Programs & Examples On #Dojo

Dojo Toolkit is an open source modular JavaScript library designed to ease the rapid development of cross-platform, JavaScript/Ajax-based applications and web sites. It is dual-licensed under the BSD License and the Academic Free License. Dojo uses the Asynchronous Module Definition (AMD) format for its source code, allowing completely modular web application development.

Node.JS: Getting error : [nodemon] Internal watch failed: watch ENOSPC

Instead of specifying a list of directories to ignore (e.g. negative), you can also specify a list of directories to watch (e.g positive):

nodemon --watch dir1 --watch dir2  dir1/examples/index.js

In my particular case, I had one directory I wanted to watch and about nine I wanted to ignore, so specifying '--watch' was much simpler than specifying '--ignore'

How to identify and switch to the frame in selenium webdriver when frame does not have id

you can use cssSelector,

driver.switchTo().frame(driver.findElement(By.cssSelector("iframe[title='Fill Quote']")));

How to export JavaScript array info to csv (on client side)?

The following is a native js solution.

_x000D_
_x000D_
function export2csv() {_x000D_
  let data = "";_x000D_
  const tableData = [];_x000D_
  const rows = [_x000D_
    ['111', '222', '333'],_x000D_
    ['aaa', 'bbb', 'ccc'],_x000D_
    ['AAA', 'BBB', 'CCC']_x000D_
  ];_x000D_
  for (const row of rows) {_x000D_
    const rowData = [];_x000D_
    for (const column of row) {_x000D_
      rowData.push(column);_x000D_
    }_x000D_
    tableData.push(rowData.join(","));_x000D_
  }_x000D_
  data += tableData.join("\n");_x000D_
  const a = document.createElement("a");_x000D_
  a.href = URL.createObjectURL(new Blob([data], { type: "text/csv" }));_x000D_
  a.setAttribute("download", "data.csv");_x000D_
  document.body.appendChild(a);_x000D_
  a.click();_x000D_
  document.body.removeChild(a);_x000D_
}
_x000D_
<button onclick="export2csv()">Export array to csv file</button>
_x000D_
_x000D_
_x000D_

JavaScript code to stop form submission

Lots of hard ways to do an easy thing:

<form name="foo" onsubmit="return false">

How to make HTML table cell editable?

Just insert <input> element in <td> dynamically, on cell click. Only simple HTML and Javascript. No need for contentEditable , jquery, HTML5

https://Jsfiddle.net/gsivanov/38tLqobw/2/

How to create a css rule for all elements except one class?

Wouldn't setting a css rule for all tables, and then a subsequent one for tables where class="dojoxGrid" work? Or am I missing something?

Can I get the name of the currently running function in JavaScript?

An updated answer to this can can be found over at this answer: https://stackoverflow.com/a/2161470/632495

and, if you don't feel like clicking:

function test() {
  var z = arguments.callee.name;
  console.log(z);
}

jQuery override default validation error message display (Css) Popup/Tooltip like

A few things:

First, I don't think you really need a validation error for a radio fieldset because you could just have one of the fields checked by default. Most people would rather correct something then provide something. For instance:

   Age: (*) 12 - 18 | () 19 - 30 | 31 - 50 

is more likely to be changed to the right answer as the person DOESN'T want it to go to the default. If they see it blank, they are more likely to think "none of your business" and skip it.

Second, I was able to get the effect I think you are wanting without any positioning properties. You just add padding-right to the form (or the div of the form, whatever) to provide enough room for your error and make sure your error will fit in that area. Then, you have a pre-set up css class called "error" and you set it as having a negative margin-top roughly the height of your input field and a margin-left about the distance from the left to where your padding-right should start. I tried this out, it's not great, but it works with three properties and requires no floats or absolutes:

   <style type="text/css">
    .error {
        width: 13em; /* Ensures that the div won't exceed right padding of form */
        margin-top: -1.5em;  /*Moves the div up to the same level as input */
        margin-left: 11em;   /*Moves div to the right */
        font-size: .9em;     /*Makes sure that the error div is smaller than input */
    }

   <form>
   <label for="name">Name:</label><input id="name" type="textbox" />
   <div class="error"><<< This field is required!</div>
   <label for="numb">Phone:</label><input id="numb" type="textbox" />
   <div class="error"><<< This field is required!</div>
   </form>

Remove all the children DOM elements in div

node.innerHTML = "";

Non-standard, but fast and well supported.

How do I implement basic "Long Polling"?

I think the client looks like a normal asynchronous AJAX request, but you expect it to take a "long time" to come back.

The server then looks like this.

while (!hasNewData())
    usleep(50);

outputNewData();

So, the AJAX request goes to the server, probably including a timestamp of when it was last update so that your hasNewData() knows what data you have already got. The server then sits in a loop sleeping until new data is available. All the while, your AJAX request is still connected, just hanging there waiting for data. Finally, when new data is available, the server gives it to your AJAX request and closes the connection.

Set cookies for cross origin requests

In order for the client to be able to read cookies from cross-origin requests, you need to have:

  1. All responses from the server need to have the following in their header:

    Access-Control-Allow-Credentials: true

  2. The client needs to send all requests with withCredentials: true option

In my implementation with Angular 7 and Spring Boot, I achieved that with the following:


Server-side:

@CrossOrigin(origins = "http://my-cross-origin-url.com", allowCredentials = "true")
@Controller
@RequestMapping(path = "/something")
public class SomethingController {
  ...
}

The origins = "http://my-cross-origin-url.com" part will add Access-Control-Allow-Origin: http://my-cross-origin-url.com to every server's response header

The allowCredentials = "true" part will add Access-Control-Allow-Credentials: true to every server's response header, which is what we need in order for the client to read the cookies


Client-side:

import { HttpInterceptor, HttpXsrfTokenExtractor, HttpRequest, HttpHandler, HttpEvent } from "@angular/common/http";
import { Injectable } from "@angular/core";
import { Observable } from 'rxjs';

@Injectable()
export class CustomHttpInterceptor implements HttpInterceptor {

    constructor(private tokenExtractor: HttpXsrfTokenExtractor) {
    }

    intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        // send request with credential options in order to be able to read cross-origin cookies
        req = req.clone({ withCredentials: true });

        // return XSRF-TOKEN in each request's header (anti-CSRF security)
        const headerName = 'X-XSRF-TOKEN';
        let token = this.tokenExtractor.getToken() as string;
        if (token !== null && !req.headers.has(headerName)) {
            req = req.clone({ headers: req.headers.set(headerName, token) });
        }
        return next.handle(req);
    }
}

With this class you actually inject additional stuff to all your request.

The first part req = req.clone({ withCredentials: true });, is what you need in order to send each request with withCredentials: true option. This practically means that an OPTION request will be send first, so that you get your cookies and the authorization token among them, before sending the actual POST/PUT/DELETE requests, which need this token attached to them (in the header), in order for the server to verify and execute the request.

The second part is the one that specifically handles an anti-CSRF token for all requests. Reads it from the cookie when needed and writes it in the header of every request.

The desired result is something like this:

response request

How do I deserialize a JSON string into an NSDictionary? (For iOS 5+)

It looks like you are passing an NSString parameter where you should be passing an NSData parameter:

NSError *jsonError;
NSData *objectData = [@"{\"2\":\"3\"}" dataUsingEncoding:NSUTF8StringEncoding];
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:objectData
                                      options:NSJSONReadingMutableContainers 
                                        error:&jsonError];

How to insert a text at the beginning of a file?

If you want to add a line at the beginning of a file, you need to add \n at the end of the string in the best solution above.

The best solution will add the string, but with the string, it will not add a line at the end of a file.

sed -i '1s/^/your text\n/' file

Add items to comboBox in WPF

You can fill it from XAML or from .cs. There are few ways to fill controls with data. It would be best for You to read more about WPF technology, it allows to do many things in many ways, depending on Your needs. It's more important to choose method based on Your project needs. You can start here. It's an easy article about creating combobox, and filling it with some data.

Name attribute in @Entity and @Table

@Entity is useful with model classes to denote that this is the entity or table

@Table is used to provide any specific name to your table if you want to provide any different name

Note: if you don't use @Table then hibernate consider that @Entity is your table name by default and @Entity must

@Entity    
@Table(name = "emp")     
public class Employee implements java.io.Serializable    
{

}

Django, creating a custom 500/404 error page

In Django 3.x, the accepted answer won't work because render_to_response has been removed completely as well as some more changes have been made since the version the accepted answer worked for.

Some other answers are also there but I'm presenting a little cleaner answer:

In your main urls.py file:

handler404 = 'yourapp.views.handler404'
handler500 = 'yourapp.views.handler500'

In yourapp/views.py file:

def handler404(request, exception):
    context = {}
    response = render(request, "pages/errors/404.html", context=context)
    response.status_code = 404
    return response


def handler500(request):
    context = {}
    response = render(request, "pages/errors/500.html", context=context)
    response.status_code = 500
    return response

Ensure that you have imported render() in yourapp/views.py file:

from django.shortcuts import render

Side note: render_to_response() was deprecated in Django 2.x and it has been completely removed in verision 3.x.

Google Gson - deserialize list<class> object? (generic type)

Wep, another way to achieve the same result. We use it for its readability.

Instead of doing this hard-to-read sentence:

Type listType = new TypeToken<ArrayList<YourClass>>(){}.getType();
List<YourClass> list = new Gson().fromJson(jsonArray, listType);

Create a empty class that extends a List of your object:

public class YourClassList extends ArrayList<YourClass> {}

And use it when parsing the JSON:

List<YourClass> list = new Gson().fromJson(jsonArray, YourClassList.class);

Tree implementation in Java (root, parents and children)

In the accepted answer

public Node(T data, Node<T> parent) {
    this.data = data;
    this.parent = parent;
}

should be

public Node(T data, Node<T> parent) {
    this.data = data;
    this.setParent(parent);
}

otherwise the parent does not have the child in its children list

Facebook Android Generate Key Hash

The right key can be obtained from the app itself by adding the following code to toast the proper key hash (in case of Facebook SDK 3.0 onwards, this works)

try {
            PackageInfo info = getPackageManager().getPackageInfo("com.package.mypackage",         PackageManager.GET_SIGNATURES);
            for (Signature signature : info.signatures) {
                MessageDigest md = MessageDigest.getInstance("SHA");
                md.update(signature.toByteArray());
                String sign=Base64.encodeToString(md.digest(), Base64.DEFAULT);
                Log.e("MY KEY HASH:", sign);
                Toast.makeText(getApplicationContext(),sign,         Toast.LENGTH_LONG).show();
            }
} catch (NameNotFoundException e) {
} catch (NoSuchAlgorithmException e) {
}

Replace com.package.mypackage with your package name

Could not resolve Spring property placeholder

make sure your properties file exist in classpath directory but not in sub folder of your classpath directory. if it is exist in sub folder then write as below classpath:subfolder/idm.properties

Calculate cosine similarity given 2 sentence strings

The short answer is "no, it is not possible to do that in a principled way that works even remotely well". It is an unsolved problem in natural language processing research and also happens to be the subject of my doctoral work. I'll very briefly summarize where we are and point you to a few publications:

Meaning of words

The most important assumption here is that it is possible to obtain a vector that represents each word in the sentence in quesion. This vector is usually chosen to capture the contexts the word can appear in. For example, if we only consider the three contexts "eat", "red" and "fluffy", the word "cat" might be represented as [98, 1, 87], because if you were to read a very very long piece of text (a few billion words is not uncommon by today's standard), the word "cat" would appear very often in the context of "fluffy" and "eat", but not that often in the context of "red". In the same way, "dog" might be represented as [87,2,34] and "umbrella" might be [1,13,0]. Imagening these vectors as points in 3D space, "cat" is clearly closer to "dog" than it is to "umbrella", therefore "cat" also means something more similar to "dog" than to an "umbrella".

This line of work has been investigated since the early 90s (e.g. this work by Greffenstette) and has yielded some surprisingly good results. For example, here is a few random entries in a thesaurus I built recently by having my computer read wikipedia:

theory -> analysis, concept, approach, idea, method
voice -> vocal, tone, sound, melody, singing
james -> william, john, thomas, robert, george, charles

These lists of similar words were obtained entirely without human intervention- you feed text in and come back a few hours later.

The problem with phrases

You might ask why we are not doing the same thing for longer phrases, such as "ginger foxes love fruit". It's because we do not have enough text. In order for us to reliably establish what X is similar to, we need to see many examples of X being used in context. When X is a single word like "voice", this is not too hard. However, as X gets longer, the chances of finding natural occurrences of X get exponentially slower. For comparison, Google has about 1B pages containing the word "fox" and not a single page containing "ginger foxes love fruit", despite the fact that it is a perfectly valid English sentence and we all understand what it means.

Composition

To tackle the problem of data sparsity, we want to perform composition, i.e. to take vectors for words, which are easy to obtain from real text, and to put the together in a way that captures their meaning. The bad news is nobody has been able to do that well so far.

The simplest and most obvious way is to add or multiply the individual word vectors together. This leads to undesirable side effect that "cats chase dogs" and "dogs chase cats" would mean the same to your system. Also, if you are multiplying, you have to be extra careful or every sentences will end up represented by [0,0,0,...,0], which defeats the point.

Further reading

I will not discuss the more sophisticated methods for composition that have been proposed so far. I suggest you read Katrin Erk's "Vector space models of word meaning and phrase meaning: a survey". This is a very good high-level survey to get you started. Unfortunately, is not freely available on the publisher's website, email the author directly to get a copy. In that paper you will find references to many more concrete methods. The more comprehensible ones are by Mitchel and Lapata (2008) and Baroni and Zamparelli (2010).


Edit after comment by @vpekar: The bottom line of this answer is to stress the fact that while naive methods do exist (e.g. addition, multiplication, surface similarity, etc), these are fundamentally flawed and in general one should not expect great performance from them.

Make a Bash alias that takes a parameter?

As has already been pointed out by others, using a function should be considered best practice.

However, here is another approach, leveraging xargs:

alias junk="xargs -I "{}" -- mv "{}" "~/.Trash" <<< "

Note that this has side effects regarding redirection of streams.

How can I add an empty directory to a Git repository?

You can't. See the Git FAQ.

Currently the design of the git index (staging area) only permits files to be listed, and nobody competent enough to make the change to allow empty directories has cared enough about this situation to remedy it.

Directories are added automatically when adding files inside them. That is, directories never have to be added to the repository, and are not tracked on their own.

You can say "git add <dir>" and it will add files in there.

If you really need a directory to exist in checkouts you should create a file in it. .gitignore works well for this purpose; you can leave it empty, or fill in the names of files you expect to show up in the directory.

connect local repo with remote repo

git remote add origin <remote_repo_url>
git push --all origin

If you want to set all of your branches to automatically use this remote repo when you use git pull, add --set-upstream to the push:

git push --all --set-upstream origin

How do I POST with multipart form data using fetch?

I was recently working with IPFS and worked this out. A curl example for IPFS to upload a file looks like this:

curl -i -H "Content-Type: multipart/form-data; boundary=CUSTOM" -d $'--CUSTOM\r\nContent-Type: multipart/octet-stream\r\nContent-Disposition: file; filename="test"\r\n\r\nHello World!\n--CUSTOM--' "http://localhost:5001/api/v0/add"

The basic idea is that each part (split by string in boundary with --) has it's own headers (Content-Type in the second part, for example.) The FormData object manages all this for you, so it's a better way to accomplish our goals.

This translates to fetch API like this:

const formData = new FormData()
formData.append('blob', new Blob(['Hello World!\n']), 'test')

fetch('http://localhost:5001/api/v0/add', {
  method: 'POST',
  body: formData
})
.then(r => r.json())
.then(data => {
  console.log(data)
})

C# Enum - How to Compare Value

You can use Enum.Parse like, if it is string

AccountType account = (AccountType)Enum.Parse(typeof(AccountType), "Retailer")

How to UPSERT (MERGE, INSERT ... ON DUPLICATE UPDATE) in PostgreSQL?

9.5 and newer:

PostgreSQL 9.5 and newer support INSERT ... ON CONFLICT (key) DO UPDATE (and ON CONFLICT (key) DO NOTHING), i.e. upsert.

Comparison with ON DUPLICATE KEY UPDATE.

Quick explanation.

For usage see the manual - specifically the conflict_action clause in the syntax diagram, and the explanatory text.

Unlike the solutions for 9.4 and older that are given below, this feature works with multiple conflicting rows and it doesn't require exclusive locking or a retry loop.

The commit adding the feature is here and the discussion around its development is here.


If you're on 9.5 and don't need to be backward-compatible you can stop reading now.


9.4 and older:

PostgreSQL doesn't have any built-in UPSERT (or MERGE) facility, and doing it efficiently in the face of concurrent use is very difficult.

This article discusses the problem in useful detail.

In general you must choose between two options:

  • Individual insert/update operations in a retry loop; or
  • Locking the table and doing batch merge

Individual row retry loop

Using individual row upserts in a retry loop is the reasonable option if you want many connections concurrently trying to perform inserts.

The PostgreSQL documentation contains a useful procedure that'll let you do this in a loop inside the database. It guards against lost updates and insert races, unlike most naive solutions. It will only work in READ COMMITTED mode and is only safe if it's the only thing you do in the transaction, though. The function won't work correctly if triggers or secondary unique keys cause unique violations.

This strategy is very inefficient. Whenever practical you should queue up work and do a bulk upsert as described below instead.

Many attempted solutions to this problem fail to consider rollbacks, so they result in incomplete updates. Two transactions race with each other; one of them successfully INSERTs; the other gets a duplicate key error and does an UPDATE instead. The UPDATE blocks waiting for the INSERT to rollback or commit. When it rolls back, the UPDATE condition re-check matches zero rows, so even though the UPDATE commits it hasn't actually done the upsert you expected. You have to check the result row counts and re-try where necessary.

Some attempted solutions also fail to consider SELECT races. If you try the obvious and simple:

-- THIS IS WRONG. DO NOT COPY IT. It's an EXAMPLE.

BEGIN;

UPDATE testtable
SET somedata = 'blah'
WHERE id = 2;

-- Remember, this is WRONG. Do NOT COPY IT.

INSERT INTO testtable (id, somedata)
SELECT 2, 'blah'
WHERE NOT EXISTS (SELECT 1 FROM testtable WHERE testtable.id = 2);

COMMIT;

then when two run at once there are several failure modes. One is the already discussed issue with an update re-check. Another is where both UPDATE at the same time, matching zero rows and continuing. Then they both do the EXISTS test, which happens before the INSERT. Both get zero rows, so both do the INSERT. One fails with a duplicate key error.

This is why you need a re-try loop. You might think that you can prevent duplicate key errors or lost updates with clever SQL, but you can't. You need to check row counts or handle duplicate key errors (depending on the chosen approach) and re-try.

Please don't roll your own solution for this. Like with message queuing, it's probably wrong.

Bulk upsert with lock

Sometimes you want to do a bulk upsert, where you have a new data set that you want to merge into an older existing data set. This is vastly more efficient than individual row upserts and should be preferred whenever practical.

In this case, you typically follow the following process:

  • CREATE a TEMPORARY table

  • COPY or bulk-insert the new data into the temp table

  • LOCK the target table IN EXCLUSIVE MODE. This permits other transactions to SELECT, but not make any changes to the table.

  • Do an UPDATE ... FROM of existing records using the values in the temp table;

  • Do an INSERT of rows that don't already exist in the target table;

  • COMMIT, releasing the lock.

For example, for the example given in the question, using multi-valued INSERT to populate the temp table:

BEGIN;

CREATE TEMPORARY TABLE newvals(id integer, somedata text);

INSERT INTO newvals(id, somedata) VALUES (2, 'Joe'), (3, 'Alan');

LOCK TABLE testtable IN EXCLUSIVE MODE;

UPDATE testtable
SET somedata = newvals.somedata
FROM newvals
WHERE newvals.id = testtable.id;

INSERT INTO testtable
SELECT newvals.id, newvals.somedata
FROM newvals
LEFT OUTER JOIN testtable ON (testtable.id = newvals.id)
WHERE testtable.id IS NULL;

COMMIT;

Related reading

What about MERGE?

SQL-standard MERGE actually has poorly defined concurrency semantics and is not suitable for upserting without locking a table first.

It's a really useful OLAP statement for data merging, but it's not actually a useful solution for concurrency-safe upsert. There's lots of advice to people using other DBMSes to use MERGE for upserts, but it's actually wrong.

Other DBs:

php: how to get associative array key from numeric index?

You might do it this way:

function asoccArrayValueWithNumKey(&$arr, $key) {
   if (!(count($arr) > $key)) return false;
   reset($array);
   $aux   = -1;
   $found = false;
   while (($auxKey = key($array)) && !$found) {
      $aux++;
      $found = ($aux == $key);
   }
   if ($found) return $array[$auxKey];
   else return false;
}

$val = asoccArrayValueWithNumKey($array, 0);
$val = asoccArrayValueWithNumKey($array, 1);
etc...

Haven't tryed the code, but i'm pretty sure it will work.

Good luck!

Press enter in textbox to and execute button command

There are some cases, when textbox will not handle enter key. I think it may be when you have accept button set on form. In that case, instead of KeyDown event you should use textbox1_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)

Maximum size for a SQL Server Query? IN clause? Is there a Better Approach

Every SQL batch has to fit in the Batch Size Limit: 65,536 * Network Packet Size.

Other than that, your query is limited by runtime conditions. It will usually run out of stack size because x IN (a,b,c) is nothing but x=a OR x=b OR x=c which creates an expression tree similar to x=a OR (x=b OR (x=c)), so it gets very deep with a large number of OR. SQL 7 would hit a SO at about 10k values in the IN, but nowdays stacks are much deeper (because of x64), so it can go pretty deep.

Update

You already found Erland's article on the topic of passing lists/arrays to SQL Server. With SQL 2008 you also have Table Valued Parameters which allow you to pass an entire DataTable as a single table type parameter and join on it.

XML and XPath is another viable solution:

SELECT ...
FROM Table
JOIN (
   SELECT x.value(N'.',N'uniqueidentifier') as guid
   FROM @values.nodes(N'/guids/guid') t(x)) as guids
 ON Table.guid = guids.guid;

Mongoose's find method with $or condition does not work properly

I solved it through googling:

var ObjectId = require('mongoose').Types.ObjectId;
var objId = new ObjectId( (param.length < 12) ? "123456789012" : param );
// You should make string 'param' as ObjectId type. To avoid exception, 
// the 'param' must consist of more than 12 characters.

User.find( { $or:[ {'_id':objId}, {'name':param}, {'nickname':param} ]}, 
  function(err,docs){
    if(!err) res.send(docs);
});

Objective-C declared @property attributes (nonatomic, copy, strong, weak)

Nonatomic

Nonatomic will not generate threadsafe routines thru @synthesize accessors. atomic will generate threadsafe accessors so atomic variables are threadsafe (can be accessed from multiple threads without botching of data)

Copy

copy is required when the object is mutable. Use this if you need the value of the object as it is at this moment, and you don't want that value to reflect any changes made by other owners of the object. You will need to release the object when you are finished with it because you are retaining the copy.

Assign

Assign is somewhat the opposite to copy. When calling the getter of an assign property, it returns a reference to the actual data. Typically you use this attribute when you have a property of primitive type (float, int, BOOL...)

Retain

retain is required when the attribute is a pointer to a reference counted object that was allocated on the heap. Allocation should look something like:

NSObject* obj = [[NSObject alloc] init]; // ref counted var

The setter generated by @synthesize will add a reference count to the object when it is copied so the underlying object is not autodestroyed if the original copy goes out of scope.

You will need to release the object when you are finished with it. @propertys using retain will increase the reference count and occupy memory in the autorelease pool.

Strong

strong is a replacement for the retain attribute, as part of Objective-C Automated Reference Counting (ARC). In non-ARC code it's just a synonym for retain.

This is a good website to learn about strong and weak for iOS 5. http://www.raywenderlich.com/5677/beginning-arc-in-ios-5-part-1

Weak

weak is similar to strong except that it won't increase the reference count by 1. It does not become an owner of that object but just holds a reference to it. If the object's reference count drops to 0, even though you may still be pointing to it here, it will be deallocated from memory.

The above link contain both Good information regarding Weak and Strong.

Test if remote TCP port is open from a shell script

While an old question, I've just dealt with a variant of it, but none of the solutions here were applicable, so I found another, and am adding it for posterity. Yes, I know the OP said they were aware of this option and it didn't suit them, but for anyone following afterwards it might prove useful.

In my case, I want to test for the availability of a local apt-cacher-ng service from a docker build. That means absolutely nothing can be installed prior to the test. No nc, nmap, expect, telnet or python. perl however is present, along with the core libraries, so I used this:

perl -MIO::Socket::INET -e 'exit(! defined( IO::Socket::INET->new("172.17.42.1:3142")))'

MongoDB Aggregation: How to get total records count?

This could be work for multiple match conditions

            const query = [
                {
                    $facet: {
                    cancelled: [
                        { $match: { orderStatus: 'Cancelled' } },
                        { $count: 'cancelled' }
                    ],
                    pending: [
                        { $match: { orderStatus: 'Pending' } },
                        { $count: 'pending' }
                    ],
                    total: [
                        { $match: { isActive: true } },
                        { $count: 'total' }
                    ]
                    }
                },
                {
                    $project: {
                    cancelled: { $arrayElemAt: ['$cancelled.cancelled', 0] },
                    pending: { $arrayElemAt: ['$pending.pending', 0] },
                    total: { $arrayElemAt: ['$total.total', 0] }
                    }
                }
                ]
                Order.aggregate(query, (error, findRes) => {})

Laravel Eloquent Sum of relation's column

Auth::user()->products->sum('price');

The documentation is a little light for some of the Collection methods but all the query builder aggregates are seemingly available besides avg() that can be found at http://laravel.com/docs/queries#aggregates.

How to access html form input from asp.net code behind

If you are accessing a plain HTML form, it has to be submitted to the server via a submit button (or via javascript post). This usually means that your form definition will look like this (I'm going off of memory, make sure you check the html elements are correct):

<form method="POST" action="page.aspx">

<input id="customerName" name="customerName" type="Text" />
<input id="customerPhone" name="customerPhone" type="Text" />
<input value="Save" type="Submit" />

</form>

You should be able to access the customerName and customerPhone data like this:

string n = String.Format("{0}", Request.Form["customerName"]);

If you have method="GET" in the form (not recommended, it messes up your URL space), you will have to access the form data like this:

string n = String.Format("{0}", Request.QueryString["customerName"]);

This of course will only work if the form was 'Posted', 'Submitted', or done via a 'Postback'. (i.e. somebody clicked the 'Save' button, or this was done programatically via javascript.)

Also, keep in mind that accessing these elements in this manner can only be done when you are not using server controls (i.e. runat="server"), with server controls the id and name are different.

How can I add a Google search box to my website?

Sorry for replying on an older question, but I would like to clarify the last question.

You use a "get" method for your form. When the name of your input-field is "g", it will make a URL like this:

https://www.google.com/search?g=[value from input-field]

But when you search with google, you notice the following URL:

https://www.google.nl/search?q=google+search+bar

Google uses the "q" Querystring variable as it's search-query. Therefor, renaming your field from "g" to "q" solved the problem.

a href link for entire div in HTML/CSS

This can be done in many ways. a. Using nested inside a tag.

<a href="link1.html">
   <div> Something in the div </div>
 </a>

b. Using the Inline JavaScript Method

<div onclick="javascript:window.location.href='link1.html' "> 
  Some Text 
</div>

c. Using jQuery inside tag

HTML:

<div class="demo" > Some text here </div>

jQuery:

$(".demo").click( function() {
  window.location.href="link1.html";
 });

Initialize a vector array of strings

same as @Moo-Juice:

const char* args[] = {"01", "02", "03", "04"};
std::vector<std::string> v(args, args + sizeof(args)/sizeof(args[0])); //get array size

GROUP BY and COUNT in PostgreSQL

I think you just need COUNT(DISTINCT post_id) FROM votes.

See "4.2.7. Aggregate Expressions" section in http://www.postgresql.org/docs/current/static/sql-expressions.html.

EDIT: Corrected my careless mistake per Erwin's comment.

getting the screen density programmatically in android?

The following answer is a small improvement based upon qwertzguy's answer.

double density = getResources().getDisplayMetrics().density;
if (density >= 4.0) {
   //"xxxhdpi";
}
else if (density >= 3.0 && density < 4.0) {
   //xxhdpi
}
else if (density >= 2.0) {
   //xhdpi
}
else if (density >= 1.5 && density < 2.0) {
   //hdpi
}
else if (density >= 1.0 && density < 1.5) {
   //mdpi
}

SQL Server : fetching records between two dates?

Try this:

select * 
from xxx 
where dates >= '2012-10-26 00:00:00.000' and dates <= '2012-10-27 23:59:59.997'

How to align LinearLayout at the center of its parent?

Try this:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    >
    <FrameLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" >
        <TableLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content" >
            <TableRow >
            <LinearLayout 
            android:orientation="horizontal"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:gravity="center_horizontal" 
                    android:layout_gravity="center_horizontal" >
                    <TextView
                    android:layout_height="wrap_content"
                    android:layout_width="wrap_content"
                    android:text="1"
                    android:textAppearance="?android:attr/textAppearanceLarge" />

                     <TextView
                    android:layout_height="wrap_content"
                    android:layout_width="wrap_content"
                    android:text="2"
                    android:textAppearance="?android:attr/textAppearanceLarge" />
             </LinearLayout>
           </TableRow>
        </TableLayout>
    </FrameLayout>
</LinearLayout>

C# Linq Group By on multiple columns

Given a list:

var list = new List<Child>()
{
    new Child()
        {School = "School1", FavoriteColor = "blue", Friend = "Bob", Name = "John"},
    new Child()
        {School = "School2", FavoriteColor = "blue", Friend = "Bob", Name = "Pete"},
    new Child()
        {School = "School1", FavoriteColor = "blue", Friend = "Bob", Name = "Fred"},
    new Child()
        {School = "School2", FavoriteColor = "blue", Friend = "Fred", Name = "Bob"},
};

The query would look like:

var newList = list
    .GroupBy(x => new {x.School, x.Friend, x.FavoriteColor})
    .Select(y => new ConsolidatedChild()
        {
            FavoriteColor = y.Key.FavoriteColor,
            Friend = y.Key.Friend,
            School = y.Key.School,
            Children = y.ToList()
        }
    );

Test code:

foreach(var item in newList)
{
    Console.WriteLine("School: {0} FavouriteColor: {1} Friend: {2}", item.School,item.FavoriteColor,item.Friend);
    foreach(var child in item.Children)
    {
        Console.WriteLine("\t Name: {0}", child.Name);
    }
}

Result:

School: School1 FavouriteColor: blue Friend: Bob
    Name: John
    Name: Fred
School: School2 FavouriteColor: blue Friend: Bob
    Name: Pete
School: School2 FavouriteColor: blue Friend: Fred
    Name: Bob

Easiest way to ignore blank lines when reading a file in Python

If you want you can just put what you had in a list comprehension:

names_list = [line for line in open("names.txt", "r").read().splitlines() if line]

or

all_lines = open("names.txt", "r").read().splitlines()
names_list = [name for name in all_lines if name]

splitlines() has already removed the line endings.

I don't think those are as clear as just looping explicitly though:

names_list = []
with open('names.txt', 'r') as _:
    for line in _:
        line = line.strip()
        if line:
            names_list.append(line)

Edit:

Although, filter looks quite readable and concise:

names_list = filter(None, open("names.txt", "r").read().splitlines())

Undefined columns selected when subsetting data frame

You want rows where that condition is true so you need a comma:

data[data$Ozone > 14, ]

Comparing object properties in c#

I think it would be best to follow the pattern for Override Object#Equals()
For a better description: Read Bill Wagner's Effective C# - Item 9 I think

public override Equals(object obOther)
{
  if (null == obOther)
    return false;
  if (object.ReferenceEquals(this, obOther)
    return true;
  if (this.GetType() != obOther.GetType())
    return false;
  # private method to compare members.
  return CompareMembers(this, obOther as ThisClass);
}
  • Also in methods that check for equality, you should return either true or false. either they are equal or they are not.. instead of throwing an exception, return false.
  • I'd consider overriding Object#Equals.
  • Even though you must have considered this, using Reflection to compare properties is supposedly slow (I dont have numbers to back this up). This is the default behavior for valueType#Equals in C# and it is recommended that you override Equals for value types and do a member wise compare for performance. (Earlier I speed-read this as you have a collection of custom Property objects... my bad.)

Update-Dec 2011:

  • Of course, if the type already has a production Equals() then you need another approach.
  • If you're using this to compare immutable data structures exclusively for test purposes, you shouldn't add an Equals to production classes (Someone might hose the tests by chainging the Equals implementation or you may prevent creation of a production-required Equals implementation).

How to delete an SVN project from SVN repository

There's no concept of "project" in svn. So, feel free to delete whatever you think belongs to the project.

XSLT equivalent for JSON

JSLT is very close to a JSON equivalent of XSLT. It's a transform language where you write the fixed part of the output in JSON syntax, then insert expressions to compute the values you want to insert in the template.

An example:

{
  "time": round(parse-time(.published, "yyyy-MM-dd'T'HH:mm:ssX") * 1000),
  "device_manufacturer": .device.manufacturer,
  "device_model": .device.model,
  "language": .device.acceptLanguage
}

It's implemented in Java on top of Jackson.

Remove Identity from a column in a table

ALTER TABLE tablename add newcolumn int
update tablename set newcolumn=existingcolumnname
ALTER TABLE tablename DROP COLUMN existingcolumnname;
EXEC sp_RENAME 'tablename.oldcolumn' , 'newcolumnname', 'COLUMN'

However above code works only if no primary-foreign key relation

matplotlib: how to draw a rectangle on image

There is no need for subplots, and pyplot can display PIL images, so this can be simplified further:

import matplotlib.pyplot as plt
from matplotlib.patches import Rectangle
from PIL import Image

im = Image.open('stinkbug.png')

# Display the image
plt.imshow(im)

# Get the current reference
ax = plt.gca()

# Create a Rectangle patch
rect = Rectangle((50,100),40,30,linewidth=1,edgecolor='r',facecolor='none')

# Add the patch to the Axes
ax.add_patch(rect)

Or, the short version:

import matplotlib.pyplot as plt
from matplotlib.patches import Rectangle
from PIL import Image

# Display the image
plt.imshow(Image.open('stinkbug.png'))

# Add the patch to the Axes
plt.gca().add_patch(Rectangle((50,100),40,30,linewidth=1,edgecolor='r',facecolor='none'))

Using an integer as a key in an associative array in JavaScript

Sometimes I use a prefixes for my keys. For example:

var pre = 'foo',
    key = pre + 1234

obj = {};

obj[key] = val;

Now you don't have any problem accessing them.

Button background as transparent

Add this in your Xml - android:background="@android:color/transparent"

        <Button
            android:id="@+id/button1"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="Button"
            android:background="@android:color/transparent"
            android:textStyle="bold"/>

How do I disable log messages from the Requests library?

import logging
urllib3_logger = logging.getLogger('urllib3')
urllib3_logger.setLevel(logging.CRITICAL)

In this way all the messages of level=INFO from urllib3 won't be present in the logfile.

So you can continue to use the level=INFO for your log messages...just modify this for the library you are using.

How do I skip a header from CSV files in Spark?

Alternatively, you can use the spark-csv package (or in Spark 2.0 this is more or less available natively as CSV). Note that this expects the header on each file (as you desire):

schema = StructType([
        StructField('lat',DoubleType(),True),
        StructField('lng',DoubleType(),True)])

df = sqlContext.read.format('com.databricks.spark.csv'). \
     options(header='true',
             delimiter="\t",
             treatEmptyValuesAsNulls=True,
             mode="DROPMALFORMED").load(input_file,schema=schema)

Pushing empty commits to remote

Is there any disadvantages/consequences of pushing empty commits?

Aside from the extreme confusion someone might get as to why there's a bunch of commits with no content in them on master, not really.

You can change the commit that you pushed to remote, but the sha1 of the commit (basically it's id number) will change permanently, which alters the source tree -- You'd then have to do a git push -f back to remote.

jQuery jump or scroll to certain position, div or target on the page from button onclick

I would style a link to look like a button, because that way there is a no-js fallback.


So this is how you could animate the jump using jquery. No-js fallback is a normal jump without animation.

Original example:

jsfiddle

_x000D_
_x000D_
$(document).ready(function() {_x000D_
  $(".jumper").on("click", function( e ) {_x000D_
_x000D_
    e.preventDefault();_x000D_
_x000D_
    $("body, html").animate({ _x000D_
      scrollTop: $( $(this).attr('href') ).offset().top _x000D_
    }, 600);_x000D_
_x000D_
  });_x000D_
});
_x000D_
#long {_x000D_
  height: 500px;_x000D_
  background-color: blue;_x000D_
}
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<!-- Links that trigger the jumping -->_x000D_
<a class="jumper" href="#pliip">Pliip</a>_x000D_
<a class="jumper" href="#ploop">Ploop</a>_x000D_
<div id="long">...</div>_x000D_
<!-- Landing elements -->_x000D_
<div id="pliip">pliip</div>_x000D_
<div id="ploop">ploop</div>
_x000D_
_x000D_
_x000D_


New example with actual button styles for the links, just to prove a point.

Everything is essentially the same, except that I changed the class .jumper to .button and I added css styling to make the links look like buttons.

Button styles example

How to create a QR code reader in a HTML5 website?

The algorithm that drives http://www.webqr.com is a JavaScript implementation of https://github.com/LazarSoft/jsqrcode. I haven't tried how reliable it is yet, but that's certainly the easier plug-and-play solution (client- or server-side) out of the two.

Removing the first 3 characters from a string

Use the substring method of the String class :

String removeCurrency=amount.getText().toString().substring(3);

How to select min and max values of a column in a datatable?

The most efficient way to do this (believe it or not) is to make two variables and write a for loop.

How to make readonly all inputs in some div in Angular2?

If using reactive forms, you can also disable the entire form or any sub-set of controls in a FormGroup with myFormGroup.disable().

How to replace plain URLs with links?

Replacing URLs with links (Answer to the General Problem)

The regular expression in the question misses a lot of edge cases. When detecting URLs, it's always better to use a specialized library that handles international domain names, new TLDs like .museum, parentheses and other punctuation within and at the end of the URL, and many other edge cases. See the Jeff Atwood's blog post The Problem With URLs for an explanation of some of the other issues.

The best summary of URL matching libraries is in Dan Dascalescu's Answer +100
(as of Feb 2014)


"Make a regular expression replace more than one match" (Answer to the specific problem)

Add a "g" to the end of the regular expression to enable global matching:

/ig;

But that only fixes the problem in the question where the regular expression was only replacing the first match. Do not use that code.

how to configure config.inc.php to have a loginform in phpmyadmin

$cfg['Servers'][$i]['AllowNoPassword'] = false;

PHP Try and Catch for SQL Insert

if you want to log the error etc you should use try/catch, if you dont; just put @ before mysql_query

edit : you can use try catch like this; so you can log the error and let the page continue to load

function throw_ex($er){  
  throw new Exception($er);  
}  
try {  
mysql_connect(localhost,'user','pass'); 
mysql_select_db('test'); 
$q = mysql_query('select * from asdasda') or throw_ex(mysql_error());  
}  
catch(exception $e) {
  echo "ex: ".$e; 
}

scp from Linux to Windows

Access from Windows by Git Bash console:

scp root@ip:/etc/../your-file "C:/Users/XXX/Download"

Java system properties and environment variables

I think the difference between the two boils down to access. Environment variables are accessible by any process and Java system properties are only accessible by the process they are added to.

Also as Bohemian stated, env variables are set in the OS (however they 'can' be set through Java) and system properties are passed as command line options or set via setProperty().

What is the difference between null and undefined in JavaScript?

The best way to understand the difference is to first clear your mind of the inner workings of JavaScript and just understand the differences in meaning between:

let supervisor = "None"
    // I have a supervisor named "None"

let supervisor = null
    // I do NOT have a supervisor. It is a FACT that I do not.

let supervisor = undefined
    // I may or may not have a supervisor. I either don't know
    // if I do or not, or I am choosing not to tell you. It is
    // irrelevant or none of your business.

There is a difference in meaning between these three cases, and JavaScript distinguishes the latter two cases with two different values, null and undefined. You are free to use those values explicitly to convey those meanings.

So what are some of the JavaScript-specific issues that arise due to this philosophical basis?

  1. A declared variable without an initializer gets the value undefined because you never said anything about the what the intended value was.

    let supervisor;
    assert(supervisor === undefined);
    
  2. A property of an object that has never been set evaluates to undefined because no one ever said anything about that property.

    const dog = { name: 'Sparky', age: 2 };
    assert(dog.breed === undefined);
    
  3. null and undefined are "similar" to each other because Brendan Eich said so. But they are emphatically not equal to each other.

    assert(null == undefined);
    assert(null !== undefined);
    
  4. null and undefined thankfully have different types. null belongs to the type Null and undefined to the type Undefined. This is in the spec, but you would never know this because of the typeof weirdness which I will not repeat here.

  5. A function reaching the end of its body without an explicit return statement returns undefined since you don't know anything about what it returned.

By the way, there are other forms of "nothingness" in JavaScript (it's good to have studied Philosophy....)

  • NaN
  • Using a variable that has never been declared and receiving a ReferenceError
  • Using a let or const defined local variable in its temporal dead zone and receiving a ReferenceError
  • Empty cells in sparse arrays. Yes these are not even undefined although they compare === to undefined.

    $ node
    > const a = [1, undefined, 2]
    > const b = [1, , 2]
    > a
    [ 1, undefined, 2 ]
    > b
    [ 1, <1 empty item>, 2 ]
    

How do I add a new class to an element dynamically?

why @Marco Berrocl get a negative feedback and his answer is totally right what about using a library to make some animation so i need to call the class in hover to element not copy the code from the library and this will make me slow.

so i think hover not the answer and he should use jquery or javascript in many cases

LINQ Using Max() to select a single row

You can also do:

(from u in table
orderby u.Status descending
select u).Take(1);

iOS app with framework crashed on device, dyld: Library not loaded, Xcode 6 Beta

In case anyone is still experiencing this issue, despite following all the steps outlined in the many other answers, you may need to revoke and recreate your code signing certificate, as per the following:

https://developer.apple.com/library/ios/qa/qa1886/_index.html

Multiple values in single-value context

No, but that is a good thing since you should always handle your errors.

There are techniques that you can employ to defer error handling, see Errors are values by Rob Pike.

ew := &errWriter{w: fd}
ew.write(p0[a:b])
ew.write(p1[c:d])
ew.write(p2[e:f])
// and so on
if ew.err != nil {
    return ew.err
}

In this example from the blog post he illustrates how you could create an errWriter type that defers error handling till you are done calling write.

What is ".NET Core"?

.NET Core is a free and open-source, managed computer software framework for Windows, Linux, and macOS operating systems. It is an open source, cross platform successor to .NET Framework.

.NET Core applications are supported on Windows, Linux, and macOS. In a nutshell .NET Core is similar to .NET framework, but it is cross-platform, i.e., it allows the .NET applications to run on Windows, Linux and MacOS. .NET framework applications can only run on the Windows system. So the basic difference between .NET framework and .NET core is that .NET Core is cross platform and .NET framework only runs on Windows.

Furthermore, .NET Core has built-in dependency injection by Microsoft and you do not have to use third-party software/DLL files for dependency injection.

jQuery select change event get selected option

You can use this jquery select change event for get selected option value

For Demo

_x000D_
_x000D_
$(document).ready(function () {   _x000D_
    $('body').on('change','#select', function() {_x000D_
         $('#show_selected').val(this.value);_x000D_
    });_x000D_
}); 
_x000D_
<!DOCTYPE html>  _x000D_
<html>  _x000D_
<title>Learn Jquery value Method</title>_x000D_
<head> _x000D_
<script src="https://code.jquery.com/jquery-3.3.1.min.js"></script> _x000D_
</head>  _x000D_
<body>  _x000D_
<select id="select">_x000D_
 <option value="">Select One</option>_x000D_
    <option value="PHP">PHP</option>_x000D_
    <option value="jAVA">JAVA</option>_x000D_
    <option value="Jquery">jQuery</option>_x000D_
    <option value="Python">Python</option>_x000D_
    <option value="Mysql">Mysql</option>_x000D_
</select>_x000D_
<br><br>  _x000D_
<input type="text" id="show_selected">_x000D_
</body>  _x000D_
</html>  
_x000D_
_x000D_
_x000D_

Why do abstract classes in Java have constructors?

Because abstract classes have state (fields) and somethimes they need to be initialized somehow.

What happens if you don't commit a transaction to a database (say, SQL Server)?

As long as you don't COMMIT or ROLLBACK a transaction, it's still "running" and potentially holding locks.

If your client (application or user) closes the connection to the database before committing, any still running transactions will be rolled back and terminated.

Prevent any form of page refresh using jQuery/Javascript

Although its not a good idea to disable F5 key you can do it in JQuery as below.

<script type="text/javascript">
function disableF5(e) { if ((e.which || e.keyCode) == 116 || (e.which || e.keyCode) == 82) e.preventDefault(); };

$(document).ready(function(){
     $(document).on("keydown", disableF5);
});
</script>

Hope this will help!

Typescript input onchange event.target.value

This is when you're working with a FileList Object:

onChange={(event: React.ChangeEvent<HTMLInputElement>): void => {
  const fileListObj: FileList | null = event.target.files;
  if (Object.keys(fileListObj as Object).length > 3) {
    alert('Only three images pleaseeeee :)');
  } else {
    // Do something
  }

  return;
}}

Is there a way to iterate over a dictionary?

The block approach avoids running the lookup algorithm for every key:

[dict enumerateKeysAndObjectsUsingBlock:^(id key, id value, BOOL* stop) {
  NSLog(@"%@ => %@", key, value);
}];

Even though NSDictionary is implemented as a hashtable (which means that the cost of looking up an element is O(1)), lookups still slow down your iteration by a constant factor.

My measurements show that for a dictionary d of numbers ...

NSMutableDictionary* dict = [NSMutableDictionary dictionary];
for (int i = 0; i < 5000000; ++i) {
  NSNumber* value = @(i);
  dict[value.stringValue] = value;
}

... summing up the numbers with the block approach ...

__block int sum = 0;
[dict enumerateKeysAndObjectsUsingBlock:^(NSString* key, NSNumber* value, BOOL* stop) {
  sum += value.intValue;
}];

... rather than the loop approach ...

int sum = 0;
for (NSString* key in dict)
  sum += [dict[key] intValue];

... is about 40% faster.

EDIT: The new SDK (6.1+) appears to optimise loop iteration, so the loop approach is now about 20% faster than the block approach, at least for the simple case above.

Using sudo with Python script

I used this for python 3.5. I did it using subprocess module.Using the password like this is very insecure.

The subprocess module takes command as a list of strings so either create a list beforehand using split() or pass the whole list later. Read the documentation for moreinformation.

#!/usr/bin/env python
import subprocess

sudoPassword = 'mypass'
command = 'mount -t vboxsf myfolder /home/myuser/myfolder'.split()

cmd1 = subprocess.Popen(['echo',sudoPassword], stdout=subprocess.PIPE)
cmd2 = subprocess.Popen(['sudo','-S'] + command, stdin=cmd1.stdout, stdout=subprocess.PIPE)

output = cmd2.stdout.read.decode()

Parse Error: Adjacent JSX elements must be wrapped in an enclosing tag

React 16 gets your return as an array so it should be wrapped by one element like div.

Wrong Approach

render(){
    return(
    <input type="text" value="" onChange={this.handleChange} />

     <button className="btn btn-primary" onClick=   {()=>this.addTodo(this.state.value)}>Submit</button>

    );
}

Right Approach (All elements in one div or other element you are using)

render(){
    return(
        <div>
            <input type="text" value="" onChange={this.handleChange} />

            <button className="btn btn-primary" onClick={()=>this.addTodo(this.state.value)}>Submit</button>
        </div>
    );
}

Reset CSS display property to default value

Unset display:

You can use the value unset which works in both Firefox and Chrome.

display: unset;

.foo     { display: none;  }
.foo.bar { display: unset; }

length and length() in Java

I was taught that for arrays, length is not retrieved through a method due to the following fear: programmers would just assign the length to a local variable before entering a loop (think a for loop where the conditional uses the array's length.) The programmer would supposedly do so to trim down on function calls (and thereby improve performance.) The problem is that the length might change during the loop, and the variable wouldn't.

View the change history of a file using Git versioning

I'm probably about where the OP was when this started, looking for something simple that would let me use git difftool with vimdiff to review changes to files in my repo starting from a specific commit. I wasn't too happy with answers I was finding, so I threw this git incremental reporter (gitincrep) script together and it's been useful to me:

#!/usr/bin/env bash

STARTWITH="${1:-}"
shift 1

DFILES=( "$@" )

RunDiff()
{
        GIT1=$1
        GIT2=$2
        shift 2

        if [ "$(git diff $GIT1 $GIT2 "$@")" ]
        then
                git log ${GIT1}..${GIT2}
                git difftool --tool=vimdiff $GIT1 $GIT2 "$@"
        fi
}

OLDVERS=""
RUNDIFF=""

for NEWVERS in $(git log --format=format:%h  --reverse)
do
        if [ "$RUNDIFF" ]
        then
                RunDiff $OLDVERS $NEWVERS "${DFILES[@]}"
        elif [ "$OLDVERS" ]
        then
                if [ "$NEWVERS" = "${STARTWITH:=${NEWVERS}}" ]
                then
                        RUNDIFF=true
                        RunDiff $OLDVERS $NEWVERS "${DFILES[@]}"
                fi
        fi
        OLDVERS=$NEWVERS
done

Called with no args, this will start from the beginning of the repo history, otherwise it will start with whatever abbreviated commit hash you provide and proceed to the present - you can ctrl-C at any time to exit. Any args after the first will limit the difference reports to include only the files listed among those args (which I think is what the OP wanted, and I'd recommend for all but tiny projects). If you're checking changes to specific files and want to start from the beginning, you'll need to provide an empty string for arg1. If you're not a vim user, you can replace vimdiff with your favorite diff tool.

Behavior is to output the commit comments when relevant changes are found and start offering vimdiff runs for each changed file (that's git difftool behavior, but it works here).

This approach is probably pretty naive, but looking through a lot of the solutions here and at a related post, many involved installing new tools on a system where I don't have admin access, with interfaces that had their own learning curve. The above script did what I wanted without dealing with any of that. I'll look into the many excellent suggestions here when I need something more sophisticated - but I think this is directly responsive to the OP.

What is the most robust way to force a UIView to redraw?

The money-back guaranteed, reinforced-concrete-solid way to force a view to draw synchronously (before returning to the calling code) is to configure the CALayer's interactions with your UIView subclass.

In your UIView subclass, create a displayNow() method that tells the layer to “set course for display” then to “make it so”:

Swift

/// Redraws the view's contents immediately.
/// Serves the same purpose as the display method in GLKView.
public func displayNow()
{
    let layer = self.layer
    layer.setNeedsDisplay()
    layer.displayIfNeeded()
}

Objective-C

/// Redraws the view's contents immediately.
/// Serves the same purpose as the display method in GLKView.
- (void)displayNow
{
    CALayer *layer = self.layer;
    [layer setNeedsDisplay];
    [layer displayIfNeeded];
}

Also implement a draw(_: CALayer, in: CGContext) method that'll call your private/internal drawing method (which works since every UIView is a CALayerDelegate):

Swift

/// Called by our CALayer when it wants us to draw
///     (in compliance with the CALayerDelegate protocol).
override func draw(_ layer: CALayer, in context: CGContext)
{
    UIGraphicsPushContext(context)
    internalDraw(self.bounds)
    UIGraphicsPopContext()
}

Objective-C

/// Called by our CALayer when it wants us to draw
///     (in compliance with the CALayerDelegate protocol).
- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)context
{
    UIGraphicsPushContext(context);
    [self internalDrawWithRect:self.bounds];
    UIGraphicsPopContext();
}

And create your custom internalDraw(_: CGRect) method, along with fail-safe draw(_: CGRect):

Swift

/// Internal drawing method; naming's up to you.
func internalDraw(_ rect: CGRect)
{
    // @FILLIN: Custom drawing code goes here.
    //  (Use `UIGraphicsGetCurrentContext()` where necessary.)
}

/// For compatibility, if something besides our display method asks for draw.
override func draw(_ rect: CGRect) {
    internalDraw(rect)
}

Objective-C

/// Internal drawing method; naming's up to you.
- (void)internalDrawWithRect:(CGRect)rect
{
    // @FILLIN: Custom drawing code goes here.
    //  (Use `UIGraphicsGetCurrentContext()` where necessary.)
}

/// For compatibility, if something besides our display method asks for draw.
- (void)drawRect:(CGRect)rect {
    [self internalDrawWithRect:rect];
}

And now just call myView.displayNow() whenever you really-really need it to draw (such as from a CADisplayLink callback).  Our displayNow() method will tell the CALayer to displayIfNeeded(), which will synchronously call back into our draw(_:,in:) and do the drawing in internalDraw(_:), updating the visual with what's drawn into the context before moving on.


This approach is similar to @RobNapier's above, but has the advantage of calling displayIfNeeded() in addition to setNeedsDisplay(), which makes it synchronous.

This is possible because CALayers expose more drawing functionality than UIViews do— layers are lower-level than views and designed explicitly for the purpose of highly-configurable drawing within the layout, and (like many things in Cocoa) are designed to be used flexibly (as a parent class, or as a delegator, or as a bridge to other drawing systems, or just on their own). Proper usage of the CALayerDelegate protocol makes all this possible.

More information about the configurability of CALayers can be found in the Setting Up Layer Objects section of the Core Animation Programming Guide.

Datetime format Issue: String was not recognized as a valid DateTime

change the culture and try out like this might work for you

string[] formats= { "MM/dd/yyyy HH:mm" }
var dateTime = DateTime.ParseExact("04/30/2013 23:00", 
     formats, new CultureInfo("en-US"), DateTimeStyles.None);

Check for details : DateTime.ParseExact Method (String, String[], IFormatProvider, DateTimeStyles)

List of encodings that Node.js supports

The encodings are spelled out in the buffer documentation.

Buffers and character encodings:

Character Encodings

  • utf8: Multi-byte encoded Unicode characters. Many web pages and other document formats use UTF-8. This is the default character encoding.
  • utf16le: Multi-byte encoded Unicode characters. Unlike utf8, each character in the string will be encoded using either 2 or 4 bytes.
  • latin1: Latin-1 stands for ISO-8859-1. This character encoding only supports the Unicode characters from U+0000 to U+00FF.

Binary-to-Text Encodings

  • base64: Base64 encoding. When creating a Buffer from a string, this encoding will also correctly accept "URL and Filename Safe Alphabet" as specified in RFC 4648, Section 5.
  • hex: Encode each byte as two hexadecimal characters.

Legacy Character Encodings

  • ascii: For 7-bit ASCII data only. Generally, there should be no reason to use this encoding, as 'utf8' (or, if the data is known to always be ASCII-only, 'latin1') will be a better choice when encoding or decoding ASCII-only text.
  • binary: Alias for 'latin1'.
  • ucs2: Alias of 'utf16le'.

Oracle 10g: Extract data (select) from XML (CLOB Type)

In case of :

<?xml version="1.0" encoding="iso-8859-1"?>
<info xmlns="http://namespaces.default" xmlns:ns2="http://namespaces.ns2" >
    <id> 954 </id>
    <idboss> 954 </idboss>
    <name> Fausto </name>
    <sorname> Anonimo </sorname>
    <phone> 040000000 </phone>
    <fax> 040000001 </fax>
</info>

Query :

Select *
from xmltable(xmlnamespaces(default 'http://namespaces.default'
                              'http://namespaces.ns2' as "ns",
                       ), 
                '/info'
                passing xmltype.createxml(xml) 
                columns id varchar2(10) path '/id',
                        idboss varchar2(500) path '/idboss',
                        etc....

                ) nice_xml_table

Replace non-ASCII characters with a single space

As a native and efficient approach, you don't need to use ord or any loop over the characters. Just encode with ascii and ignore the errors.

The following will just remove the non-ascii characters:

new_string = old_string.encode('ascii',errors='ignore')

Now if you want to replace the deleted characters just do the following:

final_string = new_string + b' ' * (len(old_string) - len(new_string))

Why does cURL return error "(23) Failed writing body"?

I had the same error but from different reason. In my case I had (tmpfs) partition with only 1GB space and I was downloading big file which finally filled all memory on that partition and I got the same error as you.

How to print the ld(linker) search path

You can do this by executing the following command:

ld --verbose | grep SEARCH_DIR | tr -s ' ;' \\012

gcc passes a few extra -L paths to the linker, which you can list with the following command:

gcc -print-search-dirs | sed '/^lib/b 1;d;:1;s,/[^/.][^/]*/\.\./,/,;t 1;s,:[^=]*=,:;,;s,;,;  ,g' | tr \; \\012

The answers suggesting to use ld.so.conf and ldconfig are not correct because they refer to the paths searched by the runtime dynamic linker (i.e. whenever a program is executed), which is not the same as the path searched by ld (i.e. whenever a program is linked).

How do I change the font color in an html table?

if you need to change specific option from the select menu you can do it like this

option[value="Basic"] {
  color:red;
 }

or you can change them all

select {
  color:red;
}

Jquery date picker z-index issue

Adding to Justin's answer, if you're worried about untidy markup or you don't want this value hard coded in CSS you can set the input before it is shown. Something like this:

$('input').datepicker({
    beforeShow:function(input){
        $(input).dialog("widget").css({
            "position": "relative",
            "z-index": 20
        });
    }
});

Note that you cannot omit the "position": "relative" rule, as the plugin either looks in the inline style for both rules or the stylesheet, but not both.

The dialog("widget") is the actual datepicker that pops up.

checking if a number is divisible by 6 PHP

result = initial number + (6 - initial number % 6)

How to apply style classes to td classes?

A more definite way to target a td is table tr td { }

How can I use Bash syntax in Makefile targets?

If portability is important you may not want to depend on a specific shell in your Makefile. Not all environments have bash available.

setSupportActionBar toolbar cannot be applied to (android.widget.Toolbar) error

import android.support.v7.widget.Toolbar;

import it into your java class

Remove empty elements from an array in Javascript

With Underscore/Lodash:

General use case:

_.without(array, emptyVal, otherEmptyVal);
_.without([1, 2, 1, 0, 3, 1, 4], 0, 1);

With empties:

_.without(['foo', 'bar', '', 'baz', '', '', 'foobar'], '');
--> ["foo", "bar", "baz", "foobar"]

See lodash documentation for without.

How can I format decimal property to currency?

Below would also work, but you cannot put in the getter of a decimal property. The getter of a decimal property can only return a decimal, for which formatting does not apply.

decimal moneyvalue = 1921.39m; 
string currencyValue = moneyvalue.ToString("C");

Passing Parameters JavaFX FXML

Yes you can.
You need to add in the first controller:

YourController controller = loader.getController();     
controller.setclient(client);

Then in the second one declare a client, then at the bottom of your controller:

public void setclien(Client c) {
    this.client = c;
}

Android Studio Run/Debug configuration error: Module not specified

I struggled with this because I'm developing a library, and every now and then want to run it as an application.

From app/build.gradle, check that you have apply plugin: 'com.android.application' instead of apply plugin: 'com.android.library'.

You should also have this in app/build.gradle:

defaultConfig { applicationId "com.your_company.your_application" ... }

Finally run Gradle sync.

The localhost page isn’t working localhost is currently unable to handle this request. HTTP ERROR 500

If you are using the codeigniter framework and are testing the project on a localhost, open the main Index.php file of your project folder and find this code:

define('ENVIRONMENT', 'production');

Change it to

define ('ENVIRONMENT', 'development');

Because same this ENVIRONMENT is in your database.php file under config folder. like this:

 'db_debug' => (ENVIRONMENT! == 'development')

So the environment should be the same in both places and problem will be solved.

How to get current value of RxJS Subject or Observable?

const observable = of('response')

function hasValue(value: any) {
  return value !== null && value !== undefined;
}

function getValue<T>(observable: Observable<T>): Promise<T> {
  return observable
    .pipe(
      filter(hasValue),
      first()
    )
    .toPromise();
}

const result = await getValue(observable)
// Do the logic with the result
// .................
// .................
// .................

You can check the full article on how to implement it from here. https://www.imkrish.com/blog/development/simple-way-get-value-from-observable

How to convert a pandas DataFrame subset of columns AND rows into a numpy array?

.loc accept row and column selectors simultaneously (as do .ix/.iloc FYI) This is done in a single pass as well.

In [1]: df = DataFrame(np.random.rand(4,5), columns = list('abcde'))

In [2]: df
Out[2]: 
          a         b         c         d         e
0  0.669701  0.780497  0.955690  0.451573  0.232194
1  0.952762  0.585579  0.890801  0.643251  0.556220
2  0.900713  0.790938  0.952628  0.505775  0.582365
3  0.994205  0.330560  0.286694  0.125061  0.575153

In [5]: df.loc[df['c']>0.5,['a','d']]
Out[5]: 
          a         d
0  0.669701  0.451573
1  0.952762  0.643251
2  0.900713  0.505775

And if you want the values (though this should pass directly to sklearn as is); frames support the array interface

In [6]: df.loc[df['c']>0.5,['a','d']].values
Out[6]: 
array([[ 0.66970138,  0.45157274],
       [ 0.95276167,  0.64325143],
       [ 0.90071271,  0.50577509]])

Iterator Loop vs index loop

With a vector iterators do no offer any real advantage. The syntax is uglier, longer to type and harder to read.

Iterating over a vector using iterators is not faster and is not safer (actually if the vector is possibly resized during the iteration using iterators will put you in big troubles).

The idea of having a generic loop that works when you will change later the container type is also mostly nonsense in real cases. Unfortunately the dark side of a strictly typed language without serious typing inference (a bit better now with C++11, however) is that you need to say what is the type of everything at each step. If you change your mind later you will still need to go around and change everything. Moreover different containers have very different trade-offs and changing container type is not something that happens that often.

The only case in which iteration should be kept if possible generic is when writing template code, but that (I hope for you) is not the most frequent case.

The only problem present in your explicit index loop is that size returns an unsigned value (a design bug of C++) and comparison between signed and unsigned is dangerous and surprising, so better avoided. If you use a decent compiler with warnings enabled there should be a diagnostic on that.

Note that the solution is not to use an unsiged as the index, because arithmetic between unsigned values is also apparently illogical (it's modulo arithmetic, and x-1 may be bigger than x). You instead should cast the size to an integer before using it. It may make some sense to use unsigned sizes and indexes (paying a LOT of attention to every expression you write) only if you're working on a 16 bit C++ implementation (16 bit was the reason for having unsigned values in sizes).

As a typical mistake that unsigned size may introduce consider:

void drawPolyline(const std::vector<P2d>& points)
{
    for (int i=0; i<points.size()-1; i++)
        drawLine(points[i], points[i+1]);
}

Here the bug is present because if you pass an empty points vector the value points.size()-1 will be a huge positive number, making you looping into a segfault. A working solution could be

for (int i=1; i<points.size(); i++)
    drawLine(points[i - 1], points[i]);

but I personally prefer to always remove unsinged-ness with int(v.size()).

PS: If you really don't want to think by to yourself to the implications and simply want an expert to tell you then consider that a quite a few world recognized C++ experts agree and expressed opinions on that unsigned values are a bad idea except for bit manipulations.

Discovering the ugliness of using iterators in the case of iterating up to second-last is left as an exercise for the reader.

How do you add a timed delay to a C++ program?

You can try this code snippet:

#include<chrono>
#include<thread>

int main(){
    std::this_thread::sleep_for(std::chrono::nanoseconds(10));
    std::this_thread::sleep_until(std::chrono::system_clock::now() + std::chrono::seconds(1));
}

Update R using RStudio

I would recommend using the Windows package installr to accomplish this. Not only will the package update your R version, but it will also copy and update all of your packages. There is a blog on the subject here. Simply run the following commands in R Studio and follow the prompts:

# installing/loading the package:
if(!require(installr)) {
install.packages("installr"); require(installr)} #load / install+load installr

# using the package:
updateR() # this will start the updating process of your R installation.  It will check for newer versions, and if one is available, will guide you through the decisions you'd need to make.

How to store a datetime in MySQL with timezone info

I once also faced such an issue where i needed to save data which was used by different collaborators and i ended up storing the time in unix timestamp form which represents the number of seconds since january 1970 which is an integer format. Example todays date and time in tanzania is Friday, September 13, 2019 9:44:01 PM which when store in unix timestamp would be 1568400241

Now when reading the data simply use something like php or any other language and extract the date from the unix timestamp. An example with php will be

echo date('m/d/Y', 1568400241);

This makes it easier even to store data with other collaborators in different locations. They can simply convert the date to unix timestamp with their own gmt offset and store it in a integer format and when outputting this simply convert with a

How to position absolute inside a div?

The problem is described (among other) in this article.

#box is relatively positioned, which makes it part of the "flow" of the page. Your other divs are absolutely positioned, so they are removed from the page's "flow".

Page flow means that the positioning of an element effects other elements in the flow.

In other words, as #box now sees the dom, .a and .b are no longer "inside" #box.

To fix this, you would want to make everything relative, or everything absolute.

One way would be:

.a {
   position:relative;
   margin-top:10px;
   margin-left:10px;
   background-color:red;
   width:210px;
   padding: 5px;
}

Adding POST parameters before submit

To add that using Jquery:

$('#commentForm').submit(function(){ //listen for submit event
    $.each(params, function(i,param){
        $('<input />').attr('type', 'hidden')
            .attr('name', param.name)
            .attr('value', param.value)
            .appendTo('#commentForm');
    });

    return true;
}); 

How can I find out a file's MIME type (Content-Type)?

file --mime works, but not --mime-type. at least for my RHEL 5.

Change color of bootstrap navbar on hover link?

Something like this has worked for me (with Bootstrap 3):

.navbar-nav > li > a:hover, .navbar-default .navbar-nav > li > a:focus{
    font-family: proxima-nova;
    font-style: normal;
    font-weight: 100;
    letter-spacing: 3px;
    text-transform: uppercase;
    color: black;
} 

In my case I also wanted the link text to remain black before the hover so i added .navbar-nav > li > a

.navbar-nav > li > a:hover, .navbar-default .navbar-nav > li > a:focus, .navbar-nav > li > a{
    font-family: proxima-nova;
    font-style: normal;
    font-weight: 100;
    letter-spacing: 3px;
    text-transform: uppercase;
    color: black;
} 

Java: Get last element after split

Or you could use lastIndexOf() method on String

String last = string.substring(string.lastIndexOf('-') + 1);

path.join vs path.resolve with __dirname

const absolutePath = path.join(__dirname, some, dir);

vs.

const absolutePath = path.resolve(__dirname, some, dir);

path.join will concatenate __dirname which is the directory name of the current file concatenated with values of some and dir with platform-specific separator.

Whereas

path.resolve will process __dirname, some and dir i.e. from right to left prepending it by processing it.

If any of the values of some or dir corresponds to a root path then the previous path will be omitted and process rest by considering it as root

In order to better understand the concept let me explain both a little bit more detail as follows:-

The path.join and path.resolve are two different methods or functions of the path module provided by nodejs.

Where both accept a list of paths but the difference comes in the result i.e. how they process these paths.

path.join concatenates all given path segments together using the platform-specific separator as a delimiter, then normalizes the resulting path. While the path.resolve() process the sequence of paths from right to left, with each subsequent path prepended until an absolute path is constructed.

When no arguments supplied

The following example will help you to clearly understand both concepts:-

My filename is index.js and the current working directory is E:\MyFolder\Pjtz\node

const path = require('path');

console.log("path.join() : ", path.join());
// outputs .
console.log("path.resolve() : ", path.resolve());
// outputs current directory or equivalent to __dirname

Result

? node index.js
path.join() :  .
path.resolve() :  E:\MyFolder\Pjtz\node

path.resolve() method will output the absolute path whereas the path.join() returns . representing the current working directory if nothing is provided

When some root path is passed as arguments

const path=require('path');

console.log("path.join() : " ,path.join('abc','/bcd'));
console.log("path.resolve() : ",path.resolve('abc','/bcd'));

Result i

? node index.js
path.join() :  abc\bcd
path.resolve() :  E:\bcd

path.join() only concatenates the input list with platform-specific separator while the path.resolve() process the sequence of paths from right to left, with each subsequent path prepended until an absolute path is constructed.

Writing to an Excel spreadsheet

You can try hfexcel Human Friendly object-oriented python library based on XlsxWriter:

from hfexcel import HFExcel

hf_workbook = HFExcel.hf_workbook('example.xlsx', set_default_styles=False)

hf_workbook.add_style(
    "headline", 
    {
       "bold": 1,
        "font_size": 14,
        "font": "Arial",
        "align": "center"
    }
)

sheet1 = hf_workbook.add_sheet("sheet1", name="Example Sheet 1")

column1, _ = sheet1.add_column('headline', name='Column 1', width=2)
column1.add_row(data='Column 1 Row 1')
column1.add_row(data='Column 1 Row 2')

column2, _ = sheet1.add_column(name='Column 2')
column2.add_row(data='Column 2 Row 1')
column2.add_row(data='Column 2 Row 2')


column3, _ = sheet1.add_column(name='Column 3')
column3.add_row(data='Column 3 Row 1')
column3.add_row(data='Column 3 Row 2')

# In order to get a row with coordinates:
# sheet[column_index][row_index] => row
print(sheet1[1][1].data)
assert(sheet1[1][1].data == 'Column 2 Row 2')

hf_workbook.save()

Is it possible to remove inline styles with jQuery?

If you want to remove a property within a style attribute – not just set it to something else – you make use of the removeProperty() method:

document.getElementById('element').style.removeProperty('display');

UPDATE:
I've made an interactive fiddle to play around with the different methods and their results. Apparently, there isn't much of a difference between set to empty string, set to faux value and removeProperty(). They all result in the same fallback – which is either a pre-given CSS rule or the browser's default value.

Clear form fields with jQuery

This won't handle cases where form input fields have non empty default values.

Something like should work

$('yourdiv').find('form')[0].reset();

How can I color dots in a xy scatterplot according to column value?

Recently I had to do something similar and I resolved it with the code below. Hope it helps!

Sub ColorCode()
Dim i As Integer
Dim j As Integer
i = 2
j = 1

Do While ActiveSheet.Cells(i, 1) <> ""


If Cells(i, 5).Value = "RED" Then
ActiveSheet.ChartObjects("YourChartName").Chart.FullSeriesCollection(1).Points(j).MarkerForegroundColor = RGB(255, 0, 0)



Else

If Cells(i, 5).Value = "GREEN" Then
ActiveSheet.ChartObjects("YourChartName").Chart.FullSeriesCollection(1).Points(j).MarkerForegroundColor = RGB(0, 255, 0)

Else

If Cells(i, 5).Value = "GREY" Then
ActiveSheet.ChartObjects("YourChartName").Chart.FullSeriesCollection(1).Points(j).MarkerForegroundColor = RGB(192, 192, 192)

Else

If Cells(i, 5).Value = "YELLOW" Then
ActiveSheet.ChartObjects("YourChartName").Chart.FullSeriesCollection(1).Points(j).MarkerForegroundColor = RGB(255, 255, 0)

End If
End If
End If
End If

i = i + 1
j = j + 1

Loop



End Sub

Accessing items in an collections.OrderedDict by index

This community wiki attempts to collect existing answers.

Python 2.7

In python 2, the keys(), values(), and items() functions of OrderedDict return lists. Using values as an example, the simplest way is

d.values()[0]  # "python"
d.values()[1]  # "spam"

For large collections where you only care about a single index, you can avoid creating the full list using the generator versions, iterkeys, itervalues and iteritems:

import itertools
next(itertools.islice(d.itervalues(), 0, 1))  # "python"
next(itertools.islice(d.itervalues(), 1, 2))  # "spam"

The indexed.py package provides IndexedOrderedDict, which is designed for this use case and will be the fastest option.

from indexed import IndexedOrderedDict
d = IndexedOrderedDict({'foo':'python','bar':'spam'})
d.values()[0]  # "python"
d.values()[1]  # "spam"

Using itervalues can be considerably faster for large dictionaries with random access:

$ python2 -m timeit -s 'from collections import OrderedDict; from random import randint; size = 1000;   d = OrderedDict({i:i for i in range(size)})'  'i = randint(0, size-1); d.values()[i:i+1]'
1000 loops, best of 3: 259 usec per loop
$ python2 -m timeit -s 'from collections import OrderedDict; from random import randint; size = 10000;  d = OrderedDict({i:i for i in range(size)})' 'i = randint(0, size-1); d.values()[i:i+1]'
100 loops, best of 3: 2.3 msec per loop
$ python2 -m timeit -s 'from collections import OrderedDict; from random import randint; size = 100000; d = OrderedDict({i:i for i in range(size)})' 'i = randint(0, size-1); d.values()[i:i+1]'
10 loops, best of 3: 24.5 msec per loop

$ python2 -m timeit -s 'from collections import OrderedDict; from random import randint; size = 1000;   d = OrderedDict({i:i for i in range(size)})' 'i = randint(0, size-1); next(itertools.islice(d.itervalues(), i, i+1))'
10000 loops, best of 3: 118 usec per loop
$ python2 -m timeit -s 'from collections import OrderedDict; from random import randint; size = 10000;  d = OrderedDict({i:i for i in range(size)})' 'i = randint(0, size-1); next(itertools.islice(d.itervalues(), i, i+1))'
1000 loops, best of 3: 1.26 msec per loop
$ python2 -m timeit -s 'from collections import OrderedDict; from random import randint; size = 100000; d = OrderedDict({i:i for i in range(size)})' 'i = randint(0, size-1); next(itertools.islice(d.itervalues(), i, i+1))'
100 loops, best of 3: 10.9 msec per loop

$ python2 -m timeit -s 'from indexed import IndexedOrderedDict; from random import randint; size = 1000;   d = IndexedOrderedDict({i:i for i in range(size)})' 'i = randint(0, size-1); d.values()[i]'
100000 loops, best of 3: 2.19 usec per loop
$ python2 -m timeit -s 'from indexed import IndexedOrderedDict; from random import randint; size = 10000;  d = IndexedOrderedDict({i:i for i in range(size)})' 'i = randint(0, size-1); d.values()[i]'
100000 loops, best of 3: 2.24 usec per loop
$ python2 -m timeit -s 'from indexed import IndexedOrderedDict; from random import randint; size = 100000; d = IndexedOrderedDict({i:i for i in range(size)})' 'i = randint(0, size-1); d.values()[i]'
100000 loops, best of 3: 2.61 usec per loop

+--------+-----------+----------------+---------+
|  size  | list (ms) | generator (ms) | indexed |
+--------+-----------+----------------+---------+
|   1000 | .259      | .118           | .00219  |
|  10000 | 2.3       | 1.26           | .00224  |
| 100000 | 24.5      | 10.9           | .00261  |
+--------+-----------+----------------+---------+

Python 3.6

Python 3 has the same two basic options (list vs generator), but the dict methods return generators by default.

List method:

list(d.values())[0]  # "python"
list(d.values())[1]  # "spam"

Generator method:

import itertools
next(itertools.islice(d.values(), 0, 1))  # "python"
next(itertools.islice(d.values(), 1, 2))  # "spam"

Python 3 dictionaries are an order of magnitude faster than python 2 and have similar speedups for using generators.

+--------+-----------+----------------+---------+
|  size  | list (ms) | generator (ms) | indexed |
+--------+-----------+----------------+---------+
|   1000 | .0316     | .0165          | .00262  |
|  10000 | .288      | .166           | .00294  |
| 100000 | 3.53      | 1.48           | .00332  |
+--------+-----------+----------------+---------+

How to check SQL Server version

select charindex(  'Express',@@version)

if this value is 0 is not a express edition

How to assign more memory to docker container

That 2GB limit you see is the total memory of the VM in which docker runs.

If you are using docker-for-windows or docker-for-mac you can easily increase it from the Whale icon in the task bar, then go to Preferences -> Advanced:

Docker Preferences

But if you are using VirtualBox behind, open VirtualBox, Select and configure the docker-machine assigned memory.

See this for Mac:

https://docs.docker.com/docker-for-mac/#memory

MEMORY By default, Docker for Mac is set to use 2 GB runtime memory, allocated from the total available memory on your Mac. You can increase the RAM on the app to get faster performance by setting this number higher (for example to 3) or lower (to 1) if you want Docker for Mac to use less memory.

For Windows:

https://docs.docker.com/docker-for-windows/#advanced

Memory - Change the amount of memory the Docker for Windows Linux VM uses

How to fix broken paste clipboard in VNC on Windows

I use Remote login with vnc-ltsp-config with GNOME Desktop Environment on CentOS 5.9. From experimenting today, I managed to get cut and paste working for the session and the login prompt (because I'm lazy and would rather copy and paste difficult passwords).

  1. I created a file vncconfig.desktop in the /etc/xdg/autostart directory which enabled cut and paste during the session after login. The vncconfig process is run as the logged in user.

    [Desktop Entry]
    Name=No name
    Encoding=UTF-8
    Version=1.0
    Exec=vncconfig -nowin
    X-GNOME-Autostart-enabled=true

  2. Added vncconfig -nowin & to the bottom of the file /etc/gdm/Init/Desktop which enabled cut and paste in the session during login but terminates after login. The vncconfig process is run as root.

  3. Adding vncconfig -nowin & to the bottom of the file /etc/gdm/PostLogin/Desktop also enabled cut and paste during the session after login. The vncconfig process is run as root however.

Unable to begin a distributed transaction

If the servers are clustered and there is a clustered DTC you have to disable security on the clustered DTC not the local DTC.

how to get the selected index of a drop down

You can also use :checked for <select> elements

e.g.,

document.querySelector('select option:checked')
document.querySelector('select option:checked').getAttribute('value')

You don't even have to get the index and then reference the element by its sibling index.

how do you increase the height of an html textbox

<input type="text" style="font-size:xxpt;height:xxpx">

Just replace "xx" with whatever values you wish.

how to get selected row value in the KendoUI

One way is to use the Grid's select() and dataItem() methods.

In single selection case, select() will return a single row which can be passed to dataItem()

var entityGrid = $("#EntitesGrid").data("kendoGrid");
var selectedItem = entityGrid.dataItem(entityGrid.select());
// selectedItem has EntityVersionId and the rest of your model

For multiple row selection select() will return an array of rows. You can then iterate through the array and the individual rows can be passed into the grid's dataItem().

var entityGrid = $("#EntitesGrid").data("kendoGrid");
var rows = entityGrid.select();
rows.each(function(index, row) {
  var selectedItem = entityGrid.dataItem(row);
  // selectedItem has EntityVersionId and the rest of your model
});

How to set a DateTime variable in SQL Server 2008?

You want to make the format/style explicit and don't rely on interpretation based on local settings (which may vary among your clients infrastructure).

DECLARE @Test AS DATETIME
SET @Test = CONVERT(DATETIME, '2011-02-15 00:00:00', 120) -- yyyy-MM-dd hh:mm:ss
SELECT @Test

While there is a plethora of styles, you may want to remember few

  • 126 (ISO 8601): yyyy-MM-ddThh:mm:ss(.mmm)
  • 120: yyyy-MM-dd hh:mm:ss
  • 112: yyyyMMdd

Note that the T in the ISO 8601 is actually the letter T and not a variable.

How to center the text in a JLabel?

The following constructor, JLabel(String, int), allow you to specify the horizontal alignment of the label.

JLabel label = new JLabel("The Label", SwingConstants.CENTER);

Remove ':hover' CSS behavior from element

You want to keep the selector, so adding/removing it won't work. Instead of writing a hard and fast CSS selectors (or two), perhaps you can just use the original selector to apply new CSS rule to that element based on some criterion:

$(".test").hover(
  if(some evaluation) {
    $(this).css('border':0);
  }
);

Where can I find "make" program for Mac OS X Lion?

there are specific builds of command line tools for different major OSX versions available from the Downloads for Apple Developers site. Be sure to get the latest release of the version for your OS.

ExecuteNonQuery doesn't return results

Could you post the exact query? The ExecuteNonQuery method returns the @@ROWCOUNT Sql Server variable what ever it is after the last query has executed is what the ExecuteNonQuery method returns.

How to wrap text in LaTeX tables?

Simple like a piece of CAKE!

You can define a new column type like (L in this case) while maintaining the current alignment (c, r or l):

\documentclass{article}
\usepackage{array}
\newcolumntype{L}{>{\centering\arraybackslash}m{3cm}}

\begin{document}

\begin{table}
    \begin{tabular}{|c|L|L|}
        \hline
        Title 1 & Title 2 & Title 3 \\
        \hline 
        one-liner & multi-line and centered & \multicolumn{1}{m{3cm}|}{multi-line piece of text to show case a multi-line and justified cell}   \\
        \hline
        apple & orange & banana \\
        \hline
        apple & orange & banana \\
        \hline
    \end{tabular}
\end{table}
\end{document}

enter image description here

How do I use cx_freeze?

find the cxfreeze script and run it. It will be in the same path as your other python helper scripts, such as pip.

cxfreeze Main.py --target-dir dist

read more at: http://cx-freeze.readthedocs.org/en/latest/script.html#script

Git diff says subproject is dirty

This is the case because the pointer you have for the submodule isn’t what is actually in the submodule directory. To fix this, you must run git submodule update again:

Getting list of pixel values from PIL

I assume you are getting an error like.. TypeError: 'PixelAccess' object is not iterable...?

See the Image.load documentation for how to access pixels..

Basically, to get the list of pixels in an image, using PIL:

from PIL import Image
i = Image.open("myfile.png")

pixels = i.load() # this is not a list, nor is it list()'able
width, height = i.size

all_pixels = []
for x in range(width):
    for y in range(height):
        cpixel = pixels[x, y]
        all_pixels.append(cpixel)

That appends every pixel to the all_pixels - if the file is an RGB image (even if it only contains a black-and-white image) these will be a tuple, for example:

(255, 255, 255)

To convert the image to monochrome, you just average the three values - so, the last three lines of code would become..

cpixel = pixels[x, y]
bw_value = int(round(sum(cpixel) / float(len(cpixel))))
# the above could probably be bw_value = sum(cpixel)/len(cpixel)
all_pixels.append(bw_value)

Or to get the luminance (weighted average):

cpixel = pixels[x, y]
luma = (0.3 * cpixel[0]) + (0.59 * cpixel[1]) + (0.11 * cpixel[2])
all_pixels.append(luma)

Or pure 1-bit looking black and white:

cpixel = pixels[x, y]
if round(sum(cpixel)) / float(len(cpixel)) > 127:
    all_pixels.append(255)
else:
    all_pixels.append(0)

There is probably methods within PIL to do such RGB -> BW conversions quicker, but this works, and isn't particularly slow.

If you only want to perform calculations on each row, you could skip adding all the pixels to an intermediate list.. For example, to calculate the average value of each row:

from PIL import Image
i = Image.open("myfile.png")

pixels = i.load() # this is not a list
width, height = i.size
row_averages = []
for y in range(height):
    cur_row_ttl = 0
    for x in range(width):
        cur_pixel = pixels[x, y]
        cur_pixel_mono = sum(cur_pixel) / len(cur_pixel)
        cur_row_ttl += cur_pixel_mono

    cur_row_avg = cur_row_ttl / width
    row_averages.append(cur_row_avg)

print "Brighest row:",
print max(row_averages)

ssh_exchange_identification: Connection closed by remote host under Git bash

I just ran into this today and it was because the server I was trying to connect to was overloaded with processing. So it may be possible that the server is low on memory or CPU starved.

How to access site through IP address when website is on a shared host?

serverIPaddress/~cpanelusername will only work for cPanel. It will not work for Parallel's Panel.

As long as you have the website created on the shared, VPS or Dedicated, you should be able to always use the following in your host file, which is what your browser will use.

67.225.235.59 somerandomservice.com www.somerandomservice.com

How to install the JDK on Ubuntu Linux

Execute these series of commands (insert, update, and install) and you are all set to go.

  1. First add the repository:

    sudo add-apt-repository ppa:webupd8team/java
    
  2. Update:

    sudo apt-get update
    
  3. Install:

    sudo apt-get install oracle-java7-installer
    

Android: Getting "Manifest merger failed" error after updating to a new version of gradle

I have updated old android project for the Wear OS. I have got this error message while build the project:

Manifest merger failed : Attribute meta-data#android.support.VERSION@value value=(26.0.2) from [com.android.support:percent:26.0.2] AndroidManifest.xml:25:13-35
is also present at [com.android.support:support-v4:26.1.0] AndroidManifest.xml:28:13-35 value=(26.1.0).
Suggestion: add 'tools:replace="android:value"' to <meta-data> element at AndroidManifest.xml:23:9-25:38 to override.

My build.gradle for Wear app contains these dependencies:

dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'com.google.android.support:wearable:2.4.0'
implementation 'com.google.android.gms:play-services-wearable:16.0.1'
compileOnly 'com.google.android.wearable:wearable:2.4.0'}

SOLUTION:

Adding implementation 'com.android.support:support-v4:28.0.0' into the dependencies solved my problem.

PHP - remove all non-numeric characters from a string

Use \D to match non-digit characters.

preg_replace('~\D~', '', $str);

How do I change the color of radio buttons?

I builded another fork of @klewis' code sample to demonstrate some playing with pure css and gradients by using :before/:after pseudo elements and a hidden radio input button.

enter image description here

HTML:

sample radio buttons:
<div style="background:lightgrey;">
    <span class="radio-item">
        <input type="radio" id="ritema" name="ritem" class="true" value="ropt1" checked="checked">
        <label for="ritema">True</label>
    </span>

    <span class="radio-item">
        <input type="radio" id="ritemb" name="ritem" class="false" value="ropt2">
        <label for="ritemb">False</label>
    </span>
</div>

:

CSS:

.radio-item input[type='radio'] {
    visibility: hidden;
    width: 20px;
    height: 20px;
    margin: 0 5px 0 5px;
    padding: 0;
}
    .radio-item input[type=radio]:before {
        position: relative;
        margin: 4px -25px -4px 0;
        display: inline-block;
        visibility: visible;
        width: 20px;
        height: 20px;
        border-radius: 10px;
        border: 2px inset rgba(150,150,150,0.75);
        background: radial-gradient(ellipse at top left, rgb(255,255,255) 0%, rgb(250,250,250) 5%, rgb(230,230,230) 95%, rgb(225,225,225) 100%);
        content: "";
    }
        .radio-item input[type=radio]:checked:after {
            position: relative;
            top: 0;
            left: 9px;
            display: inline-block;
            visibility: visible;
            border-radius: 6px;
            width: 12px;
            height: 12px;
            background: radial-gradient(ellipse at top left, rgb(245,255,200) 0%, rgb(225,250,100) 5%, rgb(75,175,0) 95%, rgb(25,100,0) 100%);
            content: "";
        }
            .radio-item input[type=radio].true:checked:after {
                background: radial-gradient(ellipse at top left, rgb(245,255,200) 0%, rgb(225,250,100) 5%, rgb(75,175,0) 95%, rgb(25,100,0) 100%);
            }
            .radio-item input[type=radio].false:checked:after {
                background: radial-gradient(ellipse at top left, rgb(255,225,200) 0%, rgb(250,200,150) 5%, rgb(200,25,0) 95%, rgb(100,25,0) 100%);
            }
.radio-item label {
    display: inline-block;
    height: 25px;
    line-height: 25px;
    margin: 0;
    padding: 0;
}

preview: https://www.codeply.com/p/y47T4ylfib

Call an overridden method from super class in typescript

below is an generic example

    //base class
    class A {
        
        // The virtual method
        protected virtualStuff1?():void;
    
        public Stuff2(){
            //Calling overridden child method by parent if implemented
            this.virtualStuff1 && this.virtualStuff1();
            alert("Baseclass Stuff2");
        }
    }
    
    //class B implementing virtual method
    class B extends A{
        
        // overriding virtual method
        public virtualStuff1()
        {
            alert("Class B virtualStuff1");
        }
    }
    
    //Class C not implementing virtual method
    class C extends A{
     
    }
    
    var b1 = new B();
    var c1= new C();
    b1.Stuff2();
    b1.virtualStuff1();
    c1.Stuff2();

Include an SVG (hosted on GitHub) in MarkDown

I have a working example with an img-tag, but your images won't display. The difference I see is the content-type.

I checked the github image from your post (the google doc images don't load at all because of connection failures). The image from github is delivered as content-type: text/plain, which won't get rendered as an image by your browser.

The correct content-type value for svg is image/svg+xml. So you have to make sure that svg files set the correct mime type, but that's a server issue.

Try it with http://svg.tutorial.aptico.de/grafik_svg/dummy3.svg and don't forget to specify width and height in the tag.

How to loop over directories in Linux?

The technique I use most often is find | xargs. For example, if you want to make every file in this directory and all of its subdirectories world-readable, you can do:

find . -type f -print0 | xargs -0 chmod go+r
find . -type d -print0 | xargs -0 chmod go+rx

The -print0 option terminates with a NULL character instead of a space. The -0 option splits its input the same way. So this is the combination to use on files with spaces.

You can picture this chain of commands as taking every line output by find and sticking it on the end of a chmod command.

If the command you want to run as its argument in the middle instead of on the end, you have to be a bit creative. For instance, I needed to change into every subdirectory and run the command latemk -c. So I used (from Wikipedia):

find . -type d -depth 1 -print0 | \
    xargs -0 sh -c 'for dir; do pushd "$dir" && latexmk -c && popd; done' fnord

This has the effect of for dir $(subdirs); do stuff; done, but is safe for directories with spaces in their names. Also, the separate calls to stuff are made in the same shell, which is why in my command we have to return back to the current directory with popd.

How can I get the order ID in WooCommerce?

I didnt test it and dont know were you need it, but:

$order = new WC_Order(post->ID);
echo $order->get_order_number();

Let me know if it works. I belive order number echoes with the "#" but you can split that if only need only the number.

How to correctly use the ASP.NET FileUpload control

ASP.NET controls should rather be placed in aspx markup file. That is the preferred way of working with them. So add FileUpload control to your page. Make sure it has all required attributes including ID and runat:

<asp:FileUpload ID="FileUpload1" runat="server" />

Instance of FileUpload1 will be automatically created in auto-generated/updated *.designer.cs file which is a partial class for your page. You usually do not have to care about what's in it, just assume that any control on an aspx page is automatically instantiated.

Add a button that will do the post back:

<asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />

Then go to your *.aspx.cs file where you have your code and add button click handler. In C# it looks like this:

protected void Button1_Click(object sender, EventArgs e)
{
  if (this.FileUpload1.HasFile)
  {
    this.FileUpload1.SaveAs("c:\\" + this.FileUpload1.FileName);
  }
}

And that's it. All should work as expected.

How do I set up access control in SVN?

@Stephen Bailey

To complete your answer, you can also delegate the user rights to the project manager, through a plain text file in your repository.

To do that, you set up your SVN database with a default authz file containing the following:

###########################################################################
# The content of this file always precedes the content of the
# $REPOS/admin/acl_descriptions.txt file.
# It describes the immutable permissions on main folders.
###########################################################################
[groups]
svnadmins = xxx,yyy,....

[/]
@svnadmins = rw
* = r
[/admin]
@svnadmins = rw
@projadmins = r
* =

[/admin/acl_descriptions.txt]
@projadmins = rw

This default authz file authorizes the SVN administrators to modify a visible plain text file within your SVN repository, called '/admin/acl_descriptions.txt', in which the SVN administrators or project managers will modify and register the users.

Then you set up a pre-commit hook which will detect if the revision is composed of that file (and only that file).

If it is, this hook's script will validate the content of your plain text file and check if each line is compliant with the SVN syntax.

Then a post-commit hook will update the \conf\authz file with the concatenation of:

  • the TEMPLATE authz file presented above
  • the plain text file /admin/acl_descriptions.txt

The first iteration is done by the SVN administrator, who adds:

[groups]
projadmins = zzzz

He commits his modification, and that updates the authz file.

Then the project manager 'zzzz' can add, remove or declare any group of users and any users he wants. He commits the file and the authz file is updated.

That way, the SVN administrator does not have to individually manage any and all users for all SVN repositories.

Best way to disable button in Twitter's Bootstrap

<div class="bs-example">
      <button class="btn btn-success btn-lg" type="button">Active</button>
      <button class="btn btn-success disabled" type="button">Disabled</button>
</div>

How to make execution pause, sleep, wait for X seconds in R?

See help(Sys.sleep).

For example, from ?Sys.sleep

testit <- function(x)
{
    p1 <- proc.time()
    Sys.sleep(x)
    proc.time() - p1 # The cpu usage should be negligible
}
testit(3.7)

Yielding

> testit(3.7)
   user  system elapsed 
  0.000   0.000   3.704 

Insert picture/table in R Markdown

When it comes to inserting a picture, r2evans's suggestion of ![Caption for the picture.](/path/to/image.png) can be problematic if PDF output is required.

The knitr function include_graphics knitr::include_graphics('/path/to/image.png') is a more portable alternative that will generate, on your behalf, the markdown that is most appropriate to the output format that you are generating.

Can I change the viewport meta tag in mobile safari on the fly?

I realize this is a little old, but, yes it can be done. Some javascript to get you started:

viewport = document.querySelector("meta[name=viewport]");
viewport.setAttribute('content', 'width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0');

Just change the parts you need and Mobile Safari will respect the new settings.

Update:

If you don't already have the meta viewport tag in the source, you can append it directly with something like this:

var metaTag=document.createElement('meta');
metaTag.name = "viewport"
metaTag.content = "width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0"
document.getElementsByTagName('head')[0].appendChild(metaTag);

Or if you're using jQuery:

$('head').append('<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0">');

How do I overload the square-bracket operator in C#?

you can find how to do it here. In short it is:

public object this[int i]
{
    get { return InnerList[i]; }
    set { InnerList[i] = value; }
}

If you only need a getter the syntax in answer below can be used as well (starting from C# 6).

append to url and refresh page

function gotoItem( item ){
    var url = window.location.href;
    var separator = (url.indexOf('?') > -1) ? "&" : "?";
    var qs = "item=" + encodeURIComponent(item);
    window.location.href = url + separator + qs;
}

More compat version

function gotoItem( item ){
    var url = window.location.href;    
    url += (url.indexOf('?') > -1)?"&":"?" + "item=" + encodeURIComponent(item);
    window.location.href = url;
}

jQuery get input value after keypress

You have to interrupt the execution thread to allow the input to update.

  $(document).ready(function(event) {
       $("#dSuggest").keypress(function() {
           //Interrupt the execution thread to allow input to update
               setTimeout(function() {
                   var dInput = $('input:text[name=dSuggest]').val();
                   console.log(dInput);
                   $(".dDimension:contains('" + dInput + "')").css("display","block");
               }, 0);
       });
  });

Git checkout: updating paths is incompatible with switching branches

For me I had a typo and my remote branch didn't exist

Use git branch -a to list remote branches

New og:image size for Facebook share?

Tried to get the 1200x630 image working. Facebook kept complaining that it couldn't read the image, or that it was too small (it was a jpeg image ~150Kb).

Switched to a 200x200 size image, worked perfectly.

https://developers.facebook.com/tools/debug/og/object?q=drift.team

$_SERVER["REMOTE_ADDR"] gives server IP rather than visitor IP

PHP 7.0 $_SERVER varibales have changed. var_dump it and see how it fits your reqs.

some of them giving remote details are, REMOTE_ADDR HTTP_X_FORWARDED_FOR HTTP_CF_CONNECTING_IP HTTP_CF_IPCOUNTRY

How can I write a regex which matches non greedy?

The other answers here presuppose that you have a regex engine which supports non-greedy matching, which is an extension introduced in Perl 5 and widely copied to other modern languages; but it is by no means ubiquitous.

Many older or more conservative languages and editors only support traditional regular expressions, which have no mechanism for controlling greediness of the repetition operator * - it always matches the longest possible string.

The trick then is to limit what it's allowed to match in the first place. Instead of .* you seem to be looking for

[^>]*

which still matches as many of something as possible; but the something is not just . "any character", but instead "any character which isn't >".

Depending on your application, you may or may not want to enable an option to permit "any character" to include newlines.

Even if your regular expression engine supports non-greedy matching, it's better to spell out what you actually mean. If this is what you mean, you should probably say this, instead of rely on non-greedy matching to (hopefully, probably) Do What I Mean.

For example, a regular expression with a trailing context after the wildcard like .*?><br/> will jump over any nested > until it finds the trailing context (here, ><br/>) even if that requires straddling multiple > instances and newlines if you let it, where [^>]*><br/> (or even [^\n>]*><br/> if you have to explicitly disallow newline) obviously can't and won't do that.

Of course, this is still not what you want if you need to cope with <img title="quoted string with > in it" src="other attributes"> and perhaps <img title="nested tags">, but at that point, you should finally give up on using regular expressions for this like we all told you in the first place.

SQL query for getting data for last 3 months

SELECT * 
FROM TABLE_NAME
WHERE Date_Column >= DATEADD(MONTH, -3, GETDATE()) 

Mureinik's suggested method will return the same results, but doing it this way your query can benefit from any indexes on Date_Column.

or you can check against last 90 days.

SELECT * 
FROM TABLE_NAME
WHERE Date_Column >= DATEADD(DAY, -90, GETDATE()) 

Bootstrap 3.0: How to have text and input on same line?

just give mother of div "class="col-lg-12""

<div class="form-group">
<div class="row">
    <div class="col-xs-3">
        <label for="class_type"><h2><span class=" label label-primary">Class Type</span></h2></label>
    </div>
    <div class="col-xs-2">
        <select name="class_type" id="class_type" class="  form-control input-lg" style="width:200px" autocomplete="off">
            <option >Economy</option>
            <option >Premium Economy</option>
            <option >Club World</option>
            <option >First Class</option>
        </select>
    </div>
 </div>

it will be

<div class="form-group">
<div class="col-lg-12">
  <div class="row">
    <div class="col-xs-3">
        <label for="class_type"><h2><span class=" label label-primary">Class Type</span></h2></label>
    </div>
    <div class="col-xs-2">
        <select name="class_type" id="class_type" class="  form-control input-lg" style="width:200px" autocomplete="off">
            <option >Economy</option>
            <option >Premium Economy</option>
            <option >Club World</option>
            <option >First Class</option>
        </select>
    </div>
</div>
</div>

Read large files in Java

You can consider using memory-mapped files, via FileChannels .

Generally a lot faster for large files. There are performance trade-offs that could make it slower, so YMMV.

Related answer: Java NIO FileChannel versus FileOutputstream performance / usefulness

How to cherry-pick multiple commits

To apply J. B. Rainsberger and sschaef's comments to specifically answer the question... To use a cherry-pick range on this example:

git checkout a
git cherry-pick b..f

or

git checkout a
git cherry-pick c^..f

How can I get the average (mean) of selected columns

Here are some examples:

> z$mean <- rowMeans(subset(z, select = c(x, y)), na.rm = TRUE)
> z
  w x  y mean
1 5 1  1    1
2 6 2  2    2
3 7 3  3    3
4 8 4 NA    4

weighted mean

> z$y <- rev(z$y)
> z
  w x  y mean
1 5 1 NA    1
2 6 2  3    2
3 7 3  2    3
4 8 4  1    4
> 
> weight <- c(1, 2) # x * 1/3 + y * 2/3
> z$wmean <- apply(subset(z, select = c(x, y)), 1, function(d) weighted.mean(d, weight, na.rm = TRUE))
> z
  w x  y mean    wmean
1 5 1 NA    1 1.000000
2 6 2  3    2 2.666667
3 7 3  2    3 2.333333
4 8 4  1    4 2.000000

How to restart Postgresql

You can also restart postgresql by using this command, should work on both the versions :

sudo service postgresql start

Change the fill color of a cell based on a selection from a Drop Down List in an adjacent cell

You could try Conditional Formatting available in the tool menu "Format -> Conditional Formatting".

Combine several images horizontally with Python

Based on DTing's answer I created a function that is easier to use:

from PIL import Image


def append_images(images, direction='horizontal',
                  bg_color=(255,255,255), aligment='center'):
    """
    Appends images in horizontal/vertical direction.

    Args:
        images: List of PIL images
        direction: direction of concatenation, 'horizontal' or 'vertical'
        bg_color: Background color (default: white)
        aligment: alignment mode if images need padding;
           'left', 'right', 'top', 'bottom', or 'center'

    Returns:
        Concatenated image as a new PIL image object.
    """
    widths, heights = zip(*(i.size for i in images))

    if direction=='horizontal':
        new_width = sum(widths)
        new_height = max(heights)
    else:
        new_width = max(widths)
        new_height = sum(heights)

    new_im = Image.new('RGB', (new_width, new_height), color=bg_color)


    offset = 0
    for im in images:
        if direction=='horizontal':
            y = 0
            if aligment == 'center':
                y = int((new_height - im.size[1])/2)
            elif aligment == 'bottom':
                y = new_height - im.size[1]
            new_im.paste(im, (offset, y))
            offset += im.size[0]
        else:
            x = 0
            if aligment == 'center':
                x = int((new_width - im.size[0])/2)
            elif aligment == 'right':
                x = new_width - im.size[0]
            new_im.paste(im, (x, offset))
            offset += im.size[1]

    return new_im

It allows choosing a background color and image alignment. It's also easy to do recursion:

images = map(Image.open, ['hummingbird.jpg', 'tiger.jpg', 'monarch.png'])

combo_1 = append_images(images, direction='horizontal')
combo_2 = append_images(images, direction='horizontal', aligment='top',
                        bg_color=(220, 140, 60))
combo_3 = append_images([combo_1, combo_2], direction='vertical')
combo_3.save('combo_3.png')

Example concatenated image

Getting random numbers in Java

The first solution is to use the java.util.Random class:

import java.util.Random;

Random rand = new Random();

// Obtain a number between [0 - 49].
int n = rand.nextInt(50);

// Add 1 to the result to get a number from the required range
// (i.e., [1 - 50]).
n += 1;

Another solution is using Math.random():

double random = Math.random() * 49 + 1;

or

int random = (int)(Math.random() * 50 + 1);

Ruby: How to get the first character of a string

You can use Ruby's open classes to make your code much more readable. For instance, this:

class String
  def initial
    self[0,1]
  end
end

will allow you to use the initial method on any string. So if you have the following variables:

last_name = "Smith"
first_name = "John"

Then you can get the initials very cleanly and readably:

puts first_name.initial   # prints J
puts last_name.initial    # prints S

The other method mentioned here doesn't work on Ruby 1.8 (not that you should be using 1.8 anymore anyway!--but when this answer was posted it was still quite common):

puts 'Smith'[0]           # prints 83

Of course, if you're not doing it on a regular basis, then defining the method might be overkill, and you could just do it directly:

puts last_name[0,1] 

Return anonymous type results?

Just to add my two cents' worth :-) I recently learned a way of handling anonymous objects. It can only be used when targeting the .NET 4 framework and that only when adding a reference to System.Web.dll but then it's quite simple:

...
using System.Web.Routing;
...

class Program
{
    static void Main(string[] args)
    {

        object anonymous = CallMethodThatReturnsObjectOfAnonymousType();
        //WHAT DO I DO WITH THIS?
        //I know! I'll use a RouteValueDictionary from System.Web.dll
        RouteValueDictionary rvd = new RouteValueDictionary(anonymous);
        Console.WriteLine("Hello, my name is {0} and I am a {1}", rvd["Name"], rvd["Occupation"]);
    }

    private static object CallMethodThatReturnsObjectOfAnonymousType()
    {
        return new { Id = 1, Name = "Peter Perhac", Occupation = "Software Developer" };
    }
}

In order to be able to add a reference to System.Web.dll you'll have to follow rushonerok's advice : Make sure your [project's] target framework is ".NET Framework 4" not ".NET Framework 4 Client Profile".

Why does ASP.NET webforms need the Runat="Server" attribute?

Not all controls that can be included in a page must be run at the server. For example:

<INPUT type="submit" runat=server />

This is essentially the same as:

<asp:Button runat=server />

Remove the runat=server tag from the first one and you have a standard HTML button that runs in the browser. There are reasons for and against running a particular control at the server, and there is no way for ASP.NET to "assume" what you want based on the HTML markup you include. It might be possible to "infer" the runat=server for the <asp:XXX /> family of controls, but my guess is that Microsoft would consider that a hack to the markup syntax and ASP.NET engine.

Java constructor/method with optional parameters?

You can simulate it with using varargs, however then you should check it for too many arguments.

public void foo(int param1, int ... param2)
{
   int param2_
   if(param2.length == 0)
      param2_ = 2
   else if(para2.length == 1)
      param2_ = param2[0]
   else
      throw new TooManyArgumentsException(); // user provided too many arguments,

   // rest of the code
}

However this approach is not a good way of doing this, therefore it is better to use overloading.

Error With Port 8080 already in use

on Mac, how I usually solve it

  1. open terminal and cd to downloaded-apache-files-folder/bin (i.e to the folder where shutdown.sh file is located)
  2. enter "sh shutdown.sh" as a terminal command
  3. restart Tomcat/Eclipse..tada!

Hope this helps OP or someone else reading

C++ sorting and keeping track of indexes

There are many ways. A rather simple solution is to use a 2D vector.

#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;

int main() {
 vector<vector<double>> val_and_id;
 val_and_id.resize(5);
 for (int i = 0; i < 5; i++) {
   val_and_id[i].resize(2); // one to store value, the other for index.
 }
 // Store value in dimension 1, and index in the other:
 // say values are 5,4,7,1,3.
 val_and_id[0][0] = 5.0;
 val_and_id[1][0] = 4.0;
 val_and_id[2][0] = 7.0;
 val_and_id[3][0] = 1.0;
 val_and_id[4][0] = 3.0;

 val_and_id[0][1] = 0.0;
 val_and_id[1][1] = 1.0;
 val_and_id[2][1] = 2.0;
 val_and_id[3][1] = 3.0;
 val_and_id[4][1] = 4.0;

 sort(val_and_id.begin(), val_and_id.end());
 // display them:
 cout << "Index \t" << "Value \n";
 for (int i = 0; i < 5; i++) {
  cout << val_and_id[i][1] << "\t" << val_and_id[i][0] << "\n";
 }
 return 0;
}

Here is the output:

   Index   Value
   3       1
   4       3
   1       4
   0       5
   2       7

getting the table row values with jquery

Here is a working example. I changed the code to output to a div instead of an alert box. Your issue was item.innerHTML I believe. I use the jQuery html function instead and that seemed to resolve the issue.

<table id='thisTable' class='disptable' style='margin-left:auto;margin-right:auto;'  >
    <tr>

   <th>Fund</th>
   <th>Organization</th>
   <th>Access</th>
   <th>Delete</th>
   </tr>
    <tr>
   <td class='fund'>100000</td><td class='org'>10110</td><td>OWNED</td><td><a  class='delbtn'ref='#'>X</a></td></tr>
   <tr><td class='fund'>100000</td><td class='org'>67130</td><td>OWNED</td><td><a class='delbtn' href='#'>X</a></td></tr>
   <tr><td class='fund'>170252</td><td class='org'>67130</td><td>OWNED</td><td><a class='delbtn' href='#'>X</a></td></tr>
   <tr><td class='fund'>100000</td><td class='org'>67150</td><td>PENDING ACCESS</td><td><a  class='delbtn' href='#'>X</a></td></tr>
   <tr><td class='fund'>100000</td><td class='org'>67120</td><td>PENDING ACCESS</td><td><a class='delbtn' href='#'>X</a>
   </td>
  </tr>
</table>
<div id="output"></div>?

the javascript:

$('#thisTable tr').on('click', function(event) {    
    var tds = $(this).addClass('row-highlight').find('td');
    var values = '';
    tds.each(function(index, item) {           
        values = values + 'td' + (index + 1) + ':' + $(item).html() + '<br/>';
    });
    $("#output").html(values);
});

Installing python module within code

You define the dependent module inside the setup.py of your own package with the "install_requires" option.

If your package needs to have some console script generated then you can use the "console_scripts" entry point in order to generate a wrapper script that will be placed within the 'bin' folder (e.g. of your virtualenv environment).

How to substitute shell variables in complex text files

envsubst seems exactly like something I wanted to use, but -v option surprised me a bit.

While envsubst < template.txt was working fine, the same with option -v was not working:

$ cat /etc/redhat-release
Red Hat Enterprise Linux Server release 7.1 (Maipo)
$ envsubst -V
envsubst (GNU gettext-runtime) 0.18.2
Copyright (C) 2003-2007 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by Bruno Haible.

As I wrote, this was not working:

$ envsubst -v < template.txt
envsubst: missing arguments
$ cat template.txt | envsubst -v
envsubst: missing arguments

I had to do this to make it work:

TEXT=`cat template.txt`; envsubst -v "$TEXT"

Maybe it helps someone.

Getting the index of the returned max or min item using max()/min() on a list

Pandas has now got a much more gentle solution, try it:

df[column].idxmax()

How to use Simple Ajax Beginform in Asp.net MVC 4?

Besides the previous post instructions, I had to install the package Microsoft.jQuery.Unobtrusive.Ajax and add to the view the following line

<script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.js")" type="text/javascript"></script>

Nodemailer with Gmail and NodeJS

For some reason, just allowing less secure app config did not work for me even the captcha thing. I had to do another step which is enabling IMAP config:

From google's help page: https://support.google.com/mail/answer/7126229?p=WebLoginRequired&visit_id=1-636691283281086184-1917832285&rd=3#cantsignin

  • In the top right, click Settings Settings.
  • Click Settings.
  • Click the Forwarding and POP/IMAP tab.
  • In the "IMAP Access" section, select Enable IMAP.
  • Click Save Changes.

How to use curl in a shell script?

Firstly, your example is looking quite correct and works well on my machine. You may go another way.

curl $CURLARGS $RVMHTTP > ./install.sh

All output now storing in ./install.sh file, which you can edit and execute.

Difference between Static methods and Instance methods

The static modifier when placed in front of a function implies that only one copy of that function exists. If the static modifier is not placed in front of the function then with every object or instance of that class a new copy of that function is made. :) Same is the case with variables.

What does "make oldconfig" do exactly in the Linux kernel makefile?

It reads the existing .config file that was used for an old kernel and prompts the user for options in the current kernel source that are not found in the file. This is useful when taking an existing configuration and moving it to a new kernel.

How do I do a not equal in Django queryset filtering?

the field=value syntax in queries is a shorthand for field__exact=value. That is to say that Django puts query operators on query fields in the identifiers. Django supports the following operators:

exact
iexact
contains
icontains
in
gt
gte
lt
lte
startswith
istartswith
endswith
iendswith
range

date
year
iso_year
month
day
week
week_day
iso_week_day
quarter
time
hour
minute
second

isnull
regex
iregex

I'm sure by combining these with the Q objects as Dave Vogt suggests and using filter() or exclude() as Jason Baker suggests you'll get exactly what you need for just about any possible query.

What are the differences between struct and class in C++?

You might consider this for guidelines on when to go for struct or class, https://msdn.microsoft.com/en-us/library/ms229017%28v=vs.110%29.aspx .

v CONSIDER defining a struct instead of a class if instances of the type are small and commonly short-lived or are commonly embedded in other objects.

X AVOID defining a struct unless the type has all of the following characteristics:

It logically represents a single value, similar to primitive types (int, double, etc.).

It has an instance size under 16 bytes.

It is immutable.

It will not have to be boxed frequently.

How to make code wait while calling asynchronous calls like Ajax

Use callbacks. Something like this should work based on your sample code.

function someFunc() {

callAjaxfunc(function() {
    console.log('Pass2');
});

}

function callAjaxfunc(callback) {
    //All ajax calls called here
    onAjaxSuccess: function() {
        callback();
    };
    console.log('Pass1');    
}

This will print Pass1 immediately (assuming ajax request takes atleast a few microseconds), then print Pass2 when the onAjaxSuccess is executed.

How to avoid page refresh after button click event in asp.net

I had the same problem with a button doing a page refresh before doing the actual button_click event (so the button had to be clicked twice). This behavior happened after a server.transfer-command (server.transfer("testpage.aspx").

In this case, the solution was to replace the server.transfer-command with response-redirect (response.redirect("testpage.aspx").

For details on the differences between the two commands, see Server.Transfer Vs. Response.Redirect

Rotating x axis labels in R for barplot

EDITED ANSWER PER DAVID'S RESPONSE:

Here's a kind of hackish way. I'm guessing there's an easier way. But you could suppress the bar labels and the plot text of the labels by saving the bar positions from barplot and do a little tweaking up and down. Here's an example with the mtcars data set:

x <- barplot(table(mtcars$cyl), xaxt="n")
labs <- paste(names(table(mtcars$cyl)), "cylinders")
text(cex=1, x=x-.25, y=-1.25, labs, xpd=TRUE, srt=45)

Java ArrayList Index

The big difference between primitive arrays & object-based collections (e.g., ArrayList) is that the latter can grow (or shrink) dynamically. Primitive arrays are fixed in size: Once you create them, their size doesn't change (though the contents can).

How to auto resize and adjust Form controls with change in resolution

add this code at page load do for all control or add all control in containers

int x;
Point pt = new Point();
x = Screen.PrimaryScreen.WorkingArea.Width - 1024;
x = x / 2;
pt.Y = groupBox1.Location.Y + 50;
pt.X = groupBox1.Location.X + x;
groupBox1.Location = pt;

Using Javamail to connect to Gmail smtp server ignores specified port and tries to use 25

For anyone looking for a full solution, I got this working with the following code based on maximdim's answer:

import javax.mail.*
import javax.mail.internet.*

private class SMTPAuthenticator extends Authenticator
{
    public PasswordAuthentication getPasswordAuthentication()
    {
        return new PasswordAuthentication('[email protected]', 'test1234');
    }
}

def  d_email = "[email protected]",
        d_uname = "email",
        d_password = "password",
        d_host = "smtp.gmail.com",
        d_port  = "465", //465,587
        m_to = "[email protected]",
        m_subject = "Testing",
        m_text = "Hey, this is the testing email."

def props = new Properties()
props.put("mail.smtp.user", d_email)
props.put("mail.smtp.host", d_host)
props.put("mail.smtp.port", d_port)
props.put("mail.smtp.starttls.enable","true")
props.put("mail.smtp.debug", "true");
props.put("mail.smtp.auth", "true")
props.put("mail.smtp.socketFactory.port", d_port)
props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory")
props.put("mail.smtp.socketFactory.fallback", "false")

def auth = new SMTPAuthenticator()
def session = Session.getInstance(props, auth)
session.setDebug(true);

def msg = new MimeMessage(session)
msg.setText(m_text)
msg.setSubject(m_subject)
msg.setFrom(new InternetAddress(d_email))
msg.addRecipient(Message.RecipientType.TO, new InternetAddress(m_to))

Transport transport = session.getTransport("smtps");
transport.connect(d_host, 465, d_uname, d_password);
transport.sendMessage(msg, msg.getAllRecipients());
transport.close();

#1146 - Table 'phpmyadmin.pma_recent' doesn't exist

After I downloaded phpmyadmin from their website, I extracted the create_tables.sql file from the examples folder and then I imported it from the 'Import' tab of phpmyadmin.
It creates the database 'phpmyadmin' and the relevant table within.

This step might not be needed as the 12 tables were already there...
The problem seemed to be the double underscore in the tables' names.

I edited 'config.inc.php' and added another underscore (__) after the 'pma_' prefix of the tables.

ie.

$cfg['Servers'][$i]['userconfig'] = 'pma_userconfig';

became

$cfg['Servers'][$i]['userconfig'] = 'pma__userconfig';

This solved the issue for me.

XSLT counting elements with a given value

Your xpath is just a little off:

count(//Property/long[text()=$parPropId])

Edit: Cerebrus quite rightly points out that the code in your OP (using the implicit value of a node) is absolutely fine for your purposes. In fact, since it's quite likely you want to work with the "Property" node rather than the "long" node, it's probably superior to ask for //Property[long=$parPropId] than the text() xpath, though you could make a case for the latter on readability grounds.

What can I say, I'm a bit tired today :)

How to find Google's IP address?

With Python 3, you could do:

import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server = "www.google.com"
port = 80
server_ip = socket.gethostbyname(server)
print(str(server_ip))

What's the difference between MyISAM and InnoDB?

The main differences between InnoDB and MyISAM ("with respect to designing a table or database" you asked about) are support for "referential integrity" and "transactions".

If you need the database to enforce foreign key constraints, or you need the database to support transactions (i.e. changes made by two or more DML operations handled as single unit of work, with all of the changes either applied, or all the changes reverted) then you would choose the InnoDB engine, since these features are absent from the MyISAM engine.

Those are the two biggest differences. Another big difference is concurrency. With MyISAM, a DML statement will obtain an exclusive lock on the table, and while that lock is held, no other session can perform a SELECT or a DML operation on the table.

Those two specific engines you asked about (InnoDB and MyISAM) have different design goals. MySQL also has other storage engines, with their own design goals.

So, in choosing between InnoDB and MyISAM, the first step is in determining if you need the features provided by InnoDB. If not, then MyISAM is up for consideration.

A more detailed discussion of differences is rather impractical (in this forum) absent a more detailed discussion of the problem space... how the application will use the database, how many tables, size of the tables, the transaction load, volumes of select, insert, updates, concurrency requirements, replication features, etc.


The logical design of the database should be centered around data analysis and user requirements; the choice to use a relational database would come later, and even later would the choice of MySQL as a relational database management system, and then the selection of a storage engine for each table.

DataAnnotations validation (Regular Expression) in asp.net mvc 4 - razor view

What browser are you using? I entered your example and tried in both IE8 and Chrome and it validated fine when I typed in the value Sam's

 public class IndexViewModel
 {
    [Required(ErrorMessage="Required")]
    [RegularExpression("^([a-zA-Z0-9 .&'-]+)$", ErrorMessage = "Invalid First Name")]
    public string Name { get; set; }
 }

When I inspect the DOM using IE Developer toolbar and Chrome Developer mode it does not show any special characters.

View's SELECT contains a subquery in the FROM clause

As the more recent MySQL documentation on view restrictions says:

Before MySQL 5.7.7, subqueries cannot be used in the FROM clause of a view.

This means, that choosing a MySQL v5.7.7 or newer or upgrading the existing MySQL instance to such a version, would remove this restriction on views completely.

However, if you have a current production MySQL version that is earlier than v5.7.7, then the removal of this restriction on views should only be one of the criteria being assessed while making a decision as to upgrade or not. Using the workaround techniques described in the other answers may be a more viable solution - at least on the shorter run.

Changing Node.js listening port

you can get the nodejs configuration from http://nodejs.org/
The important thing you need to keep in your mind is about its configuration in file app.js which consists of port number host and other settings these are settings working for me

backendSettings = {
"scheme":"https / http ",
"host":"Your website url",
"port":49165, //port number 
'sslKeyPath': 'Path for key',
'sslCertPath': 'path for SSL certificate',
'sslCAPath': '',
"resource":"/socket.io",
"baseAuthPath": '/nodejs/',
"publishUrl":"publish",
"serviceKey":"",
"backend":{
"port":443,
"scheme": 'https / http', //whatever is your website scheme
"host":"host name",
"messagePath":"/nodejs/message/"},
"clientsCanWriteToChannels":false,
"clientsCanWriteToClients":false,
"extensions":"",
"debug":false,
"addUserToChannelUrl": 'user/channel/add/:channel/:uid',
"publishMessageToContentChannelUrl": 'content/token/message',
"transports":["websocket",
"flashsocket",
"htmlfile",
"xhr-polling",
"jsonp-polling"],
"jsMinification":true,
"jsEtag":true,
"logLevel":1};

In this if you are getting "Error: listen EADDRINUSE" then please change the port number i.e, here I am using "49165" so you can use other port such as 49170 or some other port. For this you can refer to the following article
http://www.a2hosting.com/kb/installable-applications/manual-installations/installing-node-js-on-shared-hosting-accounts

Convert serial.read() into a useable string using Arduino?

I could get away with this:

void setup() {
  Serial.begin(9600);
}

void loop() {
  String message = "";
  while (Serial.available())
    message.concat((char) Serial.read());
  if (message != "")
    Serial.println(message);
}

Check if page gets reloaded or refreshed in JavaScript

<script>
    
    var currpage    = window.location.href;
    var lasturl     = sessionStorage.getItem("last_url");

    if(lasturl == null || lasturl.length === 0 || currpage !== lasturl ){
        sessionStorage.setItem("last_url", currpage);
        alert("New page loaded");
    }else{
        alert("Refreshed Page");  
    }

</script>

How to read file from relative path in Java project? java.io.File cannot find the path specified

InputStream in = FileLoader.class.getResourceAsStream("<relative path from this class to the file to be read>");
try {
    BufferedReader reader = new BufferedReader(new InputStreamReader(in));
    String line = null;
        while ((line = reader.readLine()) != null) {
            System.out.println(line);
        }
} catch (Exception e) {
    e.printStackTrace();
}

In what situations would AJAX long/short polling be preferred over HTML5 WebSockets?

WebSockets is definitely the future.

Long polling is a dirty workaround to prevent creating connections for each request like AJAX does -- but long polling was created when WebSockets didn't exist. Now due to WebSockets, long polling is going away.

WebRTC allows for peer-to-peer communication.

I recommend learning WebSockets.

Comparison:

of different communication techniques on the web

  • AJAX - requestresponse. Creates a connection to the server, sends request headers with optional data, gets a response from the server, and closes the connection. Supported in all major browsers.

  • Long poll - requestwaitresponse. Creates a connection to the server like AJAX does, but maintains a keep-alive connection open for some time (not long though). During connection, the open client can receive data from the server. The client has to reconnect periodically after the connection is closed, due to timeouts or data eof. On server side it is still treated like an HTTP request, same as AJAX, except the answer on request will happen now or some time in the future, defined by the application logic. support chart (full) | wikipedia

  • WebSockets - clientserver. Create a TCP connection to the server, and keep it open as long as needed. The server or client can easily close the connection. The client goes through an HTTP compatible handshake process. If it succeeds, then the server and client can exchange data in both directions at any time. It is efficient if the application requires frequent data exchange in both ways. WebSockets do have data framing that includes masking for each message sent from client to server, so data is simply encrypted. support chart (very good) | wikipedia

  • WebRTC - peerpeer. Transport to establish communication between clients and is transport-agnostic, so it can use UDP, TCP or even more abstract layers. This is generally used for high volume data transfer, such as video/audio streaming, where reliability is secondary and a few frames or reduction in quality progression can be sacrificed in favour of response time and, at least, some data transfer. Both sides (peers) can push data to each other independently. While it can be used totally independent from any centralised servers, it still requires some way of exchanging endPoints data, where in most cases developers still use centralised servers to "link" peers. This is required only to exchange essential data for establishing a connection, after which a centralised server is not required. support chart (medium) | wikipedia

  • Server-Sent Events - clientserver. Client establishes persistent and long-term connection to server. Only the server can send data to a client. If the client wants to send data to the server, it would require the use of another technology/protocol to do so. This protocol is HTTP compatible and simple to implement in most server-side platforms. This is a preferable protocol to be used instead of Long Polling. support chart (good, except IE) | wikipedia

Advantages:

The main advantage of WebSockets server-side, is that it is not an HTTP request (after handshake), but a proper message based communication protocol. This enables you to achieve huge performance and architecture advantages. For example, in node.js, you can share the same memory for different socket connections, so they can each access shared variables. Therefore, you don't need to use a database as an exchange point in the middle (like with AJAX or Long Polling with a language like PHP). You can store data in RAM, or even republish between sockets straight away.

Security considerations

People are often concerned about the security of WebSockets. The reality is that it makes little difference or even puts WebSockets as better option. First of all, with AJAX, there is a higher chance of MITM, as each request is a new TCP connection that is traversing through internet infrastructure. With WebSockets, once it's connected it is far more challenging to intercept in between, with additionally enforced frame masking when data is streamed from client to server as well as additional compression, which requires more effort to probe data. All modern protocols support both: HTTP and HTTPS (encrypted).

P.S.

Remember that WebSockets generally have a very different approach of logic for networking, more like real-time games had all this time, and not like http.

How does String.Index work in Swift

Create a UITextView inside of a tableViewController. I used function: textViewDidChange and then checked for return-key-input. then if it detected return-key-input, delete the input of return key and dismiss keyboard.

func textViewDidChange(_ textView: UITextView) {
    tableView.beginUpdates()
    if textView.text.contains("\n"){
        textView.text.remove(at: textView.text.index(before: textView.text.endIndex))
        textView.resignFirstResponder()
    }
    tableView.endUpdates()
}

What is the difference between <p> and <div>?

They have semantic difference - a <div> element is designed to describe a container of data whereas a <p> element is designed to describe a paragraph of content.

The semantics make all the difference. HTML is a markup language which means that it is designed to "mark up" content in a way that is meaningful to the consumer of the markup. Most developers believe that the semantics of the document are the default styles and rendering that browsers apply to these elements but that is not the case.

The elements that you choose to mark up your content should describe the content. Don't mark up your document based on how it should look - mark it up based on what it is.

If you need a generic container purely for layout purposes then use a <div>. If you need an element to describe a paragraph of content then use a <p>.

Note: It is important to understand that both <div> and <p> are block-level elements which means that most browsers will treat them in a similar fashion.

What is the best way to parse html in C#?

The Html Agility Pack has been mentioned before - if you are going for speed, you might also want to check out the Majestic-12 HTML parser. Its handling is rather clunky, but it delivers a really fast parsing experience.

ArrayList - How to modify a member of an object?

You can do this:

myList.get(3).setEmail("new email");

RegEx: How can I match all numbers greater than 49?

Next matches all greater or equal to 11100:

^([1-9][1-9][1-9]\d{2}\d*|[1-9][2-9]\d{3}\d*|[2-9]\d{4}\d*|\d{6}\d*)$

For greater or equal 50:

^([5-9]\d{1}\d*|\d{3}\d*)$

See pattern and modify to any number. Also it would be great to find some recursive forward/backward operators for large numbers.