Programs & Examples On #Lazy initialization

Lazy initialization is the tactic of delaying the creation of an object, the calculation of a value, or some other expensive process until the first time it is needed.

dbms_lob.getlength() vs. length() to find blob size in oracle

length and dbms_lob.getlength return the number of characters when applied to a CLOB (Character LOB). When applied to a BLOB (Binary LOB), dbms_lob.getlength will return the number of bytes, which may differ from the number of characters in a multi-byte character set.

As the documentation doesn't specify what happens when you apply length on a BLOB, I would advise against using it in that case. If you want the number of bytes in a BLOB, use dbms_lob.getlength.

Get elements by attribute when querySelectorAll is not available without using libraries?

Try this it works

document.querySelector('[attribute="value"]')

example :

document.querySelector('[role="button"]')

How can I count the numbers of rows that a MySQL query returned?

If you want the result plus the number of rows returned do something like this. Using PHP.

$query = "SELECT * FROM Employee";
$result = mysql_query($query);
echo "There are ".mysql_num_rows($result)." Employee(s).";

How do I implement IEnumerable<T>

Note that the IEnumerable<T> allready implemented by the System.Collections so another approach is to derive your MyObjects class from System.Collections as a base class (documentation):

System.Collections: Provides the base class for a generic collection.

We can later make our own implemenation to override the virtual System.Collections methods to provide custom behavior (only for ClearItems, InsertItem, RemoveItem, and SetItem along with Equals, GetHashCode, and ToString from Object). Unlike the List<T> which is not designed to be easily extensible.

Example:

public class FooCollection : System.Collections<Foo>
{
    //...
    protected override void InsertItem(int index, Foo newItem)
    {
        base.InsertItem(index, newItem);     
        Console.Write("An item was successfully inserted to MyCollection!");
    }
}

public static void Main()
{
    FooCollection fooCollection = new FooCollection();
    fooCollection.Add(new Foo()); //OUTPUT: An item was successfully inserted to FooCollection!
}

Please note that driving from collection recommended only in case when custom collection behavior is needed, which is rarely happens. see usage.

What is a View in Oracle?

A View in Oracle and in other database systems is simply the representation of a SQL statement that is stored in memory so that it can easily be re-used. For example, if we frequently issue the following query

SELECT customerid, customername FROM customers WHERE countryid='US';

To create a view use the CREATE VIEW command as seen in this example

CREATE VIEW view_uscustomers
AS
SELECT customerid, customername FROM customers WHERE countryid='US';

This command creates a new view called view_uscustomers. Note that this command does not result in anything being actually stored in the database at all except for a data dictionary entry that defines this view. This means that every time you query this view, Oracle has to go out and execute the view and query the database data. We can query the view like this:

SELECT * FROM view_uscustomers WHERE customerid BETWEEN 100 AND 200;

And Oracle will transform the query into this:

SELECT * 
FROM (select customerid, customername from customers WHERE countryid='US') 
WHERE customerid BETWEEN 100 AND 200

Benefits of using Views

  • Commonality of code being used. Since a view is based on one common set of SQL, this means that when it is called it’s less likely to require parsing.
  • Security. Views have long been used to hide the tables that actually contain the data you are querying. Also, views can be used to restrict the columns that a given user has access to.
  • Predicate pushing

You can find advanced topics in this article about "How to Create and Manage Views in Oracle."

What do column flags mean in MySQL Workbench?

This exact question is answered on mySql workbench-faq:

Hover over an acronym to view a description, and see the Section 8.1.11.2, “The Columns Tab” and MySQL CREATE TABLE documentation for additional details.

That means hover over an acronym in the mySql Workbench table editor.

Section 8.1.11.2, “The Columns Tab”

Why am I getting this error: No mapping specified for the following EntitySet/AssociationSet - Entity1?

Had this error when I had deleted a table from the database. Solved it by right clicking on EDMX diagram, going to Properties, selecting the table from the list in the Properties window, and deleting it (using delete key) from the diagram.

What is the difference between a JavaBean and a POJO?

POJOS with certain conventions (getter/setter,public no-arg constructor ,private variables) and are in action(ex. being used for reading data by form) are JAVABEANS.

"Unable to acquire application service" error while launching Eclipse

For me, what eventually did the trick was adding -clean at the start of eclipse.ini

Array of arrays (Python/NumPy)

You'll have problems creating lists without commas. It shouldn't be too hard to transform your data so that it uses commas as separating character.

Once you have commas in there, it's a relatively simple list creation operations:

array1 = [1,2,3]
array2 = [4,5,6]

array3 = [array1, array2]

array4 = [7,8,9]
array5 = [10,11,12]

array3 = [array3, [array4, array5]]

When testing we get:

print(array3)

[[[1, 2, 3], [4, 5, 6]], [[7, 8, 9], [10, 11, 12]]]

And if we test with indexing it works correctly reading the matrix as made up of 2 rows and 2 columns:

array3[0][1]
[4, 5, 6]

array3[1][1]
[10, 11, 12]

Hope that helps.

Find the smallest positive integer that does not occur in a given sequence

Below is my solution

int[] A = {1,2,3};
Arrays.sort(A);
Set<Integer> positiveSet = new HashSet<>();
for(int a: A) {
    if(a>0) {
        positiveSet.add(a);
    }
}
for(int a: A) {
    int res = a+1;
    if(!positiveSet.contains(res)) {
        System.out.println("result : "+res);
        break;
    }
}

How do I create an Android Spinner as a popup?

Adding a small attribute as android:spinnerMode="dialog" would show the spinner contents in a pop-up.

Remove space above and below <p> tag HTML

CSS Reset is best way to use for this issue. Right now in reset we are using p and in need bases you can add any number of tags by come separated.

p {
    margin:0;
    padding:0;
}

How do you get the width and height of a multi-dimensional array?

Use GetLength(), rather than Length.

int rowsOrHeight = ary.GetLength(0);
int colsOrWidth = ary.GetLength(1);

Is there a way to detect if an image is blurry?

Yes, it is. Compute the Fast Fourier Transform and analyse the result. The Fourier transform tells you which frequencies are present in the image. If there is a low amount of high frequencies, then the image is blurry.

Defining the terms 'low' and 'high' is up to you.

Edit:

As stated in the comments, if you want a single float representing the blurryness of a given image, you have to work out a suitable metric.

nikie's answer provide such a metric. Convolve the image with a Laplacian kernel:

   1
1 -4  1
   1

And use a robust maximum metric on the output to get a number which you can use for thresholding. Try to avoid smoothing too much the images before computing the Laplacian, because you will only find out that a smoothed image is indeed blurry :-).

How can I clear the terminal in Visual Studio Code?

You can change from settings menu (at least from version 1.30.2 and above)...

On Mac, just hit Code > Preferences > Settings.

Then just search for "clear" and check Clear Previous Output.

Settings - Clear Previous Output

Making a request to a RESTful API using python

So you want to pass data in body of a GET request, better would be to do it in POST call. You can achieve this by using both Requests.

Raw Request

GET http://ES_search_demo.com/document/record/_search?pretty=true HTTP/1.1
Host: ES_search_demo.com
Content-Length: 183
User-Agent: python-requests/2.9.0
Connection: keep-alive
Accept: */*
Accept-Encoding: gzip, deflate

{
  "query": {
    "bool": {
      "must": [
        {
          "text": {
            "record.document": "SOME_JOURNAL"
          }
        },
        {
          "text": {
            "record.articleTitle": "farmers"
          }
        }
      ],
      "must_not": [],
      "should": []
    }
  },
  "from": 0,
  "size": 50,
  "sort": [],
  "facets": {}
}

Sample call with Requests

import requests

def consumeGETRequestSync():
data = '{
  "query": {
    "bool": {
      "must": [
        {
          "text": {
            "record.document": "SOME_JOURNAL"
          }
        },
        {
          "text": {
            "record.articleTitle": "farmers"
          }
        }
      ],
      "must_not": [],
      "should": []
    }
  },
  "from": 0,
  "size": 50,
  "sort": [],
  "facets": {}
}'
url = 'http://ES_search_demo.com/document/record/_search?pretty=true'
headers = {"Accept": "application/json"}
# call get service with headers and params
response = requests.get(url,data = data)
print "code:"+ str(response.status_code)
print "******************"
print "headers:"+ str(response.headers)
print "******************"
print "content:"+ str(response.text)

consumeGETRequestSync()

Using Lato fonts in my css (@font-face)

Well, you're missing the letter 'd' in url("~/fonts/Lato-Bol.ttf"); - but assuming that's not it, I would open up your page with developer tools in Chrome and make sure there's no errors loading any of the files (you would probably see an issue in the JavaScript console, or you can check the Network tab and see if anything is red).

(I don't see anything obviously wrong with the code you have posted above)

Other things to check: 1) Are you including your CSS file in your html above the lines where you are trying to use the font-family style? 2) What do you see in the CSS panel in the developer tools for that div? Is font-family: lato crossed out?

Struct like objects in Java

As with most things, there's the general rule and then there are specific circumstances. If you are doing a closed, captured application so that you know how a given object is going to be used, then you can exercise more freedom to favor visibility and/or efficiency. If you're developing a class which is going to be used publicly by others beyond your control, then lean towards the getter/setter model. As with all things, just use common sense. It's often ok to do an initial round with publics and then change them to getter/setters later.

does linux shell support list data structure?

For make a list, simply do that

colors=(red orange white "light gray")

Technically is an array, but - of course - it has all list features.
Even python list are implemented with array

How do I add a margin between bootstrap columns without wrapping

If you do not need to add a border on columns, you can also simply add a transparent border on them:

[class*="col-"] {
    background-clip: padding-box;
    border: 10px solid transparent;
}

Adding a newline character within a cell (CSV)

I struggled with this as well but heres the solution. If you add " before and at the end of the csv string you are trying to display, it will consolidate them into 1 cell while honoring new line.

csvString += "\""+"Date Generated: \n" ; 
csvString += "Doctor: " + "\n"+"\"" + "\n"; 

Run jQuery function onclick

There's several things you can improve upon here. To start, there's no reason to use an <a> (anchor) tag since you don't have a link.

Every element can be bound to click and hover events... divs, spans, labels, inputs, etc.

I can't really identify what it is you're trying to do, though. You're mixing the goal with your own implementation and, from what I've seen so far, you're not really sure how to do it. Could you better illustrate what it is you're trying to accomplish?

== EDIT ==

The requirements are still very vague. I've implemented a very quick version of what I'm imagining you're saying ... or something close that illustrates how you might be able to do it. Left me know if I'm on the right track.

http://jsfiddle.net/THEtheChad/j9Ump/

How do I convert an NSString value to NSData?

NSString *str = @"helowrld";
// This converts the string to an NSData object
NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];

you can take reference from this link

Generating Random Number In Each Row In Oracle Query

At first I thought that this would work:

select DBMS_Random.Value(1,9) output
from   ...

However, this does not generate an even distribution of output values:

select output,
       count(*)
from   (
       select round(dbms_random.value(1,9)) output
       from   dual
       connect by level <= 1000000)
group by output
order by 1

1   62423
2   125302
3   125038
4   125207
5   124892
6   124235
7   124832
8   125514
9   62557

The reasons are pretty obvious I think.

I'd suggest using something like:

floor(dbms_random.value(1,10))

Hence:

select output,
       count(*)
from   (
       select floor(dbms_random.value(1,10)) output
       from   dual
       connect by level <= 1000000)
group by output
order by 1

1   111038
2   110912
3   111155
4   111125
5   111084
6   111328
7   110873
8   111532
9   110953

C++ template typedef

C++11 added alias declarations, which are generalization of typedef, allowing templates:

template <size_t N>
using Vector = Matrix<N, 1>;

The type Vector<3> is equivalent to Matrix<3, 1>.


In C++03, the closest approximation was:

template <size_t N>
struct Vector
{
    typedef Matrix<N, 1> type;
};

Here, the type Vector<3>::type is equivalent to Matrix<3, 1>.

Get a random item from a JavaScript array

const ArrayRandomModule = {
  // get random item from array
  random: function (array) {
    return array[Math.random() * array.length | 0];
  },

  // [mutate]: extract from given array a random item
  pick: function (array, i) {
    return array.splice(i >= 0 ? i : Math.random() * array.length | 0, 1)[0];
  },

  // [mutate]: shuffle the given array
  shuffle: function (array) {
    for (var i = array.length; i > 0; --i)
      array.push(array.splice(Math.random() * i | 0, 1)[0]);
    return array;
  }
}

How do I split a string, breaking at a particular character?

Since the splitting on commas question is duplicated to this question, adding this here.

If you want to split on a character and also handle extra whitespace that might follow that character, which often happens with commas, you can use replace then split, like this:

var items = string.replace(/,\s+/, ",").split(',')

AngularJS: How to set a variable inside of a template?

Use ngInit: https://docs.angularjs.org/api/ng/directive/ngInit

<div ng-repeat="day in forecast_days" ng-init="f = forecast[day.iso]">
  {{$index}} - {{day.iso}} - {{day.name}}
  Temperature: {{f.temperature}}<br>
  Humidity: {{f.humidity}}<br>
  ...
</div>

Example: http://jsfiddle.net/coma/UV4qF/

Minimal web server using netcat

The problem you are facing is that nc does not know when the web client is done with its request so it can respond to the request.
A web session should go something like this.

TCP session is established.
Browser Request Header: GET / HTTP/1.1
Browser Request Header: Host: www.google.com
Browser Request Header: \n #Note: Browser is telling Webserver that the request header is complete.
Server Response Header: HTTP/1.1 200 OK
Server Response Header: Content-Type: text/html
Server Response Header: Content-Length: 24
Server Response Header: \n #Note: Webserver is telling browser that response header is complete 
Server Message Body: <html>sample html</html>
Server Message Body: \n #Note: Webserver is telling the browser that the requested resource is finished. 
The server closes the TCP session.

Lines that begin with "\n" are simply empty lines without even a space and contain nothing more than a new line character.

I have my bash httpd launched by xinetd, xinetd tutorial. It also logs date, time, browser IP address, and the entire browser request to a log file, and calculates Content-Length for the Server header response.

user@machine:/usr/local/bin# cat ./bash_httpd
#!/bin/bash
x=0;
Log=$( echo -n "["$(date "+%F %T %Z")"] $REMOTE_HOST ")$(
        while read I[$x] && [ ${#I[$x]} -gt 1 ];do
              echo -n '"'${I[$x]} | sed -e's,.$,",'; let "x = $x + 1";
        done ;
); echo $Log >> /var/log/bash_httpd

Message_Body=$(echo -en '<html>Sample html</html>')
echo -en "HTTP/1.0 200 OK\nContent-Type: text/html\nContent-Length: ${#Message_Body}\n\n$Message_Body"

To add more functionality, you could incorporate.

            METHOD=$(echo ${I[0]} |cut -d" " -f1)
            REQUEST=$(echo ${I[0]} |cut -d" " -f2)
            HTTP_VERSION=$(echo ${I[0]} |cut -d" " -f3)
            If METHOD = "GET" ]; then 
                case "$REQUEST" in

                    "/") Message_Body="HTML formatted home page stuff"
                        ;;
                    /who) Message_Body="HTML formatted results of who"
                        ;;
                    /ps) Message_Body="HTML formatted results of ps"
                        ;;
                    *) Message_Body= "Error Page not found header and content"
                       ;;
                esac

            fi

Happy bashing!

How do I make my ArrayList Thread-Safe? Another approach to problem in Java?

Use Collections.synchronizedList().

Ex:

Collections.synchronizedList(new ArrayList<YourClassNameHere>())

How do I upgrade PHP in Mac OS X?

I think one simple way to do it, is:

1 - Check you where is your current PHP:

$ which php
$ /usr/local/bin/php

You see? Usually, our commands that we run is a link in /usr/local/bin so...

2 - Unlink this current link of PHP

unlink /usr/local/bin/php

If you prefere, before unlink it, check the path and then remove php files (do ls -al /usr/local/bin | grep php and then rm -rf into desired path)

3 - Install PHP 7.1

curl -s http://php-osx.liip.ch/install.sh | bash -s 7.1

4 - Create new link (using php 7.1 bin that you have installed)

ln /usr/local/php5-7.1.9-20170914-100859/bin/php /usr/local/bin/php

Like I said, its a simple way I think.

What's the best way to set a single pixel in an HTML5 canvas?

To complete Phrogz very thorough answer, there is a critical difference between fillRect() and putImageData().
The first uses context to draw over by adding a rectangle (NOT a pixel), using the fillStyle alpha value AND the context globalAlpha and the transformation matrix, line caps etc..
The second replaces an entire set of pixels (maybe one, but why ?)
The result is different as you can see on jsperf.


Nobody wants to set one pixel at a time (meaning drawing it on screen). That is why there is no specific API to do that (and rightly so).
Performance wise, if the goal is to generate a picture (for example a ray-tracing software), you always want to use an array obtained by getImageData() which is an optimized Uint8Array. Then you call putImageData() ONCE or a few times per second using setTimeout/seTInterval.

How do I get my Maven Integration tests to run

You should use maven surefire plugin to run unit tests and maven failsafe plugin to run integration tests.

Please follow below if you wish to toggle the execution of these tests using flags.

Maven Configuration

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-surefire-plugin</artifactId>
            <configuration>
                <skipTests>${skipUnitTests}</skipTests>
            </configuration>
        </plugin>

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-failsafe-plugin</artifactId>
            <configuration>
                <includes>
                    <include>**/*IT.java</include>
                </includes>
                <skipTests>${skipIntegrationTests}</skipTests>
            </configuration>
            <executions>
                <execution>
                    <goals>
                        <goal>integration-test</goal>
                        <goal>verify</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>

        <properties>
            <skipTests>false</skipTests>
            <skipUnitTests>${skipTests}</skipUnitTests>
            <skipIntegrationTests>${skipTests}</skipIntegrationTests>
        </properties>

So, tests will be skipped or switched according to below flag rules:

Tests can be skipped by below flags:

  • -DskipTests skips both unit and integration tests
  • -DskipUnitTests skips unit tests but executes integration tests
  • -DskipIntegrationTests skips integration tests but executes unit tests

Running Tests

Run below to execute only Unit Tests

mvn clean test

You can execute below command to run the tests (both unit and integration)

mvn clean verify

In order to run only Integration Tests, follow

mvn failsafe:integration-test

Or skip unit tests

mvn clean install -DskipUnitTests

Also, in order to skip integration tests during mvn install, follow

mvn clean install -DskipIntegrationTests

You can skip all tests using

mvn clean install -DskipTests

The origin server did not find a current representation for the target resource or is not willing to disclose that one exists. on deploying to tomcat

This issue can even occur when you try to run your project from controller page. Run your project from the jsp page. Go to your jsp page; right-click->Run As->Run on Server. I faced the same issue.I was running my project from the controller page. Run your project from jsp page.

Executing a batch script on Windows shutdown

I found this topic while searching for run script for startup and shutdown Windows 10. Those answers above didn't working. For me on windows 10 worked when I put scripts to task scheduler. How to do this: press window key and write Task scheduler, open it, then on the right is Add task... button. Here you can add scripts. PS: I found action for startup and logout user, there is not for shutdown.

Keep-alive header clarification

Where is this info kept ("this connection is between computer A and server F")?

A TCP connection is recognized by source IP and port and destination IP and port. Your OS, all intermediate session-aware devices and the server's OS will recognize the connection by this.

HTTP works with request-response: client connects to server, performs a request and gets a response. Without keep-alive, the connection to an HTTP server is closed after each response. With HTTP keep-alive you keep the underlying TCP connection open until certain criteria are met.

This allows for multiple request-response pairs over a single TCP connection, eliminating some of TCP's relatively slow connection startup.

When The IIS (F) sends keep alive header (or user sends keep-alive) , does it mean that (E,C,B) save a connection

No. Routers don't need to remember sessions. In fact, multiple TCP packets belonging to same TCP session need not all go through same routers - that is for TCP to manage. Routers just choose the best IP path and forward packets. Keep-alive is only for client, server and any other intermediate session-aware devices.

which is only for my session ?

Does it mean that no one else can use that connection

That is the intention of TCP connections: it is an end-to-end connection intended for only those two parties.

If so - does it mean that keep alive-header - reduce the number of overlapped connection users ?

Define "overlapped connections". See HTTP persistent connection for some advantages and disadvantages, such as:

  • Lower CPU and memory usage (because fewer connections are open simultaneously).
  • Enables HTTP pipelining of requests and responses.
  • Reduced network congestion (fewer TCP connections).
  • Reduced latency in subsequent requests (no handshaking).

if so , for how long does the connection is saved to me ? (in other words , if I set keep alive- "keep" till when?)

An typical keep-alive response looks like this:

Keep-Alive: timeout=15, max=100

See Hypertext Transfer Protocol (HTTP) Keep-Alive Header for example (a draft for HTTP/2 where the keep-alive header is explained in greater detail than both 2616 and 2086):

  • A host sets the value of the timeout parameter to the time that the host will allows an idle connection to remain open before it is closed. A connection is idle if no data is sent or received by a host.

  • The max parameter indicates the maximum number of requests that a client will make, or that a server will allow to be made on the persistent connection. Once the specified number of requests and responses have been sent, the host that included the parameter could close the connection.

However, the server is free to close the connection after an arbitrary time or number of requests (just as long as it returns the response to the current request). How this is implemented depends on your HTTP server.

Uninstalling Android ADT

I had the issue where after updating the SDK it would only update to version 20 and kept telling me that ANDROID 4.1 (API16) was available and only part of ANDROID 4.2 (API17) was available and there was no update to version 21.

After restarting several times and digging I found (was not obvious to me) going to the SDK Manager and going to FILE -> RELOAD solved the problem. Immediately the other uninstalled parts of API17 were there and I was able to update the SDK. Once updated to 4.2 then I could re-update to version 21 and voila.

Good luck! David

How to run PowerShell in CMD

You need to separate the arguments from the file path:

powershell.exe -noexit "& 'D:\Work\SQLExecutor.ps1 ' -gettedServerName 'MY-PC'"

Another option that may ease the syntax using the File parameter and positional parameters:

powershell.exe -noexit -file "D:\Work\SQLExecutor.ps1" "MY-PC"

How to get all registered routes in Express?

json output

function availableRoutes() {
  return app._router.stack
    .filter(r => r.route)
    .map(r => {
      return {
        method: Object.keys(r.route.methods)[0].toUpperCase(),
        path: r.route.path
      };
    });
}

console.log(JSON.stringify(availableRoutes(), null, 2));

looks like this:

[
  {
    "method": "GET",
    "path": "/api/todos"
  },
  {
    "method": "POST",
    "path": "/api/todos"
  },
  {
    "method": "PUT",
    "path": "/api/todos/:id"
  },
  {
    "method": "DELETE",
    "path": "/api/todos/:id"
  }
]

string output

function availableRoutesString() {
  return app._router.stack
    .filter(r => r.route)
    .map(r => Object.keys(r.route.methods)[0].toUpperCase().padEnd(7) + r.route.path)
    .join("\n  ")
}

console.log(availableRoutesString());

looks like this:

GET    /api/todos  
POST   /api/todos  
PUT    /api/todos/:id  
DELETE /api/todos/:id

these are based on @corvid's answer

hope this helps

How to condense if/else into one line in Python?

Python's if can be used as a ternary operator:

>>> 'true' if True else 'false'
'true'
>>> 'true' if False else 'false'
'false'

Build error, This project references NuGet

First I would check if your MusicKarma project has Microsoft.Net.Compilers in its packages.config file. If not then you could remove everything to do with that NuGet package from your MusicKarma.csproj.

If you are using the Microsoft.Net.Compilers NuGet package then my guess is that the path is incorrect. Looking at the directory name in the error message I would guess that the MusicKarma solution file (.sln) is in the same directory as the MusicKarma.csproj. If so then the packages directory is probably wrong since by default the packages directory would be inside the solution directory. So I am assuming that your packages directory is:

C:\Users\Bryan\Documents\Visual Studio 2015\Projects\MusicKarma\packages

Whilst your MusicKarma.csproj file is looking for the props file in:

C:\Users\Bryan\Documents\Visual Studio 2015\Projects\packages\Microsoft.Net.Compilers.1.1.1\build

So if that is the case then you can fix the problem by editing the path in your MusicKarma.csproj file or by reinstalling the NuGet package.

Get the list of stored procedures created and / or modified on a particular date?

You can try this query in any given SQL Server database:

SELECT 
    name,
    create_date,
    modify_date
FROM sys.procedures
WHERE create_date = '20120927'  

which lists out the name, the creation and the last modification date - unfortunately, it doesn't record who created and/or modified the stored procedure in question.

Java creating .jar file

Sine you've mentioned you're using Eclipse... Eclipse can create the JARs for you, so long as you've run each class that has a main once. Right-click the project and click Export, then select "Runnable JAR file" under the Java folder. Select the class name in the launch configuration, choose a place to save the jar, and make a decision how to handle libraries if necessary. Click finish, wipe hands on pants.

On duplicate key ignore?

Would suggest NOT using INSERT IGNORE as it ignores ALL errors (ie its a sloppy global ignore). Instead, since in your example tag is the unique key, use:

INSERT INTO table_tags (tag) VALUES ('tag_a'),('tab_b'),('tag_c') ON DUPLICATE KEY UPDATE tag=tag;

on duplicate key produces:

Query OK, 0 rows affected (0.07 sec)

replace String with another in java

Replacing one string with another can be done in the below methods

Method 1: Using String replaceAll

 String myInput = "HelloBrother";
 String myOutput = myInput.replaceAll("HelloBrother", "Brother"); // Replace hellobrother with brother
 ---OR---
 String myOutput = myInput.replaceAll("Hello", ""); // Replace hello with empty
 System.out.println("My Output is : " +myOutput);       

Method 2: Using Pattern.compile

 import java.util.regex.Pattern;
 String myInput = "JAVAISBEST";
 String myOutputWithRegEX = Pattern.compile("JAVAISBEST").matcher(myInput).replaceAll("BEST");
 ---OR -----
 String myOutputWithRegEX = Pattern.compile("JAVAIS").matcher(myInput).replaceAll("");
 System.out.println("My Output is : " +myOutputWithRegEX);           

Method 3: Using Apache Commons as defined in the link below:

http://commons.apache.org/proper/commons-lang/javadocs/api-z.1/org/apache/commons/lang3/StringUtils.html#replace(java.lang.String, java.lang.String, java.lang.String)

REFERENCE

HTML form readonly SELECT tag/input

another way of doing a readOnly attribute to a select element is by using css

you could do like :

$('#selection').css('pointer-events','none');

DEMO

How can I make my match non greedy in vim?

Instead of .* use .\{-}.

%s/style=".\{-}"//g

Also, see :help non-greedy

Javascript - Open a given URL in a new tab by clicking a button

<BUTTON NAME='my_button' VALUE=sequence_no TYPE='SUBMIT' style="background-color:transparent ; border:none; color:blue;" onclick="this.form.target='_blank';return true;"><u>open new page</u></BUTTON>

This button will look like a URL and can be opened in a new tab.

What is jQuery Unobtrusive Validation?

Brad Wilson has a couple great articles on unobtrusive validation and unobtrusive ajax.
It is also shown very nicely in this Pluralsight video in the section on " AJAX and JavaScript".

Basically, it is simply Javascript validation that doesn't pollute your source code with its own validation code. This is done by making use of data- attributes in HTML.

Objective-C: Reading a file line by line

Just like @porneL said, the C api is very handy.

NSString* fileRoot = [[NSBundle mainBundle] pathForResource:@"record" ofType:@"txt"];
FILE *file = fopen([fileRoot UTF8String], "r");
char buffer[256];
while (fgets(buffer, 256, file) != NULL){
    NSString* result = [NSString stringWithUTF8String:buffer];
    NSLog(@"%@",result);
}

How to get MAC address of your machine using a C program?

A very portable way is to parse the output of this command.

ifconfig | awk '$0 ~ /HWaddr/ { print $5 }'

Provided ifconfig can be run as the current user (usually can) and awk is installed (it often is). This will give you the mac address of the machine.

Avoid synchronized(this) in Java?

While I agree about not adhering blindly to dogmatic rules, does the "lock stealing" scenario seem so eccentric to you? A thread could indeed acquire the lock on your object "externally"(synchronized(theObject) {...}), blocking other threads waiting on synchronized instance methods.

If you don't believe in malicious code, consider that this code could come from third parties (for instance if you develop some sort of application server).

The "accidental" version seems less likely, but as they say, "make something idiot-proof and someone will invent a better idiot".

So I agree with the it-depends-on-what-the-class-does school of thought.


Edit following eljenso's first 3 comments:

I've never experienced the lock stealing problem but here is an imaginary scenario:

Let's say your system is a servlet container, and the object we're considering is the ServletContext implementation. Its getAttribute method must be thread-safe, as context attributes are shared data; so you declare it as synchronized. Let's also imagine that you provide a public hosting service based on your container implementation.

I'm your customer and deploy my "good" servlet on your site. It happens that my code contains a call to getAttribute.

A hacker, disguised as another customer, deploys his malicious servlet on your site. It contains the following code in the init method:

synchronized (this.getServletConfig().getServletContext()) {
   while (true) {}
}

Assuming we share the same servlet context (allowed by the spec as long as the two servlets are on the same virtual host), my call on getAttribute is locked forever. The hacker has achieved a DoS on my servlet.

This attack is not possible if getAttribute is synchronized on a private lock, because 3rd-party code cannot acquire this lock.

I admit that the example is contrived and an oversimplistic view of how a servlet container works, but IMHO it proves the point.

So I would make my design choice based on security consideration: will I have complete control over the code that has access to the instances? What would be the consequence of a thread's holding a lock on an instance indefinitely?

CSS Custom Dropdown Select that works across all browsers IE7+ FF Webkit

I was also having a similar problem. Finally found one solution at https://techmeals.com/fe/questions/htmlcss/4/How-to-customize-the-select-drop-down-in-css-which-works-for-all-the-browsers

Note:

1) For Firefox support there is special CSS handling for SELECT element's parent, please take a closer look.

2) Download the down.png from Down.png

CSS code

        /* For Firefox browser we need to style for SELECT element parent. */

        @-moz-document url-prefix() {

            /* Please note this is the parent of "SELECT" element */

            .select-example {   
                background: url('https://techmeals.com/external/images/down.png');
                background-color: #FFFFFF;
                border: 1px solid #9e9e9e;
                background-size: auto 6px;
                background-repeat: no-repeat;
                background-position: 96% 13px;
            }
        }

        /* IE specific styles */
        @media all and (-ms-high-contrast: none), (-ms-high-contrast: active) 
        {
                select.my-select-box {
                padding: 0 0 0 5px;
            }
        }

        /* IE specific styles */
        @supports (-ms-accelerator:true) {
                select.my-select-box {
                padding: 0 0 0 5px;
            }
        }

        select.my-select-box  {
            outline: none;
            background: #fff;
            -moz-appearance: window;
            -webkit-appearance: none;
            border-radius: 0px;
            text-overflow: "";
            background-image: url('https://techmeals.com/external/images/down.png');
            background-size: auto 6px;
            background-repeat: no-repeat;
            background-position: 96% 13px;
            cursor: pointer;
            height: 30px;
            width: 100%;
            border: 1px solid #9e9e9e;
            padding: 0 15px 0 5px;
            padding-right: 15px\9;      /* This will be apllied only to IE 7, IE 8 and IE 9 as */
            *padding-right: 15px;        /* This will be apllied only to IE 7 and below. */
            _padding-right: 15px;       /* This will be apllied only to IE 6 and below. */
        }

HTML code

    <div class="select-example">
        <select class="my-select-box">
            <option value="1">First Option</option>
            <option value="2">Second Option</option>
            <option value="3">Third Option</option>
            <option value="4">Fourth Option</option>
        </select>
    </div>

Entity Framework rollback and remove bad migration

You can also use

Remove-Migration -Force

This will revert and remove the last applied migration

ALTER TABLE on dependent column

you can drop the Constraint which is restricting you. If the column has access to other table. suppose a view is accessing the column which you are altering then it wont let you alter the column unless you drop the view. and after making changes you can recreate the view.

enter image description here

Node.js Web Application examples/tutorials

DailyJS has a good tutorial (long series of 24 posts) that walks you through all the aspects of building a notepad app (including all the possible extras).

Heres an overview of the tutorial: http://dailyjs.com/2010/11/01/node-tutorial/

And heres a link to all the posts: http://dailyjs.com/tags.html#nodepad

How to use Class<T> in Java?

I have found class<T> useful when I create service registry lookups. E.g.

<T> T getService(Class<T> serviceClass)
{
    ...
}

SQL query to select dates between two dates

SELECT Date, TotalAllowance  
FROM Calculation  
WHERE EmployeeId = 1 
  AND Date BETWEEN to_date('2011/02/25','yyyy-mm-dd') 
               AND to_date ('2011/02/27','yyyy-mm-dd');

Error message "unreported exception java.io.IOException; must be caught or declared to be thrown"

Your method showFile() declares that it can throw an IOException. Since this is a checked exception, any call to showFile() method must handle the exception somehow. One option is to wrap the call to showFile() in a try-catch block.

 try {
     showFile();
 }
 catch(IOException e) {
    // Code to handle an IOException here
 }

Objective-C Static Class Level variables

Issue Description:

  1. You want your ClassA to have a ClassB class variable.
  2. You are using Objective-C as programming language.
  3. Objective-C does not support class variables as C++ does.

One Alternative:

Simulate a class variable behavior using Objective-C features

  1. Declare/Define an static variable within the classA.m so it will be only accessible for the classA methods (and everything you put inside classA.m).

  2. Overwrite the NSObject initialize class method to initialize just once the static variable with an instance of ClassB.

  3. You will be wondering, why should I overwrite the NSObject initialize method. Apple documentation about this method has the answer: "The runtime sends initialize to each class in a program exactly one time just before the class, or any class that inherits from it, is sent its first message from within the program. (Thus the method may never be invoked if the class is not used.)".

  4. Feel free to use the static variable within any ClassA class/instance method.

Code sample:

file: classA.m

static ClassB *classVariableName = nil;

@implementation ClassA

...
 
+(void) initialize
{
    if (! classVariableName)
        classVariableName = [[ClassB alloc] init];
}

+(void) classMethodName
{
    [classVariableName doSomething]; 
}

-(void) instanceMethodName
{
    [classVariableName doSomething]; 
}

...

@end

References:

  1. Class variables explained comparing Objective-C and C++ approaches

Correct way to use Modernizr to detect IE?

You can use Modernizr to detect simply IE or not IE, by checking for SVG SMIL animation support.

If you've included SMIL feature detection in your Modernizr setup, you can use a simple CSS approach, and target the .no-smil class that Modernizr applies to the html element:

html.no-smil {
  /* IE/Edge specific styles go here - hide HTML5 content and show Flash content */
}

Alternatively, you could use Modernizr with a simple JavaScript approach, like so:

if ( Modernizr.smil ) {
  /* set HTML5 content */
} else {
  /* set IE/Edge/Flash content */
}

Bear in mind, IE/Edge might someday support SMIL, but there are currently no plans to do so.

For reference, here's a link to the SMIL compatibility chart at caniuse.com.

Where is git.exe located?

I'm very surprised to see that no one mentioned using the --exec-path switch.

git --exec-path

C:\Program Files\Git\mingw64/libexec/git-core

I hope this helps someone.

What is the difference between JVM, JDK, JRE & OpenJDK?

In layman terms:- JDK = JRE + Development/debugging tools, where JDK is our complete package to work with Java, from creating compiling till running it.On the other hand JRE is just of running of code(Byte Code).

Note:- Whether we are installing JDK or JRE, JVM would come bundled with both the packages and JVM is the part where JIT compiler converts the byte code into the machine specific code.

Just read the article on JDK,JRE ,JVM and JIT

Parse string to DateTime in C#

DateTime.Parse() will try figure out the format of the given date, and it usually does a good job. If you can guarantee dates will always be in a given format then you can use ParseExact():

string s = "2011-03-21 13:26";

DateTime dt = 
    DateTime.ParseExact(s, "yyyy-MM-dd HH:mm", CultureInfo.InvariantCulture);

(But note that it is usually safer to use one of the TryParse methods in case a date is not in the expected format)

Make sure to check Custom Date and Time Format Strings when constructing format string, especially pay attention to number of letters and case (i.e. "MM" and "mm" mean very different things).

Another useful resource for C# format strings is String Formatting in C#

MySQL's now() +1 day

You can use:

NOW() + INTERVAL 1 DAY

If you are only interested in the date, not the date and time then you can use CURDATE instead of NOW:

CURDATE() + INTERVAL 1 DAY

Excel VBA date formats

Thanks for the input. I'm obviously seeing some issues that aren't being replicated on others machines. Based on Jean's answer I have come up with less elegant solution that seems to work.

Since if I pass the cell a value directly from cdate, or just format it as a number it leaves the cell value as a string I've had to pass the date value into a numerical variable before passing that number back to the cell.

Function CellContentCanBeInterpretedAsADate(cell As Range) As Boolean
    Dim d As Date
    On Error Resume Next
    d = CDate(cell.Value)
    If Err.Number <> 0 Then
        CellContentCanBeInterpretedAsADate = False
    Else
        CellContentCanBeInterpretedAsADate = True
    End If
    On Error GoTo 0
End Function

Example usage:

Dim cell As Range
dim cvalue as double
Set cell = Range("A1")

If CellContentCanBeInterpretedAsADate(cell) Then
    cvalue = cdate(cell.value)
    cell.value = cvalue
    cell.NumberFormat = "mm/dd/yyyy hh:mm"
Else
    cell.NumberFormat = "General"
End If

Append text with .bat

Any line starting with a "REM" is treated as a comment, nothing is executed including the redirection.

Also, the %date% variable may contain "/" characters which are treated as path separator characters, leading to the system being unable to create the desired log file.

How to use XPath contains() here?

I already gave my +1 to Jeff Yates' solution.

Here is a quick explanation why your approach does not work. This:

//ul[@class='featureList' and contains(li, 'Model')]

encounters a limitation of the contains() function (or any other string function in XPath, for that matter).

The first argument is supposed to be a string. If you feed it a node list (giving it "li" does that), a conversion to string must take place. But this conversion is done for the first node in the list only.

In your case the first node in the list is <li><b>Type:</b> Clip Fan</li> (converted to a string: "Type: Clip Fan") which means that this:

//ul[@class='featureList' and contains(li, 'Type')]

would actually select a node!

Create a batch file to run an .exe with an additional parameter

in batch file abc.bat

cd c:\user\ben_dchost\documents\
executible.exe -flag1 -flag2 -flag3 

I am assuming that your executible.exe is present in c:\user\ben_dchost\documents\ I am also assuming that the parameters it takes are -flag1 -flag2 -flag3

Edited:

For the command you say you want to execute, do:

cd C:\Users\Ben\Desktop\BGInfo\
bginfo.exe dc_bginfo.bgi
pause

Hope this helps

When should an Excel VBA variable be killed or set to Nothing?

I have at least one situation where the data is not automatically cleaned up, which would eventually lead to "Out of Memory" errors. In a UserForm I had:

Public mainPicture As StdPicture
...
mainPicture = LoadPicture(PAGE_FILE)

When UserForm was destroyed (after Unload Me) the memory allocated for the data loaded in the mainPicture was not being de-allocated. I had to add an explicit

mainPicture = Nothing

in the terminate event.

How to find out if a Python object is a string?

I might deal with this in the duck-typing style, like others mention. How do I know a string is really a string? well, obviously by converting it to a string!

def myfunc(word):
    word = unicode(word)
    ...

If the arg is already a string or unicode type, real_word will hold its value unmodified. If the object passed implements a __unicode__ method, that is used to get its unicode representation. If the object passed cannot be used as a string, the unicode builtin raises an exception.

Prevent double submission of forms in jQuery

Please, check out jquery-safeform plugin.

Usage example:

$('.safeform').safeform({
    timeout: 5000,  // disable next submission for 5 sec
    submit: function() {
        // You can put validation and ajax stuff here...

        // When done no need to wait for timeout, re-enable the form ASAP
        $(this).safeform('complete');
        return false;
    }
});

How to create a floating action button (FAB) in android, using AppCompat v21?

Here is one aditional free Floating Action Button library for Android It has many customizations and requires SDK version 9 and higher

enter image description here

Full Demo Video

Extract data from log file in specified range of time

I used this command to find last 5 minutes logs for particular event "DHCPACK", try below:

$ grep "DHCPACK" /var/log/messages | grep "$(date +%h\ %d) [$(date --date='5 min ago' %H)-$(date +%H)]:*:*"

How to create EditText with cross(x) button at end of it?

2020 solution via Material Design Components for Android:

Add Material Components to your gradle setup:

Look for latest version from here: https://maven.google.com/

implementation 'com.google.android.material:material:1.1.0'

or if you havent updated to using AndroidX libs, you can add it this way:

implementation 'com.android.support:design:28.0.0'

Then

<com.google.android.material.textfield.TextInputLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:hint="@string/hint_text"
    app:endIconMode="clear_text">

  <com.google.android.material.textfield.TextInputEditText
      android:layout_width="match_parent"
      android:layout_height="wrap_content"/>

</com.google.android.material.textfield.TextInputLayout>

Pay attention to: app:endIconMode="clear_text"

As discussed here Material design docs

How to comment and uncomment blocks of code in the Office VBA Editor

Have you checked MZTools?? It does a lot of cool stuff...

If I'm not wrong, one of the functionalities it offers is to set your own shortcuts.

What is the fastest way to compare two sets in Java?

public boolean equals(Object o) {
        if (o == this)
            return true;
        if (!(o instanceof Set))
            return false;

        Set<String> a = this;
        Set<String> b = o;
        Set<String> thedifference_a_b = new HashSet<String>(a);


        thedifference_a_b.removeAll(b);
        if(thedifference_a_b.isEmpty() == false) return false;

        Set<String> thedifference_b_a = new HashSet<String>(b);
        thedifference_b_a.removeAll(a);

        if(thedifference_b_a.isEmpty() == false) return false;

        return true;
    }

How do I jump to a closing bracket in Visual Studio Code?

Command "editor.action.jumpToBracket" jumps between opening and closing brackets.

Here is the command's default key binding as seen in window Default Keyboard Shortcuts accessed from File | Preferences | Keyboard Shortcuts:

{ "key": "ctrl+shift+\\", "command": "editor.action.jumpToBracket",
                             "when": "editorTextFocus" }

If you're fond of quickly configuring keyboard shortcuts and VS Code settings, there are commands "workbench.action.openGlobalKeybindings" and "workbench.action.openGlobalSettings":

~/.config/Code/User/keybindings.json:

{ "key": "ctrl+numpad4", "command": "workbench.action.openGlobalKeybindings" }
{ "key": "ctrl+numpad1", "command": "workbench.action.openGlobalSettings" }

NSURLSession/NSURLConnection HTTP load failed on iOS 9

If you're having this problem with Amazon S3 as me, try to paste this on your info.plist as a direct child of your top level tag

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSExceptionDomains</key>
    <dict>
        <key>amazonaws.com</key>
        <dict>
              <key>NSThirdPartyExceptionMinimumTLSVersion</key>
              <string>TLSv1.0</string>
              <key>NSThirdPartyExceptionRequiresForwardSecrecy</key>
              <false/>
              <key>NSIncludesSubdomains</key>
              <true/>
        </dict>
        <key>amazonaws.com.cn</key>
        <dict>
              <key>NSThirdPartyExceptionMinimumTLSVersion</key>
              <string>TLSv1.0</string>
              <key>NSThirdPartyExceptionRequiresForwardSecrecy</key>
              <false/>
              <key>NSIncludesSubdomains</key>
              <true/>
        </dict>
    </dict>
</dict>

You can find more info at:

http://docs.aws.amazon.com/mobile/sdkforios/developerguide/ats.html#resolving-the-issue

window.location.reload with clear cache

In my case reload() doesn't work because the asp.net controls behavior. So, to solve this issue I've used this approach, despite seems a work around.

self.clear = function () {
    //location.reload(true); Doesn't work to IE neither Firefox;
    //also, hash tags must be removed or no postback will occur.
    window.location.href = window.location.href.replace(/#.*$/, '');
};

CSS fill remaining width

Use calc!

https://jsbin.com/wehixalome/edit?html,css,output

HTML:

<div class="left">
  100 px wide!
  </div><!-- Notice there isn't a space between the divs! *see edit for alternative* --><div class="right">
    Fills width!
  </div>

CSS:

.left {
  display: inline-block;
  width: 100px;

  background: red;
  color: white;
}
.right {
  display: inline-block;
  width: calc(100% - 100px);

  background: blue;
  color: white;
}

Update: As an alternative to not having a space between the divs you can set font-size: 0 on the outer element.

How to set the maxAllowedContentLength to 500MB while running on IIS7?

The limit of requests in .Net can be configured from two properties together:

First

  • Web.Config/system.web/httpRuntime/maxRequestLength
  • Unit of measurement: kilobytes
  • Default value 4096 KB (4 MB)
  • Max. value 2147483647 KB (2 TB)

Second

  • Web.Config/system.webServer/security/requestFiltering/requestLimits/maxAllowedContentLength (in bytes)
  • Unit of measurement: bytes
  • Default value 30000000 bytes (28.6 MB)
  • Max. value 4294967295 bytes (4 GB)

References:

Example:

<location path="upl">
   <system.web>
     <!--The default size is 4096 kilobytes (4 MB). MaxValue is 2147483647 KB (2 TB)-->
     <!-- 100 MB in kilobytes -->
     <httpRuntime maxRequestLength="102400" />
   </system.web>
   <system.webServer>
     <security>
       <requestFiltering>          
         <!--The default size is 30000000 bytes (28.6 MB). MaxValue is 4294967295 bytes (4 GB)-->
         <!-- 100 MB in bytes -->
         <requestLimits maxAllowedContentLength="104857600" />
       </requestFiltering>
     </security>
   </system.webServer>
 </location>

WHILE LOOP with IF STATEMENT MYSQL

I have discovered that you cannot have conditionals outside of the stored procedure in mysql. This is why the syntax error. As soon as I put the code that I needed between

   BEGIN
   SELECT MONTH(CURDATE()) INTO @curmonth;
   SELECT MONTHNAME(CURDATE()) INTO @curmonthname;
   SELECT DAY(LAST_DAY(CURDATE())) INTO @totaldays;
   SELECT FIRST_DAY(CURDATE()) INTO @checkweekday;
   SELECT DAY(@checkweekday) INTO @checkday;
   SET @daycount = 0;
   SET @workdays = 0;

     WHILE(@daycount < @totaldays) DO
       IF (WEEKDAY(@checkweekday) < 5) THEN
         SET @workdays = @workdays+1;
       END IF;
       SET @daycount = @daycount+1;
       SELECT ADDDATE(@checkweekday, INTERVAL 1 DAY) INTO @checkweekday;
     END WHILE;
   END

Just for others:

If you are not sure how to create a routine in phpmyadmin you can put this in the SQL query

    delimiter ;;
    drop procedure if exists test2;;
    create procedure test2()
    begin
    select ‘Hello World’;
    end
    ;;

Run the query. This will create a stored procedure or stored routine named test2. Now go to the routines tab and edit the stored procedure to be what you want. I also suggest reading http://net.tutsplus.com/tutorials/an-introduction-to-stored-procedures/ if you are beginning with stored procedures.

The first_day function you need is: How to get first day of every corresponding month in mysql?

Showing the Procedure is working Simply add the following line below END WHILE and above END

    SELECT @curmonth,@curmonthname,@totaldays,@daycount,@workdays,@checkweekday,@checkday;

Then use the following code in the SQL Query Window.

    call test2 /* or whatever you changed the name of the stored procedure to */

NOTE: If you use this please keep in mind that this code does not take in to account nationally observed holidays (or any holidays for that matter).

Show SOME invisible/whitespace characters in Eclipse

Navigate to Window > Preferences > General > Editors > Text Editors

Click on the CheckBox "Show whitespace characters".

enter image description here

Thats all.!!!

scale fit mobile web content using viewport meta tag

For Android there is the addition of target-density tag.

target-densitydpi=device-dpi

So, the code would look like

<meta name="viewport" content="width=device-width, target-densitydpi=device-dpi, initial-scale=0, maximum-scale=1, user-scalable=yes" />

Please note, that I believe this addition is only for Android (but since you have answers, I felt this was a good extra) but this should work for most mobile devices.

how to set active class to nav menu from twitter bootstrap

For single-page sites where the menu items simply jump down to other sections of the page, this simple solution works for me:

$('.nav li').on('click', function(){
    $('.nav li').removeClass('active');
    $(this).addClass('active');
  });

File Explorer in Android Studio

View > Tool Windows > Device File Explorer

What does 'low in coupling and high in cohesion' mean

Low Coupling:-- Will keep it very simple. If you change your module how does it impact other modules.

Example:- If your service API is exposed as JAR, any change to method signature will break calling API (High/Tight coupling).

If your module and other module communicate via async messages. As long as you get messages, your method change signature will be local to your module (Low coupling).

Off-course if there is change in message format, calling client will need to make some change.

CSS Classes & SubClasses

Just put a space between .area1 and .item, e.g:

.area1 .item
{
    color:red;
}

this style applies to elements with class item inside an element with class area1.

Adding new column to existing DataFrame in Python pandas

Let me just add that, just like for hum3, .loc didn't solve the SettingWithCopyWarning and I had to resort to df.insert(). In my case false positive was generated by "fake" chain indexing dict['a']['e'], where 'e' is the new column, and dict['a'] is a DataFrame coming from dictionary.

Also note that if you know what you are doing, you can switch of the warning using pd.options.mode.chained_assignment = None and than use one of the other solutions given here.

Does --disable-web-security Work In Chrome Anymore?

This should work. You may save the following in a batch file:

TASKKILL /F /IM chrome.exe
start chrome.exe --args --disable-web-security
pause

Xcode "Build and Archive" from command line

if you use next tool: https://github.com/nomad/shenzhen

then this task is very easy:

which ipa 1>/dev/null 2>&1 || echo 'no shenzhen. to install use: sudo gem install shenzhen --no-ri --no-rdoc'
ipa build --verbose --scheme "${schemeName}"

source

How can I determine the character encoding of an excel file?

For Excel 2010 it should be UTF-8. Instruction by MS :
http://msdn.microsoft.com/en-us/library/bb507946:

"The basic document structure of a SpreadsheetML document consists of the Sheets and Sheet elements, which reference the worksheets in the Workbook. A separate XML file is created for each Worksheet. For example, the SpreadsheetML for a workbook that has two worksheets name MySheet1 and MySheet2 is located in the Workbook.xml file and is shown in the following code example.

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?> 
<workbook xmlns=http://schemas.openxmlformats.org/spreadsheetml/2006/main xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships">
    <sheets>
        <sheet name="MySheet1" sheetId="1" r:id="rId1" /> 
        <sheet name="MySheet2" sheetId="2" r:id="rId2" /> 
    </sheets>
</workbook>

The worksheet XML files contain one or more block level elements such as SheetData. sheetData represents the cell table and contains one or more Row elements. A row contains one or more Cell elements. Each cell contains a CellValue element that represents the value of the cell. For example, the SpreadsheetML for the first worksheet in a workbook, that only has the value 100 in cell A1, is located in the Sheet1.xml file and is shown in the following code example.

<?xml version="1.0" encoding="UTF-8" ?> 
<worksheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main">
    <sheetData>
        <row r="1">
            <c r="A1">
                <v>100</v> 
            </c>
        </row>
    </sheetData>
</worksheet>

"

Detection of cell encodings:

https://metacpan.org/pod/Spreadsheet::ParseExcel::Cell

http://forums.asp.net/t/1608228.aspx/1

Better way to shuffle two numpy arrays in unison

There is a well-known function that can handle this:

from sklearn.model_selection import train_test_split
X, _, Y, _ = train_test_split(X,Y, test_size=0.0)

Just setting test_size to 0 will avoid splitting and give you shuffled data. Though it is usually used to split train and test data, it does shuffle them too.
From documentation

Split arrays or matrices into random train and test subsets

Quick utility that wraps input validation and next(ShuffleSplit().split(X, y)) and application to input data into a single call for splitting (and optionally subsampling) data in a oneliner.

Break a previous commit into multiple commits

A quick reference of the necessary commands, because I basically know what to do but always forget the right syntax:

git rebase -i <sha1_before_split>
# mark the targeted commit with 'edit'
git reset HEAD^
git add ...
git commit -m "First part"
git add ...
git commit -m "Second part"
git rebase --continue

Credits to Emmanuel Bernard's blog post.

Deleting a local branch with Git

Ran into this today and switching to another branch didn't help. It turned out that somehow my worktree information had gotten corrupted and there was a worktree with the same folder path as my working directory with a HEAD pointing at the branch (git worktree list). I deleted the .git/worktree/ folder that was referencing it and git branch -d worked.

Uncaught SyntaxError: Unexpected token :

In my case it was a mistaken url (not existing), so maybe your 'send' in second line should be other...

How to stop an unstoppable zombie job on Jenkins without restarting the server?

I had same issue at the last half hour...

Was not able to delete a zombie build running in my multi-branch pipeline. Even Server restarts by UI or even from commandline via sudo service jenkins restart did block the execution... The build was not stoppable... It always reapeared.

Used Version: Jenkins ver 2.150.2

I was very annoyed, but... when looking into the log of the build I found something intersting at the end of the log:

Logfile output of an zombie build and showing restart did not stop it

The red marked parts are the "frustrating parts"... As you can see I always wanted to Abort the build from UI but it did not work...

But there is a hyperlink with text Click here to forcibly terminate running steps...(first green one) Now I pressed the link...) After the link execution a message about Still paused appeared with another Link Click here to forcibily kill entire build (second green one) After pressing this link also the build finally was hard killed...

So this seems to work without any special plugins (except the multibranch-pipeline build plugin itself).

Calculating percentile of dataset column

The quantile() function will do much of what you probably want, but since the question was ambiguous, I will provide an alternate answer that does something slightly different from quantile().

ecdf(infert$age)(infert$age)

will generate a vector of the same length as infert$age giving the proportion of infert$age that is below each observation. You can read the ecdf documentation, but the basic idea is that ecdf() will give you a function that returns the empirical cumulative distribution. Thus ecdf(X)(Y) is the value of the cumulative distribution of X at the points in Y. If you wanted to know just the probability of being below 30 (thus what percentile 30 is in the sample), you could say

ecdf(infert$age)(30)

The main difference between this approach and using the quantile() function is that quantile() requires that you put in the probabilities to get out the levels, and this requires that you put in the levels to get out the probabilities.

How can bcrypt have built-in salts?

To make things even more clearer,

Registeration/Login direction ->

The password + salt is encrypted with a key generated from the: cost, salt and the password. we call that encrypted value the cipher text. then we attach the salt to this value and encoding it using base64. attaching the cost to it and this is the produced string from bcrypt:

$2a$COST$BASE64

This value is stored eventually.

What the attacker would need to do in order to find the password ? (other direction <- )

In case the attacker got control over the DB, the attacker will decode easily the base64 value, and then he will be able to see the salt. the salt is not secret. though it is random. Then he will need to decrypt the cipher text.

What is more important : There is no hashing in this process, rather CPU expensive encryption - decryption. thus rainbow tables are less relevant here.

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

A solution is to use the include statement with remote_user var (describe there : http://docs.ansible.com/playbooks_roles.html) but it has to be done at playbook instead of task level.

Given URL is not allowed by the Application configuration Facebook application error

sometimes you need to check your code (the part of redirect)

$helper = new FacebookRedirectLoginHelper('https://apps.facebook.com/xxx');
$auth_url = $helper->getLoginUrl(array('email', 'publish_actions'));
echo "<script>window.top.location.href='".$auth_url."'</script>";

if any changes happens there (for example, the name of your application "https://apps.facebook.com/xxx" in relation the application settings in facebook, you will get the above error

Undoing a 'git push'

Scenario 1: If you want to undo the last commit say 8123b7e04b3, below is the command(this worked for me):

git push origin +8123b7e04b3^:<branch_name>

Output looks like below:

Total 0 (delta 0), reused 0 (delta 0)
To https://testlocation/code.git
 + 8123b7e...92bc500 8123b7e04b3^ -> master (forced update)

Note: To update the change to your local code (to remove the commit locally as well) :

$ git reset --hard origin/<branchName>
Message displayed is :    HEAD is now at 8a3902a comments_entered_for_commit

Additional info: Scenario 2: In some situation, you may want to revert back what you just undo'ed (basically undo the undo) through the previous command, then use the below command:

git reset --hard 8123b7e04b3

Output:

HEAD is now at cc6206c Comment_that_was_entered_for_commit

More info here: https://github.com/blog/2019-how-to-undo-almost-anything-with-git

How to check if a given directory exists in Ruby

All the other answers are correct, however, you might have problems if you're trying to check directory in a user's home directory. Make sure you expand the relative path before checking:

File.exists? '~/exists'
=> false
File.directory? '~/exists'
=> false
File.exists? File.expand_path('~/exists')
=> true

Get File Path (ends with folder)

In the VBA Editor's Tools menu, click References... scroll down to "Microsoft Shell Controls And Automation" and choose it.

Sub FolderSelection()
    Dim MyPath As String
    MyPath = SelectFolder("Select Folder", "")
    If Len(MyPath) Then
        MsgBox MyPath
    Else
        MsgBox "Cancel was pressed"
    End If
End Sub

'Both arguements are optional. The first is the dialog caption and
'the second is is to specify the top-most visible folder in the
'hierarchy. The default is "My Computer."

Function SelectFolder(Optional Title As String, Optional TopFolder _
                         As String) As String
    Dim objShell As New Shell32.Shell
    Dim objFolder As Shell32.Folder

'If you use 16384 instead of 1 on the next line,
'files are also displayed
    Set objFolder = objShell.BrowseForFolder _
                            (0, Title, 1, TopFolder)
    If Not objFolder Is Nothing Then
        SelectFolder = objFolder.Items.Item.Path
    End If
End Function

Source Link.

Seeing the underlying SQL in the Spring JdbcTemplate?

This worked for me with log4j2 and xml parameters:

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="debug">
    <Properties>
        <Property name="log-path">/some_path/logs/</Property>
        <Property name="app-id">my_app</Property>
    </Properties>

    <Appenders>
        <RollingFile name="file-log" fileName="${log-path}/${app-id}.log"
            filePattern="${log-path}/${app-id}-%d{yyyy-MM-dd}.log">
            <PatternLayout>
                <pattern>[%-5level] %d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %c{1} - %msg%n
                </pattern>
            </PatternLayout>
            <Policies>
                <TimeBasedTriggeringPolicy interval="1"
                    modulate="true" />
            </Policies>
        </RollingFile>

        <Console name="console" target="SYSTEM_OUT">
            <PatternLayout
                pattern="[%-5level] %d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %c{1} - %msg%n" />
        </Console>
    </Appenders>
    <Loggers>

        <Logger name="org.springframework.jdbc.core" level="trace" additivity="false">
            <appender-ref ref="file-log" />
            <appender-ref ref="console" />
        </Logger>

        <Root level="info" additivity="false">
            <appender-ref ref="file-log" />
            <appender-ref ref="console" />
        </Root>
    </Loggers>

</Configuration>

Result console and file log was:

JdbcTemplate - Executing prepared SQL query
JdbcTemplate - Executing prepared SQL statement [select a, b from c where id = ? ]
StatementCreatorUtils - Setting SQL statement parameter value: column index 1, parameter value [my_id], value class [java.lang.String], SQL type unknown

Just copy/past

HTH

asp.net mvc3 return raw html to view

public ActionResult Questionnaire()
{
    return Redirect("~/MedicalHistory.html");
}

Const in JavaScript: when to use it and is it necessary?

I am not an expert in the JS compiling business, but it makes sense to say, that v8 makes use from the const flag

Normally a after declaring and changing a bunch of variables, the memory gets fragmented, and v8 is stopping to execute, makes a pause some time of a few seconds, to make gc, or garbage collection.

if a variable is declared with const v8 can be confident to put it in a tight fixed size container between other const variables, since it will never change. It can also save the proper operations for that datatypes since the type will not change.

Select data from "show tables" MySQL query

Have you looked into querying INFORMATION_SCHEMA.Tables? As in

SELECT ic.Table_Name,
    ic.Column_Name,
    ic.data_Type,
    IFNULL(Character_Maximum_Length,'') AS `Max`,
    ic.Numeric_precision as `Precision`,
    ic.numeric_scale as Scale,
    ic.Character_Maximum_Length as VarCharSize,
    ic.is_nullable as Nulls, 
    ic.ordinal_position as OrdinalPos, 
    ic.column_default as ColDefault, 
    ku.ordinal_position as PK,
    kcu.constraint_name,
    kcu.ordinal_position,
    tc.constraint_type
FROM INFORMATION_SCHEMA.COLUMNS ic
    left outer join INFORMATION_SCHEMA.key_column_usage ku
        on ku.table_name = ic.table_name
        and ku.column_name = ic.column_name
    left outer join information_schema.key_column_usage kcu
        on kcu.column_name = ic.column_name
        and kcu.table_name = ic.table_name
    left outer join information_schema.table_constraints tc
        on kcu.constraint_name = tc.constraint_name
order by ic.table_name, ic.ordinal_position;

Toggle display:none style with JavaScript

You can do this through straight javascript and DOM, but I really recommend learning JQuery. Here is a function you can use to actually toggle that object.

http://api.jquery.com/toggle/

EDIT: Adding the actual code:

Solution:

HTML snippet:

<a href="#" id="showAll" title="Show Tags">Show All Tags</a>
<ul id="tags" class="subforums" style="display:none;overflow-x: visible; overflow-y: visible; ">
    <li>Tag 1</li>
    <li>Tag 2</li>
    <li>Tag 3</li>
    <li>Tag 4</li>
    <li>Tag 5</li>
</ul>

Javascript code using JQuery from Google's Content Distribution Network: https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js

$(function() {
    $('#showAll').click(function(){  //Adds click event listener  
        $('#tags').toggle('slow'); // Toggles visibility.  Use the 'slow' parameter to add a nice effect.
    });
});

You can test directly from this link: http://jsfiddle.net/vssJr/5/

Additional Comments on JQuery:

Someone has suggested that using JQuery for something like this is wrong because it is a 50k Library. I have a strong opinion against that.

JQuery is widely used because of the huge advantages it offers (like many other javascript frameworks). Additionally, JQuery is hosted by Content Distribution Networks (CDNs) like Google's CDN that will guarantee that the library is cached in the client's browser. It will have minimal impact on the client.

Additionally, with JQuery you can use powerful selectors, adding event listener, and use functions that are for the most part guaranteed to be cross-browser.

If you are a beginner and want to learn Javascript, please don't discount frameworks like JQuery. It will make your life so much easier.

What integer hash function are good that accepts an integer hash key?

This page lists some simple hash functions that tend to decently in general, but any simple hash has pathological cases where it doesn't work well.

JQuery - Storing ajax response into global variable

Ran into this too. Lots of answers, yet, only one simple correct one which I'm going to provide. The key is to make your $.ajax call..sync!

$.ajax({  
    async: false, ...

How to set <Text> text to upper case in react native

@Cherniv Thanks for the answer

<Text style={{}}> {'Test'.toUpperCase()} </Text>

Using DISTINCT inner join in SQL

Is this what you mean?

SELECT DISTINCT C.valueC
FROM 
C
INNER JOIN B ON C.id = B.lookupC
INNER JOIN A ON B.id = A.lookupB

Clicking at coordinates without identifying element

import pyautogui
from selenium import webdriver

driver = webdriver.Chrome(chrome_options=options)
driver.maximize_window() #maximize the browser window
driver.implicitly_wait(30)
driver.get(url)
height=driver.get_window_size()['height']

#get browser navigation panel height
browser_navigation_panel_height = driver.execute_script('return window.outerHeight - window.innerHeight;')

act_y=y%height
scroll_Y=y/height

#scroll down page until y_off is visible
try:
    driver.execute_script("window.scrollTo(0, "+str(scroll_Y*height)+")")
except Exception as e:
    print "Exception"
#pyautogui used to generate click by passing x,y coordinates
pyautogui.FAILSAFE=False
pyautogui.moveTo(x,act_y+browser_navigation_panel_height)
pyautogui.click(x,act_y+browser_navigation_panel_height,clicks=1,interval=0.0,button="left")

This is worked for me. Hope, It will work for you guys :)...

Load HTML File Contents to Div [without the use of iframes]

Wow, from all the framework-promotional answers you'd think this was something JavaScript made incredibly difficult. It isn't really.

var xhr= new XMLHttpRequest();
xhr.open('GET', 'x.html', true);
xhr.onreadystatechange= function() {
    if (this.readyState!==4) return;
    if (this.status!==200) return; // or whatever error handling you want
    document.getElementById('y').innerHTML= this.responseText;
};
xhr.send();

If you need IE<8 compatibility, do this first to bring those browsers up to speed:

if (!window.XMLHttpRequest && 'ActiveXObject' in window) {
    window.XMLHttpRequest= function() {
        return new ActiveXObject('MSXML2.XMLHttp');
    };
}

Note that loading content into the page with scripts will make that content invisible to clients without JavaScript available, such as search engines. Use with care, and consider server-side includes if all you want is to put data in a common shared file.

converting json to string in python

json.dumps() is much more than just making a string out of a Python object, it would always produce a valid JSON string (assuming everything inside the object is serializable) following the Type Conversion Table.

For instance, if one of the values is None, the str() would produce an invalid JSON which cannot be loaded:

>>> data = {'jsonKey': None}
>>> str(data)
"{'jsonKey': None}"
>>> json.loads(str(data))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.py", line 338, in loads
    return _default_decoder.decode(s)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/decoder.py", line 366, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/decoder.py", line 382, in raw_decode
    obj, end = self.scan_once(s, idx)
ValueError: Expecting property name: line 1 column 2 (char 1)

But the dumps() would convert None into null making a valid JSON string that can be loaded:

>>> import json
>>> data = {'jsonKey': None}
>>> json.dumps(data)
'{"jsonKey": null}'
>>> json.loads(json.dumps(data))
{u'jsonKey': None}

Java Array Sort descending?

Another way with Comparator

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

Integer[] aInt = {6,2,3,4,1,5,7,8,9,10};
Arrays.sort(aInt, Comparator.reverseOrder()  );

Android 'Unable to add window -- token null is not for an application' exception

Hello there if you are using adapter there might be a chance.
All you need to know when you used any dialog in adapter,getContext(),context or activity won't work sometime.

Here is the trick I used v.getRootView().getContext() where v is the view object you are referencing.
Eg.


            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                new DatePickerDialog(v.getRootView().getContext(), date, myCalendar
                        .get(Calendar.YEAR), myCalendar.get(Calendar.MONTH),
                        myCalendar.get(Calendar.DAY_OF_MONTH)).show();
            }
        });  
If you are getting this problem because of alert dialog.
Refer [here][1] But it is same concept.


  [1]: https://stackoverflow.com/questions/6367771/displaying-alertdialog-inside-a-custom-listadapter-class

how to show progress bar(circle) in an activity having a listview before loading the listview with data

You can do this easier.
Source: http://www.tutorialspoint.com/android/android_loading_spinner.htm
It helped me.

Layout:

<ProgressBar
   android:id="@+id/progressBar1"
   style="?android:attr/progressBarStyleLarge"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_centerHorizontal="true" />

After defining it in xml, you have to get its reference in java file through ProgressBar class. Its syntax is given below:

private ProgressBar spinner;
spinner = (ProgressBar)findViewById(R.id.progressBar1);

After that you can make its disappear , and bring it back when needed through setVisibility Method. Its syntax is given below:

spinner.setVisibility(View.GONE);
spinner.setVisibility(View.VISIBLE);

Git: How to rebase to a specific commit?

I've used a mixture of solutions described above:

$ git branch temp <specific sha1>
$ git rebase --onto temp master topic
$ git branch -d temp

I found it much easier to read and understand. The accepted solution lead me to a merge conflict (too lazy to fix by hand):

$ git rebase temp
First, rewinding head to replay your work on top of it...
Applying: <git comment>
Using index info to reconstruct a base tree...
M       pom.xml
.git/rebase-apply/patch:10: trailing whitespace.
    <some code>
.git/rebase-apply/patch:17: trailing whitespace.
        <some other code>
warning: 2 lines add whitespace errors.
Falling back to patching base and 3-way merge...
Auto-merging pom.xml
CONFLICT (content): Merge conflict in pom.xml
error: Failed to merge in the changes.
Patch failed at 0001 <git comment>
The copy of the patch that failed is found in: .git/rebase-apply/patch

When you have resolved this problem, run "git rebase --continue".
If you prefer to skip this patch, run "git rebase --skip" instead.
To check out the original branch and stop rebasing, run "git rebase --abort".

How to create our own Listener interface in android?

Create a new file:

MyListener.java:

public interface MyListener {
    // you can define any parameter as per your requirement
    public void callback(View view, String result);
}

In your activity, implement the interface:

MyActivity.java:

public class MyActivity extends Activity implements MyListener {
   @override        
   public void onCreate(){
        MyButton m = new MyButton(this);
   }

    // method is invoked when MyButton is clicked
    @override
    public void callback(View view, String result) {   
        // do your stuff here
    }
}

In your custom class, invoke the interface when needed:

MyButton.java:

public class MyButton {
    MyListener ml;

    // constructor
    MyButton(MyListener ml) {
        //Setting the listener
        this.ml = ml;
    }

    public void MyLogicToIntimateOthers() {
        //Invoke the interface
        ml.callback(this, "success");
    }
}

How to use CURL via a proxy?

I have explained use of various CURL options required for CURL PROXY.

$url = 'http://dynupdate.no-ip.com/ip.php';
$proxy = '127.0.0.1:8888';
$proxyauth = 'user:password';

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);         // URL for CURL call
curl_setopt($ch, CURLOPT_PROXY, $proxy);     // PROXY details with port
curl_setopt($ch, CURLOPT_PROXYUSERPWD, $proxyauth);   // Use if proxy have username and password
curl_setopt($ch, CURLOPT_PROXYTYPE, CURLPROXY_SOCKS5); // If expected to call with specific PROXY type
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);  // If url has redirects then go to the final redirected URL.
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 0);  // Do not outputting it out directly on screen.
curl_setopt($ch, CURLOPT_HEADER, 1);   // If you want Header information of response else make 0
$curl_scraped_page = curl_exec($ch);
curl_close($ch);

echo $curl_scraped_page;

$.widget is not a function

May be include Jquery Widget first, then Draggable? I guess that will solve the problem.....

How to wait until an element exists?

A solution returning a Promise and allowing to use a timeout (compatible IE 11+).

For a single element (type Element):

"use strict";

function waitUntilElementLoaded(selector) {
    var timeout = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : 0;

    var start = performance.now();
    var now = 0;

    return new Promise(function (resolve, reject) {
        var interval = setInterval(function () {
            var element = document.querySelector(selector);

            if (element instanceof Element) {
                clearInterval(interval);

                resolve();
            }

            now = performance.now();

            if (now - start >= timeout) {
                reject("Could not find the element " + selector + " within " + timeout + " ms");
            }
        }, 100);
    });
}

For multiple elements (type NodeList):

"use strict";

function waitUntilElementsLoaded(selector) {
    var timeout = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : 0;

    var start = performance.now();
    var now = 0;

    return new Promise(function (resolve, reject) {
        var interval = setInterval(function () {
            var elements = document.querySelectorAll(selector);

            if (elements instanceof NodeList) {
                clearInterval(interval);

                resolve(elements);
            }

            now = performance.now();

            if (now - start >= timeout) {
                reject("Could not find elements " + selector + " within " + timeout + " ms");
            }
        }, 100);
    });
}

Examples:

waitUntilElementLoaded('#message', 800).then(function(element) {
    // element found and available

    element.innerHTML = '...';
}).catch(function() {
    // element not found within 800 milliseconds
});

waitUntilElementsLoaded('.message', 10000).then(function(elements) {
    for(const element of elements) {
        // ....
    }
}).catch(function(error) {
    // elements not found withing 10 seconds
});

Works for both a list of elements and a single element.

sorting a vector of structs

Use a comparison function:

bool compareByLength(const data &a, const data &b)
{
    return a.word.size() < b.word.size();
}

and then use std::sort in the header #include <algorithm>:

std::sort(info.begin(), info.end(), compareByLength);

Convert String into a Class Object

Continuing from my comment. toString is not the solution. Some good soul has written whole code for serialization and deserialization of an object in Java. See here: http://www.javabeginner.com/uncategorized/java-serialization

Suggested read:

  1. Old and good Java Technical Article on Serialization
  2. http://java.sun.com/developer/technicalArticles/ALT/serialization/
  3. http://java.sun.com/developer/onlineTraining/Programming/BasicJava2/serial.html

Convert datetime to valid JavaScript date

You can use get methods:

_x000D_
_x000D_
var fullDate = new Date();_x000D_
console.log(fullDate);_x000D_
var twoDigitMonth = fullDate.getMonth() + "";_x000D_
if (twoDigitMonth.length == 1)_x000D_
    twoDigitMonth = "0" + twoDigitMonth;_x000D_
var twoDigitDate = fullDate.getDate() + "";_x000D_
if (twoDigitDate.length == 1)_x000D_
    twoDigitDate = "0" + twoDigitDate;_x000D_
var currentDate = twoDigitDate + "/" + twoDigitMonth + "/" + fullDate.getFullYear(); console.log(currentDate);
_x000D_
_x000D_
_x000D_

generating variable names on fly in python

I got your problem , and here is my answer:

prices = [5, 12, 45]
list=['1','2','3']

for i in range(1,3):
  vars()["prices"+list[0]]=prices[0]
print ("prices[i]=" +prices[i])

so while printing:

price1 = 5 
price2 = 12
price3 = 45

Android - SMS Broadcast receiver

Also note that the Hangouts application will currently block my BroadcastReceiver from receiving SMS messages. I had to disable SMS functionality in the Hangouts application (Settings->SMS->Turn on SMS), before my SMS BroadcastReceived started getting fired.

Edit: It appears as though some applications will abortBroadcast() on the intent which will prevent other applications from receiving the intent. The solution is to increase the android:priority attribute in the intent-filter tag:

<receiver android:name="com.company.application.SMSBroadcastReceiver" >
  <intent-filter android:priority="500">
    <action android:name="android.provider.Telephony.SMS_RECEIVED" />
  </intent-filter>
</receiver>

See more details here: Enabling SMS support in Hangouts 2.0 breaks the BroadcastReceiver of SMS_RECEIVED in my app

Count the number occurrences of a character in a string

I am a fan of the pandas library, in particular the value_counts() method. You could use it to count the occurrence of each character in your string:

>>> import pandas as pd
>>> phrase = "I love the pandas library and its `value_counts()` method"
>>> pd.Series(list(phrase)).value_counts()
     8
a    5
e    4
t    4
o    3
n    3
s    3
d    3
l    3
u    2
i    2
r    2
v    2
`    2
h    2
p    1
b    1
I    1
m    1
(    1
y    1
_    1
)    1
c    1
dtype: int64

How to change the color of text in javafx TextField?

The CSS styles for text input controls such as TextField for JavaFX 8 are defined in the modena.css stylesheet as below. Create a custom CSS stylesheet and modify the colors as you wish. Use the CSS reference guide if you need help understanding the syntax and available attributes and values.

.text-input {
    -fx-text-fill: -fx-text-inner-color;
    -fx-highlight-fill: derive(-fx-control-inner-background,-20%);
    -fx-highlight-text-fill: -fx-text-inner-color;
    -fx-prompt-text-fill: derive(-fx-control-inner-background,-30%);
    -fx-background-color: linear-gradient(to bottom, derive(-fx-text-box-border, -10%), -fx-text-box-border),
        linear-gradient(from 0px 0px to 0px 5px, derive(-fx-control-inner-background, -9%), -fx-control-inner-background);
    -fx-background-insets: 0, 1;
    -fx-background-radius: 3, 2;
    -fx-cursor: text;
    -fx-padding: 0.333333em 0.583em 0.333333em 0.583em; /* 4 7 4 7 */
}
.text-input:focused {
    -fx-highlight-fill: -fx-accent;
    -fx-highlight-text-fill: white;
    -fx-background-color: 
        -fx-focus-color,
        -fx-control-inner-background,
        -fx-faint-focus-color,
        linear-gradient(from 0px 0px to 0px 5px, derive(-fx-control-inner-background, -9%), -fx-control-inner-background);
    -fx-background-insets: -0.2, 1, -1.4, 3;
    -fx-background-radius: 3, 2, 4, 0;
    -fx-prompt-text-fill: transparent;
}

Although using an external stylesheet is a preferred way to do the styling, you can style inline, using something like below:

textField.setStyle("-fx-text-inner-color: red;");

Angular 2 router no base href set

You can also use hash-based navigation by including the following in app.module.ts

import { LocationStrategy, HashLocationStrategy } from '@angular/common';

and by adding the following to the @NgModule({ ... })

@NgModule({
  ...
  providers:    [
      ProductService, {
          provide: LocationStrategy, useClass: HashLocationStrategy
      }
  ],
  ...
})

Angular 2 Development with TypeScript

“HashLocationStrategy—A hash sign (#) is added to the URL, and the URL segment after the hash uniquely identifies the route to be used as a web page fragment. This strategy works with all browsers, including the old ones.”

Excerpt From: Yakov Fain Anton Moiseev. “Angular 2 Development with TypeScript.”

How to manage local vs production settings in Django?

Remember that settings.py is a live code file. Assuming that you don't have DEBUG set on production (which is a best practice), you can do something like:

if DEBUG:
    STATIC_PATH = /path/to/dev/files
else:
    STATIC_PATH = /path/to/production/files

Pretty basic, but you could, in theory, go up to any level of complexity based on just the value of DEBUG - or any other variable or code check you wanted to use.

What is the best (and safest) way to merge a Git branch into master?

As the title says "Best way", I think it's a good idea to consider the patience merge strategy.

From: https://git-scm.com/docs/merge-strategies

With this option, 'merge-recursive' spends a little extra time to avoid mismerges that sometimes occur due to unimportant matching lines (e.g., braces from distinct functions). Use this when the branches to be merged have diverged wildly. See also git-diff[1] --patience.

Usage:

git fetch
git merge -s recursive -X patience origin/master

Git Alias

I use always an alias for this, e.g. run once:

 git config --global alias.pmerge 'merge -s recursive -X patience'

Now you could do:

git fetch
git pmerge origin/master

JavaScript Number Split into individual digits

Iterate through each number with for...of statement.

By adding a + sign before a String, it will be converted into a number.

_x000D_
_x000D_
const num = 143,
  digits = [];

for (const digit of `${num}`) {
  digits.push(+digit)
}
console.log(digits);
_x000D_
_x000D_
_x000D_

Inspired by @iampopov You can write it with spread syntax.

_x000D_
_x000D_
const num = 143;
const digits = [...`${num}`].map(Number);
console.log(digits);
_x000D_
_x000D_
_x000D_

Why are C++ inline functions in the header?

The definition of an inline function doesn't have to be in a header file but, because of the one definition rule (ODR) for inline functions, an identical definition for the function must exist in every translation unit that uses it.

The easiest way to achieve this is by putting the definition in a header file.

If you want to put the definition of a function in a single source file then you shouldn't declare it inline. A function not declared inline does not mean that the compiler cannot inline the function.

Whether you should declare a function inline or not is usually a choice that you should make based on which version of the one definition rules it makes most sense for you to follow; adding inline and then being restricted by the subsequent constraints makes little sense.

How to find out when an Oracle table was updated the last time

Since you are on 10g, you could potentially use the ORA_ROWSCN pseudocolumn. That gives you an upper bound of the last SCN (system change number) that caused a change in the row. Since this is an increasing sequence, you could store off the maximum ORA_ROWSCN that you've seen and then look only for data with an SCN greater than that.

By default, ORA_ROWSCN is actually maintained at the block level, so a change to any row in a block will change the ORA_ROWSCN for all rows in the block. This is probably quite sufficient if the intention is to minimize the number of rows you process multiple times with no changes if we're talking about "normal" data access patterns. You can rebuild the table with ROWDEPENDENCIES which will cause the ORA_ROWSCN to be tracked at the row level, which gives you more granular information but requires a one-time effort to rebuild the table.

Another option would be to configure something like Change Data Capture (CDC) and to make your OCI application a subscriber to changes to the table, but that also requires a one-time effort to configure CDC.

Unable to read repository at http://download.eclipse.org/releases/indigo

No meu caso era o anti-vírus que estava bloqueando a conexão do eclipse, desativei o anti-víruse tudo funcionou o//.

Translation: In my case it was the anti-virus that was blocking the connection from eclipse. I disabled the anti-virus and everything worked.

Why use the 'ref' keyword when passing an object?

Since TestRef is a class (which are reference objects), you can change the contents inside t without passing it as a ref. However, if you pass t as a ref, TestRef can change what the original t refers to. i.e. make it point to a different object.

Adding a HTTP header to the Angular HttpClient doesn't send the header, why?

First, you need to add HttpHeaders with HttpClient

import { HttpClient,HttpHeaders  } from '@angular/common/http';

your constructor should be like this.

constructor(private http: HttpClient) { }

then you can use like this

   let header = new HttpHeaders({ "Authorization": "Bearer "+token});

   const requestOptions = {  headers: header};                                                                                                                                                                            

    return this.http.get<any>(url, requestOptions)
        .toPromise()
        .then(data=> {
            //...
            return data;
    });

Tensorflow image reading & display

Load names with tf.train.match_filenames_once get the number of files to iterate over with tf.size open session and enjoy ;-)

import tensorflow as tf
import numpy as np
import matplotlib;
from PIL import Image

matplotlib.use('Agg')
import matplotlib.pyplot as plt


filenames = tf.train.match_filenames_once('./images/*.jpg')
count_num_files = tf.size(filenames)
filename_queue = tf.train.string_input_producer(filenames)

reader=tf.WholeFileReader()
key,value=reader.read(filename_queue)
img = tf.image.decode_jpeg(value)

init = tf.global_variables_initializer()
with tf.Session() as sess:
    sess.run(init)
    coord = tf.train.Coordinator()
    threads = tf.train.start_queue_runners(coord=coord)
    num_files = sess.run(count_num_files)
    for i in range(num_files):
        image=img.eval()
        print(image.shape)
        Image.fromarray(np.asarray(image)).save('te.jpeg')

iterating through json object javascript

My problem was actually a problem of bad planning with the JSON object rather than an actual logic issue. What I ended up doing was organize the object as follows, per a suggestion from user2736012.

{
"dialog":
{
    "trunks":[
    {
        "trunk_id" : "1",
        "message": "This is just a JSON Test"
    },
    {
        "trunk_id" : "2",
        "message": "This is a test of a bit longer text. Hopefully this will at the very least create 3 lines and trigger us to go on to another box. So we can test multi-box functionality, too."
    }
    ]
}
}

At that point, I was able to do a fairly simple for loop based on the total number of objects.

var totalMessages = Object.keys(messages.dialog.trunks).length;

    for ( var i = 0; i < totalMessages; i++)
    {
        console.log("ID: " + messages.dialog.trunks[i].trunk_id + " Message " + messages.dialog.trunks[i].message);
    }

My method for getting totalMessages is not supported in all browsers, though. For my project, it actually doesn't matter, but beware of that if you choose to use something similar to this.

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

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

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

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

TypeError: sequence item 0: expected string, int found

you can convert the integer dataframe into string first and then do the operation e.g.

df3['nID']=df3['nID'].astype(str)
grp = df3.groupby('userID')['nID'].aggregate(lambda x: '->'.join(tuple(x)))

How do I specify local .gem files in my Gemfile?

Seems bundler can't use .gem files out of the box. Pointing the :path to a directory containing .gem files doesn't work. Some people suggested to setup a local gem server (geminabox, stickler) for that purpose.

However, what I found to be much simpler is to use a local gem "server" from file system: Just put your .gem files in a local directory, then use "gem generate_index" to make it a Gem repository

mkdir repo
mkdir repo/gems
cp *.gem repo/gems
cd repo
gem generate_index

Finally point bundler to this location by adding the following line to your Gemfile

source "file://path/to/repo"

If you update the gems in the repository, make sure to regenerate the index.

Converting NSString to NSDictionary / JSON

Use the following code to get the response object from the AFHTTPSessionManager failure block; then you can convert the generic type into the required data type:

id responseObject = [NSJSONSerialization JSONObjectWithData:(NSData *)error.userInfo[AFNetworkingOperationFailingURLResponseDataErrorKey] options:0 error:nil];

Can I use a min-height for table, tr or td?

Tables and table cells don't use the min-height property, setting their height will be the min-height as tables will expand if the content stretches them.

TimeStamp on file name using PowerShell

You can insert arbitrary PowerShell script code in a double-quoted string by using a subexpression, for example, $() like so:

"C:\temp\mybackup $(get-date -f yyyy-MM-dd).zip"

And if you are getting the path from somewhere else - already as a string:

$dirName  = [io.path]::GetDirectoryName($path)
$filename = [io.path]::GetFileNameWithoutExtension($path)
$ext      = [io.path]::GetExtension($path)
$newPath  = "$dirName\$filename $(get-date -f yyyy-MM-dd)$ext"

And if the path happens to be coming from the output of Get-ChildItem:

Get-ChildItem *.zip | Foreach {
  "$($_.DirectoryName)\$($_.BaseName) $(get-date -f yyyy-MM-dd)$($_.extension)"}

Clearing all cookies with JavaScript

I have some more sophisticated and OOP-oriented cookie control module. It also contains deleteAll method to clear all existing cookie. Make notice that this version of deleteAll method has setting path=/ that causes deleting of all cookies within current domain. If you need to delete cookies only from some scope you will have to upgrade this method my adding dynamic path parameter to this method.

There is main Cookie class:

import {Setter} from './Setter';

export class Cookie {
    /**
     * @param {string} key
     * @return {string|undefined}
     */
    static get(key) {
        key = key.replace(/([\.$?*|{}\(\)\[\]\\\/\+^])/g, '\\$1');

        const regExp = new RegExp('(?:^|; )' + key + '=([^;]*)');
        const matches = document.cookie.match(regExp);

        return matches
            ? decodeURIComponent(matches[1])
            : undefined;
    }

    /**
     * @param {string} name
     */
    static delete(name) {
        this.set(name, '', { expires: -1 });
    }

    static deleteAll() {
        const cookies = document.cookie.split('; ');

        for (let cookie of cookies) {
            const index = cookie.indexOf('=');

            const name = ~index
                ? cookie.substr(0, index)
                : cookie;

            document.cookie = name + '=;expires=Thu, 01 Jan 1970 00:00:00 GMT;path=/';
        }
    }

    /**
     * @param {string} name
     * @param {string|boolean} value
     * @param {{expires?:Date|string|number,path?:string,domain?:string,secure?:boolean}} opts
     */
    static set(name, value, opts = {}) {
        Setter.set(name, value, opts);
    }
}

Cookie setter method (Cookie.set) is rather complex so I decomposed it into other class. There is code of this one:

export class Setter {
    /**
     * @param {string} name
     * @param {string|boolean} value
     * @param {{expires?:Date|string|number,path?:string,domain?:string,secure?:boolean}} opts
     */
    static set(name, value, opts = {}) {
        value = Setter.prepareValue(value);
        opts = Setter.prepareOpts(opts);

        let updatedCookie = name + '=' + value;

        for (let i in opts) {
            if (!opts.hasOwnProperty(i)) continue;

            updatedCookie += '; ' + i;

            const value = opts[i];

            if (value !== true)
                updatedCookie += '=' + value;
        }

        document.cookie = updatedCookie;
    }

    /**
     * @param {string} value
     * @return {string}
     * @private
     */
    static prepareValue(value) {
        return encodeURIComponent(value);
    }

    /**
     * @param {{expires?:Date|string|number,path?:string,domain?:string,secure?:boolean}} opts
     * @private
     */
    static prepareOpts(opts = {}) {
        opts = Object.assign({}, opts);

        let {expires} = opts;

        if (typeof expires == 'number' && expires) {
            const date = new Date();

            date.setTime(date.getTime() + expires * 1000);

            expires = opts.expires = date;
        }

        if (expires && expires.toUTCString)
            opts.expires = expires.toUTCString();

        return opts;
    }
}

Android and setting width and height programmatically in dp units

Based on drspaceboo's solution, with Kotlin you can use an extension to convert Float to dips more easily.

fun Float.toDips() =
        TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, this, resources.displayMetrics);

Usage:

(65f).toDips()

How to find serial number of Android device?

Since no answer here mentions a perfect, fail-proof ID that is both PERSISTENT through system updates and exists in ALL devices (mainly due to the fact that there isn't an individual solution from Google), I decided to post a method that is the next best thing by combining two of the available identifiers, and a check to chose between them at run-time.

Before code, 3 facts:

  1. TelephonyManager.getDeviceId() (a.k.a.IMEI) will not work well or at all for non-GSM, 3G, LTE, etc. devices, but will always return a unique ID when related hardware is present, even when no SIM is inserted or even when no SIM slot exists (some OEM's have done this).

  2. Since Gingerbread (Android 2.3) android.os.Build.SERIAL must exist on any device that doesn't provide IMEI, i.e., doesn't have the aforementioned hardware present, as per Android policy.

  3. Due to fact (2.), at least one of these two unique identifiers will ALWAYS be present, and SERIAL can be present at the same time that IMEI is.

Note: Fact (1.) and (2.) are based on Google statements

SOLUTION

With the facts above, one can always have a unique identifier by checking if there is IMEI-bound hardware, and fall back to SERIAL when it isn't, as one cannot check if the existing SERIAL is valid. The following static class presents 2 methods for checking such presence and using either IMEI or SERIAL:

import java.lang.reflect.Method;

import android.content.Context;
import android.content.pm.PackageManager;
import android.os.Build;
import android.provider.Settings;
import android.telephony.TelephonyManager;
import android.util.Log;

public class IDManagement {

    public static String getCleartextID_SIMCHECK (Context mContext){
        String ret = "";

        TelephonyManager telMgr = (TelephonyManager) mContext.getSystemService(Context.TELEPHONY_SERVICE);

        if(isSIMAvailable(mContext,telMgr)){
            Log.i("DEVICE UNIQUE IDENTIFIER",telMgr.getDeviceId());
            return telMgr.getDeviceId();

        }
        else{
            Log.i("DEVICE UNIQUE IDENTIFIER", Settings.Secure.ANDROID_ID);

//          return Settings.Secure.ANDROID_ID;
            return android.os.Build.SERIAL;
        }
    }


    public static String getCleartextID_HARDCHECK (Context mContext){
        String ret = "";

        TelephonyManager telMgr = (TelephonyManager) mContext.getSystemService(Context.TELEPHONY_SERVICE);
        if(telMgr != null && hasTelephony(mContext)){           
            Log.i("DEVICE UNIQUE IDENTIFIER",telMgr.getDeviceId() + "");

            return telMgr.getDeviceId();    
        }
        else{
            Log.i("DEVICE UNIQUE IDENTIFIER", Settings.Secure.ANDROID_ID);

//          return Settings.Secure.ANDROID_ID;
            return android.os.Build.SERIAL;
        }
    }


    public static boolean isSIMAvailable(Context mContext, 
            TelephonyManager telMgr){

        int simState = telMgr.getSimState();

        switch (simState) {
        case TelephonyManager.SIM_STATE_ABSENT:
            return false;
        case TelephonyManager.SIM_STATE_NETWORK_LOCKED:
            return false;
        case TelephonyManager.SIM_STATE_PIN_REQUIRED:
            return false;
        case TelephonyManager.SIM_STATE_PUK_REQUIRED:
            return false;
        case TelephonyManager.SIM_STATE_READY:
            return true;
        case TelephonyManager.SIM_STATE_UNKNOWN:
            return false;
        default:
            return false;
        }
    }

    static public boolean hasTelephony(Context mContext)
    {
        TelephonyManager tm = (TelephonyManager) mContext.getSystemService(Context.TELEPHONY_SERVICE);
        if (tm == null)
            return false;

        //devices below are phones only
        if (Build.VERSION.SDK_INT < 5)
            return true;

        PackageManager pm = mContext.getPackageManager();

        if (pm == null)
            return false;

        boolean retval = false;
        try
        {
            Class<?> [] parameters = new Class[1];
            parameters[0] = String.class;
            Method method = pm.getClass().getMethod("hasSystemFeature", parameters);
            Object [] parm = new Object[1];
            parm[0] = "android.hardware.telephony";
            Object retValue = method.invoke(pm, parm);
            if (retValue instanceof Boolean)
                retval = ((Boolean) retValue).booleanValue();
            else
                retval = false;
        }
        catch (Exception e)
        {
            retval = false;
        }

        return retval;
    }


}

I would advice on using getCleartextID_HARDCHECK. If the reflection doesn't stick in your environment, use the getCleartextID_SIMCHECK method instead, but take in consideration it should be adapted to your specific SIM-presence needs.

P.S.: Do please note that OEM's have managed to bug out SERIAL against Google policy (multiple devices with same SERIAL), and Google as stated there is at least one known case in a big OEM (not disclosed and I don't know which brand it is either, I'm guessing Samsung).

Disclaimer: This answers the original question of getting a unique device ID, but the OP introduced ambiguity by stating he needs a unique ID for an APP. Even if for such scenarios Android_ID would be better, it WILL NOT WORK after, say, a Titanium Backup of an app through 2 different ROM installs (can even be the same ROM). My solution maintains persistence that is independent of a flash or factory reset, and will only fail when IMEI or SERIAL tampering occurs through hacks/hardware mods.

Modify a Column's Type in sqlite3

If you prefer a GUI, DB Browser for SQLite will do this with a few clicks.

  1. "File" - "Open Database"
  2. In the "Database Structure" tab, click on the table content (not table name), then "Edit" menu, "Modify table", and now you can change the data type of any column with a drop down menu. I changed a 'text' field to 'numeric' in order to retrieve data in a number range.

DB Browser for SQLite is open source and free. For Linux it is available from the repository.

How to set HTTP header to UTF-8 using PHP which is valid in W3C validator?

First make sure the PHP files themselves are UTF-8 encoded.

The meta tag is ignored by some browser. If you only use ASCII-characters, it doesn't matter anyway.

http://en.wikipedia.org/wiki/List_of_HTTP_header_fields

header('Content-Type: text/html; charset=utf-8');

How Do I Get the Query Builder to Output Its Raw SQL Query as a String?

As much as I love this framework, I hate when it acts like crap.

DB::enableQueryLog() is totally useless. DB::listen is equally useless. It showed part of the query when I said $query->count(), but if I do $query->get(), it has nothing to say.

The only solution that appears to work consistently is to intentionally put some syntax or other error in the ORM parameters, like an nonexistent column/table name, run your code on the command line while in debug mode, and it will spit out the SQL error with the full frickin' query finally. Otherwise, hopefully the error appears in the log file if ran from the web server.

How do I get a value of a <span> using jQuery?

     $('span id').text(); worked with me

'this' is undefined in JavaScript class methods

How are you calling the start function?

This should work (new is the key)

var o = new Request(destination, stay_open);
o.start();

If you directly call it like Request.prototype.start(), this will refer to the global context (window in browsers).

Also, if this is undefined, it results in an error. The if expression does not evaluate to false.

Update: this object is not set based on declaration, but by invocation. What it means is that if you assign the function property to a variable like x = o.start and call x(), this inside start no longer refers to o. This is what happens when you do setTimeout. To make it work, do this instead:

 var o = new Request(...);
 setTimeout(function() { o.start(); }, 1000);

WCF error: The caller was not authenticated by the service

I also had the same problem in wsHtppBinding. And I just had to add security mode pointing to none, that solved my problem and no need to switch to basicHttpBinding. Check Here and check how to disable WCF security. Check the below config change for reference:

<wsHttpBinding>
    <binding name="soapBinding">
        <security mode="None">
            <transport clientCredentialType="None" />
            <message establishSecurityContext="false" />
        </security>
    </binding>
</wsHttpBinding>

How do I automatically set the $DISPLAY variable for my current session?

You'll need to tell your vnc client to export the correct $DISPLAY once you have logged in. How you do that will probably depend on your vnc client.

React-router urls don't work when refreshing or writing manually

you can try reading this all though it's not mine:

https://www.andreasreiterer.at/fix-browserrouter-on-apache/

Fixing the app’s routing Now here’s how to finally fix the routing. To tell Apache to redirect requests to index.html where our app lives, we have to modify the .htaccess file. If there is no such file in your app’s folder yet, just create it.

Then be sure that you put in those 4 lines that will magically make your routing work.

Options -MultiViews
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^ index.html [QSA,L]

After we put that .htaccess file into the same directory as the index.html, Apache will redirect each new request directly to your app.

Bonus: Deploying the React app to a sub directory

If you’re deploying your app into a sub directory, so it’s accessible e.g. via https://myapp.com/the-app, you’ll soon notice that there is another issue. Each click to a new route will transform the URL to something like https://myapp.com/route-abc – which will break again after a reload. But there is a simple fix for that:

BrowserRouter has a prop called basename where you can specify your sub-directory path:

From now on, each Route like /contacts will result in an URL like http://myapp.com/the-app/contacts.

javascript filter array multiple conditions

with the composition of some little helpers:

const filter = {address: 'England', name: 'Mark'};
console.log( 
  users.filter(and(map(propMatches)(filter)))
)

function propMatches<T>(property: string, value: any) {
  return (item: T): boolean => item[property] === value
}

function map<T>(mapper: (key: string, value: any, obj: T) => (item:T) => any) {
  return (obj: T) => {
    return Object.keys(obj).map((key) => {
      return mapper(key, obj[key], obj)
    });
  }
}

export function and<T>(predicates: ((item: T) => boolean)[]) {
  return (item: T) =>
    predicates.reduce(
        (acc: boolean, predicate: (item: T) => boolean) => {
            if (acc === undefined) {
                return !!predicate(item);
            }
            return !!predicate(item) && acc;
        },
        undefined // initial accumulator value
    );
}

How to run Pip commands from CMD

Newer versions of Python come with py, the Python Launcher, which is always in the PATH.

Here is how to invoke pip via py:

py -m pip install <packagename>

py allows having several versions of Python on the same machine.

As an example, here is how to invoke the pip from Python 2.7:

py -2.7 -m pip install <packagename>

Getting Data from Android Play Store

I've coded a small Node.js module to scrape app and list data from Google Play: google-play-scraper

var gplay = require('google-play-scrapper');

gplay.List({
    category: gplay.category.GAME_ACTION,
    collection: gplay.collection.TOP_FREE,
    num: 2
  }).then(console.log);

Results:

 [ { url: 'https://play.google.com/store/apps/details?id=com.playappking.busrush',
    appId: 'com.playappking.busrush',
    title: 'Bus Rush',
    developer: 'Play App King',
    icon: 'https://lh3.googleusercontent.com/R6hmyJ6ls6wskk5hHFoW02yEyJpSG36il4JBkVf-Aojb1q4ZJ9nrGsx6lwsRtnTqfA=w340',
    score: 3.9,
    price: '0',
    free: false },
  { url: 'https://play.google.com/store/apps/details?id=com.yodo1.crossyroad',
    appId: 'com.yodo1.crossyroad',
    title: 'Crossy Road',
    developer: 'Yodo1 Games',
    icon: 'https://lh3.googleusercontent.com/doHqbSPNekdR694M-4rAu9P2B3V6ivff76fqItheZGJiN4NBw6TrxhIxCEpqgO3jKVg=w340',
    score: 4.5,
    price: '0',
    free: false } ]

Non-resolvable parent POM for Could not find artifact and 'parent.relativePath' points at wrong local POM

You need to have the file /root/test/devenv/openstack-rhel/pom.xml

This file need to have the followings elements:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>org.openstack</groupId>
    <artifactId>openstack-rhel-rpms</artifactId>
    <version>2012.1-SNAPSHOT</version>
    <packaging>pom</packaging>
</project>

Bootstrap: Open Another Modal in Modal

Why not just change the content of the modal body?

    window.switchContent = function(myFile){
        $('.modal-body').load(myFile);
    };

In the modal just put a link or a button

    <a href="Javascript: switchContent('myFile.html'); return false;">
     click here to load another file</a>

If you just want to switch beetween 2 modals:

    window.switchModal = function(){
        $('#myModal-1').modal('hide');
        setTimeout(function(){ $('#myModal-2').modal(); }, 500);
        // the setTimeout avoid all problems with scrollbars
    };

In the modal just put a link or a button

    <a href="Javascript: switchModal(); return false;">
     click here to switch to the second modal</a>

Serializing and submitting a form with jQuery and PHP

Have you checked in console if data from form is properly serialized? Is ajax request successful? Also you didn't close placeholder quote in, which can cause some problems:

 <textarea name="comentarii" cols="36" rows="5" placeholder="Message>  

Good MapReduce examples

One set of familiar operations that you can do in MapReduce is the set of normal SQL operations: SELECT, SELECT WHERE, GROUP BY, ect.

Another good example is matrix multiply, where you pass one row of M and the entire vector x and compute one element of M * x.

How to get the first element of an array?

You can do it by lodash _.head so easily.

_x000D_
_x000D_
var arr = ['first', 'second', 'third', 'fourth', 'fifth'];_x000D_
console.log(_.head(arr));
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>
_x000D_
_x000D_
_x000D_

Difference between Node object and Element object?

Element inherits from Node, in the same way that Dog inherits from Animal.

An Element object "is-a" Node object, in the same way that a Dog object "is-a" Animal object.

Node is for implementing a tree structure, so its methods are for firstChild, lastChild, childNodes, etc. It is more of a class for a generic tree structure.

And then, some Node objects are also Element objects. Element inherits from Node. Element objects actually represents the objects as specified in the HTML file by the tags such as <div id="content"></div>. The Element class define properties and methods such as attributes, id, innerHTML, clientWidth, blur(), and focus().

Some Node objects are text nodes and they are not Element objects. Each Node object has a nodeType property that indicates what type of node it is, for HTML documents:

1: Element node
3: Text node
8: Comment node
9: the top level node, which is document

We can see some examples in the console:

> document instanceof Node
  true

> document instanceof Element
  false

> document.firstChild
  <html>...</html>

> document.firstChild instanceof Node
  true

> document.firstChild instanceof Element
  true

> document.firstChild.firstChild.nextElementSibling
  <body>...</body>

> document.firstChild.firstChild.nextElementSibling === document.body
  true

> document.firstChild.firstChild.nextSibling
  #text

> document.firstChild.firstChild.nextSibling instanceof Node
  true

> document.firstChild.firstChild.nextSibling instanceof Element
  false

> Element.prototype.__proto__ === Node.prototype
  true

The last line above shows that Element inherits from Node. (that line won't work in IE due to __proto__. Will need to use Chrome, Firefox, or Safari).

By the way, the document object is the top of the node tree, and document is a Document object, and Document inherits from Node as well:

> Document.prototype.__proto__ === Node.prototype
  true

Here are some docs for the Node and Element classes:
https://developer.mozilla.org/en-US/docs/DOM/Node
https://developer.mozilla.org/en-US/docs/DOM/Element

How to run a javascript function during a mouseover on a div

Using the title attribute:

<div id="sub1 sub2 sub3" title="some text on mouse over">some text</div>

How do I write good/correct package __init__.py files

My own __init__.py files are empty more often than not. In particular, I never have a from blah import * as part of __init__.py -- if "importing the package" means getting all sort of classes, functions etc defined directly as part of the package, then I would lexically copy the contents of blah.py into the package's __init__.py instead and remove blah.py (the multiplication of source files does no good here).

If you do insist on supporting the import * idioms (eek), then using __all__ (with as miniscule a list of names as you can bring yourself to have in it) may help for damage control. In general, namespaces and explicit imports are good things, and I strong suggest reconsidering any approach based on systematically bypassing either or both concepts!-)

How to run a subprocess with Python, wait for it to exit and get the full stdout as a string?

If your process gives a huge stdout and no stderr, communicate() might be the wrong way to go due to memory restrictions.

Instead,

process = subprocess.Popen(cmd, shell=True,
                           stdout=subprocess.PIPE, 
                           stderr=subprocess.PIPE)

# wait for the process to terminate
for line in process.stdout: do_something(line)
errcode = process.returncode

might be the way to go.

process.stdout is a file-like object which you can treat as any other such object, mainly:

  • you can read() from it
  • you can readline() from it and
  • you can iterate over it.

The latter is what I do above in order to get its contents line by line.

json_encode function: special characters

To me, it works this way:

# Creating the ARRAY from Result.
$array=array();

while($row = $result->fetch_array(MYSQL_ASSOC))
{
    # Converting each column to UTF8
    $row = array_map('utf8_encode', $row);
    array_push($array,$row);
}

json_encode($array);

Why is this HTTP request not working on AWS Lambda?

I faced this issue on Node 10.X version. below is my working code.

const https = require('https');

exports.handler = (event,context,callback) => {
    let body='';
    let jsonObject = JSON.stringify(event);

    // the post options
    var optionspost = {
      host: 'example.com', 
      path: '/api/mypath',
      method: 'POST',
      headers: {
      'Content-Type': 'application/json',
      'Authorization': 'blah blah',
    }
    };

    let reqPost =  https.request(optionspost, function(res) {
        console.log("statusCode: ", res.statusCode);
        res.on('data', function (chunk) {
            body += chunk;
        });
        res.on('end', function () {
           console.log("Result", body.toString());
           context.succeed("Sucess")
        });
        res.on('error', function () {
          console.log("Result Error", body.toString());
          context.done(null, 'FAILURE');
        });
    });
    reqPost.write(jsonObject);
    reqPost.end();
};

GDB: break if variable equal value

You can use a watchpoint for this (A breakpoint on data instead of code).

You can start by using watch i.
Then set a condition for it using condition <breakpoint num> i == 5

You can get the breakpoint number by using info watch

SQL : BETWEEN vs <= and >=

See this excellent blog post from Aaron Bertrand about why you should change your string format and how the boundary values are handled in date range queries.

Add new field to every document in a MongoDB collection

if you are using mongoose try this,after mongoose connection

async ()=> await Mongoose.model("collectionName").updateMany({}, {$set: {newField: value}})

wampserver doesn't go green - stays orange

I have had this issue before and it turned out that Skype was interferring with port 80. So you may have to look at your system to see if you have another application utilizing this port.

Anyway under Skype, to change this setting it was: Tools->Options->Advanced->Connection->Use port 80 and 443 as alternatives for incoming connections. Untick this, restart Skype, restart wamp.

Related question

Calling constructors in c++ without new

In append to JaredPar answer

1-usual ctor, 2nd-function-like-ctor with temporary object.

Compile this source somewhere here http://melpon.org/wandbox/ with different compilers

// turn off rvo for clang, gcc with '-fno-elide-constructors'

#include <stdio.h>
class Thing {
public:
    Thing(const char*){puts(__FUNCTION__ );}
    Thing(const Thing&){puts(__FUNCTION__ );}   
    ~Thing(){puts(__FUNCTION__);}
};
int main(int /*argc*/, const char** /*argv*/) {
    Thing myThing = Thing("asdf");
}

And you will see the result.

From ISO/IEC 14882 2003-10-15

8.5, part 12

Your 1st,2nd construction are called direct-initialization

12.1, part 13

A functional notation type conversion (5.2.3) can be used to create new objects of its type. [Note: The syntax looks like an explicit call of the constructor. ] ... An object created in this way is unnamed. [Note: 12.2 describes the lifetime of temporary objects. ] [Note: explicit constructor calls do not yield lvalues, see 3.10. ]


Where to read about RVO:

12 Special member functions / 12.8 Copying class objects/ Part 15

When certain criteria are met, an implementation is allowed to omit the copy construction of a class object, even if the copy constructor and/or destructor for the object have side effects.

Turn off it with compiler flag from comment to view such copy-behavior)

How to convert int[] to Integer[] in Java?

If you want to convert an int[] to an Integer[], there isn't an automated way to do it in the JDK. However, you can do something like this:

int[] oldArray;

... // Here you would assign and fill oldArray

Integer[] newArray = new Integer[oldArray.length];
int i = 0;
for (int value : oldArray) {
    newArray[i++] = Integer.valueOf(value);
}

If you have access to the Apache lang library, then you can use the ArrayUtils.toObject(int[]) method like this:

Integer[] newArray = ArrayUtils.toObject(oldArray);

How to fluently build JSON in Java?

If you are using Jackson do a lot of JsonNode building in code, you may be interesting in the following set of utilities. The benefit of using them is that they support a more natural chaining style that better shows the structure of the JSON under construction.

Here is an example usage:

import static JsonNodeBuilders.array;
import static JsonNodeBuilders.object;

...

val request = object("x", "1").with("y", array(object("z", "2"))).end();

Which is equivalent to the following JSON:

{"x":"1", "y": [{"z": "2"}]}

Here are the classes:

import static lombok.AccessLevel.PRIVATE;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.JsonNodeFactory;
import com.fasterxml.jackson.databind.node.ObjectNode;

import lombok.NoArgsConstructor;
import lombok.NonNull;
import lombok.RequiredArgsConstructor;
import lombok.val;

/**
 * Convenience {@link JsonNode} builder.
 */
@NoArgsConstructor(access = PRIVATE)
public final class JsonNodeBuilders {

  /**
   * Factory methods for an {@link ObjectNode} builder.
   */

  public static ObjectNodeBuilder object() {
    return object(JsonNodeFactory.instance);
  }

  public static ObjectNodeBuilder object(@NonNull String k1, boolean v1) {
    return object().with(k1, v1);
  }

  public static ObjectNodeBuilder object(@NonNull String k1, int v1) {
    return object().with(k1, v1);
  }

  public static ObjectNodeBuilder object(@NonNull String k1, float v1) {
    return object().with(k1, v1);
  }

  public static ObjectNodeBuilder object(@NonNull String k1, String v1) {
    return object().with(k1, v1);
  }

  public static ObjectNodeBuilder object(@NonNull String k1, String v1, @NonNull String k2, String v2) {
    return object(k1, v1).with(k2, v2);
  }

  public static ObjectNodeBuilder object(@NonNull String k1, String v1, @NonNull String k2, String v2,
      @NonNull String k3, String v3) {
    return object(k1, v1, k2, v2).with(k3, v3);
  }

  public static ObjectNodeBuilder object(@NonNull String k1, JsonNodeBuilder<?> builder) {
    return object().with(k1, builder);
  }

  public static ObjectNodeBuilder object(JsonNodeFactory factory) {
    return new ObjectNodeBuilder(factory);
  }

  /**
   * Factory methods for an {@link ArrayNode} builder.
   */

  public static ArrayNodeBuilder array() {
    return array(JsonNodeFactory.instance);
  }

  public static ArrayNodeBuilder array(@NonNull boolean... values) {
    return array().with(values);
  }

  public static ArrayNodeBuilder array(@NonNull int... values) {
    return array().with(values);
  }

  public static ArrayNodeBuilder array(@NonNull String... values) {
    return array().with(values);
  }

  public static ArrayNodeBuilder array(@NonNull JsonNodeBuilder<?>... builders) {
    return array().with(builders);
  }

  public static ArrayNodeBuilder array(JsonNodeFactory factory) {
    return new ArrayNodeBuilder(factory);
  }

  public interface JsonNodeBuilder<T extends JsonNode> {

    /**
     * Construct and return the {@link JsonNode} instance.
     */
    T end();

  }

  @RequiredArgsConstructor
  private static abstract class AbstractNodeBuilder<T extends JsonNode> implements JsonNodeBuilder<T> {

    /**
     * The source of values.
     */
    @NonNull
    protected final JsonNodeFactory factory;

    /**
     * The value under construction.
     */
    @NonNull
    protected final T node;

    /**
     * Returns a valid JSON string, so long as {@code POJONode}s not used.
     */
    @Override
    public String toString() {
      return node.toString();
    }

  }

  public final static class ObjectNodeBuilder extends AbstractNodeBuilder<ObjectNode> {

    private ObjectNodeBuilder(JsonNodeFactory factory) {
      super(factory, factory.objectNode());
    }

    public ObjectNodeBuilder withNull(@NonNull String field) {
      return with(field, factory.nullNode());
    }

    public ObjectNodeBuilder with(@NonNull String field, int value) {
      return with(field, factory.numberNode(value));
    }

    public ObjectNodeBuilder with(@NonNull String field, float value) {
      return with(field, factory.numberNode(value));
    }

    public ObjectNodeBuilder with(@NonNull String field, boolean value) {
      return with(field, factory.booleanNode(value));
    }

    public ObjectNodeBuilder with(@NonNull String field, String value) {
      return with(field, factory.textNode(value));
    }

    public ObjectNodeBuilder with(@NonNull String field, JsonNode value) {
      node.set(field, value);
      return this;
    }

    public ObjectNodeBuilder with(@NonNull String field, @NonNull JsonNodeBuilder<?> builder) {
      return with(field, builder.end());
    }

    public ObjectNodeBuilder withPOJO(@NonNull String field, @NonNull Object pojo) {
      return with(field, factory.pojoNode(pojo));
    }

    @Override
    public ObjectNode end() {
      return node;
    }

  }

  public final static class ArrayNodeBuilder extends AbstractNodeBuilder<ArrayNode> {

    private ArrayNodeBuilder(JsonNodeFactory factory) {
      super(factory, factory.arrayNode());
    }

    public ArrayNodeBuilder with(boolean value) {
      node.add(value);
      return this;
    }

    public ArrayNodeBuilder with(@NonNull boolean... values) {
      for (val value : values)
        with(value);
      return this;
    }

    public ArrayNodeBuilder with(int value) {
      node.add(value);
      return this;
    }

    public ArrayNodeBuilder with(@NonNull int... values) {
      for (val value : values)
        with(value);
      return this;
    }

    public ArrayNodeBuilder with(float value) {
      node.add(value);
      return this;
    }

    public ArrayNodeBuilder with(String value) {
      node.add(value);
      return this;
    }

    public ArrayNodeBuilder with(@NonNull String... values) {
      for (val value : values)
        with(value);
      return this;
    }

    public ArrayNodeBuilder with(@NonNull Iterable<String> values) {
      for (val value : values)
        with(value);
      return this;
    }

    public ArrayNodeBuilder with(JsonNode value) {
      node.add(value);
      return this;
    }

    public ArrayNodeBuilder with(@NonNull JsonNode... values) {
      for (val value : values)
        with(value);
      return this;
    }

    public ArrayNodeBuilder with(JsonNodeBuilder<?> value) {
      return with(value.end());
    }

    public ArrayNodeBuilder with(@NonNull JsonNodeBuilder<?>... builders) {
      for (val builder : builders)
        with(builder);
      return this;
    }

    @Override
    public ArrayNode end() {
      return node;
    }

  }

}

Note that the implementation uses Lombok, but you can easily desugar it to fill in the Java boilerplate.

How can I add some small utility functions to my AngularJS application?

Do I understand correctly that you just want to define some utility methods and make them available in templates?

You don't have to add them to every controller. Just define a single controller for all the utility methods and attach that controller to <html> or <body> (using the ngController directive). Any other controllers you attach anywhere under <html> (meaning anywhere, period) or <body> (anywhere but <head>) will inherit that $scope and will have access to those methods.

How do I parse a HTML page with Node.js

November 2020 Update

I searched for the top NodeJS html parser libraries.

Because my use cases didn't require a library with many features, I could focus on stability and performance.

By stability I mean that I want the library to be used long enough by the community in order to find bugs and that it will be still maintained and that open issues will be closed.

Its hard to understand the future of an open source library, but I did a small summary based on the top 10 libraries in openbase.

I divided into 2 groups according to the last commit (and on each group the order is according to Github starts):

Last commit is in the last 6 months:

jsdom - Last commit: 3 Months, Open issues: 331, Github stars: 14.9K.

htmlparser2 - Last commit: 8 days, Open issues: 2, Github stars: 2.7K.

parse5 - Last commit: 2 Months, Open issues: 21, Github stars: 2.5K.

swagger-parser - Last commit: 2 Months, Open issues: 48, Github stars: 663.

html-parse-stringify - Last commit: 4 Months, Open issues: 3, Github stars: 215.

node-html-parser - Last commit: 7 days, Open issues: 15, Github stars: 205.

Last commit is 6 months and above:

cheerio - Last commit: 1 year, Open issues: 174, Github stars: 22.9K.

koa-bodyparser - Last commit: 6 months, Open issues: 9, Github stars: 1.1K.

sax-js - Last commit: 3 Years, Open issues: 65, Github stars: 941.

draftjs-to-html - Last commit: 1 Year, Open issues: 27, Github stars: 233.


I picked Node-html-parser because it seems quiet fast and very active at this moment.

(*) Openbase adds much more information regarding each library like the number of contributors (with +3 commits), weekly downloads, Monthly commits, Version etc'.

(**) The table above is a snapshot according to the specific time and date - I would check the reference again and as a first step check the level of recent activity and then dive into the smaller details.

Specifying an Index (Non-Unique Key) Using JPA

EclipseLink provided an annotation (e.g. @Index) to define an index on columns. There is an example of its use. Part of the example is included...

The firstName and lastName fields are indexed, together and individually.

@Entity
@Index(name="EMP_NAME_INDEX", columnNames={"F_NAME","L_NAME"})  // Columns indexed together
public class Employee{
    @Id
    private long id;

    @Index                      // F_NAME column indexed
    @Column(name="F_NAME")
    private String firstName;

    @Index                      // L_NAME column indexed
    @Column(name="L_NAME")
    private String lastName;
    ...
}

How do you represent a JSON array of strings?

Your JSON object in this case is a list. JSON is almost always an object with attributes; a set of one or more key:value pairs, so you most likely see a dictionary:

{ "MyStringArray" : ["somestring1", "somestring2"] }

then you can ask for the value of "MyStringArray" and you would get back a list of two strings, "somestring1" and "somestring2".

Convert a Unicode string to a string in Python (containing extra symbols)

Here is an example code

import unicodedata    
raw_text = u"here $%6757 dfgdfg"
convert_text = unicodedata.normalize('NFKD', raw_text).encode('ascii','ignore')

catch specific HTTP error in python

Python 3

from urllib.error import HTTPError

Python 2

from urllib2 import HTTPError

Just catch HTTPError, handle it, and if it's not Error 404, simply use raise to re-raise the exception.

See the Python tutorial.

e.g. complete example for Pyhton 2

import urllib2
from urllib2 import HTTPError
try:
   urllib2.urlopen("some url")
except HTTPError as err:
   if err.code == 404:
       <whatever>
   else:
       raise

Android and setting alpha for (image) view alpha

No, there is not, see how the "Related XML Attributes" section is missing in the ImageView.setAlpha(int) documentation. The alternative is to use View.setAlpha(float) whose XML counterpart is android:alpha. It takes a range of 0.0 to 1.0 instead of 0 to 255. Use it e.g. like

<ImageView android:alpha="0.4">

However, the latter in available only since API level 11.

How do I set a program to launch at startup

Here is all way to add your program to startup for Windows Vista, 7, 8, 10

  • File path

C:\Users\Bureau Briffault\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup (Visible from task manager, Running on current user login success, No admin privileges required)

C:\Users\Default\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup (Visible from task manager, Running on all user login success, Admin privileges required)


  • Registry path

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run (Visible from task manager, Running on current user login success, No admin privileges required)

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce (Not visible from task manager, Running on current user login success, Running for one login time, No admin privileges required)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run (Visible from task manager, Running on all user login success, Admin privileges required)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce (Not visible from task manager, Running on all user login success, Running for one login time, Admin privileges required)


  • Task scheduler

Microsoft.Win32.Taskscheduler.dll (Not visible from task manager, Running on windows boot, Running as admin, Admin privileges required)

How to create a date and time picker in Android?

I have create a alert dialog which combine Date picker and Time picker. You can get code at https://github.com/nguyentoantuit/android Note: DateTimePicker is a library

How to preview a part of a large pandas DataFrame, in iPython notebook?

I write a method to show the four corners of the data and monkey-patch to dataframe to do so:

def _sw(df, up_rows=10, down_rows=5, left_cols=4, right_cols=3, return_df=False):
    ''' display df data at four corners
        A,B (up_pt)
        C,D (down_pt)
        parameters : up_rows=10, down_rows=5, left_cols=4, right_cols=3
        usage:
            df = pd.DataFrame(np.random.randn(20,10), columns=list('ABCDEFGHIJKLMN')[0:10])
            df.sw(5,2,3,2)
            df1 = df.set_index(['A','B'], drop=True, inplace=False)
            df1.sw(5,2,3,2)
    '''
    #pd.set_printoptions(max_columns = 80, max_rows = 40)
    ncol, nrow = len(df.columns), len(df)

    # handle columns
    if ncol <= (left_cols + right_cols) :
        up_pt = df.ix[0:up_rows, :]         # screen width can contain all columns
        down_pt = df.ix[-down_rows:, :]
    else:                                   # screen width can not contain all columns
        pt_a = df.ix[0:up_rows,  0:left_cols]
        pt_b = df.ix[0:up_rows,  -right_cols:]
        pt_c = df[-down_rows:].ix[:,0:left_cols]
        pt_d = df[-down_rows:].ix[:,-right_cols:]

        up_pt   = pt_a.join(pt_b, how='inner')
        down_pt = pt_c.join(pt_d, how='inner')
        up_pt.insert(left_cols, '..', '..')
        down_pt.insert(left_cols, '..', '..')

    overlap_qty = len(up_pt) + len(down_pt) - len(df)
    down_pt = down_pt.drop(down_pt.index[range(overlap_qty)]) # remove overlap rows

    dt_str_list = down_pt.to_string().split('\n') # transfer down_pt to string list

    # Display up part data
    print up_pt

    start_row = (1 if df.index.names[0] is None else 2) # start from 1 if without index

    # Display omit line if screen height is not enought to display all rows
    if overlap_qty < 0:
        print "." * len(dt_str_list[start_row])

    # Display down part data row by row
    for line in dt_str_list[start_row:]:
        print line

    # Display foot note
    print "\n"
    print "Index :",df.index.names
    print "Column:",",".join(list(df.columns.values))
    print "row: %d    col: %d"%(len(df), len(df.columns))
    print "\n"

    return (df if return_df else None)
DataFrame.sw = _sw  #add a method to DataFrame class

Here is the sample:

>>> df = pd.DataFrame(np.random.randn(20,10), columns=list('ABCDEFGHIJKLMN')[0:10])

>>> df.sw()
         A       B       C       D  ..       H       I       J
0  -0.8166  0.0102  0.0215 -0.0307  .. -0.0820  1.2727  0.6395
1   1.0659 -1.0102 -1.3960  0.4700  ..  1.0999  1.1222 -1.2476
2   0.4347  1.5423  0.5710 -0.5439  ..  0.2491 -0.0725  2.0645
3  -1.5952 -1.4959  2.2697 -1.1004  .. -1.9614  0.6488 -0.6190
4  -1.4426 -0.8622  0.0942 -0.1977  .. -0.7802 -1.1774  1.9682
5   1.2526 -0.2694  0.4841 -0.7568  ..  0.2481  0.3608 -0.7342
6   0.2108  2.5181  1.3631  0.4375  .. -0.1266  1.0572  0.3654
7  -1.0617 -0.4743 -1.7399 -1.4123  .. -1.0398 -1.4703 -0.9466
8  -0.5682 -1.3323 -0.6992  1.7737  ..  0.6152  0.9269  2.1854
9   0.2361  0.4873 -1.1278 -0.2251  ..  1.4232  2.1212  2.9180
10  2.0034  0.5454 -2.6337  0.1556  ..  0.0016 -1.6128 -0.8093
..............................................................
15  1.4091  0.3540 -1.3498 -1.0490  ..  0.9328  0.3668  1.3948
16  0.4528 -0.3183  0.4308 -0.1818  ..  0.1295  1.2268  0.1365
17 -0.7093  1.3991  0.9501  2.1227  .. -1.5296  1.1908  0.0318
18  1.7101  0.5962  0.8948  1.5606  .. -0.6862  0.9558 -0.5514
19  1.0329 -1.2308 -0.6896 -0.5112  ..  0.2719  1.1478 -0.1459


Index : [None]
Column: A,B,C,D,E,F,G,H,I,J
row: 20    col: 10


>>> df.sw(4,2,3,4)
        A       B       C  ..       G       H       I       J
0 -0.8166  0.0102  0.0215  ..  0.3671 -0.0820  1.2727  0.6395
1  1.0659 -1.0102 -1.3960  ..  1.0984  1.0999  1.1222 -1.2476
2  0.4347  1.5423  0.5710  ..  1.6675  0.2491 -0.0725  2.0645
3 -1.5952 -1.4959  2.2697  ..  0.4856 -1.9614  0.6488 -0.6190
4 -1.4426 -0.8622  0.0942  .. -0.0947 -0.7802 -1.1774  1.9682
..............................................................
18  1.7101  0.5962  0.8948  .. -0.8592 -0.6862  0.9558 -0.5514
19  1.0329 -1.2308 -0.6896  .. -0.3954  0.2719  1.1478 -0.1459


Index : [None]
Column: A,B,C,D,E,F,G,H,I,J
row: 20    col: 10

How to write and read java serialized objects into a file

if you serialize the whole list you also have to de-serialize the file into a list when you read it back. This means that you will inevitably load in memory a big file. It can be expensive. If you have a big file, and need to chunk it line by line (-> object by object) just proceed with your initial idea.

Serialization:

LinkedList<YourObject> listOfObjects = <something>;
try {
    FileOutputStream file = new FileOutputStream(<filePath>);
    ObjectOutputStream writer = new ObjectOutputStream(file);
    for (YourObject obj : listOfObjects) {
        writer.writeObject(obj);
    }
    writer.close();
    file.close();
} catch (Exception ex) {
    System.err.println("failed to write " + filePath + ", "+ ex);
}

De-serialization:

try {
    FileInputStream file = new FileInputStream(<filePath>);
    ObjectInputStream reader = new ObjectInputStream(file);
    while (true) {
        try { 
            YourObject obj = (YourObject)reader.readObject();
            System.out.println(obj)
        } catch (Exception ex) {
            System.err.println("end of reader file ");
            break;
        }
    }
} catch (Exception ex) {
    System.err.println("failed to read " + filePath + ", "+ ex);
}

How to rearrange Pandas column sequence?

You could also do something like this:

df = df[['x', 'y', 'a', 'b']]

You can get the list of columns with:

cols = list(df.columns.values)

The output will produce something like this:

['a', 'b', 'x', 'y']

...which is then easy to rearrange manually before dropping it into the first function

jquery to validate phone number

function validatePhone(txtPhone) {
    var a = document.getElementById(txtPhone).value;
    var filter = /^((\+[1-9]{1,4}[ \-]*)|(\([0-9]{2,3}\)[ \-]*)|([0-9]{2,4})[ \-]*)*?[0-9]{3,4}?[ \-]*[0-9]{3,4}?$/;
    if (filter.test(a)) {
        return true;
    }
    else {
        return false;
    }
}

Demo http://jsfiddle.net/dishantd/JLJMW/496/

Using an array from Observable Object with ngFor and Async Pipe Angular 2

If you don't have an array but you are trying to use your observable like an array even though it's a stream of objects, this won't work natively. I show how to fix this below assuming you only care about adding objects to the observable, not deleting them.

If you are trying to use an observable whose source is of type BehaviorSubject, change it to ReplaySubject then in your component subscribe to it like this:

Component

this.messages$ = this.chatService.messages$.pipe(scan((acc, val) => [...acc, val], []));

Html

<div class="message-list" *ngFor="let item of messages$ | async">

Excel - Sum column if condition is met by checking other column in same table

This should work, but there is a little trick. After you enter the formula, you need to hold down Ctrl+Shift while you press Enter. When you do, you'll see that the formula bar has curly-braces around your formula. This is called an array formula.

For example, if the Months are in cells A2:A100 and the amounts are in cells B2:B100, your formula would look like {=SUM(If(A2:A100="January",B2:B100))}. You don't actually type the curly-braces though.

You could also do something like =SUM((A2:A100="January")*B2:B100). You'd still need to use the trick to get it to work correctly.