Programs & Examples On #Rokon

getaddrinfo: nodename nor servname provided, or not known

I was seeing this error unrelated to rails. It turned out my test was trying to use a port that was too high (greater than 65535).

This code will produce the error in question

require 'socket'
Socket.getaddrinfo("127.0.0.1", "65536")

Android: How to overlay a bitmap and draw over a bitmap?

If the purpose is to obtain a bitmap, this is very simple:

Canvas canvas = new Canvas();
canvas.setBitmap(image);
canvas.drawBitmap(image2, new Matrix(), null);

In the end, image will contain the overlap of image and image2.

Store mysql query output into a shell variable

You have the pipe the other way around and you need to echo the query, like this:

myvariable=$(echo "SELECT A, B, C FROM table_a" | mysql db -u $user -p $password)

Another alternative is to use only the mysql client, like this

myvariable=$(mysql db -u $user -p $password -se "SELECT A, B, C FROM table_a")

(-s is required to avoid the ASCII-art)

Now, BASH isn't the most appropriate language to handle this type of scenarios, especially handling strings and splitting SQL results and the like. You have to work a lot to get things that would be very, very simple in Perl, Python or PHP.

For example, how will you get each of A, B and C on their own variable? It's certainly doable, but if you do not understand pipes and echo (very basic shell stuff), it will not be an easy task for you to do, so if at all possible I'd use a better suited language.

Error: Specified cast is not valid. (SqlManagerUI)

There are some funnies restoring old databases into SQL 2008 via the guy; have you tried doing it via TSQL ?

Use Master
Go
RESTORE DATABASE YourDB
FROM DISK = 'C:\YourBackUpFile.bak'
WITH MOVE 'YourMDFLogicalName' TO 'D:\Data\YourMDFFile.mdf',--check and adjust path
MOVE 'YourLDFLogicalName' TO 'D:\Data\YourLDFFile.ldf' 

ViewBag, ViewData and TempData

ASP.NET MVC offers us three options ViewData, ViewBag, and TempData for passing data from controller to view and in next request. ViewData and ViewBag are almost similar and TempData performs additional responsibility. Lets discuss or get key points on those three objects:

Similarities between ViewBag & ViewData :

  • Helps to maintain data when you move from controller to view.
  • Used to pass data from controller to corresponding view.
  • Short life means value becomes null when redirection occurs. This is because their goal is to provide a way to communicate between controllers and views. It’s a communication mechanism within the server call.

Difference between ViewBag & ViewData:

  • ViewData is a dictionary of objects that is derived from ViewDataDictionary class and accessible using strings as keys.
  • ViewBag is a dynamic property that takes advantage of the new dynamic features in C# 4.0.
  • ViewData requires typecasting for complex data type and check for null values to avoid error.
  • ViewBag doesn’t require typecasting for complex data type.

ViewBag & ViewData Example:

public ActionResult Index()
{
    ViewBag.Name = "Monjurul Habib";
    return View();
}


public ActionResult Index()
{
    ViewData["Name"] = "Monjurul Habib";
    return View();
} 

In View:

@ViewBag.Name 
@ViewData["Name"] 

TempData:

TempData is also a dictionary derived from TempDataDictionary class and stored in short lives session and it is a string key and object value. The difference is that the life cycle of the object. TempData keep the information for the time of an HTTP Request. This mean only from one page to another. This also work with a 302/303 redirection because it’s in the same HTTP Request. Helps to maintain data when you move from one controller to other controller or from one action to other action. In other words when you redirect, “TempData” helps to maintain data between those redirects. It internally uses session variables. Temp data use during the current and subsequent request only means it is use when you are sure that next request will be redirecting to next view. It requires typecasting for complex data type and check for null values to avoid error. Generally used to store only one time messages like error messages, validation messages.

public ActionResult Index()
{
  var model = new Review()
            {
                Body = "Start",
                Rating=5
            };
    TempData["ModelName"] = model;
    return RedirectToAction("About");
}

public ActionResult About()
{
    var model= TempData["ModelName"];
    return View(model);
}

The last mechanism is the Session which work like the ViewData, like a Dictionary that take a string for key and object for value. This one is stored into the client Cookie and can be used for a much more long time. It also need more verification to never have any confidential information. Regarding ViewData or ViewBag you should use it intelligently for application performance. Because each action goes through the whole life cycle of regular asp.net mvc request. You can use ViewData/ViewBag in your child action but be careful that you are not using it to populate the unrelated data which can pollute your controller.

How to send Request payload to REST API in java?

I tried with a rest client.

Headers :

  • POST /r/gerrit/rpc/ChangeDetailService HTTP/1.1
  • Host: git.eclipse.org
  • User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:18.0) Gecko/20100101 Firefox/18.0
  • Accept: application/json
  • Accept-Language: null
  • Accept-Encoding: gzip,deflate,sdch
  • accept-charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
  • Content-Type: application/json; charset=UTF-8
  • Content-Length: 73
  • Connection: keep-alive

it works fine. I retrieve 200 OK with a good body.

Why do you set a status code in your request? and multiple declaration "Accept" with Accept:application/json,application/json,application/jsonrequest. just a statement is enough.

MVC4 input field placeholder

This works:

@Html.TextBox("name", null,  new { placeholder = "Text" })

Android ImageView's onClickListener does not work

Try by passing the context instead of the application context (You can also add a log statement to check if the onClick method is ever run) :

imgFavorite.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            Log.d("== My activity ===","OnClick is called");
            Toast.makeText(v.getContext(), // <- Line changed
                    "The favorite list would appear on clicking this icon",
                    Toast.LENGTH_LONG).show();
        }
    });

Check existence of directory and create if doesn't exist

To find out if a path is a valid directory try:

file.info(cacheDir)[1,"isdir"]

file.info does not care about a slash on the end.

file.exists on Windows will fail for a directory if it ends in a slash, and succeeds without it. So this cannot be used to determine if a path is a directory.

file.exists("R:/data/CCAM/CCAMC160b_echam5_A2-ct-uf.-5t05N.190to240E_level1000/cache/")
[1] FALSE

file.exists("R:/data/CCAM/CCAMC160b_echam5_A2-ct-uf.-5t05N.190to240E_level1000/cache")
[1] TRUE

file.info(cacheDir)["isdir"]

Javascript: getFullyear() is not a function

One way to get this error is to forget to use the 'new' keyword when instantiating your Date in javascript like this:

> d = Date();
'Tue Mar 15 2016 20:05:53 GMT-0400 (EDT)'
> typeof(d);
'string'
> d.getFullYear();
TypeError: undefined is not a function

Had you used the 'new' keyword, it would have looked like this:

> el@defiant $ node
> d = new Date();
Tue Mar 15 2016 20:08:58 GMT-0400 (EDT)
> typeof(d);
'object'
> d.getFullYear(0);
2016

Another way to get that error is to accidentally re-instantiate a variable in javascript between when you set it and when you use it, like this:

el@defiant $ node
> d = new Date();
Tue Mar 15 2016 20:12:13 GMT-0400 (EDT)
> d.getFullYear();
2016
> d = 57 + 23;
80
> d.getFullYear();
TypeError: undefined is not a function

How to exit in Node.js

Just a note that using process.exit([number]) is not recommended practice.

Calling process.exit() will force the process to exit as quickly as possible even if there are still asynchronous operations pending that have not yet completed fully, including I/O operations to process.stdout and process.stderr.

In most situations, it is not actually necessary to call process.exit() explicitly. The Node.js process will exit on its own if there is no additional work pending in the event loop. The process.exitCode property can be set to tell the process which exit code to use when the process exits gracefully.

For instance, the following example illustrates a misuse of the process.exit() method that could lead to data printed to stdout being truncated and lost:

// This is an example of what *not* to do:
if (someConditionNotMet()) {
  printUsageToStdout();
  process.exit(1);
}

The reason this is problematic is because writes to process.stdout in Node.js are sometimes asynchronous and may occur over multiple ticks of the Node.js event loop. Calling process.exit(), however, forces the process to exit before those additional writes to stdout can be performed.

Rather than calling process.exit() directly, the code should set the process.exitCode and allow the process to exit naturally by avoiding scheduling any additional work for the event loop:

// How to properly set the exit code while letting
// the process exit gracefully.
if (someConditionNotMet()) {
  printUsageToStdout();  
  process.exitCode = 1;
}

How can I see what has changed in a file before committing to git?

git diff <path>/filename

path can your be complete system path till the file or
if you are in the project you paste the modified file path also
for Modified files with path use :git status

Pandas groupby month and year

There are different ways to do that.

  • I created the data frame to showcase the different techniques to filter your data.
df = pd.DataFrame({'Date':['01-Jun-13','03-Jun-13', '15-Aug-13', '20-Jan-14', '21-Feb-14'],

'abc':[100,-20,40,25,60],'xyz':[200,50,-5,15,80] })

  • I separated months/year/day and seperated month-year as you explained.
def getMonth(s):
  return s.split("-")[1]

def getDay(s):
  return s.split("-")[0]

def getYear(s):
  return s.split("-")[2]

def getYearMonth(s):
  return s.split("-")[1]+"-"+s.split("-")[2]
  • I created new columns: year, month, day and 'yearMonth'. In your case, you need one of both. You can group using two columns 'year','month' or using one column yearMonth
df['year']= df['Date'].apply(lambda x: getYear(x))
df['month']= df['Date'].apply(lambda x: getMonth(x))
df['day']= df['Date'].apply(lambda x: getDay(x))
df['YearMonth']= df['Date'].apply(lambda x: getYearMonth(x))

Output:

        Date  abc  xyz year month day YearMonth
0  01-Jun-13  100  200   13   Jun  01    Jun-13
1  03-Jun-13  -20   50   13   Jun  03    Jun-13
2  15-Aug-13   40   -5   13   Aug  15    Aug-13
3  20-Jan-14   25   15   14   Jan  20    Jan-14
4  21-Feb-14   60   80   14   Feb  21    Feb-14
  • You can go through the different groups in groupby(..) items.

In this case, we are grouping by two columns:

for key,g in df.groupby(['year','month']):
    print key,g

Output:

('13', 'Jun')         Date  abc  xyz year month day YearMonth
0  01-Jun-13  100  200   13   Jun  01    Jun-13
1  03-Jun-13  -20   50   13   Jun  03    Jun-13
('13', 'Aug')         Date  abc  xyz year month day YearMonth
2  15-Aug-13   40   -5   13   Aug  15    Aug-13
('14', 'Jan')         Date  abc  xyz year month day YearMonth
3  20-Jan-14   25   15   14   Jan  20    Jan-14
('14', 'Feb')         Date  abc  xyz year month day YearMonth

In this case, we are grouping by one column:

for key,g in df.groupby(['YearMonth']):
    print key,g

Output:

Jun-13         Date  abc  xyz year month day YearMonth
0  01-Jun-13  100  200   13   Jun  01    Jun-13
1  03-Jun-13  -20   50   13   Jun  03    Jun-13
Aug-13         Date  abc  xyz year month day YearMonth
2  15-Aug-13   40   -5   13   Aug  15    Aug-13
Jan-14         Date  abc  xyz year month day YearMonth
3  20-Jan-14   25   15   14   Jan  20    Jan-14
Feb-14         Date  abc  xyz year month day YearMonth
4  21-Feb-14   60   80   14   Feb  21    Feb-14
  • In case you wanna access to specific item, you can use get_group

print df.groupby(['YearMonth']).get_group('Jun-13')

Output:

        Date  abc  xyz year month day YearMonth
0  01-Jun-13  100  200   13   Jun  01    Jun-13
1  03-Jun-13  -20   50   13   Jun  03    Jun-13
  • Similar to get_group. This hack would help to filter values and get the grouped values.

This also would give the same result.

print df[df['YearMonth']=='Jun-13'] 

Output:

        Date  abc  xyz year month day YearMonth
0  01-Jun-13  100  200   13   Jun  01    Jun-13
1  03-Jun-13  -20   50   13   Jun  03    Jun-13

You can select list of abc or xyz values during Jun-13

print df[df['YearMonth']=='Jun-13'].abc.values
print df[df['YearMonth']=='Jun-13'].xyz.values

Output:

[100 -20]  #abc values
[200  50]  #xyz values

You can use this to go through the dates that you have classified as "year-month" and apply cretiria on it to get related data.

for x in set(df.YearMonth): 
    print df[df['YearMonth']==x].abc.values
    print df[df['YearMonth']==x].xyz.values

I recommend also to check this answer as well.

xampp MySQL does not start

If there are two instances of MySql it's normal that it gives such an error if they both run at the same time. If you really need 2 servers, you must change the listening port of one of them, or if you don't it's probably better to simply uninstall one of them. This is so regarless of MySql itself, because two programs cannot listen on the same port at the same time.

how to get the last part of a string before a certain character?

Difference between split and partition is split returns the list without delimiter and will split where ever it gets delimiter in string i.e.

x = 'http://test.com/lalala-134-431'

a,b,c = x.split(-)
print(a)
"http://test.com/lalala"
print(b)
"134"
print(c)
"431"

and partition will divide the string with only first delimiter and will only return 3 values in list

x = 'http://test.com/lalala-134-431'
a,b,c = x.partition('-')
print(a)
"http://test.com/lalala"
print(b)
"-"
print(c)
"134-431"

so as you want last value you can use rpartition it works in same way but it will find delimiter from end of string

x = 'http://test.com/lalala-134-431'
a,b,c = x.partition('-')
print(a)
"http://test.com/lalala-134"
print(b)
"-"
print(c)
"431"

Laravel password validation rule

This doesn't quite match the OP requirements, though hopefully it helps. With Laravel you can define your rules in an easy-to-maintain format like so:

    $inputs = [
        'email'    => 'foo',
        'password' => 'bar',
    ];

    $rules = [
        'email'    => 'required|email',
        'password' => [
            'required',
            'string',
            'min:10',             // must be at least 10 characters in length
            'regex:/[a-z]/',      // must contain at least one lowercase letter
            'regex:/[A-Z]/',      // must contain at least one uppercase letter
            'regex:/[0-9]/',      // must contain at least one digit
            'regex:/[@$!%*#?&]/', // must contain a special character
        ],
    ];

    $validation = \Validator::make( $inputs, $rules );

    if ( $validation->fails() ) {
        print_r( $validation->errors()->all() );
    }

Would output:

    [
        'The email must be a valid email address.',
        'The password must be at least 10 characters.',
        'The password format is invalid.',
    ]

(The regex rules share an error message by default—i.e. four failing regex rules result in one error message)

Are there any style options for the HTML5 Date picker?

The following eight pseudo-elements are made available by WebKit for customizing a date input’s textbox:

::-webkit-datetime-edit
::-webkit-datetime-edit-fields-wrapper
::-webkit-datetime-edit-text
::-webkit-datetime-edit-month-field
::-webkit-datetime-edit-day-field
::-webkit-datetime-edit-year-field
::-webkit-inner-spin-button
::-webkit-calendar-picker-indicator

So if you thought the date input could use more spacing and a ridiculous color scheme you could add the following:

_x000D_
_x000D_
::-webkit-datetime-edit { padding: 1em; }_x000D_
::-webkit-datetime-edit-fields-wrapper { background: silver; }_x000D_
::-webkit-datetime-edit-text { color: red; padding: 0 0.3em; }_x000D_
::-webkit-datetime-edit-month-field { color: blue; }_x000D_
::-webkit-datetime-edit-day-field { color: green; }_x000D_
::-webkit-datetime-edit-year-field { color: purple; }_x000D_
::-webkit-inner-spin-button { display: none; }_x000D_
::-webkit-calendar-picker-indicator { background: orange; }
_x000D_
<input type="date">
_x000D_
_x000D_
_x000D_

Screenshot

How to redirect on another page and pass parameter in url from table?

Do this :

<script type="text/javascript">
function showDetails(username)
{
   window.location = '/player_detail?username='+username;
}
</script>

<input type="button" name="theButton" value="Detail" onclick="showDetails('username');">

Pycharm and sys.argv arguments

The first parameter is the name of the script you want to run. From the second parameter onwards it is the the parameters that you want to pass from your command line. Below is a test script:

from sys import argv

script, first, second = argv
print "Script is ",script
print "first is ",first
print "second is ",second

And here is how you pass the input parameters : 'Path to your script','First Parameter','Second Parameter'

Lets say that the Path to your script is /home/my_folder/test.py , the output will be like :

Script is /home/my_folder/test.py
first is First Parameter
second is Second Parameter

Hope this helps as it took me sometime to figure out input parameters are comma separated.

When is JavaScript synchronous?

JavaScript is single threaded and has a synchronous execution model. Single threaded means that one command is being executed at a time. Synchronous means one at a time i.e. one line of code is being executed at time in order the code appears. So in JavaScript one thing is happening at a time.

Execution Context

The JavaScript engine interacts with other engines in the browser. In the JavaScript execution stack there is global context at the bottom and then when we invoke functions the JavaScript engine creates new execution contexts for respective functions. When the called function exits its execution context is popped from the stack, and then next execution context is popped and so on...

For example

function abc()
{
   console.log('abc');
}


function xyz()
{
   abc()
   console.log('xyz');
}
var one = 1;
xyz();

In the above code a global execution context will be created and in this context var one will be stored and its value will be 1... when the xyz() invocation is called then a new execution context will be created and if we had defined any variable in xyz function those variables would be stored in the execution context of xyz(). In the xyz function we invoke abc() and then the abc() execution context is created and put on the execution stack... Now when abc() finishes its context is popped from stack, then the xyz() context is popped from stack and then global context will be popped...

Now about asynchronous callbacks; asynchronous means more than one at a time.

Just like the execution stack there is the Event Queue. When we want to be notified about some event in the JavaScript engine we can listen to that event, and that event is placed on the queue. For example an Ajax request event, or HTTP request event.

Whenever the execution stack is empty, like shown in above code example, the JavaScript engine periodically looks at the event queue and sees if there is any event to be notified about. For example in the queue there were two events, an ajax request and a HTTP request. It also looks to see if there is a function which needs to be run on that event trigger... So the JavaScript engine is notified about the event and knows the respective function to execute on that event... So the JavaScript engine invokes the handler function, in the example case, e.g. AjaxHandler() will be invoked and like always when a function is invoked its execution context is placed on the execution context and now the function execution finishes and the event ajax request is also removed from the event queue... When AjaxHandler() finishes the execution stack is empty so the engine again looks at the event queue and runs the event handler function of HTTP request which was next in queue. It is important to remember that the event queue is processed only when execution stack is empty.

For example see the code below explaining the execution stack and event queue handling by Javascript engine.

function waitfunction() {
    var a = 5000 + new Date().getTime();
    while (new Date() < a){}
    console.log('waitfunction() context will be popped after this line');
}

function clickHandler() {
    console.log('click event handler...');   
}

document.addEventListener('click', clickHandler);


waitfunction(); //a new context for this function is created and placed on the execution stack
console.log('global context will be popped after this line');

And

<html>
    <head>

    </head>
    <body>

        <script src="program.js"></script>
    </body>
</html>

Now run the webpage and click on the page, and see the output on console. The output will be

waitfunction() context will be popped after this line
global context will be emptied after this line
click event handler...

The JavaScript engine is running the code synchronously as explained in the execution context portion, the browser is asynchronously putting things in event queue. So the functions which take a very long time to complete can interrupt event handling. Things happening in a browser like events are handled this way by JavaScript, if there is a listener supposed to run, the engine will run it when the execution stack is empty. And events are processed in the order they happen, so the asynchronous part is about what is happening outside the engine i.e. what should the engine do when those outside events happen.

So JavaScript is always synchronous.

java Arrays.sort 2d array

Although this is an old thread, here are two examples for solving the problem in Java8.

sorting by the first column ([][0]):

double[][] myArr = new double[mySize][2];
// ...
java.util.Arrays.sort(myArr, java.util.Comparator.comparingDouble(a -> a[0]));

sorting by the first two columns ([][0], [][1]):

double[][] myArr = new double[mySize][2];
// ...
java.util.Arrays.sort(myArr, java.util.Comparator.<double[]>comparingDouble(a -> a[0]).thenComparingDouble(a -> a[1]));

How to get value by class name in JavaScript or jquery?

If you get the the text inside the element use

Text()

$(".element-classname").text();

In your code:

$('.HOEnZb').text();

if you want get all the data including html Tags use:

html()

 $(".element-classname").html();

In your code:

$('.HOEnZb').html();

Hope it helps:)

javascript multiple OR conditions in IF statement

because the OR operator will return true if any one of the conditions is true, and in your code there are two conditions that are true.

javascript change background color on click

If you want change background color on button click, you should use JavaScript function and change a style in the HTML page.

function chBackcolor(color) {
   document.body.style.background = color;
}

It is a function in JavaScript for change color, and you will be call this function in your event, for example :

<input type="button" onclick="chBackcolor('red');">

I recommend to use jQuery for this.

If you want it only for some seconds, you can use setTimeout function:

window.setTimeout("chBackColor()",10000);

Get Selected value from Multi-Value Select Boxes by jquery-select2?

Try this:

  $('.select').on('select2:selecting select2:unselecting', function(e) {

      var value = e.params.args.data.id;

  });

Using Java 8 to convert a list of objects into a string obtained from the toString() method

Testing both approaches suggested in Shail016 and bpedroso answer (https://stackoverflow.com/a/24883180/2832140), the simple StringBuilder + append(String) within a for loop, seems to execute much faster than list.stream().map([...].

Example: This code walks through a Map<Long, List<Long>> builds a json string, using list.stream().map([...]:

if (mapSize > 0) {
    StringBuilder sb = new StringBuilder("[");

    for (Map.Entry<Long, List<Long>> entry : threadsMap.entrySet()) {

        sb.append("{\"" + entry.getKey().toString() + "\":[");
        sb.append(entry.getValue().stream().map(Object::toString).collect(Collectors.joining(",")));
    }
    sb.delete(sb.length()-2, sb.length());
    sb.append("]");
    System.out.println(sb.toString());
}

On my dev VM, junit usually takes between 0.35 and 1.2 seconds to execute the test. While, using this following code, it takes between 0.15 and 0.33 seconds:

if (mapSize > 0) {
    StringBuilder sb = new StringBuilder("[");

    for (Map.Entry<Long, List<Long>> entry : threadsMap.entrySet()) {

        sb.append("{\"" + entry.getKey().toString() + "\":[");

        for (Long tid : entry.getValue()) {
            sb.append(tid.toString() + ", ");
        }
        sb.delete(sb.length()-2, sb.length());
        sb.append("]}, ");
    }
    sb.delete(sb.length()-2, sb.length());
    sb.append("]");
    System.out.println(sb.toString());
}

TypeError: ufunc 'add' did not contain a loop with signature matching types

You have a numpy array of strings, not floats. This is what is meant by dtype('<U9') -- a little endian encoded unicode string with up to 9 characters.

try:

return sum(np.asarray(listOfEmb, dtype=float)) / float(len(listOfEmb))

However, you don't need numpy here at all. You can really just do:

return sum(float(embedding) for embedding in listOfEmb) / len(listOfEmb)

Or if you're really set on using numpy.

return np.asarray(listOfEmb, dtype=float).mean()

Swift Error: Editor placeholder in source file

Clean Build folder + Build

will clear any error you may have even after fixing your code.

How are "mvn clean package" and "mvn clean install" different?

package will add packaged jar or war to your target folder, We can check it when, we empty the target folder (using mvn clean) and then run mvn package.
install will do all the things that package does, additionally it will add packaged jar or war in local repository as well. We can confirm it by checking in your .m2 folder.

What is Python used for?

Why should you learn Python Programming Language?

Python offers a stepping stone into the world of programming. Even though Python Programming Language has been around for 25 years, it is still rising in popularity. Some of the biggest advantage of Python are it's

  • Easy to Read & Easy to Learn
  • Very productive or small as well as big projects
  • Big libraries for many things

enter image description here

What is Python Programming Language used for?

As a general purpose programming language, Python can be used for multiple things. Python can be easily used for small, large, online and offline projects. The best options for utilizing Python are web development, simple scripting and data analysis. Below are a few examples of what Python will let you do:

Web Development:

You can use Python to create web applications on many levels of complexity. There are many excellent Python web frameworks including, Pyramid, Django and Flask, to name a few.

Data Analysis:

Python is the leading language of choice for many data scientists. Python has grown in popularity, within this field, due to its excellent libraries including; NumPy and Pandas and its superb libraries for data visualisation like Matplotlib and Seaborn.

Machine Learning:

What if you could predict customer satisfaction or analyse what factors will affect household pricing or to predict stocks over the next few days, based on previous years data? There are many wonderful libraries implementing machine learning algorithms such as Scikit-Learn, NLTK and TensorFlow.

Computer Vision:

You can do many interesting things such as Face detection, Color detection while using Opencv and Python.

Internet Of Things With Raspberry Pi:

Raspberry Pi is a very tiny and affordable computer which was developed for education and has gained enormous popularity among hobbyists with do-it-yourself hardware and automation. You can even build a robot and automate your entire home. Raspberry Pi can be used as the brain for your robot in order to perform various actions and/or react to the environment. The coding on a Raspberry Pi can be performed using Python. The Possibilities are endless!

Game Development:

Create a video game using module Pygame. Basically, you use Python to write the logic of the game. PyGame applications can run on Android devices.

Web Scraping:

If you need to grab data from a website but the site does not have an API to expose data, use Python to scraping data.

Writing Scripts:

If you're doing something manually and want to automate repetitive stuff, such as emails, it's not difficult to automate once you know the basics of this language.

Browser Automation:

Perform some neat things such as opening a browser and posting a Facebook status, you can do it with Selenium with Python.

GUI Development:

Build a GUI application (desktop app) using Python modules Tkinter, PyQt to support it.

Rapid Prototyping:

Python has libraries for just about everything. Use it to quickly built a (lower-performance, often less powerful) prototype. Python is also great for validating ideas or products for established companies and start-ups alike.

Python can be used in so many different projects. If you're a programmer looking for a new language, you want one that is growing in popularity. As a newcomer to programming, Python is the perfect choice for learning quickly and easily.

MySQL Cannot Add Foreign Key Constraint

I faced the issue and was able to resolve it by making sure that the data types were exactly matching .

I was using SequelPro for adding the constraint and it was making the primary key as unsigned by default .

Assign format of DateTime with data annotations?

Use this, but it's a complete solution:

[DataType(DataType.Date)]
[DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:dd/MM/yyyy}")]

How to use sys.exit() in Python

In tandem with what Pedro Fontez said a few replies up, you seemed to never call the sys module initially, nor did you manage to stick the required () at the end of sys.exit:

so:

import sys

and when finished:

sys.exit()

Calling functions in a DLL from C++

When the DLL was created an import lib is usually automatically created and you should use that linked in to your program along with header files to call it but if not then you can manually call windows functions like LoadLibrary and GetProcAddress to get it working.

Numpy how to iterate over columns of array?

for c in np.hsplit(array, array.shape[1]):
    some_fun(c)

How to set space between listView Items in Android

In order to give spacing between views inside a listView please use padding on your inflate views.

You can use android:paddingBottom="(number)dp" && android:paddingTop="(number)dp" on your view or views you're inflate inside your listview.

The divider solution is just a fix, because some day, when you'll want to use a divider color (right now it's transparent) you will see that the divider line is been stretched.

C# Version Of SQL LIKE

When I ran into this on a contract, I had no other option than to have a 100% compliant TransactSQL LIKE function. Below is the result - a static function and a string extension method. I'm sure it can be optimized further, but it's pretty fast and passed my long list of test scenarios. Hope it helps someone!

using System;
using System.Collections.Generic;

namespace SqlLikeSample
{
    public class TestSqlLikeFunction
    {
        static void Main(string[] args)
        {
            TestSqlLikePattern(true, "%", "");
            TestSqlLikePattern(true, "%", " ");
            TestSqlLikePattern(true, "%", "asdfa asdf asdf");
            TestSqlLikePattern(true, "%", "%");
            TestSqlLikePattern(false, "_", "");
            TestSqlLikePattern(true, "_", " ");
            TestSqlLikePattern(true, "_", "4");
            TestSqlLikePattern(true, "_", "C");
            TestSqlLikePattern(false, "_", "CX");
            TestSqlLikePattern(false, "[ABCD]", "");
            TestSqlLikePattern(true, "[ABCD]", "A");
            TestSqlLikePattern(true, "[ABCD]", "b");
            TestSqlLikePattern(false, "[ABCD]", "X");
            TestSqlLikePattern(false, "[ABCD]", "AB");
            TestSqlLikePattern(true, "[B-D]", "C");
            TestSqlLikePattern(true, "[B-D]", "D");
            TestSqlLikePattern(false, "[B-D]", "A");
            TestSqlLikePattern(false, "[^B-D]", "C");
            TestSqlLikePattern(false, "[^B-D]", "D");
            TestSqlLikePattern(true, "[^B-D]", "A");
            TestSqlLikePattern(true, "%TEST[ABCD]XXX", "lolTESTBXXX");
            TestSqlLikePattern(false, "%TEST[ABCD]XXX", "lolTESTZXXX");
            TestSqlLikePattern(false, "%TEST[^ABCD]XXX", "lolTESTBXXX");
            TestSqlLikePattern(true, "%TEST[^ABCD]XXX", "lolTESTZXXX");
            TestSqlLikePattern(true, "%TEST[B-D]XXX", "lolTESTBXXX");
            TestSqlLikePattern(true, "%TEST[^B-D]XXX", "lolTESTZXXX");
            TestSqlLikePattern(true, "%Stuff.txt", "Stuff.txt");
            TestSqlLikePattern(true, "%Stuff.txt", "MagicStuff.txt");
            TestSqlLikePattern(false, "%Stuff.txt", "MagicStuff.txt.img");
            TestSqlLikePattern(false, "%Stuff.txt", "Stuff.txt.img");
            TestSqlLikePattern(false, "%Stuff.txt", "MagicStuff001.txt.img");
            TestSqlLikePattern(true, "Stuff.txt%", "Stuff.txt");
            TestSqlLikePattern(false, "Stuff.txt%", "MagicStuff.txt");
            TestSqlLikePattern(false, "Stuff.txt%", "MagicStuff.txt.img");
            TestSqlLikePattern(true, "Stuff.txt%", "Stuff.txt.img");
            TestSqlLikePattern(false, "Stuff.txt%", "MagicStuff001.txt.img");
            TestSqlLikePattern(true, "%Stuff.txt%", "Stuff.txt");
            TestSqlLikePattern(true, "%Stuff.txt%", "MagicStuff.txt");
            TestSqlLikePattern(true, "%Stuff.txt%", "MagicStuff.txt.img");
            TestSqlLikePattern(true, "%Stuff.txt%", "Stuff.txt.img");
            TestSqlLikePattern(false, "%Stuff.txt%", "MagicStuff001.txt.img");
            TestSqlLikePattern(true, "%Stuff%.txt", "Stuff.txt");
            TestSqlLikePattern(true, "%Stuff%.txt", "MagicStuff.txt");
            TestSqlLikePattern(false, "%Stuff%.txt", "MagicStuff.txt.img");
            TestSqlLikePattern(false, "%Stuff%.txt", "Stuff.txt.img");
            TestSqlLikePattern(false, "%Stuff%.txt", "MagicStuff001.txt.img");
            TestSqlLikePattern(true, "%Stuff%.txt", "MagicStuff001.txt");
            TestSqlLikePattern(true, "Stuff%.txt%", "Stuff.txt");
            TestSqlLikePattern(false, "Stuff%.txt%", "MagicStuff.txt");
            TestSqlLikePattern(false, "Stuff%.txt%", "MagicStuff.txt.img");
            TestSqlLikePattern(true, "Stuff%.txt%", "Stuff.txt.img");
            TestSqlLikePattern(false, "Stuff%.txt%", "MagicStuff001.txt.img");
            TestSqlLikePattern(false, "Stuff%.txt%", "MagicStuff001.txt");
            TestSqlLikePattern(true, "%Stuff%.txt%", "Stuff.txt");
            TestSqlLikePattern(true, "%Stuff%.txt%", "MagicStuff.txt");
            TestSqlLikePattern(true, "%Stuff%.txt%", "MagicStuff.txt.img");
            TestSqlLikePattern(true, "%Stuff%.txt%", "Stuff.txt.img");
            TestSqlLikePattern(true, "%Stuff%.txt%", "MagicStuff001.txt.img");
            TestSqlLikePattern(true, "%Stuff%.txt%", "MagicStuff001.txt");
            TestSqlLikePattern(true, "_Stuff_.txt_", "1Stuff3.txt4");
            TestSqlLikePattern(false, "_Stuff_.txt_", "1Stuff.txt4");
            TestSqlLikePattern(false, "_Stuff_.txt_", "1Stuff3.txt");
            TestSqlLikePattern(false, "_Stuff_.txt_", "Stuff3.txt4");

            Console.ReadKey();
        }

        public static void TestSqlLikePattern(bool expectedResult, string pattern, string testString)
        {
            bool result = testString.SqlLike(pattern);
            if (expectedResult != result)
            {
                Console.ForegroundColor = ConsoleColor.Red; System.Console.Out.Write("[SqlLike] FAIL");
            }
            else
            {
                Console.ForegroundColor = ConsoleColor.Green; Console.Write("[SqlLike] PASS");
            }
            Console.ForegroundColor = ConsoleColor.White; Console.WriteLine(": \"" + testString + "\" LIKE \"" + pattern + "\" == " + expectedResult);
        }
    }

    public static class SqlLikeStringExtensions
    {
        public static bool SqlLike(this string s, string pattern)
        {
            return SqlLikeStringUtilities.SqlLike(pattern, s);
        }
    }

    public static class SqlLikeStringUtilities
    {
        public static bool SqlLike(string pattern, string str)
        {
            bool isMatch = true,
                isWildCardOn = false,
                isCharWildCardOn = false,
                isCharSetOn = false,
                isNotCharSetOn = false,
                endOfPattern = false;
            int lastWildCard = -1;
            int patternIndex = 0;
            List<char> set = new List<char>();
            char p = '\0';

            for (int i = 0; i < str.Length; i++)
            {
                char c = str[i];
                endOfPattern = (patternIndex >= pattern.Length);
                if (!endOfPattern)
                {
                    p = pattern[patternIndex];

                    if (!isWildCardOn && p == '%')
                    {
                        lastWildCard = patternIndex;
                        isWildCardOn = true;
                        while (patternIndex < pattern.Length &&
                            pattern[patternIndex] == '%')
                        {
                            patternIndex++;
                        }
                        if (patternIndex >= pattern.Length) p = '\0';
                        else p = pattern[patternIndex];
                    }
                    else if (p == '_')
                    {
                        isCharWildCardOn = true;
                        patternIndex++;
                    }
                    else if (p == '[')
                    {
                        if (pattern[++patternIndex] == '^')
                        {
                            isNotCharSetOn = true;
                            patternIndex++;
                        }
                        else isCharSetOn = true;

                        set.Clear();
                        if (pattern[patternIndex + 1] == '-' && pattern[patternIndex + 3] == ']')
                        {
                            char start = char.ToUpper(pattern[patternIndex]);
                            patternIndex += 2;
                            char end = char.ToUpper(pattern[patternIndex]);
                            if (start <= end)
                            {
                                for (char ci = start; ci <= end; ci++)
                                {
                                    set.Add(ci);
                                }
                            }
                            patternIndex++;
                        }

                        while (patternIndex < pattern.Length &&
                            pattern[patternIndex] != ']')
                        {
                            set.Add(pattern[patternIndex]);
                            patternIndex++;
                        }
                        patternIndex++;
                    }
                }

                if (isWildCardOn)
                {
                    if (char.ToUpper(c) == char.ToUpper(p))
                    {
                        isWildCardOn = false;
                        patternIndex++;
                    }
                }
                else if (isCharWildCardOn)
                {
                    isCharWildCardOn = false;
                }
                else if (isCharSetOn || isNotCharSetOn)
                {
                    bool charMatch = (set.Contains(char.ToUpper(c)));
                    if ((isNotCharSetOn && charMatch) || (isCharSetOn && !charMatch))
                    {
                        if (lastWildCard >= 0) patternIndex = lastWildCard;
                        else
                        {
                            isMatch = false;
                            break;
                        }
                    }
                    isNotCharSetOn = isCharSetOn = false;
                }
                else
                {
                    if (char.ToUpper(c) == char.ToUpper(p))
                    {
                        patternIndex++;
                    }
                    else
                    {
                        if (lastWildCard >= 0) patternIndex = lastWildCard;
                        else
                        {
                            isMatch = false;
                            break;
                        }
                    }
                }
            }
            endOfPattern = (patternIndex >= pattern.Length);

            if (isMatch && !endOfPattern)
            {
                bool isOnlyWildCards = true;
                for (int i = patternIndex; i < pattern.Length; i++)
                {
                    if (pattern[i] != '%')
                    {
                        isOnlyWildCards = false;
                        break;
                    }
                }
                if (isOnlyWildCards) endOfPattern = true;
            }
            return isMatch && endOfPattern;
        }
    }
}

SVN- How to commit multiple files in a single shot

Use a changeset. You can add as many files as you like to the changeset, all at once, or over several commands; and then commit them all in one go.

Load external css file like scripts in jquery which is compatible in ie also

Quick function based on responses.

loadCSS = function(href) {

  var cssLink = $("<link>");
  $("head").append(cssLink); //IE hack: append before setting href

  cssLink.attr({
    rel:  "stylesheet",
    type: "text/css",
    href: href
  });

};

Usage:

loadCSS("/css/file.css");

IsNumeric function in c#

It is worth mentioning that one can check the characters in the string against Unicode categories - numbers, uppercase, lowercase, currencies and more. Here are two examples checking for numbers in a string using Linq:

var containsNumbers = s.Any(Char.IsNumber);
var isNumber = s.All(Char.IsNumber);

For clarity, the syntax above is a shorter version of:

var containsNumbers = s.Any(c=>Char.IsNumber(c));
var isNumber = s.All(c=>Char.IsNumber(c));

Link to unicode categories on MSDN:

UnicodeCategory Enumeration

how to permit an array with strong parameters

If you want to permit an array of hashes(or an array of objects from the perspective of JSON)

params.permit(:foo, array: [:key1, :key2])

2 points to notice here:

  1. array should be the last argument of the permit method.
  2. you should specify keys of the hash in the array, otherwise you will get an error Unpermitted parameter: array, which is very difficult to debug in this case.

How do I install Maven with Yum?

For future reference and for simplicity sake for the lazy people out there that don't want much explanations but just run things and make it work asap:

1) sudo wget https://repos.fedorapeople.org/repos/dchen/apache-maven/epel-apache-maven.repo -O /etc/yum.repos.d/epel-apache-maven.repo

2) sudo sed -i s/\$releasever/6/g /etc/yum.repos.d/epel-apache-maven.repo

3) sudo yum install -y apache-maven

4) mvn --version

Hope you enjoyed this copy & paste session.

HTTP post XML data in C#

AlliterativeAlice's example helped me tremendously. In my case, though, the server I was talking to didn't like having single quotes around utf-8 in the content type. It failed with a generic "Server Error" and it took hours to figure out what it didn't like:

request.ContentType = "text/xml; encoding=utf-8";

How to place object files in separate subdirectory

None of these answers seemed simple enough - the crux of the problem is not having to rebuild:

makefile

OBJDIR=out
VPATH=$(OBJDIR)

# make will look in VPATH to see if the target needs to be rebuilt
test: moo
    touch $(OBJDIR)/$@

example use

touch moo
# creates out/test
make test
# doesn't update out/test
make test
# will now update test
touch moo
make test

Executing JavaScript without a browser?

PhantomJS allows you to do this as well

http://phantomjs.org/

SVN undo delete before commit

The simplest solution I could find was to delete the parent directory from the working copy (with rm -rf, not svn delete), and then run svn update in the grandparent. Eg, if you deleted a/b/c, rm -rf a/b, cd a, svn up. That brings everything back. Of course, this is only a good solution if you have no other uncommitted changes in the parent directory that you want to keep.

Hopefully this page will be at the top of the results next time I google this question. It would be even better if someone suggested a cleaner method, of course.

Using Pairs or 2-tuples in Java

If you are looking for a built-in Java two-element tuple, try AbstractMap.SimpleEntry.

Regex Named Groups in Java

(Update: August 2011)

As geofflane mentions in his answer, Java 7 now support named groups.
tchrist points out in the comment that the support is limited.
He details the limitations in his great answer "Java Regex Helper"

Java 7 regex named group support was presented back in September 2010 in Oracle's blog.

In the official release of Java 7, the constructs to support the named capturing group are:

  • (?<name>capturing text) to define a named group "name"
  • \k<name> to backreference a named group "name"
  • ${name} to reference to captured group in Matcher's replacement string
  • Matcher.group(String name) to return the captured input subsequence by the given "named group".

Other alternatives for pre-Java 7 were:


(Original answer: Jan 2009, with the next two links now broken)

You can not refer to named group, unless you code your own version of Regex...

That is precisely what Gorbush2 did in this thread.

Regex2

(limited implementation, as pointed out again by tchrist, as it looks only for ASCII identifiers. tchrist details the limitation as:

only being able to have one named group per same name (which you don’t always have control over!) and not being able to use them for in-regex recursion.

Note: You can find true regex recursion examples in Perl and PCRE regexes, as mentioned in Regexp Power, PCRE specs and Matching Strings with Balanced Parentheses slide)

Example:

String:

"TEST 123"

RegExp:

"(?<login>\\w+) (?<id>\\d+)"

Access

matcher.group(1) ==> TEST
matcher.group("login") ==> TEST
matcher.name(1) ==> login

Replace

matcher.replaceAll("aaaaa_$1_sssss_$2____") ==> aaaaa_TEST_sssss_123____
matcher.replaceAll("aaaaa_${login}_sssss_${id}____") ==> aaaaa_TEST_sssss_123____ 

(extract from the implementation)

public final class Pattern
    implements java.io.Serializable
{
[...]
    /**
     * Parses a group and returns the head node of a set of nodes that process
     * the group. Sometimes a double return system is used where the tail is
     * returned in root.
     */
    private Node group0() {
        boolean capturingGroup = false;
        Node head = null;
        Node tail = null;
        int save = flags;
        root = null;
        int ch = next();
        if (ch == '?') {
            ch = skip();
            switch (ch) {

            case '<':   // (?<xxx)  look behind or group name
                ch = read();
                int start = cursor;
[...]
                // test forGroupName
                int startChar = ch;
                while(ASCII.isWord(ch) && ch != '>') ch=read();
                if(ch == '>'){
                    // valid group name
                    int len = cursor-start;
                    int[] newtemp = new int[2*(len) + 2];
                    //System.arraycopy(temp, start, newtemp, 0, len);
                    StringBuilder name = new StringBuilder();
                    for(int i = start; i< cursor; i++){
                        name.append((char)temp[i-1]);
                    }
                    // create Named group
                    head = createGroup(false);
                    ((GroupTail)root).name = name.toString();

                    capturingGroup = true;
                    tail = root;
                    head.next = expr(tail);
                    break;
                }

how to get the value of a textarea in jquery?

all Values is always taken with .val().

see the code bellow:

var message = $('#message').val();

Converting char* to float or double

You are missing an include : #include <stdlib.h>, so GCC creates an implicit declaration of atof and atod, leading to garbage values.

And the format specifier for double is %f, not %d (that is for integers).

#include <stdlib.h>
#include <stdio.h>

int main()
{
  char *test = "12.11";
  double temp = strtod(test,NULL);
  float ftemp = atof(test);
  printf("price: %f, %f",temp,ftemp);
  return 0;
}
/* Output */
price: 12.110000, 12.110000

SOAP Action WSDL

When soapAction is missing in the SOAP 1.2 request (and many clients do not set it, even when it is specified in WSDL), some app servers (eg. jboss) infer the "actual" soapAction from {xsd:import namespace}+{wsdl:operation name}. So, to make the inferred "actual" soapAction match the expected soapAction, you can set the expected soapAction to {xsd:import namespace}+{wsdl:operation name} in your WS definition (@WebMethod(action=...) for Java EE)

Eg. for a typical Java EE case, this helps (not the Stewart's case, National Rail WS has 'soapAction' set):

@WebMethod(action = "http://packagename.of.your.webservice.class.com/methodName")

If you cannot change the server, you will have to force client to fill soapAction.

MySQL Error 1264: out of range value for column

You are exceeding the length of int datatype. You can use UNSIGNED attribute to support that value.

SIGNED INT can support till 2147483647 and with UNSIGNED INT allows double than this. After this you still want to save data than use CHAR or VARCHAR with length 10

Trying to get property of non-object in

$sidemenu is not an object, so you can't call methods on it. It is probably not being sent to your view, or $sidemenus is empty.

%matplotlib line magic causes SyntaxError in Python script

Because line magics are only supported by the IPython command line not by Python cl, use: 'exec(%matplotlib inline)' instead of %matplotlib inline

How to reference static assets within vue javascript

I'm using typescript with vue, but this is how I went about it

<template><div><img :src="MyImage" /></div></template>
<script lang="ts">
    import { Vue } from 'vue-property-decorator';
    export default class MyPage extends Vue {
            MyImage = "../assets/images/myImage.png";
        }
</script>

How to Install Font Awesome in Laravel Mix

first install fontawsome using npm

npm install --save @fortawesome/fontawesome-free

add to resources\sass\app.scss

// Fonts
@import '~@fortawesome/fontawesome-free/scss/fontawesome';

and add to resources\js\app.js

require('@fortawesome/fontawesome-free/js/all.js');

then run

npm run dev

or

npm run production

Regular expression for matching latitude/longitude coordinates?

Ruby

Longitude -179.99999999..180

/^(-?(?:1[0-7]|[1-9])?\d(?:\.\d{1,8})?|180(?:\.0{1,8})?)$/ === longitude.to_s

Latitude -89.99999999..90

/^(-?[1-8]?\d(?:\.\d{1,8})?|90(?:\.0{1,8})?)$/ === latitude.to_s

Android Camera : data intent returns null

Simple working camera app avoiding the null intent problem

- all changed code included in this reply; close to android tutorial

I've been spending plenty of time on this issue, so I decided to create an account and share my outcomes with you.

The official android tutorial "Taking Photos Simply" turned out to not quite hold what it promised. The code provided there did not work on my device: a Samsung Galaxy S4 Mini GT-I9195 running android version 4.4.2 / KitKat / API Level 19.

I figured out that the main problem was the following line in the method invoked when capturing the photo (dispatchTakePictureIntent in the tutorial):

takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);

It resulted in the intent subsequently catched by onActivityResult being null.

To solve this problem, I pulled much inspiration out of earlier replies here and some helpful posts on github (mostly this one by deepwinter - big thanks to him; you might want to check out his reply on a closely related post as well).

Following these pleasant pieces of advice, I chose the strategy of deleting the mentioned putExtra line and doing the corresponding thing of getting back the taken picture from the camera within the onActivityResult() method instead. The decisive lines of code to get back the bitmap associated with the picture are:

        Uri uri = intent.getData();
        Bitmap bitmap = null;
        try {
            bitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), uri);
        } catch (IOException e) {
            e.printStackTrace();
        }

I created an exemplary app which just has the ability to take a picture, save it on the SD card and display it. I think this might be helpful to people in the same situation as me when I stumbled on this issue, since the current help suggestions mostly refer to rather extensive github posts which do the thing in question but aren't too easy to oversee for newbies like me. With respect to the file system Android Studio creates per default when creating a new project, I just had to change three files for my purpose:

activity_main.xml :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.example.android.simpleworkingcameraapp.MainActivity">

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:onClick="takePicAndDisplayIt"
    android:text="Take a pic and display it." />

<ImageView
    android:id="@+id/image1"
    android:layout_width="match_parent"
    android:layout_height="200dp" />

</LinearLayout>

MainActivity.java :

package com.example.android.simpleworkingcameraapp;

import android.content.Intent;
import android.graphics.Bitmap;
import android.media.Image;
import android.net.Uri;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class MainActivity extends AppCompatActivity {

private ImageView image;
static final int REQUEST_TAKE_PHOTO = 1;
String mCurrentPhotoPath;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    image = (ImageView) findViewById(R.id.image1);
}

// copied from the android development pages; just added a Toast to show the storage location
private File createImageFile() throws IOException {
    // Create an image file name
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmm").format(new Date());
    String imageFileName = "JPEG_" + timeStamp + "_";
    File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
    File image = File.createTempFile(
            imageFileName,  /* prefix */
            ".jpg",         /* suffix */
            storageDir      /* directory */
    );

    // Save a file: path for use with ACTION_VIEW intents
    mCurrentPhotoPath = image.getAbsolutePath();
    Toast.makeText(this, mCurrentPhotoPath, Toast.LENGTH_LONG).show();
    return image;
}

public void takePicAndDisplayIt(View view) {
    Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    if (intent.resolveActivity(getPackageManager()) != null) {
        File file = null;
        try {
            file = createImageFile();
        } catch (IOException ex) {
            // Error occurred while creating the File
        }

        startActivityForResult(intent, REQUEST_TAKE_PHOTO);
    }
}

@Override
protected void onActivityResult(int requestCode, int resultcode, Intent intent) {
    if (requestCode == REQUEST_TAKE_PHOTO && resultcode == RESULT_OK) {
        Uri uri = intent.getData();
        Bitmap bitmap = null;
        try {
            bitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), uri);
        } catch (IOException e) {
            e.printStackTrace();
        }
        image.setImageBitmap(bitmap);
    }
}
}

AndroidManifest.xml :

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.simpleworkingcameraapp">


<!--only added paragraph-->
<uses-feature
    android:name="android.hardware.camera"
    android:required="true" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />  <!-- only crucial line to add; for me it still worked without the other lines in this paragraph -->
<uses-permission android:name="android.permission.CAMERA" />


<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

</manifest>

Note that the solution I found for the problem also led to a simplification of the android manifest file: the changes suggested by the android tutorial in terms of adding a provider are no longer needed since I am not making use of any in my java code. Hence, only few standard lines -mostly regarding permissions- had to be added to the manifest file.

It might additionally be valuable to point out that Android Studio's autoimport may not be capable of handling java.text.SimpleDateFormat and java.util.Date. I had to import both of them manually.

Get Element value with minidom with Python

It should just be

name[0].firstChild.nodeValue

Using .text() to retrieve only text not nested in child tags

I liked this reusable implementation based on the clone() method found here to get only the text inside the parent element.

Code provided for easy reference:

$("#foo")
    .clone()    //clone the element
    .children() //select all the children
    .remove()   //remove all the children
    .end()  //again go back to selected element
    .text();

npm start error with create-react-app

This occurs when the node_modules gets out of sync with package.json.

Run the following at the root and any sub service /sub-folder that might have node_modules folder within it.

rd node_modules /S /Q
npm install

How do I kill a process using Vb.NET or C#?

In my tray app, I needed to clean Excel and Word Interops. So This simple method kills processes generically.

This uses a general exception handler, but could be easily split for multiple exceptions like stated in other answers. I may do this if my logging produces alot of false positives (ie can't kill already killed). But so far so guid (work joke).

/// <summary>
/// Kills Processes By Name
/// </summary>
/// <param name="names">List of Process Names</param>
private void killProcesses(List<string> names)
{
    var processes = new List<Process>();
    foreach (var name in names)
        processes.AddRange(Process.GetProcessesByName(name).ToList());
    foreach (Process p in processes)
    {
        try
        {
            p.Kill();
            p.WaitForExit();
        }
        catch (Exception ex)
        {
            // Logging
            RunProcess.insertFeedback("Clean Processes Failed", ex);
        }
    }
}

This is how i called it then:

killProcesses((new List<string>() { "winword", "excel" }));

Responsive background image in div full width

Here is one way of getting the design that you want.

Start with the following HTML:

<div class="container">
    <div class="row-fluid">
        <div class="span12">
            <div class="nav">nav area</div>
            <div class="bg-image">
                <img src="http://unplugged.ee/wp-content/uploads/2013/03/frank2.jpg">
                 <h1>This is centered text.</h1>
            </div>
            <div class="main">main area</div>
        </div>
    </div>
</div>

Note that the background image is now part of the regular flow of the document.

Apply the following CSS:

.bg-image {
    position: relative;
}
.bg-image img {
    display: block;
    width: 100%;
    max-width: 1200px; /* corresponds to max height of 450px */
    margin: 0 auto;
}
.bg-image h1 {
    position: absolute;
    text-align: center;
    bottom: 0;
    left: 0;
    right: 0;
    color: white;
}
.nav, .main {
    background-color: #f6f6f6;
    text-align: center;
}

How This Works

The image is set an regular flow content with a width of 100%, so it will adjust itself responsively to the width of the parent container. However, you want the height to be no more than 450px, which corresponds to the image width of 1200px, so set the maximum width of the image to 1200px. You can keep the image centered by using display: block and margin: 0 auto.

The text is painted over the image by using absolute positioning. In the simplest case, I stretch the h1 element to be the full width of the parent and use text-align: center to center the text. Use the top or bottom offsets to place the text where it is needed.

If your banner images are going to vary in aspect ratio, you will need to adjust the maximum width value for .bg-image img dynamically using jQuery/Javascript, but otherwise, this approach has a lot to offer.

See demo at: http://jsfiddle.net/audetwebdesign/EGgaN/

How do I position an image at the bottom of div?

Using flexbox:

HTML:

<div class="wrapper">
    <img src="pikachu.gif"/>
</div>

CSS:

.wrapper {
    height: 300px;
    width: 300px;
    display: flex;
    align-items: flex-end;
}

As requested in some comments on another answer, the image can also be horizontally centred with justify-content: center;

Changing Tint / Background color of UITabBar

I have an addendum to the final answer. While the essential scheme is correct, the trick of using a partially transparent color can be improved upon. I assume that it's only for letting the default gradient to show through. Oh, also, the height of the TabBar is 49 pixels rather than 48, at least in OS 3.

So, if you have a appropriate 1 x 49 image with a gradient, this is the version of viewDidLoad you should use:

- (void)viewDidLoad {

    [super viewDidLoad]; 

    CGRect frame = CGRectMake(0, 0, 480, 49);
    UIView *v = [[UIView alloc] initWithFrame:frame];
    UIImage *i = [UIImage imageNamed:@"GO-21-TabBarColorx49.png"];
    UIColor *c = [[UIColor alloc] initWithPatternImage:i];
    v.backgroundColor = c;
    [c release];
    [[self tabBar] addSubview:v];
    [v release];

}

What is the correct value for the disabled attribute?

From MDN by setAttribute():

To set the value of a Boolean attribute, such as disabled, you can specify any value. An empty string or the name of the attribute are recommended values. All that matters is that if the attribute is present at all, regardless of its actual value, its value is considered to be true. The absence of the attribute means its value is false. By setting the value of the disabled attribute to the empty string (""), we are setting disabled to true, which results in the button being disabled.

Link to MDN

Solution

  • I mean that in XHTML Strict is right disabled="disabled",
  • and in HTML5 is only disabled, like <input name="myinput" disabled>
  • In javascript, I set the value to true via e.disabled = true;
    or to "" via setAttribute( "disabled", "" );

Test in Chrome

var f = document.querySelectorAll( "label.disabled input" );
for( var i = 0; i < f.length; i++ )
{
    // Reference
    var e = f[ i ];

    // Actions
    e.setAttribute( "disabled", false|null|undefined|""|0|"disabled" );
    /*
        <input disabled="false"|"null"|"undefined"|empty|"0"|"disabled">
        e.getAttribute( "disabled" ) === "false"|"null"|"undefined"|""|"0"|"disabled"
        e.disabled === true
    */
    
    e.removeAttribute( "disabled" );
    /*
        <input>
        e.getAttribute( "disabled" ) === null
        e.disabled === false
    */

    e.disabled = false|null|undefined|""|0;
    /*
        <input>
        e.getAttribute( "disabled" ) === null|null|null|null|null
        e.disabled === false
    */

    e.disabled = true|" "|"disabled"|1;
    /*
        <input disabled>
        e.getAttribute( "disabled" ) === ""|""|""|""
        e.disabled === true
    */
}

How to display a readable array - Laravel

I have added a helper da() to Laravel which in fact works as an alias for dd($object->toArray())

Here is the Gist: https://gist.github.com/TommyZG/0505eb331f240a6324b0527bc588769c

Postgres FOR LOOP

I find it more convenient to make a connection using a procedural programming language (like Python) and do these types of queries.

import psycopg2
connection_psql = psycopg2.connect( user="admin_user"
                                  , password="***"
                                  , port="5432"
                                  , database="myDB"
                                  , host="[ENDPOINT]")
cursor_psql = connection_psql.cursor()

myList = [...]
for item in myList:
  cursor_psql.execute('''
    -- The query goes here
  ''')

connection_psql.commit()
cursor_psql.close()

MySQL - Using If Then Else in MySQL UPDATE or SELECT Queries

Here's a query to update a table based on a comparison of another table. If record is not found in tableB, it will update the "active" value to "n". If it's found, will set the value to NULL

UPDATE tableA
LEFT JOIN tableB ON tableA.id = tableB.id
SET active = IF(tableB.id IS NULL, 'n', NULL)";

Hope this helps someone else.

How can I get the source directory of a Bash script from within the script itself?

Here is an easy-to-remember script:

DIR="$(dirname "${BASH_SOURCE[0]}")"  # Get the directory name
DIR="$(realpath "${DIR}")"    # Resolve its full path if need be

How to load CSS Asynchronously

The trick to triggering an asynchronous stylesheet download is to use a <link> element and set an invalid value for the media attribute (I'm using media="none", but any value will do). When a media query evaluates to false, the browser will still download the stylesheet, but it won't wait for the content to be available before rendering the page.

<link rel="stylesheet" href="css.css" media="none">

Once the stylesheet has finished downloading the media attribute must be set to a valid value so the style rules will be applied to the document. The onload event is used to switch the media property to all:

<link rel="stylesheet" href="css.css" media="none" onload="if(media!='all')media='all'">

This method of loading CSS will deliver useable content to visitors much quicker than the standard approach. Critical CSS can still be served with the usual blocking approach (or you can inline it for ultimate performance) and non-critical styles can be progressively downloaded and applied later in the parsing / rendering process.

This technique uses JavaScript, but you can cater for non-JavaScript browsers by wrapping the equivalent blocking <link> elements in a <noscript> element:

<link rel="stylesheet" href="css.css" media="none" onload="if(media!='all')media='all'"><noscript><link rel="stylesheet" href="css.css"></noscript>

You can see the operation in www.itcha.edu.sv

enter image description here

Source in http://keithclark.co.uk/

wait process until all subprocess finish?

A Popen object has a .wait() method exactly defined for this: to wait for the completion of a given subprocess (and, besides, for retuning its exit status).

If you use this method, you'll prevent that the process zombies are lying around for too long.

(Alternatively, you can use subprocess.call() or subprocess.check_call() for calling and waiting. If you don't need IO with the process, that might be enough. But probably this is not an option, because your if the two subprocesses seem to be supposed to run in parallel, which they won't with (check_)call().)

If you have several subprocesses to wait for, you can do

exit_codes = [p.wait() for p in p1, p2]

which returns as soon as all subprocesses have finished. You then have a list of return codes which you maybe can evaluate.

An unhandled exception occurred during the execution of the current web request. ASP.NET

I had the same problem and found out that I had forgotten to include the script in the file which I want to include in the live site.

Also, you should try this:

bundles.Add(new ScriptBundle("~/bundles/jquery").Include(
"~/Scripts/jquery-{version}.js"));

Creating columns in listView and add items

            listView1.View = View.Details;
        listView1.Columns.Add("Target No.", 83, HorizontalAlignment.Center);
        listView1.Columns.Add("   Range   ", 100, HorizontalAlignment.Center);
        listView1.Columns.Add(" Azimuth ", 100, HorizontalAlignment.Center);     

i also had same problem .. i drag column to left .. but now ok .. so let's say i have 283*196 size of listview ..... We declared in the column width -2 for auto width .. For fitting in the listview ,we can divide listview width into 3 parts (83,100,100) ...

C++ convert from 1 char to string?

All of

std::string s(1, c); std::cout << s << std::endl;

and

std::cout << std::string(1, c) << std::endl;

and

std::string s; s.push_back(c); std::cout << s << std::endl;

worked for me.

How to use sed to remove the last n lines of a file

It can be done in 3 steps:

a) Count the number of lines in the file you want to edit:

 n=`cat myfile |wc -l`

b) Subtract from that number the number of lines to delete:

 x=$((n-3))

c) Tell sed to delete from that line number ($x) to the end:

 sed "$x,\$d" myfile

Rails filtering array of objects by attribute value

have you tried eager loading?

@attachments = Job.includes(:attachments).find(1).attachments

How can I delete (not disable) ActiveX add-ons in Internet Explorer (7 and 8 Beta 2)?

You can go to IE Tools -> Internet options -> Advanced Tab. Under Advanced, check for security and put a check on the 1st 2 options which says,"Allow active content from CDs to run on My Computer* and Allow active content to run in files on My Computer*"

Restart your browser and the ActiveX scripts will not be shown.

How to check if an alert exists using WebDriver?

The following (C# implementation, but similar in Java) allows you to determine if there is an alert without exceptions and without creating the WebDriverWait object.

boolean isDialogPresent(WebDriver driver) {
    IAlert alert = ExpectedConditions.AlertIsPresent().Invoke(driver);
    return (alert != null);
}

What are SP (stack) and LR in ARM?

SP is the stack register a shortcut for typing r13. LR is the link register a shortcut for r14. And PC is the program counter a shortcut for typing r15.

When you perform a call, called a branch link instruction, bl, the return address is placed in r14, the link register. the program counter pc is changed to the address you are branching to.

There are a few stack pointers in the traditional ARM cores (the cortex-m series being an exception) when you hit an interrupt for example you are using a different stack than when running in the foreground, you dont have to change your code just use sp or r13 as normal the hardware has done the switch for you and uses the correct one when it decodes the instructions.

The traditional ARM instruction set (not thumb) gives you the freedom to use the stack in a grows up from lower addresses to higher addresses or grows down from high address to low addresses. the compilers and most folks set the stack pointer high and have it grow down from high addresses to lower addresses. For example maybe you have ram from 0x20000000 to 0x20008000 you set your linker script to build your program to run/use 0x20000000 and set your stack pointer to 0x20008000 in your startup code, at least the system/user stack pointer, you have to divide up the memory for other stacks if you need/use them.

Stack is just memory. Processors normally have special memory read/write instructions that are PC based and some that are stack based. The stack ones at a minimum are usually named push and pop but dont have to be (as with the traditional arm instructions).

If you go to http://github.com/lsasim I created a teaching processor and have an assembly language tutorial. Somewhere in there I go through a discussion about stacks. It is NOT an arm processor but the story is the same it should translate directly to what you are trying to understand on the arm or most other processors.

Say for example you have 20 variables you need in your program but only 16 registers minus at least three of them (sp, lr, pc) that are special purpose. You are going to have to keep some of your variables in ram. Lets say that r5 holds a variable that you use often enough that you dont want to keep it in ram, but there is one section of code where you really need another register to do something and r5 is not being used, you can save r5 on the stack with minimal effort while you reuse r5 for something else, then later, easily, restore it.

Traditional (well not all the way back to the beginning) arm syntax:

...
stmdb r13!,{r5}
...temporarily use r5 for something else...
ldmia r13!,{r5}
...

stm is store multiple you can save more than one register at a time, up to all of them in one instruction.

db means decrement before, this is a downward moving stack from high addresses to lower addresses.

You can use r13 or sp here to indicate the stack pointer. This particular instruction is not limited to stack operations, can be used for other things.

The ! means update the r13 register with the new address after it completes, here again stm can be used for non-stack operations so you might not want to change the base address register, leave the ! off in that case.

Then in the brackets { } list the registers you want to save, comma separated.

ldmia is the reverse, ldm means load multiple. ia means increment after and the rest is the same as stm

So if your stack pointer were at 0x20008000 when you hit the stmdb instruction seeing as there is one 32 bit register in the list it will decrement before it uses it the value in r13 so 0x20007FFC then it writes r5 to 0x20007FFC in memory and saves the value 0x20007FFC in r13. Later, assuming you have no bugs when you get to the ldmia instruction r13 has 0x20007FFC in it there is a single register in the list r5. So it reads memory at 0x20007FFC puts that value in r5, ia means increment after so 0x20007FFC increments one register size to 0x20008000 and the ! means write that number to r13 to complete the instruction.

Why would you use the stack instead of just a fixed memory location? Well the beauty of the above is that r13 can be anywhere it could be 0x20007654 when you run that code or 0x20002000 or whatever and the code still functions, even better if you use that code in a loop or with recursion it works and for each level of recursion you go you save a new copy of r5, you might have 30 saved copies depending on where you are in that loop. and as it unrolls it puts all the copies back as desired. with a single fixed memory location that doesnt work. This translates directly to C code as an example:

void myfun ( void )
{
   int somedata;
}

In a C program like that the variable somedata lives on the stack, if you called myfun recursively you would have multiple copies of the value for somedata depending on how deep in the recursion. Also since that variable is only used within the function and is not needed elsewhere then you perhaps dont want to burn an amount of system memory for that variable for the life of the program you only want those bytes when in that function and free that memory when not in that function. that is what a stack is used for.

A global variable would not be found on the stack.

Going back...

Say you wanted to implement and call that function you would have some code/function you are in when you call the myfun function. The myfun function wants to use r5 and r6 when it is operating on something but it doesnt want to trash whatever someone called it was using r5 and r6 for so for the duration of myfun() you would want to save those registers on the stack. Likewise if you look into the branch link instruction (bl) and the link register lr (r14) there is only one link register, if you call a function from a function you will need to save the link register on each call otherwise you cant return.

...
bl myfun
    <--- the return from my fun returns here
...


myfun:
stmdb sp!,{r5,r6,lr}
sub sp,#4 <--- make room for the somedata variable
...
some code here that uses r5 and r6
bl more_fun <-- this modifies lr, if we didnt save lr we wouldnt be able to return from myfun
   <---- more_fun() returns here
...
add sp,#4 <-- take back the stack memory we allocated for the somedata variable
ldmia sp!,{r5,r6,lr}
mov pc,lr <---- return to whomever called myfun.

So hopefully you can see both the stack usage and link register. Other processors do the same kinds of things in a different way. for example some will put the return value on the stack and when you execute the return function it knows where to return to by pulling a value off of the stack. Compilers C/C++, etc will normally have a "calling convention" or application interface (ABI and EABI are names for the ones ARM has defined). if every function follows the calling convention, puts parameters it is passing to functions being called in the right registers or on the stack per the convention. And each function follows the rules as to what registers it does not have to preserve the contents of and what registers it has to preserve the contents of then you can have functions call functions call functions and do recursion and all kinds of things, so long as the stack does not go so deep that it runs into the memory used for globals and the heap and such, you can call functions and return from them all day long. The above implementation of myfun is very similar to what you would see a compiler produce.

ARM has many cores now and a few instruction sets the cortex-m series works a little differently as far as not having a bunch of modes and different stack pointers. And when executing thumb instructions in thumb mode you use the push and pop instructions which do not give you the freedom to use any register like stm it only uses r13 (sp) and you cannot save all the registers only a specific subset of them. the popular arm assemblers allow you to use

push {r5,r6}
...
pop {r5,r6}

in arm code as well as thumb code. For the arm code it encodes the proper stmdb and ldmia. (in thumb mode you also dont have the choice as to when and where you use db, decrement before, and ia, increment after).

No you absolutly do not have to use the same registers and you dont have to pair up the same number of registers.

push {r5,r6,r7}
...
pop {r2,r3}
...
pop {r1}

assuming there is no other stack pointer modifications in between those instructions if you remember the sp is going to be decremented 12 bytes for the push lets say from 0x1000 to 0x0FF4, r5 will be written to 0xFF4, r6 to 0xFF8 and r7 to 0xFFC the stack pointer will change to 0x0FF4. the first pop will take the value at 0x0FF4 and put that in r2 then the value at 0x0FF8 and put that in r3 the stack pointer gets the value 0x0FFC. later the last pop, the sp is 0x0FFC that is read and the value placed in r1, the stack pointer then gets the value 0x1000, where it started.

The ARM ARM, ARM Architectural Reference Manual (infocenter.arm.com, reference manuals, find the one for ARMv5 and download it, this is the traditional ARM ARM with ARM and thumb instructions) contains pseudo code for the ldm and stm ARM istructions for the complete picture as to how these are used. Likewise well the whole book is about the arm and how to program it. Up front the programmers model chapter walks you through all of the registers in all of the modes, etc.

If you are programming an ARM processor you should start by determining (the chip vendor should tell you, ARM does not make chips it makes cores that chip vendors put in their chips) exactly which core you have. Then go to the arm website and find the ARM ARM for that family and find the TRM (technical reference manual) for the specific core including revision if the vendor has supplied that (r2p0 means revision 2.0 (two point zero, 2p0)), even if there is a newer rev, use the manual that goes with the one the vendor used in their design. Not every core supports every instruction or mode the TRM tells you the modes and instructions supported the ARM ARM throws a blanket over the features for the whole family of processors that that core lives in. Note that the ARM7TDMI is an ARMv4 NOT an ARMv7 likewise the ARM9 is not an ARMv9. ARMvNUMBER is the family name ARM7, ARM11 without a v is the core name. The newer cores have names like Cortex and mpcore instead of the ARMNUMBER thing, which reduces confusion. Of course they had to add the confusion back by making an ARMv7-m (cortex-MNUMBER) and the ARMv7-a (Cortex-ANUMBER) which are very different families, one is for heavy loads, desktops, laptops, etc the other is for microcontrollers, clocks and blinking lights on a coffee maker and things like that. google beagleboard (Cortex-A) and the stm32 value line discovery board (Cortex-M) to get a feel for the differences. Or even the open-rd.org board which uses multiple cores at more than a gigahertz or the newer tegra 2 from nvidia, same deal super scaler, muti core, multi gigahertz. A cortex-m barely brakes the 100MHz barrier and has memory measured in kbytes although it probably runs of a battery for months if you wanted it to where a cortex-a not so much.

sorry for the very long post, hope it is useful.

Best way to check if a Data Table has a null value in it

DataTable dt = new DataTable();
foreach (DataRow dr in dt.Rows)
{
    if (dr["Column_Name"] == DBNull.Value)
    {
        //Do something
    }
    else
    {
        //Do something
    }
}

How to break out of while loop in Python?

ans=(R)
while True:
    print('Your score is so far '+str(myScore)+'.')
    print("Would you like to roll or quit?")
    ans=input("Roll...")
    if ans=='R':
        R=random.randint(1, 8)
        print("You rolled a "+str(R)+".")
        myScore=R+myScore
    else:
        print("Now I'll see if I can break your score...")
        ans = False
        break

How to find largest objects in a SQL Server database?

I've found this query also very helpful in SqlServerCentral, here is the link to original post

Sql Server largest tables

  select name=object_schema_name(object_id) + '.' + object_name(object_id)
, rows=sum(case when index_id < 2 then row_count else 0 end)
, reserved_kb=8*sum(reserved_page_count)
, data_kb=8*sum( case 
     when index_id<2 then in_row_data_page_count + lob_used_page_count + row_overflow_used_page_count 
     else lob_used_page_count + row_overflow_used_page_count 
    end )
, index_kb=8*(sum(used_page_count) 
    - sum( case 
           when index_id<2 then in_row_data_page_count + lob_used_page_count + row_overflow_used_page_count 
        else lob_used_page_count + row_overflow_used_page_count 
        end )
     )    
, unused_kb=8*sum(reserved_page_count-used_page_count)
from sys.dm_db_partition_stats
where object_id > 1024
group by object_id
order by 
rows desc   

In my database they gave different results between this query and the 1st answer.

Hope somebody finds useful

How do I read an attribute on a class at runtime?

' Simplified Generic version. 
Shared Function GetAttribute(Of TAttribute)(info As MemberInfo) As TAttribute
    Return info.GetCustomAttributes(GetType(TAttribute), _
                                    False).FirstOrDefault()
End Function

' Example usage over PropertyInfo
Dim fieldAttr = GetAttribute(Of DataObjectFieldAttribute)(pInfo)
If fieldAttr IsNot Nothing AndAlso fieldAttr.PrimaryKey Then
    keys.Add(pInfo.Name)
End If

Probably just as easy to use the body of generic function inline. It doesn't make any sense to me to make the function generic over the type MyClass.

string DomainName = GetAttribute<DomainNameAttribute>(typeof(MyClass)).Name
// null reference exception if MyClass doesn't have the attribute.

Transaction marked as rollback only: How do I find the cause

There is always a reason why the nested method roll back. If you don't see the reason, you need to change your logger level to debug, where you will see the more details where transaction failed. I changed my logback.xml by adding

<logger name="org.springframework.transaction" level="debug"/>
<logger name="org.springframework.orm.jpa" level="debug"/>

then I got this line in the log:

Participating transaction failed - marking existing transaction as rollback-only

So I just stepped through my code to see where this line is generated and found that there is a catch block which did not throw anything.

private Student add(Student s) {
        try {
            Student retval = studentRepository.save(s);
            return retval;
        } catch (Exception e) {
            
        }
        return null;
    }

Why does Git tell me "No such remote 'origin'" when I try to push to origin?

I'm guessing you didn't run this command after the commit failed so just actually run this to create the remote :

 git remote add origin https://github.com/VijayNew/NewExample.git

And the commit failed because you need to git add some files you want to track.

How to change the integrated terminal in visual studio code or VSCode

To change the integrated terminal on Windows, you just need to change the terminal.integrated.shell.windows line:

  1. Open VS User Settings (Preferences > User Settings). This will open two side-by-side documents.
  2. Add a new "terminal.integrated.shell.windows": "C:\\Bin\\Cmder\\Cmder.exe" setting to the User Settings document on the right if it's not already there. This is so you aren't editing the Default Setting directly, but instead adding to it.
  3. Save the User Settings file.

You can then access it with keys Ctrl+backtick by default.

How to check if any value is NaN in a Pandas DataFrame

Super Simple Syntax: df.isna().any(axis=None)

Starting from v0.23.2, you can use DataFrame.isna + DataFrame.any(axis=None) where axis=None specifies logical reduction over the entire DataFrame.

# Setup
df = pd.DataFrame({'A': [1, 2, np.nan], 'B' : [np.nan, 4, 5]})
df
     A    B
0  1.0  NaN
1  2.0  4.0
2  NaN  5.0

df.isna()

       A      B
0  False   True
1  False  False
2   True  False

df.isna().any(axis=None)
# True

Useful Alternatives

numpy.isnan
Another performant option if you're running older versions of pandas.

np.isnan(df.values)

array([[False,  True],
       [False, False],
       [ True, False]])

np.isnan(df.values).any()
# True

Alternatively, check the sum:

np.isnan(df.values).sum()
# 2

np.isnan(df.values).sum() > 0
# True

Series.hasnans
You can also iteratively call Series.hasnans. For example, to check if a single column has NaNs,

df['A'].hasnans
# True

And to check if any column has NaNs, you can use a comprehension with any (which is a short-circuiting operation).

any(df[c].hasnans for c in df)
# True

This is actually very fast.

Select from multiple tables without a join?

You could try something like this:

SELECT ...
FROM (
    SELECT f1,f2,f3 FROM table1
    UNION
    SELECT f1,f2,f3 FROM table2
)
WHERE ...

Create a new file in git bash

Yes, it is. Just create files in the windows explorer and git automatically detects these files as currently untracked. Then add it with the command you already mentioned.

git add does not create any files. See also http://gitref.org/basic/#add

Github probably creates the file with touch and adds the file for tracking automatically. You can do this on the bash as well.

Converting an integer to a hexadecimal string in Ruby

Just in case you have a preference for how negative numbers are formatted:

p "%x" % -1   #=> "..f"
p -1.to_s(16) #=> "-1"

Declaring an unsigned int in Java

We needed unsigned numbers to model MySQL's unsigned TINYINT, SMALLINT, INT, BIGINT in jOOQ, which is why we have created jOOU, a minimalistic library offering wrapper types for unsigned integer numbers in Java. Example:

import static org.joou.Unsigned.*;

// and then...
UByte    b = ubyte(1);
UShort   s = ushort(1);
UInteger i = uint(1);
ULong    l = ulong(1);

All of these types extend java.lang.Number and can be converted into higher-order primitive types and BigInteger. Hope this helps.

(Disclaimer: I work for the company behind these libraries)

How to create a regex for accepting only alphanumeric characters?

Only ASCII or are other characters allowed too?

^\w*$

restricts (in Java) to ASCII letters/digits und underscore,

^[\pL\pN\p{Pc}]*$

also allows international characters/digits and "connecting punctuation".

Get the generated SQL statement from a SqlCommand object?

needed to cover non-Stored procedures too so I augmented CommandAsSql library (see comments under @Flapper's answer above) with this logic:

    private static void CommandAsSql_Text(this SqlCommand command, System.Text.StringBuilder sql)
    {
        string query = command.CommandText;

        foreach (SqlParameter p in command.Parameters)
            query = Regex.Replace(query, "\\B" + p.ParameterName + "\\b", p.ParameterValueForSQL()); //the first one is \B, the 2nd one is \b, since ParameterName starts with @ which is a non-word character in RegEx (see https://stackoverflow.com/a/2544661)

        sql.AppendLine(query);
    }

the pull request is at: https://github.com/jphellemons/CommandAsSql/pull/3/commits/527d696dc6055c5bcf858b9700b83dc863f04896

the Regex idea was based on @stambikk's and EvZ's comments above and the "Update:" section of https://stackoverflow.com/a/2544661/903783 that mentions "negative look-behind assertion". The use of \B instead of \b for word boundary detection at the start of the regular expression is because the p.parameterName will always start with a "@" which is not a word character.

note that ParameterValueForSQL() is an extension method defined at the CommandAsSql library to handle issues like single-quoting string parameter values etc.

javax.net.ssl.SSLHandshakeException: Received fatal alert: handshake_failure

I am getting similar errors recently because recent JDKs (and browsers, and the Linux TLS stack, etc.) refuse to communicate with some servers in my customer's corporate network. The reason of this is that some servers in this network still have SHA-1 certificates.

Please see: https://www.entrust.com/understanding-sha-1-vulnerabilities-ssl-longer-secure/ https://blog.qualys.com/ssllabs/2014/09/09/sha1-deprecation-what-you-need-to-know

If this would be your current case (recent JDK vs deprecated certificate encription) then your best move is to update your network to the proper encription technology.

In case that you should provide a temporal solution for that, please see another answers to have an idea about how to make your JDK trust or distrust certain encription algorithms:

How to force java server to accept only tls 1.2 and reject tls 1.0 and tls 1.1 connections

Anyway I insist that, in case that I have guessed properly your problem, this is not a good solution to the problem and that your network admin should consider removing these deprecated certificates and get a new one.

How to write trycatch in R

tryCatch has a slightly complex syntax structure. However, once we understand the 4 parts which constitute a complete tryCatch call as shown below, it becomes easy to remember:

expr: [Required] R code(s) to be evaluated

error : [Optional] What should run if an error occured while evaluating the codes in expr

warning : [Optional] What should run if a warning occured while evaluating the codes in expr

finally : [Optional] What should run just before quitting the tryCatch call, irrespective of if expr ran successfully, with an error, or with a warning

tryCatch(
    expr = {
        # Your code...
        # goes here...
        # ...
    },
    error = function(e){ 
        # (Optional)
        # Do this if an error is caught...
    },
    warning = function(w){
        # (Optional)
        # Do this if an warning is caught...
    },
    finally = {
        # (Optional)
        # Do this at the end before quitting the tryCatch structure...
    }
)

Thus, a toy example, to calculate the log of a value might look like:

log_calculator <- function(x){
    tryCatch(
        expr = {
            message(log(x))
            message("Successfully executed the log(x) call.")
        },
        error = function(e){
            message('Caught an error!')
            print(e)
        },
        warning = function(w){
            message('Caught an warning!')
            print(w)
        },
        finally = {
            message('All done, quitting.')
        }
    )    
}

Now, running three cases:

A valid case

log_calculator(10)
# 2.30258509299405
# Successfully executed the log(x) call.
# All done, quitting.

A "warning" case

log_calculator(-10)
# Caught an warning!
# <simpleWarning in log(x): NaNs produced>
# All done, quitting.

An "error" case

log_calculator("log_me")
# Caught an error!
# <simpleError in log(x): non-numeric argument to mathematical function>
# All done, quitting.

I've written about some useful use-cases which I use regularly. Find more details here: https://rsangole.netlify.com/post/try-catch/

Hope this is helpful.

Creating a list of pairs in java

just fixing some small mistakes in Mark Elliot's code:

public class Pair<L,R> {
    private L l;
    private R r;
    public Pair(L l, R r){
        this.l = l;
        this.r = r;
    }
    public L getL(){ return l; }
    public R getR(){ return r; }
    public void setL(L l){ this.l = l; }
    public void setR(R r){ this.r = r; }
}

How to git clone a specific tag

Use --single-branch option to only clone history leading to tip of the tag. This saves a lot of unnecessary code from being cloned.

git clone <repo_url> --branch <tag_name> --single-branch

Rounding numbers to 2 digits after comma

Previous answers forgot to type the output as an Number again. There is several ways to do this, depending on your tastes.

+my_float.toFixed(2)

Number(my_float.toFixed(2))

parseFloat(my_float.toFixed(2))

How to get a thread and heap dump of a Java process on Windows that's not running in a console

Inorder to take thread dump/heap dump from a child java process in windows, you need to identify the child process Id as first step.

By issuing the command: jps you will be able get all java process Ids that are running on your windows machine. From this list you need to select child process Id. Once you have child process Id, there are various options to capture thread dump and heap dumps.

Capturing Thread Dumps:

There are 8 options to capture thread dumps:

  1. jstack
  2. kill -3
  3. jvisualVM
  4. JMC
  5. Windows (Ctrl + Break)
  6. ThreadMXBean
  7. APM Tools
  8. jcmd

Details about each option can be found in this article. Once you have capture thread dumps, you can use tools like fastThread, Samuraito analyze thread dumps.

Capturing Heap Dumps:

There are 7 options to capture heap dumps:

  1. jmap

  2. -XX:+HeapDumpOnOutOfMemoryError

  3. jcmd

  4. JVisualVM

  5. JMX

  6. Programmatic Approach

  7. Administrative consoles

Details about each option can be found in this article. Once you have captured heap dump, you may use tools like Eclipse Memory Analysis tool, HeapHero to analyze the captured heap dumps.

Converting a double to an int in C#

Because Convert.ToInt32 rounds:

Return Value: rounded to the nearest 32-bit signed integer. If value is halfway between two whole numbers, the even number is returned; that is, 4.5 is converted to 4, and 5.5 is converted to 6.

...while the cast truncates:

When you convert from a double or float value to an integral type, the value is truncated.

Update: See Jeppe Stig Nielsen's comment below for additional differences (which however do not come into play if score is a real number as is the case here).

How do I get a list of all subdomains of a domain?

You can use:

$ host -l domain.com

Under the hood, this uses the AXFR query mentioned above. You might not be allowed to do this though. In that case, you'll get a transfer failed message.

Convert DateTime to long and also the other way around

From long to DateTime: new DateTime(long ticks)

From DateTime to long: DateTime.Ticks

How to retrieve GET parameters from JavaScript

My solution expands on @tak3r's.

It returns an empty object when there are no query parameters and supports the array notation ?a=1&a=2&a=3:

function getQueryParams () {
  function identity (e) { return e; }
  function toKeyValue (params, param) {
    var keyValue = param.split('=');
    var key = keyValue[0], value = keyValue[1];

    params[key] = params[key]?[value].concat(params[key]):value;
    return params;
  }
  return decodeURIComponent(window.location.search).
    replace(/^\?/, '').split('&').
    filter(identity).
    reduce(toKeyValue, {});
}

Get root password for Google Cloud Engine VM

I tried "ManiIOT"'s solution and it worked surprisingly. I've added another role (Compute Admin Role) for my google user account from IAM admin. Then stopped and restarted the VM. Afterwards 'sudo passwd' let me to generate a new password for the user.

So here are steps.

  1. Go to IAM & Admin
  2. Select IAM
  3. Find your user name service account (basically your google account) and click Edit-member
  4. Add another role --> select 'Compute Engine' - 'Compute Admin'
  5. Restart your Compute VM
  6. open SSH shell and run the command 'sudo passwd'
  7. enter a brand new password. Voilà!

Why does using an Underscore character in a LIKE filter give me all the results?

Underscore is a wildcard for something. for example 'A_%' will look for all match that Start whit 'A' and have minimum 1 extra character after that

How to know if docker is already logged in to a docker registry server

Just checked, today it looks like this:

$ docker login
Authenticating with existing credentials...
Login Succeeded

NOTE: this is on a macOS with the latest version of Docker CE, docker-credential-helper - both installed with homebrew.

Configuring Git over SSH to login once

I have being trying to avoid typing the passphrase all the time also because i am using ssh on windows. What i did was to modify my .profile file, so that i enter my passphrase one in a particular session. So this is the piece of code:

    SSH_ENV="$HOME/.ssh/environment"

    # start the ssh-agent
    function start_agent {
        echo "Initializing new SSH agent..."
        # spawn ssh-agent
        ssh-agent | sed 's/^echo/#echo/' > "$SSH_ENV"
        echo succeeded
        chmod 600 "$SSH_ENV"
        . "$SSH_ENV" > /dev/null
        ssh-add
    }

    # test for identities
    function test_identities {
        # test whether standard identities have been added to the agent already
        ssh-add -l | grep "The agent has no identities" > /dev/null
        if [ $? -eq 0 ]; then
            ssh-add
            # $SSH_AUTH_SOCK broken so we start a new proper agent
            if [ $? -eq 2 ];then
                start_agent
            fi
        fi
    }

    # check for running ssh-agent with proper $SSH_AGENT_PID
    if [ -n "$SSH_AGENT_PID" ]; then
        ps -fU$USER | grep "$SSH_AGENT_PID" | grep ssh-agent > /dev/null
        if [ $? -eq 0 ]; then
      test_identities
        fi
    # if $SSH_AGENT_PID is not properly set, we might be able to load one from
    # $SSH_ENV
    else
        if [ -f "$SSH_ENV" ]; then
      . "$SSH_ENV" > /dev/null
        fi
        ps -fU$USER | grep "$SSH_AGENT_PID" | grep ssh-agent > /dev/null
        if [ $? -eq 0 ]; then
            test_identities
        else
            start_agent
        fi
    fi

so with this i type my passphrase once in a session..

How to do an INNER JOIN on multiple columns

something like....

SELECT f.*
      ,a1.city as from
      ,a2.city as to
FROM flights f
INNER JOIN airports a1
ON f.fairport = a1. code
INNER JOIN airports a2
ON f.tairport = a2. code

what does this mean ? image/png;base64?

They serve the actual image inside CSS so there will be less HTTP requests per page.

How to compute the sum and average of elements in an array?

I use these methods in my personal library:

Array.prototype.sum = Array.prototype.sum || function() {
  return this.reduce(function(sum, a) { return sum + Number(a) }, 0);
}

Array.prototype.average = Array.prototype.average || function() {
  return this.sum() / (this.length || 1);
}

EDIT: To use them, simply ask the array for its sum or average, like:

[1,2,3].sum() // = 6
[1,2,3].average() // = 2

Could not resolve placeholder in string value

In my case, I was careless while merging the application.yml file, and I've unnecessary indented my properties to the right.

I've indented it like this:

spring:
    application:
       name: applicationName
............................
    myProperties:
       property1: property1value

While the code expected it to be like this:

spring:
    application:
        name: applicationName
.............................
myProperties:
    property1: property1value

EnterKey to press button in VBA Userform

Be sure to avoid "magic numbers" whenever possible, either by defining your own constants, or by using the built-in vbXXX constants.

In this instance we could use vbKeyReturn to indicate the enter key's keycode (replacing YourInputControl and SubToBeCalled).

   Private Sub YourInputControl_KeyDown(ByVal KeyCode As MSForms.ReturnInteger, ByVal Shift As Integer)
        If KeyCode = vbKeyReturn Then
             SubToBeCalled
        End If
   End Sub

This prevents a whole category of compatibility issues and simple typos, especially because VBA capitalizes identifiers for us.

Cheers!

How to count lines of Java code using IntelliJ IDEA?

Just like Neil said:

Ctrl-Shift-F -> Text to find = '\n' -> Find.

With only one improvement, if you enter "\n+", you can search for non-empty lines

If lines with only whitespace can be considered empty too, then you can use the regex "(\s*\n\s*)+" to not count them.

Error : No resource found that matches the given name (at 'icon' with value '@drawable/icon')

You need to add icon.png through visual.

Resouces... / Dravable/ Add ///

How to restart adb from root to user mode?

Try this to make sure you get your shell back:

enter adb shell (root). Then type below comamnd.

stop adbd && setprop service.adb.root 0 && start adbd &

This command will stop adbd, then setprop service.adb.root 0 if adbd has been successfully stopped, and finally restart adbd should the .root property have successfully been set to 0. And all this will be done in the background thanks to the last &.

Convert Json Array to normal Java list

we starting from conversion [ JSONArray -> List < JSONObject > ]

public static List<JSONObject> getJSONObjectListFromJSONArray(JSONArray array) 
        throws JSONException {
  ArrayList<JSONObject> jsonObjects = new ArrayList<>();
  for (int i = 0; 
           i < (array != null ? array.length() : 0);           
           jsonObjects.add(array.getJSONObject(i++)) 
       );
  return jsonObjects;
}

next create generic version replacing array.getJSONObject(i++) with POJO

example :

public <T> static List<T> getJSONObjectListFromJSONArray(Class<T> forClass, JSONArray array) 
        throws JSONException {
  ArrayList<Tt> tObjects = new ArrayList<>();
  for (int i = 0; 
           i < (array != null ? array.length() : 0);           
           tObjects.add( (T) createT(forClass, array.getJSONObject(i++))) 
       );
  return tObjects;
}

private static T createT(Class<T> forCLass, JSONObject jObject) {
   // instantiate via reflection / use constructor or whatsoever 
   T tObject = forClass.newInstance(); 
   // if not using constuctor args  fill up 
   // 
   // return new pojo filled object 
   return tObject;
}

How to change font size in a textbox in html

Here are some ways to edit the text and the size of the box:

rows="insertNumber"
cols="insertNumber"
style="font-size:12pt"

Example:

<textarea rows="5" cols="30" style="font-size: 12pt" id="myText">Enter 
Text Here</textarea>

Arduino IDE can't find ESP8266WiFi.h file

For those who are having trouble with fatal error: ESP8266WiFi.h: No such file or directory, you can install the package manually.

  1. Download the Arduino ESP8266 core from here https://github.com/esp8266/Arduino
  2. Go into library from the downloaded core and grab ESP8266WiFi.
  3. Drag that into your local Arduino/library folder. This can be found by going into preferences and looking at your Sketchbook location

You may still need to have the http://arduino.esp8266.com/stable/package_esp8266com_index.json package installed beforehand, however.

Edit: That wasn't the full issue, you need to make sure you have the correct ESP8266 Board selected before compiling.

Hope this helps others.

Add IIS 7 AppPool Identities as SQL Server Logons

CREATE LOGIN [IIS APPPOOL\MyAppPool] FROM WINDOWS;
CREATE USER MyAppPoolUser FOR LOGIN [IIS APPPOOL\MyAppPool];

Finding second occurrence of a substring in a string in Java

if you want to find index for more than 2 occurrence:

public static int ordinalIndexOf(String fullText,String subText,int pos){

    if(fullText.contains(subText)){
        if(pos <= 1){
            return fullText.indexOf(subText);
        }else{
            --pos;
            return fullText.indexOf(subText, ( ordinalIndexOf(fullText,subText,pos) + 1) );
        }
    }else{
        return -1;
    }

}

How to change Screen buffer size in Windows Command Prompt from batch script

I know the question is 9 years old, but maybe for someone it will be interested furthermore. According to the question, to change the buffer size only, it can be used Powershell. The shortest command with Powershell is:

powershell -command "&{(get-host).ui.rawui.buffersize=@{width=155;height=999};}"

Replace the values of width and height with your wanted values.

But supposedly the reason of your question is to modify the size of command line window without reducing of the buffer size. For that you can use the following command:

start /b powershell -command "&{$w=(get-host).ui.rawui;$w.buffersize=@{width=177;height=999};$w.windowsize=@{width=155;height=55};}"

There you can modify the size of buffer and window independly. To avoid an error message, consider that the values of buffersize must be bigger or equal to the values of windowsize.

Additional implemented is the start /b command. The Powershell command sometimes takes a few seconds to execute. With this additional command, Powershell runs parallel and does not significantly delay the processing of the following commands.

Docker: adding a file from a parent directory

You can build the Dockerfile from the parent directory:

docker build -t <some tag> -f <dir/dir/Dockerfile> .

Convert time fields to strings in Excel

The below worked for me

  • First copy the content say "1:00:15" in notepad
  • Then select a new column where you need to copy the text from notepad.
  • Then right click and select format cell option and in that select numbers tab and in that tab select the option "Text".
  • Now copy the content from notepad and paste in this Excel column. it will be text but in format "1:00:15".

How to select all columns, except one column in pandas?

df[df.columns.difference(['b'])]

Out: 
          a         c         d
0  0.427809  0.459807  0.333869
1  0.678031  0.668346  0.645951
2  0.996573  0.673730  0.314911
3  0.786942  0.719665  0.330833

What exactly does the Access-Control-Allow-Credentials header do?

By default, CORS does not include cookies on cross-origin requests. This is different from other cross-origin techniques such as JSON-P. JSON-P always includes cookies with the request, and this behavior can lead to a class of vulnerabilities called cross-site request forgery, or CSRF.

In order to reduce the chance of CSRF vulnerabilities in CORS, CORS requires both the server and the client to acknowledge that it is ok to include cookies on requests. Doing this makes cookies an active decision, rather than something that happens passively without any control.

The client code must set the withCredentials property on the XMLHttpRequest to true in order to give permission.

However, this header alone is not enough. The server must respond with the Access-Control-Allow-Credentials header. Responding with this header to true means that the server allows cookies (or other user credentials) to be included on cross-origin requests.

You also need to make sure your browser isn't blocking third-party cookies if you want cross-origin credentialed requests to work.

Note that regardless of whether you are making same-origin or cross-origin requests, you need to protect your site from CSRF (especially if your request includes cookies).

How to search multiple columns in MySQL?

You can use the AND or OR operators, depending on what you want the search to return.

SELECT title FROM pages WHERE my_col LIKE %$param1% AND another_col LIKE %$param2%;

Both clauses have to match for a record to be returned. Alternatively:

SELECT title FROM pages WHERE my_col LIKE %$param1% OR another_col LIKE %$param2%;

If either clause matches then the record will be returned.

For more about what you can do with MySQL SELECT queries, try the documentation.

How to remove constraints from my MySQL table?

To add a little to Robert Knight's answer, since the title of the post itself doesn't mention foreign keys (and since his doesn't have complete code samples and since SO's comment code blocks don't show as well as the answers' code blocks), I'll add this for unique constraints. Either of these work to drop the constraint:

ALTER TABLE `table_name` DROP KEY `uc_name`;

or

ALTER TABLE `table_name` DROP INDEX `uc_name`;

java.io.FileNotFoundException: the system cannot find the file specified

Try to create a file using the code, so you will get to know the path of the file where the system create

File test=new File("check.txt");
if (test.createNewFile()) {
    System.out.println("File created: " + test.getName());
  }

How can I specify a display?

$ export DISPLAY=yourmachine.yourdomain.com:0.0
$ firefox &

Set a div width, align div center and text align left

All of these answers should suffice. However if you don't have a defined width, auto margins will not work.

I have found this nifty little trick to centre some of the more stubborn elements (Particularly images).

.div {
   position: absolute;
   left: 0;
   right: 0;
   margin-left: 0;
   margin-right: 0;
}

How to change JFrame icon

Just add the following code:

setIconImage(new ImageIcon(PathOfFile).getImage());

Adding a line break in MySQL INSERT INTO text

For the record, I wanted to add some line breaks into existing data and I got \n to work ok...

Sample data:

Sentence. Sentence. Sentence

I did:

UPDATE table SET field = REPLACE(field, '. ', '.\r\n')

However, it also worked with just \r and just \n.

Catch an exception thrown by an async void method

The reason the exception is not caught is because the Foo() method has a void return type and so when await is called, it simply returns. As DoFoo() is not awaiting the completion of Foo, the exception handler cannot be used.

This opens up a simpler solution if you can change the method signatures - alter Foo() so that it returns type Task and then DoFoo() can await Foo(), as in this code:

public async Task Foo() {
    var x = await DoSomethingThatThrows();
}

public async void DoFoo() {
    try {
        await Foo();
    } catch (ProtocolException ex) {
        // This will catch exceptions from DoSomethingThatThrows
    }
}

How to import a Python class that is in a directory above?

How to load a module that is a directory up

preface: I did a substantial rewrite of a previous answer with the hopes of helping ease people into python's ecosystem, and hopefully give everyone the best change of success with python's import system.

This will cover relative imports within a package, which I think is the most probable case to OP's question.

Python is a modular system

This is why we write import foo to load a module "foo" from the root namespace, instead of writing:

foo = dict();  # please avoid doing this
with open(os.path.join(os.path.dirname(__file__), '../foo.py') as foo_fh:  # please avoid doing this
    exec(compile(foo_fh.read(), 'foo.py', 'exec'), foo)  # please avoid doing this

Python isn't coupled to a file-system

This is why we can embed python in environment where there isn't a defacto filesystem without providing a virtual one, such as Jython.

Being decoupled from a filesystem lets imports be flexible, this design allows for things like imports from archive/zip files, import singletons, bytecode caching, cffi extensions, even remote code definition loading.

So if imports are not coupled to a filesystem what does "one directory up" mean? We have to pick out some heuristics but we can do that, for example when working within a package, some heuristics have already been defined that makes relative imports like .foo and ..foo work within the same package. Cool!

If you sincerely want to couple your source code loading patterns to a filesystem, you can do that. You'll have to choose your own heuristics, and use some kind of importing machinery, I recommend importlib

Python's importlib example looks something like so:

import importlib.util
import sys

# For illustrative purposes.
file_path = os.path.join(os.path.dirname(__file__), '../foo.py')
module_name = 'foo'

foo_spec = importlib.util.spec_from_file_location(module_name, file_path)
# foo_spec is a ModuleSpec specifying a SourceFileLoader
foo_module = importlib.util.module_from_spec(foo_spec)
sys.modules[module_name] = foo_module
foo_spec.loader.exec_module(foo_module)

foo = sys.modules[module_name]
# foo is the sys.modules['foo'] singleton

Packaging

There is a great example project available officially here: https://github.com/pypa/sampleproject

A python package is a collection of information about your source code, that can inform other tools how to copy your source code to other computers, and how to integrate your source code into that system's path so that import foo works for other computers (regardless of interpreter, host operating system, etc)

Directory Structure

Lets have a package name foo, in some directory (preferably an empty directory).

some_directory/
    foo.py  # `if __name__ == "__main__":`  lives here

My preference is to create setup.py as sibling to foo.py, because it makes writing the setup.py file simpler, however you can write configuration to change/redirect everything setuptools does by default if you like; for example putting foo.py under a "src/" directory is somewhat popular, not covered here.

some_directory/
    foo.py
    setup.py

.

#!/usr/bin/env python3
# setup.py

import setuptools

setuptools.setup(
    name="foo",
    ...
    py_modules=['foo'],
)

.

python3 -m pip install --editable ./  # or path/to/some_directory/

"editable" aka -e will yet-again redirect the importing machinery to load the source files in this directory, instead copying the current exact files to the installing-environment's library. This can also cause behavioral differences on a developer's machine, be sure to test your code! There are tools other than pip, however I'd recommend pip be the introductory one :)

I also like to make foo a "package" (a directory containing __init__.py) instead of a module (a single ".py" file), both "packages" and "modules" can be loaded into the root namespace, modules allow for nested namespaces, which is helpful if we want to have a "relative one directory up" import.

some_directory/
    foo/
        __init__.py
    setup.py

.

#!/usr/bin/env python3
# setup.py

import setuptools

setuptools.setup(
    name="foo",
    ...
    packages=['foo'],
)

I also like to make a foo/__main__.py, this allows python to execute the package as a module, eg python3 -m foo will execute foo/__main__.py as __main__.

some_directory/
    foo/
        __init__.py
        __main__.py  # `if __name__ == "__main__":`  lives here, `def main():` too!
    setup.py

.

#!/usr/bin/env python3
# setup.py

import setuptools

setuptools.setup(
    name="foo",
    ...
    packages=['foo'],
    ...
    entry_points={
        'console_scripts': [
            # "foo" will be added to the installing-environment's text mode shell, eg `bash -c foo`
            'foo=foo.__main__:main',
        ]
    },
)

Lets flesh this out with some more modules: Basically, you can have a directory structure like so:

some_directory/
    bar.py           # `import bar`
    foo/
        __init__.py  # `import foo`
        __main__.py
        baz.py       # `import foo.baz
        spam/           
            __init__.py  # `import foo.spam`
            eggs.py      # `import foo.spam.eggs`
    setup.py

setup.py conventionally holds metadata information about the source code within, such as:

  • what dependencies are needed to install named "install_requires"
  • what name should be used for package management (install/uninstall "name"), I suggest this match your primary python package name in our case foo, though substituting underscores for hyphens is popular
  • licensing information
  • maturity tags (alpha/beta/etc),
  • audience tags (for developers, for machine learning, etc),
  • single-page documentation content (like a README),
  • shell names (names you type at user shell like bash, or names you find in a graphical user shell like a start menu),
  • a list of python modules this package will install (and uninstall)
  • a defacto "run tests" entry point python ./setup.py test

Its very expansive, it can even compile c extensions on the fly if a source module is being installed on a development machine. For a every-day example I recommend the PYPA Sample Repository's setup.py

If you are releasing a build artifact, eg a copy of the code that is meant to run nearly identical computers, a requirements.txt file is a popular way to snapshot exact dependency information, where "install_requires" is a good way to capture minimum and maximum compatible versions. However, given that the target machines are nearly identical anyway, I highly recommend creating a tarball of an entire python prefix. This can be tricky, too detailed to get into here. Check out pip install's --target option, or virtualenv aka venv for leads.

back to the example

how to import a file one directory up:

From foo/spam/eggs.py, if we wanted code from foo/baz we could ask for it by its absolute namespace:

import foo.baz

If we wanted to reserve capability to move eggs.py into some other directory in the future with some other relative baz implementation, we could use a relative import like:

import ..baz

Get SSID when WIFI is connected

For me it only worked when I set the permission on the phone itself (settings -> app permissions -> location always on).

rails generate model

For me what happened was that I generated the app with rails new rails new chapter_2 but the RVM --default had rails 4.0.2 gem, but my chapter_2 project use a new gemset with rails 3.2.16.

So when I ran

rails generate scaffold User name:string email:string

the console showed

Usage:
   rails new APP_PATH [options]

So I fixed the RVM and the gemset with the rails 3.2.16 gem , and then generated the app again then I executed

 rails generate scaffold User name:string email:string

and it worked

How to get a list of MySQL views?

Try moving that mysql.bak directory out of /var/lib/mysql to say /root/ or something. It seems like mysql is finding that and it may be causing that ERROR 1102 (42000): Incorrect database name 'mysql.bak' error.

How to set a Header field on POST a form?

You could use $.ajax to avoid the natural behaviour of <form method="POST">. You could, for example, add an event to the submission button and treat the POST request as AJAX.

How do I clear my Jenkins/Hudson build history?

If using the Script Console method then try using the following instead to take into account if jobs are being grouped into folder containers.

def jobName = "Your Job Name"
def job = Jenkins.instance.getItemByFullName(jobName)

or

def jobName = "My Folder/Your Job Name
def job = Jenkins.instance.getItemByFullName(jobName)

HTML Tags in Javascript Alert() method

No, you can use only some escape sequences - \n for example (maybe only this one).

Get the current URL with JavaScript?

if you are referring to a specific link that has an id this code can help you.

$(".disapprove").click(function(){
    var id = $(this).attr("id");

    $.ajax({
        url: "<?php echo base_url('index.php/sample/page/"+id+"')?>",
        type: "post",
        success:function()
        {
            alert("The Request has been Disapproved");
            window.location.replace("http://localhost/sample/page/"+id+"");
        }
    });
});

I am using ajax here to submit an id and redirect the page using window.location.replace. just add an attribute id="" as stated.

How to display (print) vector in Matlab?

You can use

x = [1, 2, 3]
disp(sprintf('Answer: (%d, %d, %d)', x))

This results in

Answer: (1, 2, 3)

For vectors of arbitrary size, you can use

disp(strrep(['Answer: (' sprintf(' %d,', x) ')'], ',)', ')'))

An alternative way would be

disp(strrep(['Answer: (' num2str(x, ' %d,') ')'], ',)', ')'))

How to remove td border with html?

_x000D_
_x000D_
  <table border="1">
  <tr>
    <td>one</td>
    <td style="border-bottom-style: hidden;">two</td>
  </tr>
  <tr>
    <td>one</td>
    <td style="border-top-style: hidden;">two</td>
</tr>
</table>
_x000D_
_x000D_
_x000D_

Eclipse will not open due to environment variables

Ok...Ok... Don't worry i am also ruined by this error and fatal and when i got it i was so serious even i was not giving an attention to other work, but i got it, Simply first of all copy this code and paste in your system variable Under path ...

C:\Program Files;C:\Winnt;C:\Winnt\System32;C:\Program Files\Java\jre6\bin\javaw.exe

Now copy the "jre" folder from your path like i have have "jre" under this path

            C:\Program Files\Java

and paste it in your eclipse folder means where your eclipse.exe file is placed. like i have my eclipse set up in this location

    F:\Softwares\LANGUAGES SOFTEARE\Android Setup\eclipse

So inside the eclipse Folder paste the "jre" FOLDER . If you have "jre6" then rename it as "jre"....and run your eclipse you will got the solution...

   //<<<<<<<<<<<<<<----------------------------->>>>>>>>>>>>>>>>>>>                 

OTHER SOLUTION: 2

If the problem could't solve with the above steps, then follow these steps

  1. Copy the folder "jre" from your Java path like C:\Program Files\Java\jre6* etc, and paste it in your eclipse directory(Where is your eclipse available)
  2. Go to eclipse.ini file , open it up.
  3. Change the directory of your javaw.exe file like

-vmF:\Softwares\LANGUAGES SOFTEARE\Android Setup\eclipse Indigo version 32 Bit\jre\bin/javaw.exe

Now this time when you will start eclipse it will search for javaw.exe, so it will search the path in the eclipse.ini, as it is now in the same folder so, it will start the javaw.exe and it will start working.

If You still have any query you can ask it again, just go on my profile and find out my email id. because i love stack overflow forum, and it made me a programmer.*

npm install error - MSB3428: Could not load the Visual C++ component "VCBuild.exe"

I know it's a very old question, but is the first in my google search and after some time I got how to solve this.

find node on your windows with
$ npm install -g which
$ which node
after cd into the directory, inside the directory cd into node_modules\npm folder and finally:
$ npm install node-gyp@latest
here worked, the answer is from this site

How do I "Add Existing Item" an entire directory structure in Visual Studio?

What worked for me was to drag the folder into Visual Studio, then right click the folder and select "Open Folder in File Explorer". Then select all and drag them into the folder in Visual Studio.

Determine if running on a rooted device

Further to @Kevins answer, I've recently found while using his system, that the Nexus 7.1 was returning false for all three methods - No which command, no test-keys and SuperSU was not installed in /system/app.

I added this:

public static boolean checkRootMethod4(Context context) {
    return isPackageInstalled("eu.chainfire.supersu", context);     
}

private static boolean isPackageInstalled(String packagename, Context context) {
    PackageManager pm = context.getPackageManager();
    try {
        pm.getPackageInfo(packagename, PackageManager.GET_ACTIVITIES);
        return true;
    } catch (NameNotFoundException e) {
        return false;
    }
}

This is slightly less useful in some situations (if you need guaranteed root access) as it's completely possible for SuperSU to be installed on devices which don't have SU access.

However, since it's possible to have SuperSU installed and working but not in the /system/app directory, this extra case will root (haha) out such cases.

Promise.all().then() resolve?

Today NodeJS supports new async/await syntax. This is an easy syntax and makes the life much easier

async function process(promises) { // must be an async function
    let x = await Promise.all(promises);  // now x will be an array
    x = x.map( tmp => tmp * 10);              // proccessing the data.
}

const promises = [
   new Promise(resolve => setTimeout(resolve, 0, 1)),
   new Promise(resolve => setTimeout(resolve, 0, 2))
];

process(promises)

Learn more:

Get the value of a dropdown in jQuery

var sal = $('.selectSal option:selected').eq(0).val();

selectSal is a class.

Go to beginning of line without opening new line in VI

There is another way:

|

That is the "pipe" - the symbol found under the backspace in ANSI layout.

Vim quickref (:help quickref) describes it as:

N      |      to column N (default: 1)

What about wrapped lines?

If you have wrap lines enabled, 0 and | will no longer take you to the beginning of the screen line. In that case use:

g0

Again, vim quickref doc:

 g0   to first character in screen line (differs from "0"
      when lines wrap)

Export SQL query data to Excel

If you're just needing to export to excel, you can use the export data wizard. Right click the database, Tasks->Export data.

White space showing up on right side of page when background image should extend full length of page

I see the question has been answered to a general standard, but when I looked at your site I noticed there is still a horizontal scroll-bar. I also notice the reason for this: You have used the code:

.homepageconference .container {
padding-left: 12%;
}

which is being used alongside code stating that the element has a width of 100%, causing an element with a total width of 112% of screen size. To fix this, either remove the padding, replace the padding with a margin of 12% for the same effect, or change the width (or max-width) of the element to 88%. This occurs in main.css at line 343. Hope this helps!

NSURLErrorDomain error codes description

IN SWIFT 3. Here are the NSURLErrorDomain error codes description in a Swift 3 enum: (copied from answer above and converted what i can).

enum NSURLError: Int {
    case unknown = -1
    case cancelled = -999
    case badURL = -1000
    case timedOut = -1001
    case unsupportedURL = -1002
    case cannotFindHost = -1003
    case cannotConnectToHost = -1004
    case connectionLost = -1005
    case lookupFailed = -1006
    case HTTPTooManyRedirects = -1007
    case resourceUnavailable = -1008
    case notConnectedToInternet = -1009
    case redirectToNonExistentLocation = -1010
    case badServerResponse = -1011
    case userCancelledAuthentication = -1012
    case userAuthenticationRequired = -1013
    case zeroByteResource = -1014
    case cannotDecodeRawData = -1015
    case cannotDecodeContentData = -1016
    case cannotParseResponse = -1017
    //case NSURLErrorAppTransportSecurityRequiresSecureConnection NS_ENUM_AVAILABLE(10_11, 9_0) = -1022
    case fileDoesNotExist = -1100
    case fileIsDirectory = -1101
    case noPermissionsToReadFile = -1102
    //case NSURLErrorDataLengthExceedsMaximum NS_ENUM_AVAILABLE(10_5, 2_0) =   -1103

    // SSL errors
    case secureConnectionFailed = -1200
    case serverCertificateHasBadDate = -1201
    case serverCertificateUntrusted = -1202
    case serverCertificateHasUnknownRoot = -1203
    case serverCertificateNotYetValid = -1204
    case clientCertificateRejected = -1205
    case clientCertificateRequired = -1206
    case cannotLoadFromNetwork = -2000

    // Download and file I/O errors
    case cannotCreateFile = -3000
    case cannotOpenFile = -3001
    case cannotCloseFile = -3002
    case cannotWriteToFile = -3003
    case cannotRemoveFile = -3004
    case cannotMoveFile = -3005
    case downloadDecodingFailedMidStream = -3006
    case downloadDecodingFailedToComplete = -3007

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

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

Direct link to URLError.Code in the Swift github repository, which contains the up to date list of error codes being used (github link).

How to make the window full screen with Javascript (stretching all over the screen)

Luckily for unsuspecting web users this cannot be done with just javascript. You would need to write browser specific plugins, if they didn't already exist, and then somehow get people to download them. The closest you can get is a maximized window with no tool or navigation bars but users will still be able to see the url.

window.open('http://www.web-page.com', 'title' , 'type=fullWindow, fullscreen, scrollbars=yes');">

This is generally considered bad practice though as it removes a lot of browser functionality from the user.

Pointer to a string in C?

The very same. A C string is nothing but an array of characters, so a pointer to a string is a pointer to an array of characters. And a pointer to an array is the very same as a pointer to its first element.

UTC Date/Time String to Timezone

Assuming the UTC is not included in the string then:

date_default_timezone_set('America/New_York');
$datestring = '2011-01-01 15:00:00';  //Pulled in from somewhere
$date = date('Y-m-d H:i:s T',strtotime($datestring . ' UTC'));
echo $date;  //Should get '2011-01-01 10:00:00 EST' or something like that

Or you could use the DateTime object.

How to free memory from char array in C

The memory associated with arr is freed automatically when arr goes out of scope. It is either a local variable, or allocated statically, but it is not dynamically allocated.

A simple rule for you to follow is that you must only every call free() on a pointer that was returned by a call to malloc, calloc or realloc.

How to count number of records per day?

If your timestamp includes time, not only date, use:

SELECT DATE_FORMAT('timestamp', '%Y-%m-%d') AS date, COUNT(id) AS count FROM table GROUP BY DATE_FORMAT('timestamp', '%Y-%m-%d')

How to convert dataframe into time series?

With library fpp, you can easily create time series with date format: time_ser=ts(data,frequency=4,start=c(1954,2))

here we start at the 2nd quarter of 1954 with quarter fequency.

How to analyze information from a Java core dump?

If you are using an IBM JVM, download the IBM Thread and Monitor Dump Analyzer. It is an excellent tool. It provides thread detail and can point out deadlocks, etc. The following blog post provides a nice overview on how to use it.

Repeat rows of a data.frame

The rep.row function seems to sometimes make lists for columns, which leads to bad memory hijinks. I have written the following which seems to work well:

library(plyr)
rep.row <- function(r, n){
  colwise(function(x) rep(x, n))(r)
}

How to check if element in groovy array/hash/collection/list?

IMPORTANT Gotcha for using .contains() on a Collection of Objects, such as Domains. If the Domain declaration contains a EqualsAndHashCode, or some other equals() implementation to determine if those Ojbects are equal, and you've set it like this...

import groovy.transform.EqualsAndHashCode
@EqualsAndHashCode(includes = "settingNameId, value")

then the .contains(myObjectToCompareTo) will evaluate the data in myObjectToCompareTo with the data for each Object instance in the Collection. So, if your equals method isn't up to snuff, as mine was not, you might see unexpected results.

Oracle SQL query for Date format

if you are using same date format and have select query where date in oracle :

   select count(id) from Table_name where TO_DATE(Column_date)='07-OCT-2015';

To_DATE provided by oracle

npm behind a proxy fails with status 403

OK, so within minutes after posting the question, I found the answer myself here: https://github.com/npm/npm/issues/2119#issuecomment-5321857

The issue seems to be that npm is not that great with HTTPS over a proxy. Changing the registry URL from HTTPS to HTTP fixed it for me:

npm config set registry http://registry.npmjs.org/

I still have to provide the proxy config (through Authoxy in my case), but everything works fine now.

Seems to be a common issue, but not well documented. I hope this answer here will make it easier for people to find if they run into this issue.

How do I syntax check a Bash script without running it?

I also enable the 'u' option on every bash script I write in order to do some extra checking:

set -u 

This will report the usage of uninitialized variables, like in the following script 'check_init.sh'

#!/bin/sh
set -u
message=hello
echo $mesage

Running the script :

$ check_init.sh

Will report the following :

./check_init.sh[4]: mesage: Parameter not set.

Very useful to catch typos

How to import a jar in Eclipse

Eclipse -> Preferences -> Java -> Build Path -> User Libraries -> New(Name it) -> Add external Jars

(I recommend dragging your new libraries into the eclipse folder before any of these steps to keep everything together, that way if you reinstall Eclipse or your OS you won't have to rwlink anything except the JDK) Now select the jar files you want. Click OK.

Right click on your project and choose Build Path -> Add Library

FYI just code and then right click and Source->Organize Imports

Best way to verify string is empty or null

Just to show java 8's stance to remove null values.

String s = Optional.ofNullable(myString).orElse("");
if (s.trim().isEmpty()) {
    ...
}

Makes sense if you can use Optional<String>.

How to check if element exists using a lambda expression?

While the accepted answer is correct, I'll add a more elegant version (in my opinion):

boolean idExists = tabPane.getTabs().stream()
    .map(Tab::getId)
    .anyMatch(idToCheck::equals);

Don't neglect using Stream#map() which allows to flatten the data structure before applying the Predicate.

Aliases in Windows command prompt

You want to create an alias by simply typing:

c:\>alias kgs kubectl get svc

Created alias for kgs=kubectl get svc

And use the alias as follows:

c:\>kgs alfresco-svc

NAME           TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
alfresco-svc   ClusterIP   10.7.249.219   <none>        80/TCP    8d

Just add the following alias.bat file to you path. It simply creates additional batch files in the same directory as itself.

  @echo off
  echo.
  for /f "tokens=1,* delims= " %%a in ("%*") do set ALL_BUT_FIRST=%%b
  echo @echo off > C:\Development\alias-script\%1.bat
  echo echo. >> C:\Development\alias-script\%1.bat
  echo %ALL_BUT_FIRST% %%* >> C:\Development\alias-script\%1.bat
  echo Created alias for %1=%ALL_BUT_FIRST%

An example of the batch file this created called kgs.bat is:

@echo off 
echo. 
kubectl get svc %* 

Launch an app from within another (iPhone)

In Swift 4.1 and Xcode 9.4.1

I have two apps 1)PageViewControllerExample and 2)DelegateExample. Now i want to open DelegateExample app with PageViewControllerExample app. When i click open button in PageViewControllerExample, DelegateExample app will be opened.

For this we need to make some changes in .plist files for both the apps.

Step 1

In DelegateExample app open .plist file and add URL Types and URL Schemes. Here we need to add our required name like "myapp".

enter image description here

Step 2

In PageViewControllerExample app open .plist file and add this code

<key>LSApplicationQueriesSchemes</key>
<array>
    <string>myapp</string>
</array>

Now we can open DelegateExample app when we click button in PageViewControllerExample.

//In PageViewControllerExample create IBAction
@IBAction func openapp(_ sender: UIButton) {

    let customURL = URL(string: "myapp://")
    if UIApplication.shared.canOpenURL(customURL!) {

        //let systemVersion = UIDevice.current.systemVersion//Get OS version
        //if Double(systemVersion)! >= 10.0 {//10 or above versions
            //print(systemVersion)
            //UIApplication.shared.open(customURL!, options: [:], completionHandler: nil)
        //} else {
            //UIApplication.shared.openURL(customURL!)
        //}

        //OR

        if #available(iOS 10.0, *) {
            UIApplication.shared.open(customURL!, options: [:], completionHandler: nil)
        } else {
            UIApplication.shared.openURL(customURL!)
        }
    } else {
         //Print alert here
    }
}

How to set label size in Bootstrap

In Bootstrap 3 they do not have separate classes for different styles of labels.

http://getbootstrap.com/components/

However, you can customize bootstrap classes that way. In your css file

.lb-sm {
  font-size: 12px;
}

.lb-md {
  font-size: 16px;
}

.lb-lg {
  font-size: 20px;
}

Alternatively, you can use header tags to change the sizes. For example, here is a medium sized label and a small-sized label

_x000D_
_x000D_
<link href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet"/>_x000D_
<h3>Example heading <span class="label label-default">New</span></h3>_x000D_
<h6>Example heading <span class="label label-default">New</span></h6>
_x000D_
_x000D_
_x000D_

They might add size classes for labels in future Bootstrap versions.

Full width layout with twitter bootstrap

Because the accepted answer isn't on the same planet as BS3, I'll share what I'm using to achieve nearly full-width capabilities.

First off, this is cheating. It's not really fluid width - but it appears to be - depending on the size of the screen viewing the site.

The problem with BS3 and fluid width sites is that they have taken this "mobile first" approach, which requires that they define every freaking screen width up to what they consider to be desktop (1200px) I'm working on a laptop with a 1900px wide screen - so I end up with 350px on either side of the content at what BS3 thinks is a desktop sized width.

They have defined 10 screen widths (really only 5, but anyway). I don't really feel comfortable changing those, because they are common widths. So, I chose to define some extra widths for BS to choose from when deciding the width of the container class.

The way I use BS is to take all of the Bootstrap provided LESS files, omit the variables.less file to provide my own, and add one of my own to the end to override the things I want to change. Within my less file, I add the following to achieve 2 common screen width settings:

@media screen and (min-width: 1600px) {
    .container {
        max-width: (1600px - @grid-gutter-width);
    }
}
@media screen and (min-width: 1900px) {
    .container {
        max-width: (1900px - @grid-gutter-width);
    }
}

These two settings set the example for what you need to do to achieve different screen widths. Here, you get full width at 1600px, and 1900px. Any less than 1600 - BS falls back to the 1200px width, then to 768px and so forth - down to phone size.

If you have larger to support, just create more @media screen statements like these. If you're building the CSS instead, you'll want to determine what gutter width was used and subtract it from your target screen width.

Update:

Bootstrap 3.0.1 and up (so far) - it's as easy as setting @container-large-desktop to 100%

File upload from <input type="file">

just try (onclick)="this.value = null"

in your html page add onclick method to remove previous value so user can select same file again.

jQuery show/hide not working

Just add the document ready function, this way it waits until the DOM has been loaded, also by using the :visible pseudo you can write a simple show and hide function.

Sample

 $(document).ready(function(){

    $( '.expand' ).click(function() {
         if($( '.img_display_content' ).is(":visible")){
              $( '.img_display_content' ).hide();
         } else{
              $( '.img_display_content' ).show();
         }

    });
});

How to ssh from within a bash script?

There's yet another way to do it using Shared Connections, ie: somebody initiates the connection, using a password, and every subsequent connection will multiplex over the same channel, negating the need for re-authentication. ( And its faster too )

# ~/.ssh/config 
ControlMaster auto
ControlPath ~/.ssh/pool/%r@%h

then you just have to log in, and as long as you are logged in, the bash script will be able to open ssh connections.

You can then stop your script from working when somebody has not already opened the channel by:

ssh ... -o KbdInteractiveAuthentication=no ....

Laravel Escaping All HTML in Blade Template

I had the same issue. Thanks for the answers above, I solved my issue. If there are people facing the same problem, here is two way to solve it:

  • You can use {!! $news->body !!}
  • You can use traditional php openning (It is not recommended) like: <?php echo $string ?>

I hope it helps.

Resolve build errors due to circular dependency amongst classes

I'm late answering this, but there's not one reasonable answer to date, despite being a popular question with highly upvoted answers....

Best practice: forward declaration headers

As illustrated by the Standard library's <iosfwd> header, the proper way to provide forward declarations for others is to have a forward declaration header. For example:

a.fwd.h:

#pragma once
class A;

a.h:

#pragma once
#include "a.fwd.h"
#include "b.fwd.h"

class A
{
  public:
    void f(B*);
};

b.fwd.h:

#pragma once
class B;

b.h:

#pragma once
#include "b.fwd.h"
#include "a.fwd.h"

class B
{
  public:
    void f(A*);
};

The maintainers of the A and B libraries should each be responsible for keeping their forward declaration headers in sync with their headers and implementation files, so - for example - if the maintainer of "B" comes along and rewrites the code to be...

b.fwd.h:

template <typename T> class Basic_B;
typedef Basic_B<char> B;

b.h:

template <typename T>
class Basic_B
{
    ...class definition...
};
typedef Basic_B<char> B;

...then recompilation of the code for "A" will be triggered by the changes to the included b.fwd.h and should complete cleanly.


Poor but common practice: forward declare stuff in other libs

Say - instead of using a forward declaration header as explained above - code in a.h or a.cc instead forward-declares class B; itself:

  • if a.h or a.cc did include b.h later:
    • compilation of A will terminate with an error once it gets to the conflicting declaration/definition of B (i.e. the above change to B broke A and any other clients abusing forward declarations, instead of working transparently).
  • otherwise (if A didn't eventually include b.h - possible if A just stores/passes around Bs by pointer and/or reference)
    • build tools relying on #include analysis and changed file timestamps won't rebuild A (and its further-dependent code) after the change to B, causing errors at link time or run time. If B is distributed as a runtime loaded DLL, code in "A" may fail to find the differently-mangled symbols at runtime, which may or may not be handled well enough to trigger orderly shutdown or acceptably reduced functionality.

If A's code has template specialisations / "traits" for the old B, they won't take effect.

Bind failed: Address already in use

I was also facing that problem, but I resolved it. Make sure that both the programs for client-side and server-side are on different projects in your IDE, in my case NetBeans. Then assuming you're using localhost, I recommend you to implement both the programs as two different projects.

null check in jsf expression language

Use empty (it checks both nullness and emptiness) and group the nested ternary expression by parentheses (EL is in certain implementations/versions namely somewhat problematic with nested ternary expressions). Thus, so:

styleClass="#{empty obj.validationErrorMap ? ' ' :  
 (obj.validationErrorMap.contains('key') ? 'highlight_field' : 'highlight_row')}"

If still in vain (I would then check JBoss EL configs), use the "normal" EL approach:

styleClass="#{empty obj.validationErrorMap ? ' ' :  
 (obj.validationErrorMap['key'] ne null ? 'highlight_field' : 'highlight_row')}"

Update: as per the comments, the Map turns out to actually be a List (please work on your naming conventions). To check if a List contains an item the "normal" EL way, use JSTL fn:contains (although not explicitly documented, it works for List as well).

styleClass="#{empty obj.validationErrorMap ? ' ' :  
 (fn:contains(obj.validationErrorMap, 'key') ? 'highlight_field' : 'highlight_row')}"

Disable all Database related auto configuration in Spring Boot

I add in myApp.java, after @SpringBootApplication

@EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class, DataSourceTransactionManagerAutoConfiguration.class, HibernateJpaAutoConfiguration.class})

And changed

@SpringBootApplication => @Configuration

So, I have this in my main class (myApp.java)

package br.com.company.project.app;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration;
import org.springframework.context.annotation.Configuration;

@Configuration
@EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class, DataSourceTransactionManagerAutoConfiguration.class, HibernateJpaAutoConfiguration.class})
public class SomeApplication {

public static void main(String[] args) {
    SpringApplication.run(SomeApplication.class, args);
}

}

And work for me! =)

How do I print a datetime in the local timezone?

Think your should look around: datetime.astimezone()

http://docs.python.org/library/datetime.html#datetime.datetime.astimezone

Also see pytz module - it's quite easy to use -- as example:

eastern = timezone('US/Eastern')

http://pytz.sourceforge.net/

Example:

from datetime import datetime
import pytz
from tzlocal import get_localzone # $ pip install tzlocal

utc_dt = datetime(2009, 7, 10, 18, 44, 59, 193982, tzinfo=pytz.utc)
print(utc_dt.astimezone(get_localzone())) # print local time
# -> 2009-07-10 14:44:59.193982-04:00

Escaping ampersand in URL

If you can't use any libraries to encode the value, http://www.urlencoder.org/ or http://www.urlencode-urldecode.com/ or ...

Just enter your value "M&M", not the full URL ;-)

sql use statement with variable

I case that someone need a solution for this, this is one:

if you use a dynamic USE statement all your query need to be dynamic, because it need to be everything in the same context.

You can try with SYNONYM, is basically an ALIAS to a specific Table, this SYNONYM is inserted into the sys.synonyms table so you have access to it from any context

Look this static statement:

CREATE SYNONYM MASTER_SCHEMACOLUMNS FOR Master.INFORMATION_SCHEMA.COLUMNS
SELECT * FROM MASTER_SCHEMACOLUMNS

Now dynamic:

DECLARE @SQL VARCHAR(200)
DECLARE @CATALOG VARCHAR(200) = 'Master'

IF EXISTS(SELECT * FROM  sys.synonyms s WHERE s.name = 'CURRENT_SCHEMACOLUMNS')
BEGIN
DROP SYNONYM CURRENT_SCHEMACOLUMNS
END

SELECT @SQL = 'CREATE SYNONYM CURRENT_SCHEMACOLUMNS FOR '+ @CATALOG +'.INFORMATION_SCHEMA.COLUMNS';
EXEC sp_sqlexec @SQL

--Your not dynamic Code
SELECT * FROM CURRENT_SCHEMACOLUMNS

Now just change the value of @CATALOG and you will be able to list the same table but from different catalog.

iOS9 getting error “an SSL error has occurred and a secure connection to the server cannot be made”

In my case I faced this issue in my simulator because my computer's date was behind of current date. So do check this case too when you face SSL error.

Adding null values to arraylist

Yes, you can always use null instead of an object. Just be careful because some methods might throw error.

It would be 1.

also nulls would be factored in in the for loop, but you could use

 for(Item i : itemList) {
        if (i!= null) {
               //code here
        }
 }

How do I perform query filtering in django templates

I run into this problem on a regular basis and often use the "add a method" solution. However, there are definitely cases where "add a method" or "compute it in the view" don't work (or don't work well). E.g. when you are caching template fragments and need some non-trivial DB computation to produce it. You don't want to do the DB work unless you need to, but you won't know if you need to until you are deep in the template logic.

Some other possible solutions:

  1. Use the {% expr <expression> as <var_name> %} template tag found at http://www.djangosnippets.org/snippets/9/ The expression is any legal Python expression with your template's Context as your local scope.

  2. Change your template processor. Jinja2 (http://jinja.pocoo.org/2/) has syntax that is almost identical to the Django template language, but with full Python power available. It's also faster. You can do this wholesale, or you might limit its use to templates that you are working on, but use Django's "safer" templates for designer-maintained pages.

Add data to JSONObject

The accepted answer by Francisco Spaeth works and is easy to follow. However, I think that method of building JSON sucks! This was really driven home for me as I converted some Python to Java where I could use dictionaries and nested lists, etc. to build JSON with ridiculously greater ease.

What I really don't like is having to instantiate separate objects (and generally even name them) to build up these nestings. If you have a lot of objects or data to deal with, or your use is more abstract, that is a real pain!

I tried getting around some of that by attempting to clear and reuse temp json objects and lists, but that didn't work for me because all the puts and gets, etc. in these Java objects work by reference not value. So, I'd end up with JSON objects containing a bunch of screwy data after still having some ugly (albeit differently styled) code.

So, here's what I came up with to clean this up. It could use further development, but this should help serve as a base for those of you looking for more reasonable JSON building code:

import java.util.AbstractMap.SimpleEntry;
import java.util.ArrayList;
import java.util.List;
import org.json.simple.JSONObject;

//  create and initialize an object 
public static JSONObject buildObject( final SimpleEntry... entries ) { 
    JSONObject object = new JSONObject();
    for( SimpleEntry e : entries ) object.put( e.getKey(), e.getValue() );
    return object;
}

//  nest a list of objects inside another                          
public static void putObjects( final JSONObject parentObject, final String key,
                               final JSONObject... objects ) { 
    List objectList = new ArrayList<JSONObject>();
    for( JSONObject o : objects ) objectList.add( o );
    parentObject.put( key, objectList );
}   

Implementation example:

JSONObject jsonRequest = new JSONObject();
putObjects( jsonRequest, "parent1Key",
    buildObject( 
        new SimpleEntry( "child1Key1", "someValue" )
      , new SimpleEntry( "child1Key2", "someValue" ) 
    )
  , buildObject( 
        new SimpleEntry( "child2Key1", "someValue" )
      , new SimpleEntry( "child2Key2", "someValue" ) 
    )
);      

android on Text Change Listener

check String before set another EditText to empty. if Field1 is empty then why need to change again to ( "" )? so you can check the size of Your String with s.lenght() or any other solution

another way that you can check lenght of String is:

String sUsername = Field1.getText().toString();
if (!sUsername.matches(""))
{
// do your job
}

Python, HTTPS GET with basic authentication

In Python 3 the following will work. I am using the lower level http.client from the standard library. Also check out section 2 of rfc2617 for details of basic authorization. This code won't check the certificate is valid, but will set up a https connection. See the http.client docs on how to do that.

from http.client import HTTPSConnection
from base64 import b64encode
#This sets up the https connection
c = HTTPSConnection("www.google.com")
#we need to base 64 encode it 
#and then decode it to acsii as python 3 stores it as a byte string
userAndPass = b64encode(b"username:password").decode("ascii")
headers = { 'Authorization' : 'Basic %s' %  userAndPass }
#then connect
c.request('GET', '/', headers=headers)
#get the response back
res = c.getresponse()
# at this point you could check the status etc
# this gets the page text
data = res.read()  

How to check if a "lateinit" variable has been initialized?

There is a lateinit improvement in Kotlin 1.2 that allows to check the initialization state of lateinit variable directly:

lateinit var file: File    

if (this::file.isInitialized) { ... }

See the annoucement on JetBrains blog or the KEEP proposal.

UPDATE: Kotlin 1.2 has been released. You can find lateinit enhancements here:

How do I pretty-print existing JSON data with Java?

Another way to use gson:

String json_String_to_print = ...
Gson gson = new GsonBuilder().setPrettyPrinting().create();
JsonParser jp = new JsonParser();
return gson.toJson(jp.parse(json_String_to_print));

It can be used when you don't have the bean as in susemi99's post.

How to put the legend out of the plot

To place the legend outside the plot area, use loc and bbox_to_anchor keywords of legend(). For example, the following code will place the legend to the right of the plot area:

legend(loc="upper left", bbox_to_anchor=(1,1))

For more info, see the legend guide

Different CURRENT_TIMESTAMP and SYSDATE in oracle

CURRENT_DATE and CURRENT_TIMESTAMP return the current date and time in the session time zone.

SYSDATE and SYSTIMESTAMP return the system date and time - that is, of the system on which the database resides.

If your client session isn't in the same timezone as the server the database is on (or says it isn't anyway, via your NLS settings), mixing the SYS* and CURRENT_* functions will return different values. They are all correct, they just represent different things. It looks like your server is (or thinks it is) in a +4:00 timezone, while your client session is in a +4:30 timezone.

You might also see small differences in the time if the clocks aren't synchronised, which doesn't seem to be an issue here.

Convert List<DerivedClass> to List<BaseClass>

To quote the great explanation of Eric

What happens? Do you want the list of giraffes to contain a tiger? Do you want a crash? or do you want the compiler to protect you from the crash by making the assignment illegal in the first place? We choose the latter.

But what if you want to choose for a runtime crash instead of a compile error? You would normally use Cast<> or ConvertAll<> but then you will have 2 problems: It will create a copy of the list. If you add or remove something in the new list, this won't be reflected in the original list. And secondly, there is a big performance and memory penalty since it creates a new list with the existing objects.

I had the same problem and therefore I created a wrapper class that can cast a generic list without creating an entirely new list.

In the original question you could then use:

class Test
{
    static void Main(string[] args)
    {
        A a = new C(); // OK
        IList<A> listOfA = new List<C>().CastList<C,A>(); // now ok!
    }
}

and here the wrapper class (+ an extention method CastList for easy use)

public class CastedList<TTo, TFrom> : IList<TTo>
{
    public IList<TFrom> BaseList;

    public CastedList(IList<TFrom> baseList)
    {
        BaseList = baseList;
    }

    // IEnumerable
    IEnumerator IEnumerable.GetEnumerator() { return BaseList.GetEnumerator(); }

    // IEnumerable<>
    public IEnumerator<TTo> GetEnumerator() { return new CastedEnumerator<TTo, TFrom>(BaseList.GetEnumerator()); }

    // ICollection
    public int Count { get { return BaseList.Count; } }
    public bool IsReadOnly { get { return BaseList.IsReadOnly; } }
    public void Add(TTo item) { BaseList.Add((TFrom)(object)item); }
    public void Clear() { BaseList.Clear(); }
    public bool Contains(TTo item) { return BaseList.Contains((TFrom)(object)item); }
    public void CopyTo(TTo[] array, int arrayIndex) { BaseList.CopyTo((TFrom[])(object)array, arrayIndex); }
    public bool Remove(TTo item) { return BaseList.Remove((TFrom)(object)item); }

    // IList
    public TTo this[int index]
    {
        get { return (TTo)(object)BaseList[index]; }
        set { BaseList[index] = (TFrom)(object)value; }
    }

    public int IndexOf(TTo item) { return BaseList.IndexOf((TFrom)(object)item); }
    public void Insert(int index, TTo item) { BaseList.Insert(index, (TFrom)(object)item); }
    public void RemoveAt(int index) { BaseList.RemoveAt(index); }
}

public class CastedEnumerator<TTo, TFrom> : IEnumerator<TTo>
{
    public IEnumerator<TFrom> BaseEnumerator;

    public CastedEnumerator(IEnumerator<TFrom> baseEnumerator)
    {
        BaseEnumerator = baseEnumerator;
    }

    // IDisposable
    public void Dispose() { BaseEnumerator.Dispose(); }

    // IEnumerator
    object IEnumerator.Current { get { return BaseEnumerator.Current; } }
    public bool MoveNext() { return BaseEnumerator.MoveNext(); }
    public void Reset() { BaseEnumerator.Reset(); }

    // IEnumerator<>
    public TTo Current { get { return (TTo)(object)BaseEnumerator.Current; } }
}

public static class ListExtensions
{
    public static IList<TTo> CastList<TFrom, TTo>(this IList<TFrom> list)
    {
        return new CastedList<TTo, TFrom>(list);
    }
}

CSS "color" vs. "font-color"

The same way Boston came up with its street plan. They followed the cow paths already there, and built houses where the streets weren't, and after a while it was too much trouble to change.

When to use "ON UPDATE CASCADE"

The ON UPDATE and ON DELETE specify which action will execute when a row in the parent table is updated and deleted. The following are permitted actions : NO ACTION, CASCADE, SET NULL, and SET DEFAULT.

Delete actions of rows in the parent table

If you delete one or more rows in the parent table, you can set one of the following actions:

  • ON DELETE NO ACTION: SQL Server raises an error and rolls back the delete action on the row in the parent table.
  • ON DELETE CASCADE: SQL Server deletes the rows in the child table that is corresponding to the row deleted from the parent table.
  • ON DELETE SET NULL: SQL Server sets the rows in the child table to NULL if the corresponding rows in the parent table are deleted. To execute this action, the foreign key columns must be nullable.
  • ON DELETE SET DEFAULT: SQL Server sets the rows in the child table to their default values if the corresponding rows in the parent table are deleted. To execute this action, the foreign key columns must have default definitions. Note that a nullable column has a default value of NULL if no default value specified. By default, SQL Server appliesON DELETE NO ACTION if you don’t explicitly specify any action.

Update action of rows in the parent table

If you update one or more rows in the parent table, you can set one of the following actions:

  • ON UPDATE NO ACTION: SQL Server raises an error and rolls back the update action on the row in the parent table.
  • ON UPDATE CASCADE: SQL Server updates the corresponding rows in the child table when the rows in the parent table are updated.
  • ON UPDATE SET NULL: SQL Server sets the rows in the child table to NULL when the corresponding row in the parent table is updated. Note that the foreign key columns must be nullable for this action to execute.
  • ON UPDATE SET DEFAULT: SQL Server sets the default values for the rows in the child table that have the corresponding rows in the parent table updated.
FOREIGN KEY (foreign_key_columns)
    REFERENCES parent_table(parent_key_columns)
    ON UPDATE <action> 
    ON DELETE <action>;

See the reference tutorial.