo' + '","args":""}', '*');
});

$('a.pause-video').click(function(){
    $('.youtube-video')[0].contentWindow.postMessage('{"event":"command","func":"' + 'pauseVideo' + '","args":""}', '*');
});

Additionally, if you want it to autoplay in a DOM-object that is not yet visible, such as a modal window, if I used the same button to play the video that I was using to show the modal it would not work so I used THIS:

https://www.youtube.com/embed/EzAGZCPSOfg?autoplay=1&enablejsapi=1&version=3&playerapiid=ytplayer

Note: The ?autoplay=1& where it's placed and the use of the '&' before the next property to allow the pause to continue to work.

How to get JSON object from Razor Model object in javascript

You could use the following:

var json = @Html.Raw(Json.Encode(@Model.CollegeInformationlist));

This would output the following (without seeing your model I've only included one field):

<script>
    var json = [{"State":"a state"}];   
</script>

Working Fiddle

AspNetCore

AspNetCore uses Json.Serialize intead of Json.Encode

var json = @Html.Raw(Json.Serialize(@Model.CollegeInformationlist));

MVC 5/6

You can use Newtonsoft for this:

    @Html.Raw(Newtonsoft.Json.JsonConvert.SerializeObject(Model, 
Newtonsoft.Json.Formatting.Indented))

This gives you more control of the json formatting i.e. indenting as above, camelcasing etc.

BeautifulSoup getText from between <p>, not picking up subsequent paragraphs

This works well for specific articles where the text is all wrapped in <p> tags. Since the web is an ugly place, it's not always the case.

Often, websites will have text scattered all over, wrapped in different types of tags (e.g. maybe in a <span> or a <div>, or an <li>).

To find all text nodes in the DOM, you can use soup.find_all(text=True).

This is going to return some undesired text, like the contents of <script> and <style> tags. You'll need to filter out the text contents of elements you don't want.

blacklist = [
  'style',
  'script',
  # other elements,
]

text_elements = [t for t in soup.find_all(text=True) if t.parent.name not in blacklist]

If you are working with a known set of tags, you can tag the opposite approach:

whitelist = [
  'p'
]

text_elements = [t for t in soup.find_all(text=True) if t.parent.name in whitelist]

C# compiler error: "not all code paths return a value"

The compiler doesn't get the intricate logic where you return in the last iteration of the loop, so it thinks that you could exit out of the loop and end up not returning anything at all.

Instead of returning in the last iteration, just return true after the loop:

public static bool isTwenty(int num) {
  for(int j = 1; j <= 20; j++) {
    if(num % j != 0) {
      return false;
    }
  }
  return true;
}

Side note, there is a logical error in the original code. You are checking if num == 20 in the last condition, but you should have checked if j == 20. Also checking if num % j == 0 was superflous, as that is always true when you get there.

No space left on device

Maybe you are out of inodes. Try df -i

                     2591792  136322 2455470    6% /home
/dev/sdb1            1887488 1887488       0  100% /data

Disk used 6% but inode table full.

Debugging iframes with Chrome developer tools

Currently evaluation in the console is performed in the context of the main frame in the page and it adheres to the same cross-origin policy as the main frame itself. This means that you cannot access elements in the iframe unless the main frame can. You can still set breakpoints in and debug your code using Scripts panel though.

Update: This is no longer true. See Metagrapher's answer.

How to filter Android logcat by application?

On Linux/Un*X/Cygwin you can get list of all tags in project (with appended :V after each) with this command (split because readability):

$ git grep 'String\s\+TAG\s*=\s*' |  \
  perl -ne 's/.*String\s+TAG\s*=\s*"?([^".]+).*;.*/$1:V/g && print ' | \
  sort | xargs
AccelerometerListener:V ADNList:V Ashared:V AudioDialog:V BitmapUtils:V # ...

It covers tags defined both ways of defining tags:

private static final String TAG = "AudioDialog";
private static final String TAG = SipProfileDb.class.getSimpleName();

And then just use it for adb logcat.

How to declare a variable in SQL Server and use it in the same Stored Procedure

CREATE PROCEDURE AddBrand
@BrandName nvarchar(50) = null,
@CategoryID int = null
AS    
BEGIN

DECLARE @BrandID int = null
SELECT @BrandID = BrandID FROM tblBrand 
WHERE BrandName = @BrandName

INSERT INTO tblBrandinCategory (CategoryID, BrandID) 
       VALUES (@CategoryID, @BrandID)

END

EXEC AddBrand @BrandName = 'BMW', @CategoryId = 1

Notification Icon with the new Firebase Cloud Messaging system

I'm triggering my notifications from FCM console and through HTTP/JSON ... with the same result.

I can handle the title, full message, but the icon is always a default white circle:

Notification screenshot

Instead of my custom icon in the code (setSmallIcon or setSmallIcon) or default icon from the app:

 Intent intent = new Intent(this, MainActivity.class);
    // use System.currentTimeMillis() to have a unique ID for the pending intent
    PendingIntent pIntent = PendingIntent.getActivity(this, (int) System.currentTimeMillis(), intent, 0);

    if (Build.VERSION.SDK_INT < 16) {
        Notification n  = new Notification.Builder(this)
                .setContentTitle(messageTitle)
                .setContentText(messageBody)
                .setSmallIcon(R.mipmap.ic_launcher)
                .setContentIntent(pIntent)
                .setAutoCancel(true).getNotification();
        NotificationManager notificationManager =
                (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        //notificationManager.notify(0, n);
        notificationManager.notify(id, n);
    } else {
        Bitmap bm = BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher);

        Notification n  = new Notification.Builder(this)
                .setContentTitle(messageTitle)
                .setContentText(messageBody)
                .setSmallIcon(R.drawable.ic_stat_ic_notification)
                .setLargeIcon(bm)
                .setContentIntent(pIntent)
                .setAutoCancel(true).build();

        NotificationManager notificationManager =
                (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        //notificationManager.notify(0, n);
        notificationManager.notify(id, n);
    }

how to measure running time of algorithms in python

I am not 100% sure what is meant by "running times of my algorithms written in python", so I thought I might try to offer a broader look at some of the potential answers.

  • Algorithms don't have running times; implementations can be timed, but an algorithm is an abstract approach to doing something. The most common and often the most valuable part of optimizing a program is analyzing the algorithm, usually using asymptotic analysis and computing the big O complexity in time, space, disk use and so forth.

    A computer cannot really do this step for you. This requires doing the math to figure out how something works. Optimizing this side of things is the main component to having scalable performance.

  • You can time your specific implementation. The nicest way to do this in Python is to use timeit. The way it seems most to want to be used is to make a module with a function encapsulating what you want to call and call it from the command line with python -m timeit ....

    Using timeit to compare multiple snippets when doing microoptimization, but often isn't the correct tool you want for comparing two different algorithms. It is common that what you want is asymptotic analysis, but it's possible you want more complicated types of analysis.

  • You have to know what to time. Most snippets aren't worth improving. You need to make changes where they actually count, especially when you're doing micro-optimisation and not improving the asymptotic complexity of your algorithm.

    If you quadruple the speed of a function in which your code spends 1% of the time, that's not a real speedup. If you make a 20% speed increase on a function in which your program spends 50% of the time, you have a real gain.

    To determine the time spent by a real Python program, use the stdlib profiling utilities. This will tell you where in an example program your code is spending its time.