Programs & Examples On #Hungarian notation

Hungarian notation is a language-independent naming convention in which an identifier's prefix indicates its type. Examples include iCustomerId, sFirstName, etc.

Why shouldn't I use "Hungarian Notation"?

Several reasons:

  • Any modern IDE will give you the variable type by simply hovering your mouse over the variable.
  • Most type names are way long (think HttpClientRequestProvider) to be reasonably used as prefix.
  • The type information does not carry the right information, it is just paraphrasing the variable declaration, instead of outlining the purpose of the variable (think myInteger vs. pageSize).

What does `m_` variable prefix mean?

This is typical programming practice for defining variables that are member variables. So when you're using them later, you don't need to see where they're defined to know their scope. This is also great if you already know the scope and you're using something like intelliSense, you can start with m_ and a list of all your member variables are shown. Part of Hungarian notation, see the part about scope in the examples here.

Chosen Jquery Plugin - getting selected values

$("#select-id").chosen().val()

TypeError: You provided an invalid object where a stream was expected. You can provide an Observable, Promise, Array, or Iterable

In my case in Angular-5, service file was not imported from which i was accessing the method and subscribing the data.After importing service file it worked fine.

Twitter Bootstrap date picker

Much confusion stems from the existence of at least three major libraries named bootstrap-datepicker:

  1. A popular fork of eyecon's datepicker by Andrew 'eternicode' Rowls (use this one!):
  2. The original version by Stefan 'eyecon' Petre, still available at http://www.eyecon.ro/bootstrap-datepicker/
  3. A totally unrelated datepicker widget that 'storborg' sought to have merged into bootstrap. It wasn't merged and no proper release version of the widget was ever created.

If you're starting a new project - or heck, even if you're taking over an old project using the eyecon version - I recommend that you use eternicode's version, not eyecon's. The original eyecon version is outright inferior in terms of both functionality and documentation, and this is unlikely to change - it has not been updated since March 2013.

You can see most of the capabilities of the eternicode datepicker on the demo page which lets you play with the datepicker's configuration and observe the results. For more detail, see the succinct but comprehensive documentation, which you can probably consume in its entirety in under an hour.

In case you're impatient, though, here's a very short step-by-step guide to the simplest and most common use case for the datepicker.

Quick start guide

  1. Include the following libraries (minimum versions noted here) on your page:
  2. Put an input element on your page somewhere, e.g.

    <input id="my-date-input">
    
  3. With jQuery, select your input and call the .datepicker() method:

    jQuery('#my-date-input').datepicker();
    
  4. Load your page and click on or tab into your input element. A datepicker will appear:

    Picture of a datepicker

jQuery Mobile: document ready vs. page events

This is the correct way:

To execute code that will only be available to the index page, we could use this syntax:

$(document).on('pageinit', "#index",  function() {
    ...
});

How to remove all the occurrences of a char in c++ string

The algorithm std::replace works per element on a given sequence (so it replaces elements with different elements, and can not replace it with nothing). But there is no empty character. If you want to remove elements from a sequence, the following elements have to be moved, and std::replace doesn't work like this.

You can try to use std::remove (together with std::erase) to achieve this.

str.erase(std::remove(str.begin(), str.end(), 'a'), str.end());

Oracle: SQL query that returns rows with only numeric values

If you use Oracle 10 or higher you can use regexp functions as codaddict suggested. In earlier versions translate function will help you:

select * from tablename  where translate(x, '.1234567890', '.') is null;

More info about Oracle translate function can be found here or in official documentation "SQL Reference"

UPD: If you have signs or spaces in your numbers you can add "+-" characters to the second parameter of translate function.

How to create war files

Another option would be to build it automatically using Eclipse. Of course if you have continuous integration environment Ant or Maven is recommended. The export alternative is not very convenient because you have to configure every time the export properties.

STEPS:

  1. Enable "Project Archives" support; this might depend on your project (I used it on Java EE/Web project). Right-click project root directory; Configure -> Add Project Archives Support.

  2. Go and create a new archive in the "Project Archives" top dir. You have only jar option, but name you archive *.war.

  3. Configure Fileset-s, i.e what files to be included. Typical is to configure two filesets similar how the Web Deployment Assembly (project property) is configured.

    • copy /WebContent to /
    • copy /build/classes to WEB-INF/classes (create this fileset after you define the WEB-INF/classes directory in the archive)
  4. You might need to tweek the fileset exclude property depending where you placed some of the config files or you might need more filesets, but the idea is that once you configured this you don't need to change it.

  5. Build the archive manually or publish directly to server; but is also automatically built for you by Eclipse

How to get all keys with their values in redis

scan 0 MATCH * COUNT 1000 // it gets all the keys if return is "0" as first element then count is less than 1000 if more then it will return the pointer as first element and >scan pointer_val MATCH * COUNT 1000 to get the next set of keys it continues till the first value is "0".

Bootstrap 3 only for mobile

I found a solution wich is to do:

<span class="visible-sm"> your code without col </span>
<span class="visible-xs"> your code with col </span>

It's not very optimized but it works. Did you find something better? It really miss a class like col-sm-0 to apply colons just to the xs size...

\r\n, \r and \n what is the difference between them?

A carriage return (\r) makes the cursor jump to the first column (begin of the line) while the newline (\n) jumps to the next line and eventually to the beginning of that line. So to be sure to be at the first position within the next line one uses both.

Is there a CSS parent selector?

The pseudo element :focus-within allows a parent to be selected if a descendent has focus.

An element can be focused if it has a tabindex attribute.

Browser support for focus-within

Tabindex

Example

_x000D_
_x000D_
.click {_x000D_
  cursor: pointer;_x000D_
}_x000D_
_x000D_
.color:focus-within .change {_x000D_
  color: red;_x000D_
}_x000D_
_x000D_
.color:focus-within p {_x000D_
  outline: 0;_x000D_
}
_x000D_
<div class="color">_x000D_
  <p class="change" tabindex="0">_x000D_
    I will change color_x000D_
  </p>_x000D_
  <p class="click" tabindex="1">_x000D_
    Click me_x000D_
  </p>_x000D_
</div>
_x000D_
_x000D_
_x000D_

Cannot implicitly convert type 'System.Collections.Generic.IEnumerable<AnonymousType#1>' to 'System.Collections.Generic.List<string>

If you want it to be List<string>, get rid of the anonymous type and add a .ToList() call:

List<string> list = (from char c in source
                     select c.ToString()).ToList();

pycharm running way slow

I found a solution to this problem that works beautifully on Windows, and wanted to share it.

Solutions that didn't work: I have 16GB of RAM and was still having horrible lag. PyCharm takes less than 1GB of RAM for me, so that wasn't the issue. Turning off inspections didn't help at all, and I didn't have any special plugins that I recall. I also tried playing around with CPU affinities for the process, which briefly worked but not really.

What worked beautifully, almost perfectly:

  1. Set PyCharm's CPU priority to Above Normal
  2. Set the CPU priority for Python processes to Below Normal

You can do this manually, but I recommend using a program which will preserve the setting across restarts and for multiple instances. I used Process Hacker: Right click on the process -> Priority -> Set the priority. Then right click again -> Process -> and select "Save for pycharm64.exe" and similarly for python "Save for python.exe." Finally in Process Hacker go to Options and select "Start when I log on." This will make it so that ALL Pycharm and python executables acquire these CPU priorities, even after restarting the program and/or Windows, and no matter how many python instances you launch.

Basically, much of the PyCharm's lag may be due to conflict with other programs. Think about it: Yes PyCharm requires a lot of CPU, but the PyCharm developers aren't stupid. They have probably at least ensured it can run without lag on an empty core. But now you open Chrome and 30 tabs, Fiddler, an FTP program, iTunes, Word, Slack, etc, and they all compete with PyCharm at the same CPU priority level. Whenever the sum of all programs > 100% on a core, you see lag. Switching to Above Normal priority gives PyCharm something closer to the empty core that it was probably tested on.

As for Below Normal on python.exe, basically you don't want to slow your computer down with your own development. Most python programs are essentially "batch" programs, and you probably won't notice the extra time it takes to run. I don't recommend this if you are developing a graphical interactive program.

ORDER BY date and time BEFORE GROUP BY name in mysql

This is not the exact answer, but this might be helpful for the people looking to solve some problem with the approach of ordering row before group by in mysql.

I came to this thread, when I wanted to find the latest row(which is order by date desc but get the only one result for a particular column type, which is group by column name).

One other approach to solve such problem is to make use of aggregation.

So, we can let the query run as usual, which sorted asc and introduce new field as max(doc) as latest_doc, which will give the latest date, with grouped by the same column.

Suppose, you want to find the data of a particular column now and max aggregation cannot be done. In general, to finding the data of a particular column, you can make use of GROUP_CONCAT aggregator, with some unique separator which can't be present in that column, like GROUP_CONCAT(string SEPARATOR ' ') as new_column, and while you're accessing it, you can split/explode the new_column field.

Again, this might not sound to everyone. I did it, and liked it as well because I had written few functions and I couldn't run subqueries. I am working on codeigniter framework for php.

Not sure of the complexity as well, may be someone can put some light on that.

Regards :)

How to position the Button exactly in CSS

It seems some what center of the screen. So I would like to do like this

body { 
     background: url('http://oi44.tinypic.com/33tjudk.jpg') no-repeat center center fixed;    
     background-size:cover; 
     text-align: 0 auto; // Make the play button horizontal center
}

#play_button {
    position:absolute;  // absolutely positioned
    transition: .5s ease;
    top: 50%;  // Makes vertical center
} 

Get installed applications in a system

Your best bet is to use WMI. Specifically the Win32_Product class.

Find provisioning profile in Xcode 5

I found a way to find out how your provisioning profile is named. Select the profile that you want in the code sign section in the build settings, then open the selection view again and click on "other" at the bottom. Then occur a view with the naming of the current selected provisioning profile.

You can now find the profile file on the path:

~/Library/MobileDevice/Provisioning Profiles

Update:

For Terminal:

cd ~/Library/MobileDevice/Provisioning\ Profiles

How to find files modified in last x minutes (find -mmin does not work as expected)

Actually, there's more than one issue here. The main one is that xargs by default executes the command you specified, even when no arguments have been passed. To change that you might use a GNU extension to xargs:

--no-run-if-empty
-r
If the standard input does not contain any nonblanks, do not run the command. Normally, the command is run once even if there is no input. This option is a GNU extension.

Simple example:

find . -mmin -60 | xargs -r ls -l

But this might match to all subdirectories, including . (the current directory), and ls will list each of them individually. So the output will be a mess. Solution: pass -d to ls, which prohibits listing the directory contents:

find . -mmin -60 | xargs -r ls -ld

Now you don't like . (the current directory) in your list? Solution: exclude the first directory level (0) from find output:

find . -mindepth 1 -mmin -60 | xargs -r ls -ld

Now you'd need only the files in your list? Solution: exclude the directories:

find . -type f -mmin -60 | xargs -r ls -l

Now you have some files with names containing white space, quote marks, or backslashes? Solution: use null-terminated output (find) and input (xargs) (these are also GNU extensions, afaik):

find . -type f -mmin -60 -print0 | xargs -r0 ls -l

How can I parse JSON with C#?

         string json = @"{
            'Name': 'Wide Web',
            'Url': 'www.wideweb.com.br'}";

        JavaScriptSerializer jsonSerializer = new JavaScriptSerializer();
        dynamic j = jsonSerializer.Deserialize<dynamic>(json);
        string name = j["Name"].ToString();
        string url = j["Url"].ToString();

How is a JavaScript hash map implemented?

Here is an easy and convenient way of using something similar to the Java map:

var map= {
    'map_name_1': map_value_1,
    'map_name_2': map_value_2,
    'map_name_3': map_value_3,
    'map_name_4': map_value_4
    }

And to get the value:

alert( map['map_name_1'] );    // fives the value of map_value_1

......  etc  .....

jQuery UI DatePicker to show year only

**NOTE : **If anyone have objection that "why i have answered this Question now !" Because i tried all the answers of this post and got no any solution.So i tried my way and got Solution So i am Sharing to next comers****

HTML

<label for="startYear"> Start Year: </label>
  <input name="startYear" id="startYear" class="date-picker-year" />   

jQuery

 <script type="text/javascript">
        $(function() {
            $('.date-picker-year').datepicker({
                changeYear: true,
                showButtonPanel: true,
                dateFormat: 'yy',
                onClose: function(dateText, inst) { 
                    var year = $("#ui-datepicker-div .ui-datepicker-year :selected").val();
                    $(this).datepicker('setDate', new Date(year, 1));
                }
            });
        $(".date-picker-year").focus(function () {
                $(".ui-datepicker-month").hide();
            });
        });

</script>

What is a lambda (function)?

Lambda explained for everyone:

Lambda is an annonymous function. This means lambda is a function objekt in Python that doesnt require a reference before. Let's concider this bit of code here:

def name_of_func():
    #command/instruction
    print('hello')

print(type(name_of_func))   #the name of the function is a reference
                            #the reference contains a function Objekt with command/instruction

To proof my proposition I print out the type of name_of_func which returns us:

<class 'function'>

A function must have a interface, but a interface dosent needs to contain something. What does this mean? Let's look a little bit closer to our function and we may notice that out of the name of the functions there are some more details we need to explain to understand what a function is.

A regular function will be defined with the syntax "def", then we type in the name and settle the interface with "()" and ending our definition by the syntax ":". Now we enter the functions body with our instructions/commands.

So let's consider this bit of code here:

def print_my_argument(x):
    print(x)


print_my_argument('Hello')

In this case we run our function, named "print_my_argument" and passing a parameter/argument through the interface. The Output will be:

Hello

So now that we know what a function is and how the architecture works for a function, we can take a look to an annonymous function. Let's consicder this bit of code here:

def name_of_func():
    print('Hello')



lambda: print('Hello')

these function objekts are pretty much the same except of the fact that the upper, regular function have a name and the other function is an annonymous one. Let's take a closer look on our annonymous function, to understand how to use it.

So let's concider this bit of code here:

def delete_last_char(arg1=None):
    print(arg1[:-1])

string = 'Hello World'
delete_last_char(string)

f = lambda arg1=None: print(arg1[:-1])
f(string)

So what we have done in the above code is to write once againg, a regular function and an anonymous function. Our anonymous function we had assignd to a var, which is pretty much the same as to give this function a name. Anyway, the output will be:

Hello Worl
Hello Worl

To fully proof that lambda is a function object and doesnt just mimik a function we run this bit of code here:

string = 'Hello World'
f = lambda arg1=string: print(arg1[:-1])
f()
print(type(f))

and the Output will be:

Hello Worl
<class 'function'>

Last but not least you should know that every function in python needs to return something. If nothing is defined in the body of the function, None will be returned by default. look at this bit of code here:

def delete_last_char(arg1):
    print(arg1[:-1])

string = 'Hello World'
x = delete_last_char(string)

f = lambda arg1=string: print(arg1[:-1])
x2 = f()

print(x)
print(x2)

Output will be:

Hello Worl
Hello Worl
None
None

Is there a way to 'uniq' by column?

sort -u -t, -k1,1 file
  • -u for unique
  • -t, so comma is the delimiter
  • -k1,1 for the key field 1

Test result:

[email protected],2009-11-27 00:58:29.793000000,xx3.net,255.255.255.0 
[email protected],2009-11-27 01:05:47.893000000,xx2.net,127.0.0.1 

Replace String in all files in Eclipse

ctrl + H  will show the option to replace in the bottom . 

enter image description here

Once you click on replace it will show as below

enter image description here

Remove duplicated rows

Here's a very simple, fast dplyr/tidy solution:

Remove rows that are entirely the same:

library(dplyr)
iris %>% 
  distinct(.keep_all = TRUE)

Remove rows that are the same only in certain columns:

iris %>% 
  distinct(Sepal.Length, Sepal.Width, .keep_all = TRUE)

Saving image from PHP URL

Create a folder named images located in the path you are planning to place the php script you are about to create. Make sure it has write rights for everybody or the scripts won't work ( it won't be able to upload the files into the directory).

Fastest way to serialize and deserialize .NET objects

Here's your model (with invented CT and TE) using protobuf-net (yet retaining the ability to use XmlSerializer, which can be useful - in particular for migration); I humbly submit (with lots of evidence if you need it) that this is the fastest (or certainly one of the fastest) general purpose serializer in .NET.

If you need strings, just base-64 encode the binary.

[XmlType]
public class CT {
    [XmlElement(Order = 1)]
    public int Foo { get; set; }
}
[XmlType]
public class TE {
    [XmlElement(Order = 1)]
    public int Bar { get; set; }
}
[XmlType]
public class TD {
    [XmlElement(Order=1)]
    public List<CT> CTs { get; set; }
    [XmlElement(Order=2)]
    public List<TE> TEs { get; set; }
    [XmlElement(Order = 3)]
    public string Code { get; set; }
    [XmlElement(Order = 4)]
    public string Message { get; set; }
    [XmlElement(Order = 5)]
    public DateTime StartDate { get; set; }
    [XmlElement(Order = 6)]
    public DateTime EndDate { get; set; }

    public static byte[] Serialize(List<TD> tData) {
        using (var ms = new MemoryStream()) {
            ProtoBuf.Serializer.Serialize(ms, tData);
            return ms.ToArray();
        }            
    }

    public static List<TD> Deserialize(byte[] tData) {
        using (var ms = new MemoryStream(tData)) {
            return ProtoBuf.Serializer.Deserialize<List<TD>>(ms);
        }
    }
}

Find the most popular element in int[] array

This one without maps:

public class Main {       

    public static void main(String[] args) {
        int[] a = new int[]{ 1, 2, 3, 4, 5, 6, 7, 7, 7, 7 };
        System.out.println(getMostPopularElement(a));        
    }

    private static int getMostPopularElement(int[] a) {             
        int maxElementIndex = getArrayMaximumElementIndex(a); 
        int[] b = new int[a[maxElementIndex] + 1]

        for (int i = 0; i < a.length; i++) {
            ++b[a[i]];
        }

        return getArrayMaximumElementIndex(b);
    }

    private static int getArrayMaximumElementIndex(int[] a) {
        int maxElementIndex = 0;

        for (int i = 1; i < a.length; i++) {
            if (a[i] >= a[maxElementIndex]) {
                maxElementIndex = i;
            }
        }

        return maxElementIndex;
    }      

}

You only have to change some code if your array can have elements which are < 0. And this algorithm is useful when your array items are not big numbers.

Git Bash won't run my python files?

Adapting the PATH should work. Just tried on my Git bash:

$ python --version
sh.exe": python: command not found

$ PATH=$PATH:/c/Python27/

$ python --version
Python 2.7.6

In particular, only provide the directory; don't specify the .exe on the PATH ; and use slashes.

C# delete a folder and all files and folders within that folder

Try This:

foreach (string files in Directory.GetFiles(SourcePath))
{
   FileInfo fileInfo = new FileInfo(files);
   fileInfo.Delete(); //delete the files first. 
}
Directory.Delete(SourcePath);// delete the directory as it is empty now.

Search for string within text column in MySQL

SELECT * FROM items WHERE `items.xml` LIKE '%123456%'

The % operator in LIKE means "anything can be here".

Local storage in Angular 2

The syntax of set item is

localStorage.setItem(key,value);

The syntax of get item is

localStorage.getItem(key); 

An example of this is:

localStorage.setItem('email','[email protected]');
    let mail = localStorage.getItem("email");
    if(mail){ 
       console.log('your email id is', mail);
    }
  }

How to use a SQL SELECT statement with Access VBA

If you wish to use the bound column value, you can simply refer to the combo:

sSQL = "SELECT * FROM MyTable WHERE ID = " & Me.MyCombo

You can also refer to the column property:

sSQL = "SELECT * FROM MyTable WHERE AText = '" & Me.MyCombo.Column(1) & "'"

Dim rs As DAO.Recordset     
Set rs = CurrentDB.OpenRecordset(sSQL)

strText = rs!AText
strText = rs.Fields(1)

In a textbox:

= DlookUp("AText","MyTable","ID=" & MyCombo)

*edited

Create a Bitmap/Drawable from file path

Create bitmap from file path:

File sd = Environment.getExternalStorageDirectory();
File image = new File(sd+filePath, imageName);
BitmapFactory.Options bmOptions = new BitmapFactory.Options();
Bitmap bitmap = BitmapFactory.decodeFile(image.getAbsolutePath(),bmOptions);
bitmap = Bitmap.createScaledBitmap(bitmap,parent.getWidth(),parent.getHeight(),true);
imageView.setImageBitmap(bitmap);

If you want to scale the bitmap to the parent's height and width then use Bitmap.createScaledBitmap function.

I think you are giving the wrong file path. :) Hope this helps.

Alternative to google finance api

Updating answer a bit

1. Try Twelve Data API

For beginners try to run the following query with a JSON response:

https://api.twelvedata.com/time_series?symbol=AAPL&interval=1min&apikey=demo&source=docs

NO more real time Alpha Vantage API

For beginners you can try to get a JSON output from query such as

https://www.alphavantage.co/query?function=TIME_SERIES_DAILY&symbol=MSFT&apikey=demo

DON'T Try Yahoo Finance API (it is DEPRECATED or UNAVAILABLE NOW).

For beginners, you can generate a CSV with a simple API call:

http://finance.yahoo.com/d/quotes.csv?s=AAPL+GOOG+MSFT&f=sb2b3jk

(This will generate and save a CSV for AAPL, GOOG, and MSFT)

Note that you must append the format to the query string (f=..). For an overview of all of the formats see this page.

For more examples, visit this page.

For XML and JSON-based data, you can do the following:

Don't use YQL (Yahoo Query Language)

For example:

http://developer.yahoo.com/yql/console/?q=select%20*%20from%20yahoo.finance
.quotes%20where%20symbol%20in%20(%22YHOO%22%2C%22AAPL%22%2C%22GOOG%22%2C%22
MSFT%22)%0A%09%09&env=http%3A%2F%2Fdatatables.org%2Falltables.env

2. Use the webservice

For example, to get all stock quotes in XML:

http://finance.yahoo.com/webservice/v1/symbols/allcurrencies/quote

To get all stock quotes in JSON, just add format=JSON to the end of the URL:

http://finance.yahoo.com/webservice/v1/symbols/allcurrencies/quote?format=json

Alternatives:

  1. Currency API

    • 165+ real time currency rates, including few cryptos. Docs here.
  2. Financial Content API

  3. IEX

  4. Open Exchange Rates

  5. Polygon

  6. XE API

  7. Xignite API

  8. currencylayer API

  9. Other APIs - discussed at programmableWeb

Functional style of Java 8's Optional.ifPresent and if-not-Present?

You cannot call orElse after ifPresent, the reason is, orElse is called on an optiional but ifPresent returns void. So the best approach to achieve is ifPresentOrElse. It could be like this:

op.ifPresentOrElse( 
            (value) 
                -> { System.out.println( 
                         "Value is present, its: "
                         + value); }, 
            () 
                -> { System.out.println( 
                         "Value is empty"); }); 

Clear dropdownlist with JQuery

How about storing the new options in a variable, and then using .html(variable) to replace the data in the container?

PHP: check if any posted vars are empty - form: all fields required

I use my own custom function...

public function areNull() {
    if (func_num_args() == 0) return false;
    $arguments = func_get_args();
    foreach ($arguments as $argument):
        if (is_null($argument)) return true;
    endforeach;
    return false;
}
$var = areNull("username", "password", "etc");

I'm sure it can easily be changed for you scenario. Basically it returns true if any of the values are NULL, so you could change it to empty or whatever.

How to use XPath in Python?

If you want to have the power of XPATH combined with the ability to also use CSS at any point you can use parsel:

>>> from parsel import Selector
>>> sel = Selector(text=u"""<html>
        <body>
            <h1>Hello, Parsel!</h1>
            <ul>
                <li><a href="http://example.com">Link 1</a></li>
                <li><a href="http://scrapy.org">Link 2</a></li>
            </ul
        </body>
        </html>""")
>>>
>>> sel.css('h1::text').extract_first()
'Hello, Parsel!'
>>> sel.xpath('//h1/text()').extract_first()
'Hello, Parsel!'

Capturing multiple line output into a Bash variable

In addition to the answer given by @l0b0 I just had the situation where I needed to both keep any trailing newlines output by the script and check the script's return code. And the problem with l0b0's answer is that the 'echo x' was resetting $? back to zero... so I managed to come up with this very cunning solution:

RESULTX="$(./myscript; echo x$?)"
RETURNCODE=${RESULTX##*x}
RESULT="${RESULTX%x*}"

Hamcrest compare collections

Make sure that the Objects in your list have equals() defined on them. Then

assertThat(generatedList, is(equalTo(expectedList)));

works.

MySQL: Insert record if not exists in table

I had a similar problem and I needed to insert multiple if not existing. So from the examples above I came to this combination... it's here just in case somebody would need it.

Notice: I had to define name everywhere as MSSQL required it... MySQL works with * too.

INSERT INTO names (name)
SELECT name
FROM
(
  SELECT name
  FROM
  (
     SELECT 'Test 4' as name
  ) AS tmp_single
  WHERE NOT EXISTS
  (
     SELECT name FROM names WHERE name = 'Test 4'
  )
  UNION ALL
  SELECT name
  FROM
  (
     SELECT 'Test 5' as name
  ) AS tmp_single
  WHERE NOT EXISTS
  (
     SELECT name FROM names WHERE name = 'Test 5'
  )
) tmp_all;

MySQL: CREATE TABLE names ( OID int(11) NOT NULL AUTO_INCREMENT, name varchar(32) COLLATE utf8_unicode_ci NOT NULL, PRIMARY KEY (OID), UNIQUE KEY name_UNIQUE (name) ) ENGINE=InnoDB AUTO_INCREMENT=1;

or

MSSQL: CREATE TABLE [names] ( [OID] INT IDENTITY (1, 1) NOT NULL, [name] NVARCHAR (32) NOT NULL, PRIMARY KEY CLUSTERED ([OID] ASC) ); CREATE UNIQUE NONCLUSTERED INDEX [Index_Names_Name] ON [names]([name] ASC);

How Do I 'git fetch' and 'git merge' from a Remote Tracking Branch (like 'git pull')

You don't fetch a branch, you fetch an entire remote:

git fetch origin
git merge origin/an-other-branch

How can I one hot encode in Python?

Much easier to use Pandas for basic one-hot encoding. If you're looking for more options you can use scikit-learn.

For basic one-hot encoding with Pandas you pass your data frame into the get_dummies function.

For example, if I have a dataframe called imdb_movies:

enter image description here

...and I want to one-hot encode the Rated column, I do this:

pd.get_dummies(imdb_movies.Rated)

enter image description here

This returns a new dataframe with a column for every "level" of rating that exists, along with either a 1 or 0 specifying the presence of that rating for a given observation.

Usually, we want this to be part of the original dataframe. In this case, we attach our new dummy coded frame onto the original frame using "column-binding.

We can column-bind by using Pandas concat function:

rated_dummies = pd.get_dummies(imdb_movies.Rated)
pd.concat([imdb_movies, rated_dummies], axis=1)

enter image description here

We can now run an analysis on our full dataframe.

SIMPLE UTILITY FUNCTION

I would recommend making yourself a utility function to do this quickly:

def encode_and_bind(original_dataframe, feature_to_encode):
    dummies = pd.get_dummies(original_dataframe[[feature_to_encode]])
    res = pd.concat([original_dataframe, dummies], axis=1)
    return(res)

Usage:

encode_and_bind(imdb_movies, 'Rated')

Result:

enter image description here

Also, as per @pmalbu comment, if you would like the function to remove the original feature_to_encode then use this version:

def encode_and_bind(original_dataframe, feature_to_encode):
    dummies = pd.get_dummies(original_dataframe[[feature_to_encode]])
    res = pd.concat([original_dataframe, dummies], axis=1)
    res = res.drop([feature_to_encode], axis=1)
    return(res) 

You can encode multiple features at the same time as follows:

features_to_encode = ['feature_1', 'feature_2', 'feature_3',
                      'feature_4']
for feature in features_to_encode:
    res = encode_and_bind(train_set, feature)

Error:(9, 5) error: resource android:attr/dialogCornerRadius not found

This error occurs because of mismatched compileSdkVersion and library version.

for example:

compileSdkVersion 27
implementation 'com.android.support:appcompat-v7:26.1.0'
implementation 'com.android.support:design:26.1.0'

and also avoid to use + sign with library as in the following:

implementation 'com.android.support:appcompat-v7:26.+'

use exact library version like this

implementation 'com.android.support:appcompat-v7:26.1.0'

Using + sign with the library makes it difficult for the building process to gather the exact version that is required, making system unstable, hence should be discouraged.

Convert HTML string to image

Try the following:

using System;
using System.Drawing;
using System.Threading;
using System.Windows.Forms;

class Program
{
    static void Main(string[] args)
    {
        var source =  @"
        <!DOCTYPE html>
        <html>
            <body>
                <p>An image from W3Schools:</p>
                <img 
                    src=""http://www.w3schools.com/images/w3schools_green.jpg"" 
                    alt=""W3Schools.com"" 
                    width=""104"" 
                    height=""142"">
            </body>
        </html>";
        StartBrowser(source);
        Console.ReadLine();
    }

    private static void StartBrowser(string source)
    {
        var th = new Thread(() =>
        {
            var webBrowser = new WebBrowser();
            webBrowser.ScrollBarsEnabled = false;
            webBrowser.DocumentCompleted +=
                webBrowser_DocumentCompleted;
            webBrowser.DocumentText = source;
            Application.Run();
        });
        th.SetApartmentState(ApartmentState.STA);
        th.Start();
    }

    static void 
        webBrowser_DocumentCompleted(
        object sender, 
        WebBrowserDocumentCompletedEventArgs e)
    {
        var webBrowser = (WebBrowser)sender;
        using (Bitmap bitmap = 
            new Bitmap(
                webBrowser.Width, 
                webBrowser.Height))
        {
            webBrowser
                .DrawToBitmap(
                bitmap, 
                new System.Drawing
                    .Rectangle(0, 0, bitmap.Width, bitmap.Height));
            bitmap.Save(@"filename.jpg", 
                System.Drawing.Imaging.ImageFormat.Jpeg);
        }
    }
}

Note: Credits should go to Hans Passant for his excellent answer on the question WebBrowser Control in a new thread which inspired this solution.

Python equivalent to 'hold on' in Matlab

Just call plt.show() at the end:

import numpy as np
import matplotlib.pyplot as plt

plt.axis([0,50,60,80])
for i in np.arange(1,5):
    z = 68 + 4 * np.random.randn(50)
    zm = np.cumsum(z) / range(1,len(z)+1)
    plt.plot(zm)    

n = np.arange(1,51)
su = 68 + 4 / np.sqrt(n)
sl = 68 - 4 / np.sqrt(n)

plt.plot(n,su,n,sl)

plt.show()

Failed to load ApplicationContext (with annotation)

In my case, I had to do the following while running with Junit5

@SpringBootTest(classes = {abc.class}) @ExtendWith(SpringExtension.class

Here abc.class was the class that was being tested

How to switch a user per task or set of tasks?

In Ansible >1.4 you can actually specify a remote user at the task level which should allow you to login as that user and execute that command without resorting to sudo. If you can't login as that user then the sudo_user solution will work too.

---
- hosts: webservers
  remote_user: root
  tasks:
    - name: test connection
      ping:
      remote_user: yourname

See http://docs.ansible.com/playbooks_intro.html#hosts-and-users

Search for string and get count in vi editor

You need the n flag. To count words use:

:%s/\i\+/&/gn   

and a particular word:

:%s/the/&/gn        

See count-items documentation section.

If you simply type in:

%s/pattern/pattern/g

then the status line will give you the number of matches in vi as well.

Getting realtime output using subprocess

Using pexpect with non-blocking readlines will resolve this problem. It stems from the fact that pipes are buffered, and so your app's output is getting buffered by the pipe, therefore you can't get to that output until the buffer fills or the process dies.

How to execute an SSIS package from .NET?

You can use this Function if you have some variable in the SSIS.

    Package pkg;

    Microsoft.SqlServer.Dts.Runtime.Application app;
    DTSExecResult pkgResults;
    Variables vars;

    app = new Microsoft.SqlServer.Dts.Runtime.Application();
    pkg = app.LoadPackage(" Location of your SSIS package", null);

    vars = pkg.Variables;

    // your variables
    vars["somevariable1"].Value = "yourvariable1";
    vars["somevariable2"].Value = "yourvariable2";

    pkgResults = pkg.Execute(null, vars, null, null, null);

    if (pkgResults == DTSExecResult.Success)
    {
        Console.WriteLine("Package ran successfully");
    }
    else
    {

        Console.WriteLine("Package failed");
    }

How can I ssh directly to a particular directory?

Based on additions to @rogeriopvl's answer, I suggest the following:

ssh -t xxx.xxx.xxx.xxx "cd /directory_wanted && bash"

Chaining commands by && will make the next command run only when the previous one was successful (as opposed to using ;, which executes commands sequentially). This is particularly useful when needing to cd to a directory performing the command.

Imagine doing the following:

/home/me$ cd /usr/share/teminal; rm -R *

The directory teminal doesn't exist, which causes you to stay in the home directory and remove all the files in there with the following command.

If you use &&:

/home/me$ cd /usr/share/teminal && rm -R *

The command will fail after not finding the directory.

How to install MySQLdb package? (ImportError: No module named setuptools)

#!/usr/bin/env python

import os
import sys
from **distutils.core** import setup, Extension

if sys.version_info < (2, 3):
    raise Error("Python-2.3 or newer is required")

if os.name == "posix":
    from setup_posix import get_config
else: # assume windows
    from setup_windows import get_config

metadata, options = get_config()
metadata['ext_modules'] = [Extension(sources=['_mysql.c'], **options)]
metadata['long_description'] = metadata['long_description'].replace(r'\n', '')
setup(**metadata)

ORA-12154 could not resolve the connect identifier specified

I have an Entity Framework web application that works on my local machine, but this error appears when pushed to another environment. There are other non-Entity Framework applications that work, and I'm able to connect with sqlplus.

Using sysinternals Process Monitor shows that tns names file is not being loaded correctly:

tnsnames.ora status NAME NOT FOUND

Following the documentation I tried to add a section giving the location of the tnsnames file like so:

<configuration>

  <configSections>
    <section name="oracle.manageddataaccess.client"
      type="OracleInternal.Common.ODPMSectionHandler, Oracle.ManagedDataAccess, Version=4.122.1.0, Culture=neutral, PublicKeyToken=89b483f429c47342"/>
  </configSections>
  
  <oracle.manageddataaccess.client>
    <version number="*">
      <settings>
        <setting name="TNS_ADMIN" value="C:\Oracle\product\12.1.0\client_1\Network\Admin"/>
      </settings>
    </version>
  </oracle.manageddataaccess.client>
  
<configuration>

However, this resulted in an immediate 500 server error.

Further investigation showed that the dll I was packaging with the web application was version 4.122.1.0, while the Oracle client environment installed on the machine was 4.121.2.0. As explained in the Oracle EntityFramework package documentation

Note: If your application is a web application and the above entry was added to a web.config and the same config section handler for "oracle.manageddataaccess.client" also exists in machine.config but the "Version" attribute values are different, an error message of "There is a duplicate 'oracle.manageddataaccess.client' section defined." may be observed at runtime. If so, the config section handler entry in the machine.config for "oracle.manageddataaccess.client" has to be removed from the machine.config for the web application to not encounter this error. But given that there may be other applications on the machine that depended on this entry in the machine.config, this config section handler entry may need to be moved to all of the application's .NET config file on that machine that depend on it.

I attempted to add a separate version section in the .NET machine.config without success (there existed a section for version 4.121.2.0 and I added a section for version 4.122.1.0). After I removed the "oracle.manageddataaccess.client" section from the machine.config, the above addition to the web.config resolved ORA-12154.

Solution #1 summary:

  1. Remove "oracle.manageddataaccess.client" from .NET machine.config
  2. Give TNS_ADMIN configuration setting in web.config as above

Solution 2

While researching this problem I found that the TNS_ADMIN environmental variable was not set. I created a new environmental variable called TNS_ADMIN and set the value to "C:\Oracle\product\12.1.0\client_1\Network\Admin". I removed the web.config changes, and removed the "oracle.manageddataaccess.client" section from .NET machine.config, but still received ORA-12154. Only after I restarted the machine did this resolve the issue.

Solution #2 summary:

  1. Create a new environmental variable called TNS_ADMIN and set the value to "C:\Oracle\product\12.1.0\client_1\Network\Admin"
  2. Restart machine

Solution 3

I added an entry for the correct version in the registry and this resolved the issue:

HKLM\Software\Wow6432Node\Oracle\ODP.NET.Managed\4.121.2.0  

The name of the key is TNS_ADMIN and this points to the folder containing the tnsnames file:

C:\Oracle\product\12.1.0\client_1\network 

Not the C:\Oracle\product\12.1.0\client_1\network\admin folder.

Getting request payload from POST request in Java servlet

You can use Buffer Reader from request to read

    // Read from request
    StringBuilder buffer = new StringBuilder();
    BufferedReader reader = request.getReader();
    String line;
    while ((line = reader.readLine()) != null) {
        buffer.append(line);
        buffer.append(System.lineSeparator());
    }
    String data = buffer.toString()

Sending a JSON HTTP POST request from Android

try some thing like blow:

SString otherParametersUrServiceNeed =  "Company=acompany&Lng=test&MainPeriod=test&UserID=123&CourseDate=8:10:10";
String request = "http://android.schoolportal.gr/Service.svc/SaveValues";

URL url = new URL(request); 
HttpURLConnection connection = (HttpURLConnection) url.openConnection();   
connection.setDoOutput(true);
connection.setDoInput(true);
connection.setInstanceFollowRedirects(false); 
connection.setRequestMethod("POST"); 
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); 
connection.setRequestProperty("charset", "utf-8");
connection.setRequestProperty("Content-Length", "" + Integer.toString(otherParametersUrServiceNeed.getBytes().length));
connection.setUseCaches (false);

DataOutputStream wr = new DataOutputStream(connection.getOutputStream ());
wr.writeBytes(otherParametersUrServiceNeed);

   JSONObject jsonParam = new JSONObject();
jsonParam.put("ID", "25");
jsonParam.put("description", "Real");
jsonParam.put("enable", "true");

wr.writeBytes(jsonParam.toString());

wr.flush();
wr.close();

References :

  1. http://www.xyzws.com/Javafaq/how-to-use-httpurlconnection-post-data-to-web-server/139
  2. Java - sending HTTP parameters via POST method easily

How do you create a custom AuthorizeAttribute in ASP.NET Core?

As of this writing I believe this can be accomplished with the IClaimsTransformation interface in asp.net core 2 and above. I just implemented a proof of concept which is sharable enough to post here.

public class PrivilegesToClaimsTransformer : IClaimsTransformation
{
    private readonly IPrivilegeProvider privilegeProvider;
    public const string DidItClaim = "http://foo.bar/privileges/resolved";

    public PrivilegesToClaimsTransformer(IPrivilegeProvider privilegeProvider)
    {
        this.privilegeProvider = privilegeProvider;
    }

    public async Task<ClaimsPrincipal> TransformAsync(ClaimsPrincipal principal)
    {
        if (principal.Identity is ClaimsIdentity claimer)
        {
            if (claimer.HasClaim(DidItClaim, bool.TrueString))
            {
                return principal;
            }

            var privileges = await this.privilegeProvider.GetPrivileges( ... );
            claimer.AddClaim(new Claim(DidItClaim, bool.TrueString));

            foreach (var privilegeAsRole in privileges)
            {
                claimer.AddClaim(new Claim(ClaimTypes.Role /*"http://schemas.microsoft.com/ws/2008/06/identity/claims/role" */, privilegeAsRole));
            }
        }

        return principal;
    }
}

To use this in your Controller just add an appropriate [Authorize(Roles="whatever")] to your methods.

[HttpGet]
[Route("poc")]
[Authorize(Roles = "plugh,blast")]
public JsonResult PocAuthorization()
{
    var result = Json(new
    {
        when = DateTime.UtcNow,
    });

    result.StatusCode = (int)HttpStatusCode.OK;

    return result;
}

In our case every request includes an Authorization header that is a JWT. This is the prototype and I believe we will do something super close to this in our production system next week.

Future voters, consider the date of writing when you vote. As of today, this works on my machine.™ You will probably want more error handling and logging on your implementation.

Select elements by attribute

To select elements having a certain attribute, see the answers above.

To determine if a given jQuery element has a specific attribute I'm using a small plugin that returns true if the first element in ajQuery collection has this attribute:

/** hasAttr
 ** helper plugin returning boolean if the first element of the collection has a certain attribute
 **/
$.fn.hasAttr = function(attr) {
   return 0 < this.length
       && 'undefined' !== typeof attr
       && undefined !== attr
       && this[0].hasAttribute(attr)
}

Why is my JQuery selector returning a n.fn.init[0], and what is it?

Here is how to do a quick check to see if n.fn.init[0] is caused by your DOM-elements not loading in time. Delay your selector function by wrapping it in setTimeout function like this:

function timeout(){ 

    ...your selector function that returns n.fn.init[0] goes here...

}

setTimeout(timeout, 5000)

This will cause your selector function to execute with a 5 second delay, which should be enough for pretty much anything to load.

This is just a coarse hack to check if DOM is ready for your selector function or not. This is not a (permanent) solution.

The preferred ways to check if the DOM is loaded before executing your function are as follows:

1) Wrap your selector function in

$(document).ready(function(){  ... your selector function...  };

2) If that doesn't work, use DOMContentLoaded

3) Try window.onload, which waits for all the images to load first, so its least preferred

window.onload = function () {  ... your selector function...  }

4) If you are waiting for a library to load that loads in several steps or has some sort of delay of its own, then you might need some complicated custom solution. This is what happened to me with "MathJax" library. This question discusses how to check when MathJax library loaded its DOM elements, if it is of any help.

5) Finally, you can stick with hard-coded setTimeout function, making it maybe 1-3 seconds. This is actually the very least preferred method in my opinion.

This list of fixes is probably far from perfect so everyone is welcome to edit it.

Change form size at runtime in C#

As a complement to the answers given above; do not forget about Form MinimumSize Property, in case you require to create smaller Forms.

Example Bellow:

private void SetDefaultWindowSize()
{
   int sizeW, sizeH;
   sizeW = 180;
   sizeH = 100;

   var size = new Size(sizeW, sizeH);

   Size = size;
   MinimumSize = size;
}

private void SetNewSize()
{
   Size = new Size(Width, 10);
}

Hibernate: get entity by id

use get instead of load

// ...
        try {
            session = HibernateUtil.getSessionFactory().openSession();
            user =  (User) session.get(User.class, user_id);
        } catch (Exception e) {
 // ...

How to split a delimited string in Ruby and convert it to an array?

"1,2,3,4".split(",") as strings

"1,2,3,4".split(",").map { |s| s.to_i } as integers

Return JSON with error status code MVC

I was running Asp.Net Web Api 5.2.7 and it looks like the JsonResult class has changed to use generics and an asynchronous execute method. I ended up altering Richard Garside's solution:

public class JsonHttpStatusResult<T> : JsonResult<T>
{
    private readonly HttpStatusCode _httpStatus;

    public JsonHttpStatusResult(T content, JsonSerializerSettings serializer, Encoding encoding, ApiController controller, HttpStatusCode httpStatus) 
    : base(content, serializer, encoding, controller)
    {
        _httpStatus = httpStatus;
    }

    public override Task<HttpResponseMessage> ExecuteAsync(CancellationToken cancellationToken)
    {
        var returnTask = base.ExecuteAsync(cancellationToken);
        returnTask.Result.StatusCode = HttpStatusCode.BadRequest;
        return returnTask;
    }
}

Following Richard's example, you could then use this class like this:

if(thereWereErrors)
{
    var errorModel = new CustomErrorModel("There was an error");
    return new JsonHttpStatusResult<CustomErrorModel>(errorModel, new JsonSerializerSettings(), new UTF8Encoding(), this, HttpStatusCode.InternalServerError);
}

Unfortunately, you can't use an anonymous type for the content, as you need to pass a concrete type (ex: CustomErrorType) to the JsonHttpStatusResult initializer. If you want to use anonymous types, or you just want to be really slick, you can build on this solution by subclassing ApiController to add an HttpStatusCode param to the Json methods :)

public abstract class MyApiController : ApiController
{
    protected internal virtual JsonHttpStatusResult<T> Json<T>(T content, HttpStatusCode httpStatus, JsonSerializerSettings serializerSettings, Encoding encoding)
    {
        return new JsonHttpStatusResult<T>(content, httpStatus, serializerSettings, encoding, this);
    }

    protected internal JsonHttpStatusResult<T> Json<T>(T content, HttpStatusCode httpStatus, JsonSerializerSettings serializerSettings)
    {
        return Json(content, httpStatus, serializerSettings, new UTF8Encoding());
    }

    protected internal JsonHttpStatusResult<T> Json<T>(T content, HttpStatusCode httpStatus)
    {
        return Json(content, httpStatus, new JsonSerializerSettings());
    }
}

Then you can use it with an anonymous type like this:

if(thereWereErrors)
{
    var errorModel = new { error = "There was an error" };
    return Json(errorModel, HttpStatusCode.InternalServerError);
}

Are static class variables possible in Python?

One special thing to note about static properties & instance properties, shown in the example below:

class my_cls:
  my_prop = 0

#static property
print my_cls.my_prop  #--> 0

#assign value to static property
my_cls.my_prop = 1 
print my_cls.my_prop  #--> 1

#access static property thru' instance
my_inst = my_cls()
print my_inst.my_prop #--> 1

#instance property is different from static property 
#after being assigned a value
my_inst.my_prop = 2
print my_cls.my_prop  #--> 1
print my_inst.my_prop #--> 2

This means before assigning the value to instance property, if we try to access the property thru' instance, the static value is used. Each property declared in python class always has a static slot in memory.

How to get text and a variable in a messagebox

As has been suggested, using the string.format method is nice and simple and very readable.

In vb.net the " + " is used for addition and the " & " is used for string concatenation.

In your example:

MsgBox("Variable = " + variable)

becomes:

MsgBox("Variable = " & variable)

I may have been a bit quick answering this as it appears these operators can both be used for concatenation, but recommended use is the "&", source http://msdn.microsoft.com/en-us/library/te2585xw(v=VS.100).aspx

maybe call

variable.ToString()

update:

Use string interpolation (vs2015 onwards I believe):

MsgBox($"Variable = {variable}")

How to set input type date's default value to today?

The JavaScript Date object provides enough built-in support for the required format to avoid doing it manually:

Add this for correct timezone support:

Date.prototype.toDateInputValue = (function() {
    var local = new Date(this);
    local.setMinutes(this.getMinutes() - this.getTimezoneOffset());
    return local.toJSON().slice(0,10);
});


jQuery:

$(document).ready( function() {
    $('#datePicker').val(new Date().toDateInputValue());
});?


Pure JS:

document.getElementById('datePicker').value = new Date().toDateInputValue();

How to set ObjectId as a data type in mongoose

Unlike traditional RBDMs, mongoDB doesn't allow you to define any random field as the primary key, the _id field MUST exist for all standard documents.

For this reason, it doesn't make sense to create a separate uuid field.

In mongoose, the ObjectId type is used not to create a new uuid, rather it is mostly used to reference other documents.

Here is an example:

var mongoose = require('mongoose');

var Schema = mongoose.Schema,
    ObjectId = Schema.ObjectId;
var Schema_Product = new Schema({
    categoryId  : ObjectId, // a product references a category _id with type ObjectId
    title       : String,
    price       : Number
});

As you can see, it wouldn't make much sense to populate categoryId with a ObjectId.

However, if you do want a nicely named uuid field, mongoose provides virtual properties that allow you to proxy (reference) a field.

Check it out:

var mongoose = require('mongoose');

var Schema = mongoose.Schema,
    ObjectId = Schema.ObjectId;
var Schema_Category = new Schema({
    title       : String,
    sortIndex   : String
});

Schema_Category.virtual('categoryId').get(function() {
    return this._id;
});

So now, whenever you call category.categoryId, mongoose just returns the _id instead.

You can also create a "set" method so that you can set virtual properties, check out this link for more info

How Do I Convert an Integer to a String in Excel VBA?

enter image description here

    Sub NumToText(ByRef sRng As String, Optional ByVal WS As Worksheet)
    '---Converting visible range form Numbers to Text
        Dim Temp As Double
        Dim vRng As Range
        Dim Cel As Object

        If WS Is Nothing Then Set WS = ActiveSheet
            Set vRng = WS.Range(sRng).SpecialCells(xlCellTypeVisible)
            For Each Cel In vRng
                If Not IsEmpty(Cel.Value) And IsNumeric(Cel.Value) Then
                    Temp = Cel.Value
                    Cel.ClearContents
                    Cel.NumberFormat = "@"
                    Cel.Value = CStr(Temp)
                End If
            Next Cel
    End Sub


    Sub Macro1()
        Call NumToText("A2:A100", ActiveSheet)
    End Sub

Reffer: MrExcel.com – Convert numbers to text with VBA

Input button target="_blank" isn't causing the link to load in a new window/tab

use formtarget="_blank" its working for me

<input type="button" onClick="parent.location='http://www.facebook.com/'" value="facebook" formtarget="_blank">

Browser compatibility: from caniuse.com
IE: 10+ | Edge: 12+ | Firefox: 4+ | Chrome: 15+ | Safari/iOS: 5.1+ | Android: 4+

SyntaxError of Non-ASCII character

You should define source code encoding, add this to the top of your script:

# -*- coding: utf-8 -*-

The reason why it works differently in console and in the IDE is, likely, because of different default encodings set. You can check it by running:

import sys
print sys.getdefaultencoding()

Also see:

How do I add an image to a JButton

This code work for me:

    BufferedImage image = null;
    try {
        URL file = getClass().getResource("water.bmp");
        image = ImageIO.read(file);
    } catch (IOException ioex) {
        System.err.println("load error: " + ioex.getMessage());
    }
    ImageIcon icon = new ImageIcon(image);
    JButton quitButton = new JButton(icon);

SQL query, store result of SELECT in local variable

Isn't this a much simpler solution, if I correctly understand the question, of course.

I want to load email addresses that are in a table called "spam" into a variable.

select email from spam

produces the following list, say:

.accountant
.bid
.buiilldanything.com
.club
.cn
.cricket
.date
.download
.eu

To load into the variable @list:

declare @list as varchar(8000)
set @list += @list (select email from spam)

@list may now be INSERTed into a table, etc.

I hope this helps.

To use it for a .csv file or in VB, spike the code:

declare @list as varchar(8000)
set @list += @list (select '"'+email+',"' from spam)
print @list

and it produces ready-made code to use elsewhere:

".accountant,"
".bid,"
".buiilldanything.com,"
".club,"
".cn,"
".cricket,"
".date,"
".download,"
".eu,"

One can be very creative.

Thanks

Nico

JWT authentication for ASP.NET Web API

I've managed to achieve it with minimal effort (just as simple as with ASP.NET Core).

For that I use OWIN Startup.cs file and Microsoft.Owin.Security.Jwt library.

In order for the app to hit Startup.cs we need to amend Web.config:

<configuration>
  <appSettings>
    <add key="owin:AutomaticAppStartup" value="true" />
    ...

Here's how Startup.cs should look:

using MyApp.Helpers;
using Microsoft.IdentityModel.Tokens;
using Microsoft.Owin;
using Microsoft.Owin.Security;
using Microsoft.Owin.Security.Jwt;
using Owin;

[assembly: OwinStartup(typeof(MyApp.App_Start.Startup))]

namespace MyApp.App_Start
{
    public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            app.UseJwtBearerAuthentication(
                new JwtBearerAuthenticationOptions
                {
                    AuthenticationMode = AuthenticationMode.Active,
                    TokenValidationParameters = new TokenValidationParameters()
                    {
                        ValidAudience = ConfigHelper.GetAudience(),
                        ValidIssuer = ConfigHelper.GetIssuer(),
                        IssuerSigningKey = ConfigHelper.GetSymmetricSecurityKey(),
                        ValidateLifetime = true,
                        ValidateIssuerSigningKey = true
                    }
                });
        }
    }
}

Many of you guys use ASP.NET Core nowadays, so as you can see it doesn't differ a lot from what we have there.

It really got me perplexed first, I was trying to implement custom providers, etc. But I didn't expect it to be so simple. OWIN just rocks!

Just one thing to mention - after I enabled OWIN Startup NSWag library stopped working for me (e.g. some of you might want to auto-generate typescript HTTP proxies for Angular app).

The solution was also very simple - I replaced NSWag with Swashbuckle and didn't have any further issues.


Ok, now sharing ConfigHelper code:

public class ConfigHelper
{
    public static string GetIssuer()
    {
        string result = System.Configuration.ConfigurationManager.AppSettings["Issuer"];
        return result;
    }

    public static string GetAudience()
    {
        string result = System.Configuration.ConfigurationManager.AppSettings["Audience"];
        return result;
    }

    public static SigningCredentials GetSigningCredentials()
    {
        var result = new SigningCredentials(GetSymmetricSecurityKey(), SecurityAlgorithms.HmacSha256);
        return result;
    }

    public static string GetSecurityKey()
    {
        string result = System.Configuration.ConfigurationManager.AppSettings["SecurityKey"];
        return result;
    }

    public static byte[] GetSymmetricSecurityKeyAsBytes()
    {
        var issuerSigningKey = GetSecurityKey();
        byte[] data = Encoding.UTF8.GetBytes(issuerSigningKey);
        return data;
    }

    public static SymmetricSecurityKey GetSymmetricSecurityKey()
    {
        byte[] data = GetSymmetricSecurityKeyAsBytes();
        var result = new SymmetricSecurityKey(data);
        return result;
    }

    public static string GetCorsOrigins()
    {
        string result = System.Configuration.ConfigurationManager.AppSettings["CorsOrigins"];
        return result;
    }
}

Another important aspect - I sent JWT Token via Authorization header, so typescript code looks for me as follows:

(the code below is generated by NSWag)

@Injectable()
export class TeamsServiceProxy {
    private http: HttpClient;
    private baseUrl: string;
    protected jsonParseReviver: ((key: string, value: any) => any) | undefined = undefined;

    constructor(@Inject(HttpClient) http: HttpClient, @Optional() @Inject(API_BASE_URL) baseUrl?: string) {
        this.http = http;
        this.baseUrl = baseUrl ? baseUrl : "https://localhost:44384";
    }

    add(input: TeamDto | null): Observable<boolean> {
        let url_ = this.baseUrl + "/api/Teams/Add";
        url_ = url_.replace(/[?&]$/, "");

        const content_ = JSON.stringify(input);

        let options_ : any = {
            body: content_,
            observe: "response",
            responseType: "blob",
            headers: new HttpHeaders({
                "Content-Type": "application/json", 
                "Accept": "application/json",
                "Authorization": "Bearer " + localStorage.getItem('token')
            })
        };

See headers part - "Authorization": "Bearer " + localStorage.getItem('token')

Load different application.yml in SpringBoot Test

You can use @TestPropertySource to load different properties/yaml file

@TestPropertySource(locations="classpath:test.properties")
@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(Application.class)
public class MyIntTest{

}

OR if you want to override only specific properties/yaml you can use

@TestPropertySource(
        properties = {
                "spring.jpa.hibernate.ddl-auto=validate",
                "liquibase.enabled=false"
        }
)

Import an existing git project into GitLab?

Add the new gitlab remote to your existing repository and push:

git remote add gitlab url-to-gitlab-repo
git push gitlab master

How to encode a URL in Swift

I needed to encode my parameters with ISO-8859-1, so the addingPercentEncoding() method doesn't work for me. I made a solution my self in Swift 4:

extension String {

  // Url percent encoding according to RFC3986 specifications
  // https://tools.ietf.org/html/rfc3986#section-2.1
  func urlPercentEncoded(withAllowedCharacters allowedCharacters: 
    CharacterSet, encoding: String.Encoding) -> String {
    var returnStr = ""

    // Compute each char seperatly
    for char in self {
      let charStr = String(char)
      let charScalar = charStr.unicodeScalars[charStr.unicodeScalars.startIndex]
      if allowedCharacters.contains(charScalar) == false,
        let bytesOfChar = charStr.data(using: encoding) {
        // Get the hexStr of every notAllowed-char-byte and put a % infront of it, append the result to the returnString
        for byte in bytesOfChar {
          returnStr += "%" + String(format: "%02hhX", byte as CVarArg)
        }
      } else {
        returnStr += charStr
      }
    }

    return returnStr
  }

}

Usage:

"aouäöü!".urlPercentEncoded(withAllowedCharacters: .urlQueryAllowed,
                                         encoding: .isoLatin1) 
// Results in -> "aou%E4%F6%FC!"

C++, how to declare a struct in a header file

C++, how to declare a struct in a header file:

Put this in a file called main.cpp:

#include <cstdlib>
#include <iostream>
#include "student.h"

using namespace std;    //Watchout for clashes between std and other libraries

int main(int argc, char** argv) {
    struct Student s1;
    s1.firstName = "fred"; s1.lastName = "flintstone";
    cout << s1.firstName << " " << s1.lastName << endl;
    return 0;
}

put this in a file named student.h

#ifndef STUDENT_H
#define STUDENT_H

#include<string>
struct Student {
    std::string lastName, firstName;
};

#endif

Compile it and run it, it should produce this output:

s1.firstName = "fred";

Protip:

You should not place a using namespace std; directive in the C++ header file because you may cause silent name clashes between different libraries. To remedy this, use the fully qualified name: std::string foobarstring; instead of including the std namespace with string foobarstring;.

What is the reason for having '//' in Python?

To complement these other answers, the // operator also offers significant (3x) performance benefits over /, presuming you want integer division.

$ python -m timeit '20.5 // 2'
100,000,000 loops, best of 3: 14.9 nsec per loop

$ python -m timeit '20.5 / 2'
 10,000,000 loops, best of 3: 48.4 nsec per loop

$ python -m timeit '20 / 2'
 10,000,000 loops, best of 3: 43.0 nsec per loop

$ python -m timeit '20 // 2'
100,000,000 loops, best of 3: 14.4 nsec per loop

jQuery Screen Resolution Height Adjustment

Another example for vertically and horizontally centered div or any object(s):

 var obj = $("#divID");
 var halfsc = $(window).height()/2;
 var halfh = $(obj).height() / 2; 

 var halfscrn = screen.width/2;
 var halfobj =$(obj).width() / 2; 

 var goRight =  halfscrn - halfobj ;
 var goBottom = halfsc - halfh;

 $(obj).css({marginLeft: goRight }).css({marginTop: goBottom });

Regular expression to match numbers with or without commas and decimals in text

\d+(,\d+)*(\.\d+)?

This assumes that there is always at least one digit before or after any comma or decimal and also assumes that there is at most one decimal and that all the commas precede the decimal.

Only one expression can be specified in the select list when the subquery is not introduced with EXISTS

Apart from very good responses here, you could try this as well if you want to use your sub query as is.

Approach:

1) Select the desired column (Only 1) from your sub query

2) Use where to map the column name

Code:

 SELECT count(distinct dNum)
 FROM myDB.dbo.AQ
 WHERE A_ID in 
   (
    SELECT A_ID 
    FROM (SELECT DISTINCT TOP (0.1) PERCENT A_ID, COUNT(DISTINCT dNum) AS ud 
          FROM         myDB.dbo.AQ
          WHERE     M > 1 and B = 0 
          GROUP BY A_ID ORDER BY ud DESC
         ) a 
   )

How to place a JButton at a desired location in a JFrame using Java

I have figured it out lol. for the button do .setBounds(0, 0, 220, 30) The .setBounds layout is like this (int x, int y, int width, int height)

Laravel view not found exception

In my case I was calling View::make('User/index'), where in fact my view was in user directory and it was called index.blade.php. Ergo after I changed it to View@make('user.index') all started working.

Fastest way to set all values of an array?

Arrays.fill is the best option for general purpose use. If you need to fill large arrays though as of latest idk 1.8 u102, there is a faster way that leverages System.arraycopy. You can take a look at this alternate Arrays.fill implementation:

According to the JMH benchmarks you can get almost 2x performance boost for large arrays (1000 +)

In any case, these implementations should be used only where needed. JDKs Arrays.fill should be the preferred choice.

Declaring a variable and setting its value from a SELECT query in Oracle

One Additional point:

When you are converting from tsql to plsql you have to worry about no_data_found exception

DECLARE
   v_var NUMBER;
BEGIN
   SELECT clmn INTO v_var FROM tbl;
Exception when no_data_found then v_var := null; --what ever handle the exception.
END;

In tsql if no data found then the variable will be null but no exception

Replacement for "rename" in dplyr

The next version of dplyr will support an improved version of select that also incorporates renaming:

> mtcars2 <- select( mtcars, disp2 = disp )
> head( mtcars2 )
                  disp2
Mazda RX4         160
Mazda RX4 Wag     160
Datsun 710        108
Hornet 4 Drive    258
Hornet Sportabout 360
Valiant           225
> changes( mtcars, mtcars2 )
Changed variables:
      old         new
disp  0x105500400
disp2             0x105500400

Changed attributes:
      old         new
names 0x106d2cf50 0x106d28a98

How to add subject alernative name to ssl certs?

Although this question was more specifically about IP addresses in Subject Alt. Names, the commands are similar (using DNS entries for a host name and IP entries for IP addresses).

To quote myself:

If you're using keytool, as of Java 7, keytool has an option to include a Subject Alternative Name (see the table in the documentation for -ext): you could use -ext san=dns:www.example.com or -ext san=ip:10.0.0.1

Note that you only need Java 7's keytool to use this command. Once you've prepared your keystore, it should work with previous versions of Java.

(The rest of this answer also mentions how to do this with OpenSSL, but it doesn't seem to be what you're using.)

JavaScript blob filename without link

saveFileOnUserDevice = function(file){ // content: blob, name: string
        if(navigator.msSaveBlob){ // For ie and Edge
            return navigator.msSaveBlob(file.content, file.name);
        }
        else{
            let link = document.createElement('a');
            link.href = window.URL.createObjectURL(file.content);
            link.download = file.name;
            document.body.appendChild(link);
            link.dispatchEvent(new MouseEvent('click', {bubbles: true, cancelable: true, view: window}));
            link.remove();
            window.URL.revokeObjectURL(link.href);
        }
    }

difference between width auto and width 100 percent

The initial width of a block level element like div or p is auto.

Use width:auto to undo explicitly specified widths.

if you specify width:100%, the element’s total width will be 100% of its containing block plus any horizontal margin, padding and border.

So, next time you find yourself setting the width of a block level element to 100% to make it occupy all available width, consider if what you really want is setting it to auto.

Testing pointers for validity (C/C++)

Preventing a crash caused by the caller sending in an invalid pointer is a good way to make silent bugs that are hard to find.

Isn't it better for the programmer using your API to get a clear message that his code is bogus by crashing it rather than hiding it?

How to View Oracle Stored Procedure using SQLPlus?

check your casing, the name is typically stored in upper case

SELECT * FROM all_source WHERE name = 'DAILY_UPDATE' ORDER BY TYPE, LINE;

How to change the default collation of a table?

MySQL has 4 levels of collation: server, database, table, column. If you change the collation of the server, database or table, you don't change the setting for each column, but you change the default collations.

E.g if you change the default collation of a database, each new table you create in that database will use that collation, and if you change the default collation of a table, each column you create in that table will get that collation.

The superclass "javax.servlet.http.HttpServlet" was not found on the Java Build Path

And if nothing works by whatever reason, build it from the command line:

ant -Dj2ee.server.home=D:\apache-tomcat-8.0.23 clean

ant -Dj2ee.server.home=D:\apache-tomcat-8.0.23 compile

ant -Dj2ee.server.home=D:\apache-tomcat-8.0.23 dist

List of special characters for SQL LIKE clause

You should add that you have to add an extra ' to escape an exising ' in SQL Server:

smith's -> smith''s

I keep getting "Uncaught SyntaxError: Unexpected token o"

Another hints for Unexpected token errors. There are two major differences between javascript objects and json:

  1. json data must be always quoted with double quotes.
  2. keys must be quoted

Correct JSON

 {
    "english": "bag",
    "kana": "kaban",
    "kanji": "K"
}

Error JSON 1

 {
    'english': 'bag',
    'kana': 'kaban',
    'kanji': 'K'
 }

Error JSON 2

 {
    english: "bag",
    kana: "kaban",
    kanji: "K"
}

Remark

This is not a direct answer for that question. But it's an answer for Unexpected token errors. So it may be help others who stumple upon that question.

Docker - Bind for 0.0.0.0:4000 failed: port is already allocated

The quick fix is ??a just restart docker:

  1. sudo service docker stop
  2. sudo service docker start

Show spinner GIF during an $http request in AngularJS?

If you're wrapping your api calls within a service/factory, then you can track the loading counter there (per answer and excellent simultaneous suggestion by @JMaylin), and reference the loading counter via a directive. Or any combination thereof.

API WRAPPER

yourModule
    .factory('yourApi', ['$http', function ($http) {
        var api = {}

        //#region ------------ spinner -------------

        // ajax loading counter
        api._loading = 0;

        /**
         * Toggle check
         */
        api.isOn = function () { return api._loading > 0; }

        /**
         * Based on a configuration setting to ignore the loading spinner, update the loading counter
         * (for multiple ajax calls at one time)
         */
        api.spinner = function(delta, config) {
            // if we haven't been told to ignore the spinner, change the loading counter
            // so we can show/hide the spinner

            if (NG.isUndefined(config.spin) || config.spin) api._loading += delta;

            // don't let runaway triggers break stuff...
            if (api._loading < 0) api._loading = 0;

            console.log('spinner:', api._loading, delta);
        }
        /**
         * Track an ajax load begin, if not specifically disallowed by request configuration
         */
        api.loadBegin = function(config) {
            api.spinner(1, config);
        }
        /**
         * Track an ajax load end, if not specifically disallowed by request configuration
         */
        api.loadEnd = function (config) {
            api.spinner(-1, config);
        }

        //#endregion ------------ spinner -------------

        var baseConfig = {
            method: 'post'
            // don't need to declare `spin` here
        }

        /**
         * $http wrapper to standardize all api calls
         * @param args stuff sent to request
         * @param config $http configuration, such as url, methods, etc
         */
        var callWrapper = function(args, config) {
            var p = angular.extend(baseConfig, config); // override defaults

            // fix for 'get' vs 'post' param attachment
            if (!angular.isUndefined(args)) p[p.method == 'get' ? 'params' : 'data'] = args;

            // trigger the spinner
            api.loadBegin(p);

            // make the call, and turn of the spinner on completion
            // note: may want to use `then`/`catch` instead since `finally` has delayed completion if down-chain returns more promises
            return $http(p)['finally'](function(response) {
                api.loadEnd(response.config);
                return response;
            });
        }

        api.DoSomething = function(args) {
            // yes spinner
            return callWrapper(args, { cache: true });
        }
        api.DoSomethingInBackground = function(args) {
            // no spinner
            return callWrapper(args, { cache: true, spin: false });
        }

        // expose
        return api;
    });

SPINNER DIRECTIVE

(function (NG) {
    var loaderTemplate = '<div class="ui active dimmer" data-ng-show="hasSpinner()"><div class="ui large loader"></div></div>';

    /**
     * Show/Hide spinner with ajax
     */
    function spinnerDirective($compile, api) {
        return {
            restrict: 'EA',
            link: function (scope, element) {
                // listen for api trigger
                scope.hasSpinner = api.isOn;

                // attach spinner html
                var spin = NG.element(loaderTemplate);
                $compile(spin)(scope); // bind+parse
                element.append(spin);
            }
        }
    }

    NG.module('yourModule')
        .directive('yourApiSpinner', ['$compile', 'yourApi', spinnerDirective]);
})(angular);

USAGE

<div ng-controller="myCtrl" your-api-spinner> ... </div>

Server.Transfer Vs. Response.Redirect

Transfer is entirely server-side. Client address bar stays constant. Some complexity about the transfer of context between requests. Flushing and restarting page handlers can be expensive so do your transfer early in the pipeline e.g. in an HttpModule during BeginRequest. Read the MSDN docs carefully, and test and understand the new values of HttpContext.Request - especially in Postback scenarios. We usually use Server.Transfer for error scenarios.

Redirect terminates the request with a 302 status and client-side roundtrip response with and internally eats an exception (minor server perf hit - depends how many you do a day) Client then navigates to new address. Browser address bar & history updates etc. Client pays the cost of an extra roundtrip - cost varies depending on latency. In our business we redirect a lot we wrote our own module to avoid the exception cost.

svn list of files that are modified in local copy

If you only want the filenames and also want any files that have been added (A).

svn st | grep ^[AM] | cut -c9-

Note: The first 7 columns are each one character wide followed by a space then the filename.

java.lang.UnsupportedClassVersionError: Bad version number in .class file?

Always check for the obvious too. I got this error once when I accidently grabbed the wrong resource for the server's add and remove action. It can be easy to overlook.

set height of imageview as matchparent programmatically

imageView.getLayoutParams().height= ViewGroup.LayoutParams.MATCH_PARENT;

In Python, how do you convert seconds since epoch to a `datetime` object?

Note that datetime.datetime.fromtimestamp(timestamp) and .utcfromtimestamp(timestamp) fail on windows for dates before Jan. 1, 1970 while negative unix timestamps seem to work on unix-based platforms. The docs say this:

"This may raise ValueError, if the timestamp is out of the range of values supported by the platform C gmtime() function. It’s common for this to be restricted to years in 1970 through 2038"

See also Issue1646728

git: updates were rejected because the remote contains work that you do not have locally

git pull --rebase origin master

git push origin master


git push -f origin master

Warning git push -f origin master

  • forcefully pushes on existing repository and also delete previous repositories so if you don`t need previous versions than this might be helpful

Resize UIImage and change the size of UIImageView

Use the category below and then apply border from Quartz into your image:

[yourimage.layer setBorderColor:[[UIColor whiteColor] CGColor]];
[yourimage.layer setBorderWidth:2];

The category: UIImage+AutoScaleResize.h

#import <Foundation/Foundation.h>

@interface UIImage (AutoScaleResize)

- (UIImage *)imageByScalingAndCroppingForSize:(CGSize)targetSize;

@end

UIImage+AutoScaleResize.m

#import "UIImage+AutoScaleResize.h"

@implementation UIImage (AutoScaleResize)

- (UIImage *)imageByScalingAndCroppingForSize:(CGSize)targetSize
{
    UIImage *sourceImage = self;
    UIImage *newImage = nil;
    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;
    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;
    CGFloat scaleFactor = 0.0;
    CGFloat scaledWidth = targetWidth;
    CGFloat scaledHeight = targetHeight;
    CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

    if (CGSizeEqualToSize(imageSize, targetSize) == NO)
    {
        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;

        if (widthFactor > heightFactor)
        {
            scaleFactor = widthFactor; // scale to fit height
        }
        else
        {
            scaleFactor = heightFactor; // scale to fit width
        }

        scaledWidth  = width * scaleFactor;
        scaledHeight = height * scaleFactor;

        // center the image
        if (widthFactor > heightFactor)
        {
            thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
        }
        else
        {
            if (widthFactor < heightFactor)
            {
                thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
            }
        }
    }

    UIGraphicsBeginImageContext(targetSize); // this will crop

    CGRect thumbnailRect = CGRectZero;
    thumbnailRect.origin = thumbnailPoint;
    thumbnailRect.size.width  = scaledWidth;
    thumbnailRect.size.height = scaledHeight;

    [sourceImage drawInRect:thumbnailRect];

    newImage = UIGraphicsGetImageFromCurrentImageContext();

    if(newImage == nil)
    {
        NSLog(@"could not scale image");
    }

    //pop the context to get back to the default
    UIGraphicsEndImageContext();

    return newImage;
}

@end

Have border wrap around text

Try putting it in a span element:

_x000D_
_x000D_
<div id='page' style='width: 600px'>_x000D_
  <h1><span style='border:2px black solid; font-size:42px;'>Title</span></h1>_x000D_
</div>
_x000D_
_x000D_
_x000D_

R: Plotting a 3D surface from x, y, z

You can use the function outer() to generate it.

Have a look at the demo for the function persp(), which is a base graphics function to draw perspective plots for surfaces.

Here is their first example:

x <- seq(-10, 10, length.out = 50)  
y <- x  
rotsinc <- function(x,y) {
    sinc <- function(x) { y <- sin(x)/x ; y[is.na(y)] <- 1; y }  
    10 * sinc( sqrt(x^2+y^2) )  
}

z <- outer(x, y, rotsinc)  
persp(x, y, z)

The same applies to surface3d():

require(rgl)  
surface3d(x, y, z)

Install Chrome extension form outside the Chrome Web Store

For regular Windows users who are not skilled with computers, it is practically not possible to install and use extensions from outside the Chrome Web Store.

Users of other operating systems (Linux, Mac, Chrome OS) can easily install unpacked extensions (in developer mode).
Windows users can also load an unpacked extension, but they will always see an information bubble with "Disable developer mode extensions" when they start Chrome or open a new incognito window, which is really annoying. The only way for Windows users to use unpacked extensions without such dialogs is to switch to Chrome on the developer channel, by installing https://www.google.com/chrome/browser/index.html?extra=devchannel#eula.

Extensions can be loaded in unpacked mode by following the following steps:

  1. Visit chrome://extensions (via omnibox or menu -> Tools -> Extensions).
  2. Enable Developer mode by ticking the checkbox in the upper-right corner.
  3. Click on the "Load unpacked extension..." button.
  4. Select the directory containing your unpacked extension.

If you have a crx file, then it needs to be extracted first. CRX files are zip files with a different header. Any capable zip program should be able to open it. If you don't have such a program, I recommend 7-zip.

These steps will work for almost every extension, except extensions that rely on their extension ID. If you use the previous method, you will get an extension with a random extension ID. If it is important to preserve the extension ID, then you need to know the public key of your CRX file and insert this in your manifest.json. I have previously given a detailed explanation on how to get and use this key at https://stackoverflow.com/a/21500707.

Eclipse - no Java (JRE) / (JDK) ... no virtual machine

Just Add the JRE PATH FOR Ex: C:\Program Files\Java\jre5\bin in the environmental variable Put ";" in between every path. Then click the eclipse.exe It will work.....

Using Mockito to mock classes with generic parameters

As the other answers mentioned, there's not a great way to use the mock() & spy() methods directly without unsafe generics access and/or suppressing generics warnings.

There is currently an open issue in the Mockito project (#1531) to add support for using the mock() & spy() methods without generics warnings. The issue was opened in November 2018, but there aren't any indications whether it will be prioritized.

Using "If cell contains #N/A" as a formula condition.

You can also use IFNA(expression, value)

Using number_format method in Laravel

This should work :

<td>{{ number_format($Expense->price, 2) }}</td>

How to define custom sort function in javascript?

function msort(arr){
    for(var i =0;i<arr.length;i++){
        for(var j= i+1;j<arr.length;j++){
            if(arr[i]>arr[j]){
                var swap = arr[i];
                arr[i] = arr[j];
                arr[j] = swap;
            }
        }
    }
return arr;
}

How to view kafka message

You can use console consumer to view messages produced on some topic:

bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic test --from-beginning

Printing tuple with string formatting in Python

Besides the methods proposed in the other answers, since Python 3.6 you can also use Literal String Interpolation (f-strings):

>>> tup = (1,2,3)
>>> print(f'this is a tuple {tup}')
this is a tuple (1, 2, 3)

Why is it OK to return a 'vector' from a function?

Pre C++11:

The function will not return the local variable, but rather a copy of it. Your compiler might however perform an optimization where no actual copy action is made.

See this question & answer for further details.

C++11:

The function will move the value. See this answer for further details.

How can I enable the MySQLi extension in PHP 7?

sudo phpenmod mysqli
sudo service apache2 restart

  • phpenmod moduleName enables a module to PHP 7 (restart Apache after that sudo service apache2 restart)
  • phpdismod moduleName disables a module to PHP 7 (restart Apache after that sudo service apache2 restart)
  • php -m lists the loaded modules

Execute PHP scripts within Node.js web server

A simple, fast approach in my opinion would be to use dnode-php for that.

You can see a brief introduction here. Simple, quick and easy!

How to add hyperlink in JLabel?

I know I'm kinda late to the party but I made a little method others might find cool/useful.

public static JLabel linkify(final String text, String URL, String toolTip)
{
    URI temp = null;
    try
    {
        temp = new URI(URL);
    }
    catch (Exception e)
    {
        e.printStackTrace();
    }
    final URI uri = temp;
    final JLabel link = new JLabel();
    link.setText("<HTML><FONT color=\"#000099\">"+text+"</FONT></HTML>");
    if(!toolTip.equals(""))
        link.setToolTipText(toolTip);
    link.setCursor(new Cursor(Cursor.HAND_CURSOR));
    link.addMouseListener(new MouseListener()
    {
        public void mouseExited(MouseEvent arg0)
        {
            link.setText("<HTML><FONT color=\"#000099\">"+text+"</FONT></HTML>");
        }

        public void mouseEntered(MouseEvent arg0)
        {
            link.setText("<HTML><FONT color=\"#000099\"><U>"+text+"</U></FONT></HTML>");
        }

        public void mouseClicked(MouseEvent arg0)
        {
            if (Desktop.isDesktopSupported())
            {
                try
                {
                    Desktop.getDesktop().browse(uri);
                }
                catch (Exception e)
                {
                    e.printStackTrace();
                }
            }
            else
            {
                JOptionPane pane = new JOptionPane("Could not open link.");
                JDialog dialog = pane.createDialog(new JFrame(), "");
                dialog.setVisible(true);
            }
        }

        public void mousePressed(MouseEvent e)
        {
        }

        public void mouseReleased(MouseEvent e)
        {
        }
    });
    return link;
}

It'll give you a JLabel that acts like a proper link.

In action:

public static void main(String[] args)
{
    JFrame frame = new JFrame("Linkify Test");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(400, 100);
    frame.setLocationRelativeTo(null);
    Container container = frame.getContentPane();
    container.setLayout(new GridBagLayout());
    container.add(new JLabel("Click "));
    container.add(linkify("this", "http://facebook.com", "Facebook"));
    container.add(new JLabel(" link to open Facebook."));
    frame.setVisible(true);
}

If you'd like no tooltip just send a null.

Hope someone finds this useful! (If you do, be sure to let me know, I'd be happy to hear.)

How do I log errors and warnings into a file?

See

  • error_log — Send an error message somewhere

Example

error_log("You messed up!", 3, "/var/tmp/my-errors.log");

You can customize error handling with your own error handlers to call this function for you whenever an error or warning or whatever you need to log occurs. For additional information, please refer to the Chapter Error Handling in the PHP Manual

how do I change text in a label with swift?

swift solution

yourlabel.text = yourvariable

or self is use for when you are in async {brackets} or in some Extension

DispatchQueue.main.async{
    self.yourlabel.text = "typestring"
}

How to replace multiple patterns at once with sed?

Here is a variation on ooga's answer that works for multiple search and replace pairs without having to check how values might be reused:

sed -i '
s/\bAB\b/________BC________/g
s/\bBC\b/________CD________/g
s/________//g
' path_to_your_files/*.txt

Here is an example:

before:

some text AB some more text "BC" and more text.

after:

some text BC some more text "CD" and more text.

Note that \b denotes word boundaries, which is what prevents the ________ from interfering with the search (I'm using GNU sed 4.2.2 on Ubuntu). If you are not using a word boundary search, then this technique may not work.

Also note that this gives the same results as removing the s/________//g and appending && sed -i 's/________//g' path_to_your_files/*.txt to the end of the command, but doesn't require specifying the path twice.

A general variation on this would be to use \x0 or _\x0_ in place of ________ if you know that no nulls appear in your files, as jthill suggested.

How do I import an SQL file using the command line in MySQL?

I kept running into the problem where the database wasn't created.

I fixed it like this

mysql -u root -e "CREATE DATABASE db_name"
mysql db_name --force < import_script.sql

How to solve this java.lang.NoClassDefFoundError: org/apache/commons/io/output/DeferredFileOutputStream?

You will have to download file from here https://commons.apache.org/proper/commons-io/download_io.cgi and select https://prnt.sc/tk5ewt

Now, Next add this downloaded files into your project:

Right click to your project ->Build path->Configure BuidPath -> https://prnt.sc/tk5d93

How to set a default Value of a UIPickerView

For example: you populated your UIPickerView with array values, then you wanted 

to select a certain array value in the first load of pickerView like "Arizona". Note that the word "Arizona" is at index 2. This how to do it :) Enjoy coding.

NSArray *countryArray =[NSArray arrayWithObjects:@"Alabama",@"Alaska",@"Arizona",@"Arkansas", nil];
UIPickerView *countryPicker=[[UIPickerView alloc]initWithFrame:self.view.bounds];
countryPicker.delegate=self;
countryPicker.dataSource=self;
[countryPicker selectRow:2 inComponent:0 animated:YES];
[self.view addSubview:countryPicker];

converting a javascript string to a html object

In addition to Gaby aka's method, we can find elements inside htmlObject in this way -

htmlObj.find("#box").html();

Fiddle is available here - http://jsfiddle.net/ashwyn/76gL3/

jQuery UI tabs. How to select a tab based on its id not based on index

From the most recent document, the select method takes an index or the id of the tab's panel (the href hash value). The documentation states:

Select a tab, as if it were clicked. The second argument is the zero-based index of the tab to be selected or the id selector of the panel the tab is associated with (the tab's href fragment identifier, e.g. hash, points to the panel's id).

So, given a layout like

<div id="myTabs">    
    <ul  class="tabs">
      <li><a href="#tabone">tabone</a></li>
      <li><a href="#tabtwo">tabtwo</a></li>
    </ul>   
</div>

the following works

$('#myTabs').tabs('select', '#tabtwo');

Here is an example.

UPDATE

The above solution works in jQuery UI versions less than 1.9. For a solution in versions 1.9+ see @stankovski's answer.

What is move semantics?

Here's an answer from the book "The C++ Programming Language" by Bjarne Stroustrup. If you don't want to see the video, you can see the text below:

Consider this snippet. Returning from an operator+ involves copying the result out of the local variable res and into someplace where the caller can access it.

Vector operator+(const Vector& a, const Vector& b)
{
    if (a.size()!=b.size())
        throw Vector_siz e_mismatch{};
    Vector res(a.size());
        for (int i=0; i!=a.size(); ++i)
            res[i]=a[i]+b[i];
    return res;
}

We didn’t really want a copy; we just wanted to get the result out of a function. So we need to move a Vector rather than to copy it. We can define move constructor as follows:

class Vector {
    // ...
    Vector(const Vector& a); // copy constructor
    Vector& operator=(const Vector& a); // copy assignment
    Vector(Vector&& a); // move constructor
    Vector& operator=(Vector&& a); // move assignment
};

Vector::Vector(Vector&& a)
    :elem{a.elem}, // "grab the elements" from a
    sz{a.sz}
{
    a.elem = nullptr; // now a has no elements
    a.sz = 0;
}

The && means "rvalue reference" and is a reference to which we can bind an rvalue. "rvalue"’ is intended to complement "lvalue" which roughly means "something that can appear on the left-hand side of an assignment." So an rvalue means roughly "a value that you can’t assign to", such as an integer returned by a function call, and the res local variable in operator+() for Vectors.

Now, the statement return res; will not copy!

Using $setValidity inside a Controller

A better and optimised solution to display multiple validation messages for a single element would be like this.

<div ng-messages="myForm.file.$error" ng-show="myForm.file.$touched">
 <span class="error" ng-message="required"> <your message> </span>
 <span class="error" ng-message="size"> <your message> </span>
 <span class="error" ng-message="filetype"> <your message> </span>
</div>

Controller Code should be the one suggested by @ Ben Lesh

How can I test that a variable is more than eight characters in PowerShell?

You can also use -match against a Regular expression. Ex:

if ($dbUserName -match ".{8}" )
{
    Write-Output " Please enter more than 8 characters "
    $dbUserName=read-host " Re-enter database user name"
}

Also if you're like me and like your curly braces to be in the same horizontal position for your code blocks, you can put that on a new line, since it's expecting a code block it will look on next line. In some commands where the first curly brace has to be in-line with your command, you can use a grave accent marker (`) to tell powershell to treat the next line as a continuation.

Getting Data from Android Play Store

There's an unofficial open-source API for the Android Market you may try to use to get the information you need. Hope this helps.

Validation failed for one or more entities. See 'EntityValidationErrors' property for more details

If you are simply catching a generic exception, it may benefit you to cast this as a DbEntityValidationException. This type of an exception has a Validation Errors property, and continuing to expand your way into them, you will find all the problems.

For example, if you put a break point in the catch, you can throw the following into a watch:

((System.Data.Entity.Validation.DbEntityValidationException ) ex)

An example of an error is if a field does not allow nulls, and you have a null string, you'll see it say that the field is required.

How to send a model in jQuery $.ajax() post request to MVC controller method

In ajax call mention-

data:MakeModel(),

use the below function to bind data to model

function MakeModel() {

    var MyModel = {};

    MyModel.value = $('#input element id').val() or your value;

    return JSON.stringify(MyModel);
}

Attach [HttpPost] attribute to your controller action

on POST this data will get available

href around input type submit

Why would you want to put a submit button inside an anchor? You are either trying to submit a form or go to a different page. Which one is it?

Either submit the form:

<input type="submit" class="button_active" value="1" />

Or go to another page:

<input type="button" class="button_active" onclick="location.href='1.html';" />

Get a Windows Forms control by name in C#

this.Controls["name"];

This is the actual code that is ran:

public virtual Control this[string key]
{
    get
    {
        if (!string.IsNullOrEmpty(key))
        {
            int index = this.IndexOfKey(key);
            if (this.IsValidIndex(index))
            {
                return this[index];
            }
        }
        return null;
    }
}

vs:

public Control[] Find(string key, bool searchAllChildren)
{
    if (string.IsNullOrEmpty(key))
    {
        throw new ArgumentNullException("key", SR.GetString("FindKeyMayNotBeEmptyOrNull"));
    }
    ArrayList list = this.FindInternal(key, searchAllChildren, this, new ArrayList());
    Control[] array = new Control[list.Count];
    list.CopyTo(array, 0);
    return array;
}

private ArrayList FindInternal(string key, bool searchAllChildren, Control.ControlCollection controlsToLookIn, ArrayList foundControls)
{
    if ((controlsToLookIn == null) || (foundControls == null))
    {
        return null;
    }
    try
    {
        for (int i = 0; i < controlsToLookIn.Count; i++)
        {
            if ((controlsToLookIn[i] != null) && WindowsFormsUtils.SafeCompareStrings(controlsToLookIn[i].Name, key, true))
            {
                foundControls.Add(controlsToLookIn[i]);
            }
        }
        if (!searchAllChildren)
        {
            return foundControls;
        }
        for (int j = 0; j < controlsToLookIn.Count; j++)
        {
            if (((controlsToLookIn[j] != null) && (controlsToLookIn[j].Controls != null)) && (controlsToLookIn[j].Controls.Count > 0))
            {
                foundControls = this.FindInternal(key, searchAllChildren, controlsToLookIn[j].Controls, foundControls);
            }
        }
    }
    catch (Exception exception)
    {
        if (ClientUtils.IsSecurityOrCriticalException(exception))
        {
            throw;
        }
    }
    return foundControls;
}

Writing to a file in a for loop

That is because you are opening , writing and closing the file 10 times inside your for loop

myfile = open('xyz.txt', 'w')
myfile.writelines(var1)
myfile.close()

You should open and close your file outside for loop.

myfile = open('xyz.txt', 'w')
for line in lines:
    var1, var2 = line.split(",");
    myfile.write("%s\n" % var1)

myfile.close()
text_file.close()

You should also notice to use write and not writelines.

writelines writes a list of lines to your file.

Also you should check out the answers posted by folks here that uses with statement. That is the elegant way to do file read/write operations in Python

numpy division with RuntimeWarning: invalid value encountered in double_scalars

You can't solve it. Simply answer1.sum()==0, and you can't perform a division by zero.

This happens because answer1 is the exponential of 2 very large, negative numbers, so that the result is rounded to zero.

nan is returned in this case because of the division by zero.

Now to solve your problem you could:

  • go for a library for high-precision mathematics, like mpmath. But that's less fun.
  • as an alternative to a bigger weapon, do some math manipulation, as detailed below.
  • go for a tailored scipy/numpy function that does exactly what you want! Check out @Warren Weckesser answer.

Here I explain how to do some math manipulation that helps on this problem. We have that for the numerator:

exp(-x)+exp(-y) = exp(log(exp(-x)+exp(-y)))
                = exp(log(exp(-x)*[1+exp(-y+x)]))
                = exp(log(exp(-x) + log(1+exp(-y+x)))
                = exp(-x + log(1+exp(-y+x)))

where above x=3* 1089 and y=3* 1093. Now, the argument of this exponential is

-x + log(1+exp(-y+x)) = -x + 6.1441934777474324e-06

For the denominator you could proceed similarly but obtain that log(1+exp(-z+k)) is already rounded to 0, so that the argument of the exponential function at the denominator is simply rounded to -z=-3000. You then have that your result is

exp(-x + log(1+exp(-y+x)))/exp(-z) = exp(-x+z+log(1+exp(-y+x)) 
                                   = exp(-266.99999385580668)

which is already extremely close to the result that you would get if you were to keep only the 2 leading terms (i.e. the first number 1089 in the numerator and the first number 1000 at the denominator):

exp(3*(1089-1000))=exp(-267)

For the sake of it, let's see how close we are from the solution of Wolfram alpha (link):

Log[(exp[-3*1089]+exp[-3*1093])/([exp[-3*1000]+exp[-3*4443])] -> -266.999993855806522267194565420933791813296828742310997510523

The difference between this number and the exponent above is +1.7053025658242404e-13, so the approximation we made at the denominator was fine.

The final result is

'exp(-266.99999385580668) = 1.1050349147204485e-116

From wolfram alpha is (link)

1.105034914720621496.. × 10^-116 # Wolfram alpha.

and again, it is safe to use numpy here too.

How to "git show" a merge commit with combined diff output even when every changed file agrees with one of the parents?

Look at the commit message:

commit 0e1329e551a5700614a2a34d8101e92fd9f2cad6 (HEAD, master)
Merge: fc17405 ee2de56
Author: Tilman Vogel <email@email>
Date:   Tue Feb 22 00:27:17 2011 +0100

Merge branch 'testing' into master

notice the line:

Merge: fc17405 ee2de56

take those two commit ids and reverse them. so in order get the diff that you want, you would do:

git diff ee2de56..fc17405

to show just the names of the changed files:

git diff --name-only ee2de56..fc17405

and to extract them, you can add this to your gitconfig:

exportfiles = !sh -c 'git diff $0 --name-only | "while read files; do mkdir -p \"$1/$(dirname $files)\"; cp -vf $files $1/$(dirname $files); done"'

then use it by doing:

git exportfiles ee2de56..fc17405 /c/temp/myproject

cannot find module "lodash"

Be sure to install lodash in the required folder. This is probably your C:\gwsk directory.

If that folder has a package.json file, it is also best to add --save behind the install command.

$ npm install lodash --save

The package.json file holds information about the project, but to keep it simple, it holds your project dependencies.

The save command will add the installed module to the project dependencies.

If the package.json file exists, and if it contains the lodash dependency you could try to remove the node_modules folder and run following command:

$ npm cache clean    
$ npm install

The first command will clean the npm cache. (just to be sure) The second command will install all (missing) dependencies of the project.

Hope this helps you understand the node package manager a little bit more.

How to quickly and conveniently create a one element arraylist

You can use the utility method Arrays.asList and feed that result into a new ArrayList.

List<String> list = new ArrayList<String>(Arrays.asList(s));

Other options:

List<String> list = new ArrayList<String>(Collections.nCopies(1, s));

and

List<String> list = new ArrayList<String>(Collections.singletonList(s));

With Java 7+, you may use the "diamond operator", replacing new ArrayList<String>(...) with new ArrayList<>(...).

Java 9

If you're using Java 9+, you can use the List.of method:

List<String> list = new ArrayList<>(List.of(s));

Regardless of the use of each option above, you may choose not to use the new ArrayList<>() wrapper if you don't need your list to be mutable.

JQuery How to extract value from href tag?

Here's a method that works by transforming the querystring into JSON...

var link = $('a').attr('href');

if (link.indexOf("?") != -1) {
    var query = link.split("?")[1];

    eval("query = {" + query.replace(/&/ig, "\",").replace(/=/ig, ":\"") + "\"};");

    if (query.page)
        alert(unescape(query.page));
    else
        alert('No page parameter');

} else {
    alert('No querystring');
}

I'd go with a library like the others suggest though... =)

Npm Error - No matching version found for

Probably not the case of everybody but I had the same problem. I was using the last, in my case, the error was because I was using jfrog manage from the company where I am working.

 npm config list

The result was

; cli configs
metrics-registry = "https://COMPANYNAME.jfrog.io/COMPANYNAM/api/npm/npm/"
scope = ""
user-agent = "npm/6.3.0 node/v8.11.2 win32 x64"

; userconfig C:\Users\USER\.npmrc
always-auth = true
email = "XXXXXXXXX"
registry = "https://COMPANYNAME.jfrog.io/COMPANYNAME/api/npm/npm/"

; builtin config undefined
prefix = "C:\\Users\\XXXXX\\AppData\\Roaming\\npm"

; node bin location = C:\Program Files\nodejs\node.exe
; cwd = C:\WINDOWS\system32
; HOME = C:\Users\XXXXXX
; "npm config ls -l" to show all defaults.

I solve the problem by using the global metrics.

#ifdef replacement in the Swift language

There are some processors that take an argument and I listed them below. you can change the argument as you like:

#if os(macOS) /* Checks the target operating system */

#if canImport(UIKit) /* Check if a module presents */

#if swift(<5) /* Check the Swift version */

#if targetEnvironment(simulator) /* Check envrionments like Simulator or Catalyst */

#if compiler(<7) /* Check compiler version */

Also, You can use any custom flags like DEBUG or any other flags you defined

#if DEBUG
print("Debug mode")
#endif

How to modify list entries during for loop?

The answer given by Jemshit Iskenderov and Ignacio Vazquez-Abrams is really good. It can be further illustrated with this example: imagine that

a) A list with two vectors is given to you;

b) you would like to traverse the list and reverse the order of each one of the arrays

Let's say you have

v = np.array([1, 2,3,4])
b = np.array([3,4,6])

for i in [v, b]:
    i = i[::-1]   # this command does not reverse the string

print([v,b])

You will get

[array([1, 2, 3, 4]), array([3, 4, 6])]

On the other hand, if you do

v = np.array([1, 2,3,4])
b = np.array([3,4,6])

for i in [v, b]:
   i[:] = i[::-1]   # this command reverses the string

print([v,b])

The result is

[array([4, 3, 2, 1]), array([6, 4, 3])]

Xcode 12, building for iOS Simulator, but linking in object file built for iOS, for architecture arm64

I understand the issue with arm64 and Xcode 12 and I was able to resolve build issues by excluding the arm64 architecture for iPhone Simulator or by setting ONLY_ACTIVE_ARCH for Release scheme. However I still have problems to push my framework using pod repo push.

I found out that setting s.pod_target_xcconfig in my podspec does not apply this setting to dependencies defined in the same podspec. I can see it in the dummy App project that Cocoapods is generating during the validation. Cocoapods validation is running release scheme for simulator and this is failing when one or more dependencies doesn't exclude arm64 or is not set to build active architecture only.

A solution could be to force Cocoapods to add post install script while validating the project or let it build Debug scheme, because the Debug scheme is only building active architecture.

I ended up using Xcode 11 to release my pod to pass the validation. You can download Xcode 11 from developer.apple.com, copy it to Applications folder as Xcode11.app and switch using sudo xcode-select --switch /Applications/Xcode11.app/Contents/Developer. Don't forget to switch back when done.

Build an iOS app without owning a mac?

You can use Phonegap (Cordova) to develop iOS Apps without a Mac, but yout would still need a Mac to submit your application to the App Store. We developed a cloud application which also can publish your app without a Mac https://www.wenz.io/ApplicationLoader. Currently we are in beta and you can use the service for free.

Best regards, Steffen Wenz

(I'm the creator of the site)

How to sum a variable by group

Since dplyr 1.0.0, the across() function could be used:

df %>%
 group_by(Category) %>%
 summarise(across(Frequency, sum))

  Category Frequency
  <chr>        <int>
1 First           30
2 Second           5
3 Third           34

If interested in multiple variables:

df %>%
 group_by(Category) %>%
 summarise(across(c(Frequency, Frequency2), sum))

  Category Frequency Frequency2
  <chr>        <int>      <int>
1 First           30         55
2 Second           5         29
3 Third           34        190

And the selection of variables using select helpers:

df %>%
 group_by(Category) %>%
 summarise(across(starts_with("Freq"), sum))

  Category Frequency Frequency2 Frequency3
  <chr>        <int>      <int>      <dbl>
1 First           30         55        110
2 Second           5         29         58
3 Third           34        190        380

Sample data:

df <- read.table(text = "Category Frequency Frequency2 Frequency3
                 1    First        10         10         20
                 2    First        15         30         60
                 3    First         5         15         30
                 4   Second         2          8         16
                 5    Third        14         70        140
                 6    Third        20        120        240
                 7   Second         3         21         42",
                 header = TRUE,
                 stringsAsFactors = FALSE)

How to make a radio button unchecked by clicking it?

The code below will do the trick.

_x000D_
_x000D_
$('input[type=radio]').click(function() {_x000D_
        if($(this).hasClass("checked")){_x000D_
            this.checked = false;_x000D_
            $(this).removeClass("checked")_x000D_
        }else{_x000D_
            $(this).addClass("checked")_x000D_
        }_x000D_
    });
_x000D_
_x000D_
_x000D_

How can I check the extension of a file?

#!/usr/bin/python

import shutil, os

source = ['test_sound.flac','ts.mp3']

for files in source:
  fileName,fileExtension = os.path.splitext(files)

  if fileExtension==".flac" :
    print 'This file is flac file %s' %files
  elif  fileExtension==".mp3":
    print 'This file is mp3 file %s' %files
  else:
    print 'Format is not valid'

Why is the Java main method static?

Why public static void main(String[] args) ?

This is how Java Language is designed and Java Virtual Machine is designed and written.

Oracle Java Language Specification

Check out Chapter 12 Execution - Section 12.1.4 Invoke Test.main:

Finally, after completion of the initialization for class Test (during which other consequential loading, linking, and initializing may have occurred), the method main of Test is invoked.

The method main must be declared public, static, and void. It must accept a single argument that is an array of strings. This method can be declared as either

public static void main(String[] args)

or

public static void main(String... args)

Oracle Java Virtual Machine Specification

Check out Chapter 2 Java Programming Language Concepts - Section 2.17 Execution:

The Java virtual machine starts execution by invoking the method main of some specified class and passing it a single argument, which is an array of strings. This causes the specified class to be loaded (§2.17.2), linked (§2.17.3) to other types that it uses, and initialized (§2.17.4). The method main must be declared public, static, and void.

Oracle OpenJDK Source

Download and extract the source jar and see how JVM is written, check out ../launcher/java.c, which contains native C code behind command java [-options] class [args...]:

/*
 * Get the application's main class.
 * ... ...
 */
if (jarfile != 0) {
    mainClassName = GetMainClassName(env, jarfile);

... ...

    mainClass = LoadClass(env, classname);
    if(mainClass == NULL) { /* exception occured */

... ...

/* Get the application's main method */
mainID = (*env)->GetStaticMethodID(env, mainClass, "main",
                                   "([Ljava/lang/String;)V");

... ...

{    /* Make sure the main method is public */
    jint mods;
    jmethodID mid;
    jobject obj = (*env)->ToReflectedMethod(env, mainClass,
                                            mainID, JNI_TRUE);

... ...

/* Build argument array */
mainArgs = NewPlatformStringArray(env, argv, argc);
if (mainArgs == NULL) {
    ReportExceptionDescription(env);
    goto leave;
}

/* Invoke main method. */
(*env)->CallStaticVoidMethod(env, mainClass, mainID, mainArgs);

... ...

How to force HTTPS using a web.config file

For those using ASP.NET MVC. You can use the RequireHttpsAttribute to force all responses to be HTTPS:

GlobalFilters.Filters.Add(new RequireHttpsAttribute());

Other things you may also want to do to help secure your site:

  1. Force Anti-Forgery tokens to use SSL/TLS:

    AntiForgeryConfig.RequireSsl = true;
    
  2. Require Cookies to require HTTPS by default by changing the Web.config file:

    <system.web>
        <httpCookies httpOnlyCookies="true" requireSSL="true" />
    </system.web>
    
  3. Use the NWebSec.Owin NuGet package and add the following line of code to enable Strict Transport Security (HSTS) across the site. Don't forget to add the Preload directive below and submit your site to the HSTS Preload site. More information here and here. Note that if you are not using OWIN, there is a Web.config method you can read up on on the NWebSec site.

    // app is your OWIN IAppBuilder app in Startup.cs
    app.UseHsts(options => options.MaxAge(days: 720).Preload());
    
  4. Use the NWebSec.Owin NuGet package and add the following line of code to enable Public Key Pinning (HPKP) across the site. More information here and here.

    // app is your OWIN IAppBuilder app in Startup.cs
    app.UseHpkp(options => options
        .Sha256Pins(
            "Base64 encoded SHA-256 hash of your first certificate e.g. cUPcTAZWKaASuYWhhneDttWpY3oBAkE3h2+soZS7sWs=",
            "Base64 encoded SHA-256 hash of your second backup certificate e.g. M8HztCzM3elUxkcjR2S5P4hhyBNf6lHkmjAHKhpGPWE=")
        .MaxAge(days: 30));
    
  5. Include the https scheme in any URL's used. Content Security Policy (CSP) HTTP header and Subresource Integrity (SRI) do not play nice when you imit the scheme in some browsers. It is better to be explicit about HTTPS. e.g.

    <script src="https://ajax.aspnetcdn.com/ajax/bootstrap/3.3.4/bootstrap.min.js">
    </script>
    
  6. Use the ASP.NET MVC Boilerplate Visual Studio project template to generate a project with all of this and much more built in. You can also view the code on GitHub.

Any way to declare an array in-line?

I'd like to add that the array initialization syntax is very succinct and flexible. I use it a LOT to extract data from my code and place it somewhere more usable.

As an example, I've often created menus like this:

Menu menu=initMenus(menuHandler, new String[]{"File", "+Save", "+Load", "Edit", "+Copy", ...});

This would allow me to write come code to set up a menu system. The "+" is enough to tell it to place that item under the previous item.

I could bind it to the menuHandler class either by a method naming convention by naming my methods something like "menuFile, menuFileSave, menuFileLoad, ..." and binding them reflectively (there are other alternatives).

This syntax allows AMAZINGLY brief menu definition and an extremely reusable "initMenus" method. (Yet I don't bother reusing it because it's always fun to write and only takes a few minutes+a few lines of code).

any time you see a pattern in your code, see if you can replace it with something like this, and always remember how succinct the array initialization syntax is!.

Async always WaitingForActivation

I had the same problem. The answers got me on the right track. So the problem is that functions marked with async don't return a task of the function itself as expected (but another continuation task of the function).

So its the "await"and "async" keywords that screws thing up. The simplest solution then is simply to remove them. Then it works as expected. As in:

static void Main(string[] args)
{
    Console.WriteLine("Foo called");
    var result = Foo(5);

    while (result.Status != TaskStatus.RanToCompletion)
    {
        Console.WriteLine("Thread ID: {0}, Status: {1}", Thread.CurrentThread.ManagedThreadId, result.Status);
        Task.Delay(100).Wait();
    }

    Console.WriteLine("Result: {0}", result.Result);
    Console.WriteLine("Finished.");
    Console.ReadKey(true);
}

private static Task<string> Foo(int seconds)
{
    return Task.Run(() =>
    {
        for (int i = 0; i < seconds; i++)
        {
            Console.WriteLine("Thread ID: {0}, second {1}.", Thread.CurrentThread.ManagedThreadId, i);
            Task.Delay(TimeSpan.FromSeconds(1)).Wait();
        }

        return "Foo Completed.";
    });
}

Which outputs:

Foo called
Thread ID: 1, Status: WaitingToRun
Thread ID: 3, second 0.
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 3, second 1.
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 3, second 2.
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 3, second 3.
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 3, second 4.
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Thread ID: 1, Status: Running
Result: Foo Completed.
Finished.

C# switch statement limitations - why?

While on the topic, according to Jeff Atwood, the switch statement is a programming atrocity. Use them sparingly.

You can often accomplish the same task using a table. For example:

var table = new Dictionary<Type, string>()
{
   { typeof(int), "it's an int!" }
   { typeof(string), "it's a string!" }
};

Type someType = typeof(int);
Console.WriteLine(table[someType]);

How to find the default JMX port number?

Now I need to connect that application from my local computer, but I don't know the JMX port number of the remote computer. Where can I find it? Or, must I restart that application with some VM parameters to specify the port number?

By default JMX does not publish on a port unless you specify the arguments from this page: How to activate JMX...

-Dcom.sun.management.jmxremote # no longer required for JDK6
-Dcom.sun.management.jmxremote.port=9010
-Dcom.sun.management.jmxremote.local.only=false # careful with security implications
-Dcom.sun.management.jmxremote.authenticate=false # careful with security implications

If you are running you should be able to access any of those system properties to see if they have been set:

if (System.getProperty("com.sun.management.jmxremote") == null) {
    System.out.println("JMX remote is disabled");
} else [
    String portString = System.getProperty("com.sun.management.jmxremote.port");
    if (portString != null) {
        System.out.println("JMX running on port "
            + Integer.parseInt(portString));
    }
}

Depending on how the server is connected, you might also have to specify the following parameter. As part of the initial JMX connection, jconsole connects up to the RMI port to determine which port the JMX server is running on. When you initially start up a JMX enabled application, it looks its own hostname to determine what address to return in that initial RMI transaction. If your hostname is not in /etc/hosts or if it is set to an incorrect interface address then you can override it with the following:

-Djava.rmi.server.hostname=<IP address>

As an aside, my SimpleJMX package allows you to define both the JMX server and the RMI port or set them both to the same port. The above port defined with com.sun.management.jmxremote.port is actually the RMI port. This tells the client what port the JMX server is running on.

iText - add content to existing PDF file

iText has more than one way of doing this. The PdfStamper class is one option. But I find the easiest method is to create a new PDF document then import individual pages from the existing document into the new PDF.

// Create output PDF
Document document = new Document(PageSize.A4);
PdfWriter writer = PdfWriter.getInstance(document, outputStream);
document.open();
PdfContentByte cb = writer.getDirectContent();

// Load existing PDF
PdfReader reader = new PdfReader(templateInputStream);
PdfImportedPage page = writer.getImportedPage(reader, 1); 

// Copy first page of existing PDF into output PDF
document.newPage();
cb.addTemplate(page, 0, 0);

// Add your new data / text here
// for example...
document.add(new Paragraph("my timestamp")); 

document.close();

This will read in a PDF from templateInputStream and write it out to outputStream. These might be file streams or memory streams or whatever suits your application.

What is the purpose of the "role" attribute in HTML?

Role attribute mainly improve accessibility for people using screen readers. For several cases we use it such as accessibility, device adaptation,server-side processing, and complex data description. Know more click: https://www.w3.org/WAI/PF/HTML/wiki/RoleAttribute.

Sorting arrays in NumPy by column

I suppose this works: a[a[:,1].argsort()]

This indicates the second column of a and sort it based on it accordingly.

How can a file be copied?

Here is a simple way to do it, without any module. It's similar to this answer, but has the benefit to also work if it's a big file that doesn't fit in RAM:

with open('sourcefile', 'rb') as f, open('destfile', 'wb') as g:
    while True:
        block = f.read(16*1024*1024)  # work by blocks of 16 MB
        if not block:  # end of file
            break
        g.write(block)

Since we're writing a new file, it does not preserve the modification time, etc.
We can then use os.utime for this if needed.

Android studio takes too much memory

I have used all of Sam's recommendations above, but I found that the VM command line options are no longer supported as described. (I received an error when used)

As an alternative, I was able to reduce gradle dramatically by adding the following line to the "gradle.properties" file

org.gradle.jvmargs=-Xms512m -Xmx1024m

As of A.S. ver 1.3, the file is located in the same folder level as "gradle.build".

The above configuration is a "memory stack" of 512 meg, and "memory heap" of 1024 meg.

I tested this on a small project, using settings where both memory sizes were set to 256 meg. It limited the JVM sizes as expected. In all my tests, I restarted A.S. to force the JVM to restart.

Hopefully, this will save others dealing with this issue from getting those "Get yourself a better computer" responses. :-)

Dilber

How do you run a single test/spec file in RSpec?

The raw invocation:

rake spec SPEC=spec/controllers/sessions_controller_spec.rb \
          SPEC_OPTS="-e \"should log in with cookie\""

Now figure out how to embed this into your editor.

Where does Chrome store cookies?

On Windows the path is:

C:\Users\<current_user>\AppData\Local\Google\Chrome\User Data\<Profile 1>\Cookies(Type:File)

Chrome doesn't store each cookies in separate text file. It stores all of the cookies together in a single file in the profile folder. That file is not readable.

Get selected element's outer HTML

Here is a very optimized outerHTML plugin for jquery: (http://jsperf.com/outerhtml-vs-jquery-clone-hack/5 => the 2 others fast code snippets are not compatible with some browsers like FF < 11)

(function($) {

  var DIV = document.createElement("div"),
      outerHTML;

  if ('outerHTML' in DIV) {
    outerHTML = function(node) {
      return node.outerHTML;
    };
  } else {
    outerHTML = function(node) {
      var div = DIV.cloneNode();
      div.appendChild(node.cloneNode(true));
      return div.innerHTML;
    };
  }

  $.fn.outerHTML = function() {
    return this.length ? outerHTML(this[0]) : void(0);
  };

})(jQuery);

@Andy E => I don't agree with you. outerHMTL doesn't need a getter AND a setter: jQuery already give us 'replaceWith'...

@mindplay => Why are you joining all outerHTML? jquery.html return only the HTML content of the FIRST element.

(Sorry, don't have enough reputation to write comments)

How to provide password to a command that prompts for one in bash?

Secure commands will not allow this, and rightly so, I'm afraid - it's a security hole you could drive a truck through.

If your command does not allow it using input redirection, or a command-line parameter, or a configuration file, then you're going to have to resort to serious trickery.

Some applications will actually open up /dev/tty to ensure you will have a hard time defeating security. You can get around them by temporarily taking over /dev/tty (creating your own as a pipe, for example) but this requires serious privileges and even it can be defeated.

Bootstrap 4 datapicker.js not included

Most of bootstrap datepickers as I write this answer are rather buggy when included in Bootstrap 4. In my view the least code adding solution is a jQuery plugin. I used this one https://plugins.jquery.com/datetimepicker/ - you can see its usage here: https://xdsoft.net/jqplugins/datetimepicker/ It sure is not as smooth as the whole BS interface, but it only requires its css and js files along with jQuery which is already included in bootstrap.

TypeError: 'dict_keys' object does not support indexing

Convert an iterable to a list may have a cost. Instead, to get the the first item, you can use:

next(iter(keys))

Or, if you want to iterate over all items, you can use:

items = iter(keys)
while True:
    try:
        item = next(items)
    except StopIteration as e:
        pass # finish

Capture Video of Android's Screen

AirPlay Mirroring and Screen Recording is now in CyanogenMod with Mirror APK (Beta).

Get filename and path from URI from mediastore

After getting an image from the gallery, just pass the URI in the below method only for Android 4.4 (KitKat):

public String getPath(Uri contentUri) {// Will return "image:x*"

    String wholeID = DocumentsContract.getDocumentId(contentUri);

    // Split at colon, use second item in the array
    String id = wholeID.split(":")[1];

    String[] column = { MediaStore.Images.Media.DATA };

    // Where id is equal to
    String sel = MediaStore.Images.Media._ID + "=?";

    Cursor cursor = getContentResolver().query(
            MediaStore.Images.Media.EXTERNAL_CONTENT_URI, column, sel,
            new String[] { id }, null);

    String filePath = "";

    int columnIndex = cursor.getColumnIndex(column[0]);

    if (cursor.moveToFirst()) {
        filePath = cursor.getString(columnIndex);
    }

    cursor.close();
    return filePath;
}

MySQL select all rows from last month until (now() - 1 month), for comparative purposes

You can get the first of the month, by calculating the last_day of the month before and add one day. It is awkward, but I think it is better than formatting a date as string and use that for calculation.

select 
  *
from
  yourtable t
where
  /* Greater or equal to the start of last month */
  t.date >= DATE_ADD(LAST_DAY(DATE_SUB(NOW(), INTERVAL 2 MONTH)), INTERVAL 1 DAY) and
  /* Smaller or equal than one month ago */
  t.date <= DATE_SUB(NOW(), INTERVAL 1 MONTH)

What does random.sample() method in python do?

random.sample(population, k)

It is used for randomly sampling a sample of length 'k' from a population. returns a 'k' length list of unique elements chosen from the population sequence or set

it returns a new list and leaves the original population unchanged and the resulting list is in selection order so that all sub-slices will also be valid random samples

I am putting up an example in which I am splitting a dataset randomly. It is basically a function in which you pass x_train(population) as an argument and return indices of 60% of the data as D_test.

import random

def randomly_select_70_percent_of_data_from_1_to_length(x_train):
    return random.sample(range(0, len(x_train)), int(0.6*len(x_train)))

How can I compare two ordered lists in python?

If you want to just check if they are identical or not, a == b should give you true / false with ordering taken into account.

In case you want to compare elements, you can use numpy for comparison

c = (numpy.array(a) == numpy.array(b))

Here, c will contain an array with 3 elements all of which are true (for your example). In the event elements of a and b don't match, then the corresponding elements in c will be false.

How do I redirect a user when a button is clicked?

$("#yourbuttonid").click(function(){ document.location = "<%= Url.Action("Youraction") %>";})

How to create a bash script to check the SSH connection?

Following @user156676, to check a range of ips:

#!/bin/sh
IP='192.168.0.'
PWD='your_password'
USR='your_usr'

for i in $(seq 229 255);do
    sshpass -p $PWD ssh -q -o ConnectTimeout=3 ${USR}@${IP}${i} exit
    let ret=$?
    if [ $ret -eq 5 ]; then
        echo $IP$i "Refused!"  $ret
    elif [ $ret -eq 255 ] ; then
        echo $IP$i "Server Down!" $ret
    elif [ $ret -eq 0 ] ; then
        echo $IP$i "Connnected!" $ret
    else
        echo $IP$i "Unknown return code!" $ret
    fi  
done

What is String pool in Java?

When the JVM loads classes, or otherwise sees a literal string, or some code interns a string, it adds the string to a mostly-hidden lookup table that has one copy of each such string. If another copy is added, the runtime arranges it so that all the literals refer to the same string object. This is called "interning". If you say something like

String s = "test";
return (s == "test");

it'll return true, because the first and second "test" are actually the same object. Comparing interned strings this way can be much, much faster than String.equals, as there's a single reference comparison rather than a bunch of char comparisons.

You can add a string to the pool by calling String.intern(), which will give you back the pooled version of the string (which could be the same string you're interning, but you'd be crazy to rely on that -- you often can't be sure exactly what code has been loaded and run up til now and interned the same string). The pooled version (the string returned from intern) will be equal to any identical literal. For example:

String s1 = "test";
String s2 = new String("test");  // "new String" guarantees a different object

System.out.println(s1 == s2);  // should print "false"

s2 = s2.intern();
System.out.println(s1 == s2);  // should print "true"

Transaction count after EXECUTE indicates a mismatching number of BEGIN and COMMIT statements. Previous count = 1, current count = 0

For me after extensive debugging the fix was a simple missing throw; statement in the catch after the rollback. Without it this ugly error message is what you end up with.

begin catch
    if @@trancount > 0 rollback transaction;
    throw; --allows capture of useful info when an exception happens within the transaction
end catch

How to check if a scope variable is undefined in AngularJS template?

<p ng-show="angular.isUndefined(foo)">Show this if $scope.foo === undefined</p>

How can I create persistent cookies in ASP.NET?

//add cookie

var panelIdCookie = new HttpCookie("panelIdCookie");
panelIdCookie.Values.Add("panelId", panelId.ToString(CultureInfo.InvariantCulture));
panelIdCookie.Expires = DateTime.Now.AddMonths(2); 
Response.Cookies.Add(panelIdCookie);

//read cookie

    var httpCookie = Request.Cookies["panelIdCookie"];
                if (httpCookie != null)
                {
                    panelId = Convert.ToInt32(httpCookie["panelId"]);
                }

Curl command line for consuming webServices?

Posting a string:

curl -d "String to post" "http://www.example.com/target"

Posting the contents of a file:

curl -d @soap.xml "http://www.example.com/target"

How to convert array values to lowercase in PHP?

Just for completeness: you may also use array_walk:

array_walk($yourArray, function(&$value)
{
  $value = strtolower($value);
});

From PHP docs:

If callback needs to be working with the actual values of the array, specify the first parameter of callback as a reference. Then, any changes made to those elements will be made in the original array itself.

Or directly via foreach loop using references:

foreach($yourArray as &$value)
  $value = strtolower($value);

Note that these two methods change the array "in place", whereas array_map creates and returns a copy of the array, which may not be desirable in case of very large arrays.

How to maintain aspect ratio using HTML IMG tag

With css:

.img {
    display:table-cell;
    max-width:...px;
    max-height:...px;
    width:100%;
}

HTML5 Canvas 100% Width Height of Viewport?

http://jsfiddle.net/mqFdk/10/

<!DOCTYPE html>
<html>
<head>
    <title>aj</title>
</head>
<body>

    <canvas id="c"></canvas>

</body>
</html>

with CSS

body { 
       margin: 0; 
       padding: 0
     }
#c { 
     position: absolute; 
     width: 100%; 
     height: 100%; 
     overflow: hidden
   }

Change color of PNG image via CSS?

You might want to take a look at Icon fonts. http://css-tricks.com/examples/IconFont/

EDIT: I'm using Font-Awesome on my latest project. You can even bootstrap it. Simply put this in your <head>:

<link href="//netdna.bootstrapcdn.com/font-awesome/3.2.1/css/font-awesome.min.css" rel="stylesheet">

<!-- And if you want to support IE7, add this aswell -->
<link href="//netdna.bootstrapcdn.com/font-awesome/3.2.1/css/font-awesome-ie7.min.css" rel="stylesheet">

And then go ahead and add some icon-links like this:

<a class="icon-thumbs-up"></a>

Here's the full cheat sheet

--edit--

Font-Awesome uses different class names in the new version, probably because this makes the CSS files drastically smaller, and to avoid ambiguous css classes. So now you should use:

<a class="fa fa-thumbs-up"></a>

EDIT 2:

Just found out github also uses its own icon font: Octicons It's free to download. They also have some tips on how to create your very own icon fonts.

OpenCV in Android Studio

Integrating OpenCV v3.1.0 into Android Studio v1.4.1, instructions with additional detail and this-is-what-you-should-get type screenshots.

Most of the credit goes to Kiran, Kool, 1", and SteveLiles over at opencv.org for their explanations. I'm adding this answer because I believe that Android Studio's interface is now stable enough to work with on this type of integration stuff. Also I have to write these instructions anyway for our project.

Experienced A.S. developers will find some of this pedantic. This answer is targeted at people with limited experience in Android Studio.

  1. Create a new Android Studio project using the project wizard (Menu:/File/New Project):

    • Call it "cvtest1"
    • Form factor: API 19, Android 4.4 (KitKat)
    • Blank Activity named MainActivity

      You should have a cvtest1 directory where this project is stored. (the title bar of Android studio shows you where cvtest1 is when you open the project)

  2. Verify that your app runs correctly. Try changing something like the "Hello World" text to confirm that the build/test cycle is OK for you. (I'm testing with an emulator of an API 19 device).

  3. Download the OpenCV package for Android v3.1.0 and unzip it in some temporary directory somewhere. (Make sure it is the package specifically for Android and not just the OpenCV for Java package.) I'll call this directory "unzip-dir" Below unzip-dir you should have a sdk/native/libs directory with subdirectories that start with things like arm..., mips... and x86... (one for each type of "architecture" Android runs on)

  4. From Android Studio import OpenCV into your project as a module: Menu:/File/New/Import_Module:

    • Source-directory: {unzip-dir}/sdk/java
    • Module name: Android studio automatically fills in this field with openCVLibrary310 (the exact name probably doesn't matter but we'll go with this).
    • Click on next. You get a screen with three checkboxes and questions about jars, libraries and import options. All three should be checked. Click on Finish.

      Android Studio starts to import the module and you are shown an import-summary.txt file that has a list of what was not imported (mostly javadoc files) and other pieces of information. enter image description here

      But you also get an error message saying failed to find target with hash string 'android-14'.... This happens because the build.gradle file in the OpenCV zip file you downloaded says to compile using android API version 14, which by default you don't have with Android Studio v1.4.1. enter image description here

  5. Open the project structure dialogue (Menu:/File/Project_Structure). Select the "app" module, click on the Dependencies tab and add :openCVLibrary310 as a Module Dependency. When you select Add/Module_Dependency it should appear in the list of modules you can add. It will now show up as a dependency but you will get a few more cannot-find-android-14 errors in the event log.

  6. Look in the build.gradle file for your app module. There are multiple build.gradle files in an Android project. The one you want is in the cvtest1/app directory and from the project view it looks like build.gradle (Module: app). Note the values of these four fields:

    • compileSDKVersion (mine says 23)
    • buildToolsVersion (mine says 23.0.2)
    • minSdkVersion (mine says 19)
    • targetSdkVersion (mine says 23)
  7. Your project now has a cvtest1/OpenCVLibrary310 directory but it is not visible from the project view:

enter image description here

Use some other tool, such as any file manager, and go to this directory. You can also switch the project view from Android to Project Files and you can find this directory as shown in this screenshot: enter image description here

Inside there is another build.gradle file (it's highlighted in the above screenshot). Update this file with the four values from step 6.

  1. Resynch your project and then clean/rebuild it. (Menu:/Build/Clean_Project) It should clean and build without errors and you should see many references to :openCVLibrary310 in the 0:Messages screen.

    enter image description here

    At this point the module should appear in the project hierarchy as openCVLibrary310, just like app. (Note that in that little drop-down menu I switched back from Project View to Android View ). You should also see an additional build.gradle file under "Gradle Scripts" but I find the Android Studio interface a little bit glitchy and sometimes it does not do this right away. So try resynching, cleaning, even restarting Android Studio.

    You should see the openCVLibrary310 module with all the OpenCV functions under java like in this screenshot:

    enter image description here

  2. Copy the {unzip-dir}/sdk/native/libs directory (and everything under it) to your Android project, to cvtest1/OpenCVLibrary310/src/main/, and then rename your copy from libs to jniLibs. You should now have a cvtest1/OpenCVLibrary310/src/main/jniLibs directory. Resynch your project and this directory should now appear in the project view under openCVLibrary310.

    enter image description here

  3. Go to the onCreate method of MainActivity.java and append this code:

    if (!OpenCVLoader.initDebug()) {
        Log.e(this.getClass().getSimpleName(), "  OpenCVLoader.initDebug(), not working.");
    } else {
        Log.d(this.getClass().getSimpleName(), "  OpenCVLoader.initDebug(), working.");
    }
    

    Then run your application. You should see lines like this in the Android Monitor: enter image description here (I don't know why that line with the error message is there)

  4. Now try to actually use some openCV code. In the example below I copied a .jpg file to the cache directory of the cvtest1 application on the android emulator. The code below loads this image, runs the canny edge detection algorithm and then writes the results back to a .png file in the same directory.

    Put this code just below the code from the previous step and alter it to match your own files/directories.

    String inputFileName="simm_01";
    String inputExtension = "jpg";
    String inputDir = getCacheDir().getAbsolutePath();  // use the cache directory for i/o
    String outputDir = getCacheDir().getAbsolutePath();
    String outputExtension = "png";
    String inputFilePath = inputDir + File.separator + inputFileName + "." + inputExtension;
    
    
    Log.d (this.getClass().getSimpleName(), "loading " + inputFilePath + "...");
    Mat image = Imgcodecs.imread(inputFilePath);  
    Log.d (this.getClass().getSimpleName(), "width of " + inputFileName + ": " + image.width());
    // if width is 0 then it did not read your image.
    
    
    // for the canny edge detection algorithm, play with these to see different results
    int threshold1 = 70;
    int threshold2 = 100;
    
    Mat im_canny = new Mat();  // you have to initialize output image before giving it to the Canny method
    Imgproc.Canny(image, im_canny, threshold1, threshold2);
    String cannyFilename = outputDir + File.separator + inputFileName + "_canny-" + threshold1 + "-" + threshold2 + "." + outputExtension;
    Log.d (this.getClass().getSimpleName(), "Writing " + cannyFilename);
    Imgcodecs.imwrite(cannyFilename, im_canny);
    
  5. Run your application. Your emulator should create a black and white "edge" image. You can use the Android Device Monitor to retrieve the output or write an activity to show it.

The Gotchas:

  • If you lower your target platform below KitKat some of the OpenCV libraries will no longer function, specifically the classes related to org.opencv.android.Camera2Renderer and other related classes. You can probably get around this by simply removing the apprpriate OpenCV .java files.
  • If you raise your target platform to Lollipop or above my example of loading a file might not work because use of absolute file paths is frowned upon. So you might have to change the example to load a file from the gallery or somewhere else. There are numerous examples floating around.

Composer install error - requires ext_curl when it's actually enabled

According to https://github.com/composer/composer/issues/2119 you could extend your local composer.json to state that it provides the extension (which it doesn't really do - that's why you shouldn't publicly publish your package, only use it internally).

When to use MyISAM and InnoDB?

Read about Storage Engines.

MyISAM:

The MyISAM storage engine in MySQL.

  • Simpler to design and create, thus better for beginners. No worries about the foreign relationships between tables.
  • Faster than InnoDB on the whole as a result of the simpler structure thus much less costs of server resources. -- Mostly no longer true.
  • Full-text indexing. -- InnoDB has it now
  • Especially good for read-intensive (select) tables. -- Mostly no longer true.
  • Disk footprint is 2x-3x less than InnoDB's. -- As of Version 5.7, this is perhaps the only real advantage of MyISAM.

InnoDB:

The InnoDB storage engine in MySQL.

  • Support for transactions (giving you support for the ACID property).
  • Row-level locking. Having a more fine grained locking-mechanism gives you higher concurrency compared to, for instance, MyISAM.
  • Foreign key constraints. Allowing you to let the database ensure the integrity of the state of the database, and the relationships between tables.
  • InnoDB is more resistant to table corruption than MyISAM.
  • Support for large buffer pool for both data and indexes. MyISAM key buffer is only for indexes.
  • MyISAM is stagnant; all future enhancements will be in InnoDB. This was made abundantly clear with the roll out of Version 8.0.

MyISAM Limitations:

  • No foreign keys and cascading deletes/updates
  • No transactional integrity (ACID compliance)
  • No rollback abilities
  • 4,284,867,296 row limit (2^32) -- This is old default. The configurable limit (for many versions) has been 2**56 bytes.
  • Maximum of 64 indexes per table

InnoDB Limitations:

  • No full text indexing (Below-5.6 mysql version)
  • Cannot be compressed for fast, read-only (5.5.14 introduced ROW_FORMAT=COMPRESSED)
  • You cannot repair an InnoDB table

For brief understanding read below links:

  1. MySQL Engines: InnoDB vs. MyISAM – A Comparison of Pros and Cons
  2. MySQL Engines: MyISAM vs. InnoDB
  3. What are the main differences between InnoDB and MyISAM?
  4. MyISAM versus InnoDB
  5. What's the difference between MyISAM and InnoDB?
  6. MySql: MyISAM vs. Inno DB!

Assigning strings to arrays of characters

When initializing an array, C allows you to fill it with values. So

char s[100] = "abcd";

is basically the same as

int s[3] = { 1, 2, 3 };

but it doesn't allow you to do the assignment since s is an array and not a free pointer. The meaning of

s = "abcd" 

is to assign the pointer value of abcd to s but you can't change s since then nothing will be pointing to the array.
This can and does work if s is a char* - a pointer that can point to anything.

If you want to copy the string simple use strcpy.

Assigning the return value of new by reference is deprecated

C:\wamp\www\..\libraries\pattemplate

1.ini_set('display_errors', 0);

$this->_modules[$moduleType][$sig]  =&new $moduleClass;   wrong

$this->_modules[$moduleType][$sig]  =new $moduleClass;   Right

How to pass boolean parameter value in pipeline to downstream jobs?

Assuming

value: update_composer

was the issue, try

value: Boolean.valueOf(update_composer)

is there a less cumbersome way in which I can just pass ALL the pipeline parameters to the downstream job

Not that I know of, at least not without using Jenkins API calls and disabling the Groovy sandbox.

RestSharp JSON Parameter Posting

In the current version of RestSharp (105.2.3.0) you can add a JSON object to the request body with:

request.AddJsonBody(new { A = "foo", B = "bar" });

This method sets content type to application/json and serializes the object to a JSON string.

Getting the exception value in Python

Another way hasn't been given yet:

try:
    1/0
except Exception, e:
    print e.message

Output:

integer division or modulo by zero

args[0] might actually not be a message.

str(e) might return the string with surrounding quotes and possibly with the leading u if unicode:

'integer division or modulo by zero'

repr(e) gives the full exception representation which is not probably what you want:

"ZeroDivisionError('integer division or modulo by zero',)"

edit

My bad !!! It seems that BaseException.message has been deprecated from 2.6, finally, it definitely seems that there is still not a standardized way to display exception messages. So I guess the best is to do deal with e.args and str(e) depending on your needs (and possibly e.message if the lib you are using is relying on that mechanism).

For instance, with pygraphviz, e.message is the only way to display correctly the exception, using str(e) will surround the message with u''.

But with MySQLdb, the proper way to retrieve the message is e.args[1]: e.message is empty, and str(e) will display '(ERR_CODE, "ERR_MSG")'

Cannot use Server.MapPath

Your project needs to reference assembly System.Web.dll. Server is an object of type HttpServerUtility. Example:

HttpContext.Current.Server.MapPath(path);

In CSS how do you change font size of h1 and h2

h1 {
  font-weight: bold;
  color: #fff;
  font-size: 32px;
}

h2 {
  font-weight: bold;
  color: #fff;
  font-size: 24px;
}

Note that after color you can use a word (e.g. white), a hex code (e.g. #fff) or RGB (e.g. rgb(255,255,255)) or RGBA (e.g. rgba(255,255,255,0.3)).

Convert a PHP object to an associative array

This answer is only the union of the different answers of this post, but it's the solution to convert a PHP object with public or private properties with simple values or arrays to an associative array...

function object_to_array($obj)
{
    if (is_object($obj))
        $obj = (array)$this->dismount($obj);
    if (is_array($obj)) {
        $new = array();
        foreach ($obj as $key => $val) {
            $new[$key] = $this->object_to_array($val);
        }
    }
    else
        $new = $obj;
    return $new;
}

function dismount($object)
{
    $reflectionClass = new \ReflectionClass(get_class($object));
    $array = array();
    foreach ($reflectionClass->getProperties() as $property) {
        $property->setAccessible(true);
        $array[$property->getName()] = $property->getValue($object);
        $property->setAccessible(false);
    }
    return $array;
}

How to make a ssh connection with python?

Twisted has SSH support : http://www.devshed.com/c/a/Python/SSH-with-Twisted/

The twisted.conch package adds SSH support to Twisted. This chapter shows how you can use the modules in twisted.conch to build SSH servers and clients.

Setting Up a Custom SSH Server

The command line is an incredibly efficient interface for certain tasks. System administrators love the ability to manage applications by typing commands without having to click through a graphical user interface. An SSH shell is even better, as it’s accessible from anywhere on the Internet.

You can use twisted.conch to create an SSH server that provides access to a custom shell with commands you define. This shell will even support some extra features like command history, so that you can scroll through the commands you’ve already typed.

How Do I Do That? Write a subclass of twisted.conch.recvline.HistoricRecvLine that implements your shell protocol. HistoricRecvLine is similar to twisted.protocols.basic.LineReceiver , but with higher-level features for controlling the terminal.

Write a subclass of twisted.conch.recvline.HistoricRecvLine that implements your shell protocol. HistoricRecvLine is similar to twisted.protocols.basic.LineReceiver, but with higher-level features for controlling the terminal.

To make your shell available through SSH, you need to implement a few different classes that twisted.conch needs to build an SSH server. First, you need the twisted.cred authentication classes: a portal, credentials checkers, and a realm that returns avatars. Use twisted.conch.avatar.ConchUser as the base class for your avatar. Your avatar class should also implement twisted.conch.interfaces.ISession , which includes an openShell method in which you create a Protocol to manage the user’s interactive session. Finally, create a twisted.conch.ssh.factory.SSHFactory object and set its portal attribute to an instance of your portal.

Example 10-1 demonstrates a custom SSH server that authenticates users by their username and password. It gives each user a shell that provides several commands.

Example 10-1. sshserver.py

from twisted.cred import portal, checkers, credentials
from twisted.conch import error, avatar, recvline, interfaces as conchinterfaces
from twisted.conch.ssh import factory, userauth, connection, keys, session, common from twisted.conch.insults import insults from twisted.application import service, internet
from zope.interface import implements
import os

class SSHDemoProtocol(recvline.HistoricRecvLine):
    def __init__(self, user):
        self.user = user

    def connectionMade(self) : 
     recvline.HistoricRecvLine.connectionMade(self)
        self.terminal.write("Welcome to my test SSH server.")
        self.terminal.nextLine() 
        self.do_help()
        self.showPrompt()

    def showPrompt(self): 
        self.terminal.write("$ ")

    def getCommandFunc(self, cmd):
        return getattr(self, ‘do_’ + cmd, None)

    def lineReceived(self, line):
        line = line.strip()
        if line: 
            cmdAndArgs = line.split()
            cmd = cmdAndArgs[0]
            args = cmdAndArgs[1:]
            func = self.getCommandFunc(cmd)
            if func: 
               try:
                   func(*args)
               except Exception, e: 
                   self.terminal.write("Error: %s" % e)
                   self.terminal.nextLine()
            else:
               self.terminal.write("No such command.")
               self.terminal.nextLine()
        self.showPrompt()

    def do_help(self, cmd=”):
        "Get help on a command. Usage: help command"
        if cmd: 
            func = self.getCommandFunc(cmd)
            if func:
                self.terminal.write(func.__doc__)
                self.terminal.nextLine()
                return

        publicMethods = filter(
            lambda funcname: funcname.startswith(‘do_’), dir(self)) 
        commands = [cmd.replace(‘do_’, ”, 1) for cmd in publicMethods] 
        self.terminal.write("Commands: " + " ".join(commands))
        self.terminal.nextLine()

    def do_echo(self, *args):
        "Echo a string. Usage: echo my line of text"
        self.terminal.write(" ".join(args)) 
        self.terminal.nextLine()

    def do_whoami(self):
        "Prints your user name. Usage: whoami"
        self.terminal.write(self.user.username)
        self.terminal.nextLine()

    def do_quit(self):
        "Ends your session. Usage: quit" 
        self.terminal.write("Thanks for playing!")
        self.terminal.nextLine() 
        self.terminal.loseConnection()

    def do_clear(self):
        "Clears the screen. Usage: clear" 
        self.terminal.reset()

class SSHDemoAvatar(avatar.ConchUser): 
    implements(conchinterfaces.ISession)

    def __init__(self, username): 
        avatar.ConchUser.__init__(self) 
        self.username = username 
        self.channelLookup.update({‘session’:session.SSHSession})

    def openShell(self, protocol): 
        serverProtocol = insults.ServerProtocol(SSHDemoProtocol, self)
        serverProtocol.makeConnection(protocol)
        protocol.makeConnection(session.wrapProtocol(serverProtocol))

    def getPty(self, terminal, windowSize, attrs):
        return None

    def execCommand(self, protocol, cmd): 
        raise NotImplementedError

    def closed(self):
        pass

class SSHDemoRealm:
    implements(portal.IRealm)

    def requestAvatar(self, avatarId, mind, *interfaces):
        if conchinterfaces.IConchUser in interfaces:
            return interfaces[0], SSHDemoAvatar(avatarId), lambda: None
        else:
            raise Exception, "No supported interfaces found."

def getRSAKeys():
    if not (os.path.exists(‘public.key’) and os.path.exists(‘private.key’)):
        # generate a RSA keypair
        print "Generating RSA keypair…" 
        from Crypto.PublicKey import RSA 
        KEY_LENGTH = 1024
        rsaKey = RSA.generate(KEY_LENGTH, common.entropy.get_bytes)
        publicKeyString = keys.makePublicKeyString(rsaKey) 
        privateKeyString = keys.makePrivateKeyString(rsaKey)
        # save keys for next time
        file(‘public.key’, ‘w+b’).write(publicKeyString)
        file(‘private.key’, ‘w+b’).write(privateKeyString)
        print "done."
    else:
        publicKeyString = file(‘public.key’).read()
        privateKeyString = file(‘private.key’).read() 
    return publicKeyString, privateKeyString

if __name__ == "__main__":
    sshFactory = factory.SSHFactory() 
    sshFactory.portal = portal.Portal(SSHDemoRealm())
    users = {‘admin’: ‘aaa’, ‘guest’: ‘bbb’}
    sshFactory.portal.registerChecker(
 checkers.InMemoryUsernamePasswordDatabaseDontUse(**users))

    pubKeyString, privKeyString =
getRSAKeys()
    sshFactory.publicKeys = {
        ‘ssh-rsa’: keys.getPublicKeyString(data=pubKeyString)}
    sshFactory.privateKeys = {
        ‘ssh-rsa’: keys.getPrivateKeyObject(data=privKeyString)}

    from twisted.internet import reactor 
    reactor.listenTCP(2222, sshFactory) 
    reactor.run()

{mospagebreak title=Setting Up a Custom SSH Server continued}

sshserver.py will run an SSH server on port 2222. Connect to this server with an SSH client using the username admin and password aaa, and try typing some commands:

$ ssh admin@localhost -p 2222 
admin@localhost’s password: aaa

>>> Welcome to my test SSH server.  
Commands: clear echo help quit whoami
$ whoami
admin
$ help echo
Echo a string. Usage: echo my line of text
$ echo hello SSH world!
hello SSH world!
$ quit

Connection to localhost closed.

Can an AWS Lambda function call another

I was working with the answer provided by blueskin but I could not read the Payload response because the InvocationType='Event' is async, so I changed as InvocationType='RequestResponse' and now all works good.

Where are the python modules stored?

  1. You can iterate through directories listed in sys.path to find all modules (except builtin ones).
  2. It'll probably be somewhere around /usr/lib/pythonX.X/site-packages (again, see sys.path). And consider using native Python package management (via pip or easy_install, plus yolk) instead, packages in Linux distros-maintained repositories tend to be outdated.