Programs & Examples On #Text extraction

How can I read pdf in python?

You can use textract module in python


for install

pip install textract

for read pdf

import textract
text = textract.process('path/to/pdf/file', method='pdfminer')

For detail Textract

Extract a single (unsigned) integer from a string

You can use following function:

function extract_numbers($string)
   preg_match_all('/([\d]+)/', $string, $match);

   return $match[0];

How to extract string following a pattern with grep, regex or perl

Oops, the sed command has to precede the tidy command of course:

echo "$htmlstr" | 
sed '/type="global"/d' |
tidy -q -c -wrap 0 -numeric -asxml -utf8 --merge-divs yes --merge-spans yes 2>/dev/null |
xmlstarlet sel -N x="" -T -t -m "//x:table" -v '@name' -n

How to extract text from a PDF?

An efficient command line tool, open source, free of any fee, available on both linux & windows : simply named pdftotext. This tool is a part of the xpdf library.

Getting URL parameter in java and extract a specific text from that URL

I think the one of the easiest ways out would be to parse the string returned by URL.getQuery() as

public static Map<String, String> getQueryMap(String query) {  
    String[] params = query.split("&");  
    Map<String, String> map = new HashMap<String, String>();

    for (String param : params) {  
        String name = param.split("=")[0];  
        String value = param.split("=")[1];  
        map.put(name, value);  
    return map;  

You can use the map returned by this function to retrieve the value keying in the parameter name.

How to extract a substring using regex

Because you also ticked Scala, a solution without regex which easily deals with multiple quoted strings:

val text = "some string with 'the data i want' inside 'and even more data'"
text.split("'").zipWithIndex.filter(_._2 % 2 != 0).map(_._1)

res: Array[java.lang.String] = Array(the data i want, and even more data)

Python module for converting PDF to text

I needed to convert a specific PDF to plain text within a python module. I used PDFMiner 20110515, after reading through their tool I wrote this simple snippet:

from cStringIO import StringIO
from pdfminer.pdfinterp import PDFResourceManager, process_pdf
from pdfminer.converter import TextConverter
from pdfminer.layout import LAParams

def to_txt(pdf_path):
    input_ = file(pdf_path, 'rb')
    output = StringIO()

    manager = PDFResourceManager()
    converter = TextConverter(manager, output, laparams=LAParams())
    process_pdf(manager, converter, input_)

    return output.getvalue() 

PDF Parsing Using Python - extracting formatted and plain texts

That's a difficult problem to solve since visually similar PDFs may have a wildly differing structure depending on how they were produced. In the worst case the library would need to basically act like an OCR. On the other hand, the PDF may contain sufficient structure and metadata for easy removal of tables and figures, which the library can be tailored to take advantage of.

I'm pretty sure there are no open source tools which solve your problem for a wide variety of PDFs, but I remember having heard of commercial software claiming to do exactly what you ask for. I'm sure you'll run into them while googling.

Extracting text from a PDF file using PDFMiner in python?

Here is a working example of extracting text from a PDF file using the current version of PDFMiner(September 2016)

from pdfminer.pdfinterp import PDFResourceManager, PDFPageInterpreter
from pdfminer.converter import TextConverter
from pdfminer.layout import LAParams
from pdfminer.pdfpage import PDFPage
from io import StringIO

def convert_pdf_to_txt(path):
    rsrcmgr = PDFResourceManager()
    retstr = StringIO()
    codec = 'utf-8'
    laparams = LAParams()
    device = TextConverter(rsrcmgr, retstr, codec=codec, laparams=laparams)
    fp = open(path, 'rb')
    interpreter = PDFPageInterpreter(rsrcmgr, device)
    password = ""
    maxpages = 0
    caching = True

    for page in PDFPage.get_pages(fp, pagenos, maxpages=maxpages, password=password,caching=caching, check_extractable=True):

    text = retstr.getvalue()

    return text

PDFMiner's structure changed recently, so this should work for extracting text from the PDF files.

Edit : Still working as of the June 7th of 2018. Verified in Python Version 3.x

Edit: The solution works with Python 3.7 at October 3, 2019. I used the Python library pdfminer.six, released on November 2018.

What is CMake equivalent of 'configure --prefix=DIR && make all install '?

You can pass in any CMake variable on the command line, or edit cached variables using ccmake/cmake-gui. On the command line,

cmake -DCMAKE_INSTALL_PREFIX:PATH=/usr . && make all install

Would configure the project, build all targets and install to the /usr prefix. The type (PATH) is not strictly necessary, but would cause the Qt based cmake-gui to present the directory chooser dialog.

Some minor additions as comments make it clear that providing a simple equivalence is not enough for some. Best practice would be to use an external build directory, i.e. not the source directly. Also to use more generic CMake syntax abstracting the generator.

mkdir build && cd build && cmake -DCMAKE_INSTALL_PREFIX:PATH=/usr .. && cmake --build . --target install --config Release

You can see it gets quite a bit longer, and isn't directly equivalent anymore, but is closer to best practices in a fairly concise form... The --config is only used by multi-configuration generators (i.e. MSVC), ignored by others.

In CSS how do you change font size of h1 and h2

h1 {
  font-weight: bold;
  color: #fff;
  font-size: 32px;

h2 {
  font-weight: bold;
  color: #fff;
  font-size: 24px;

Note that after color you can use a word (e.g. white), a hex code (e.g. #fff) or RGB (e.g. rgb(255,255,255)) or RGBA (e.g. rgba(255,255,255,0.3)).

Gets byte array from a ByteBuffer in java

final ByteBuffer buffer;
if (buffer.hasArray()) {
    final byte[] array = buffer.array();
    final int arrayOffset = buffer.arrayOffset();
    return Arrays.copyOfRange(array, arrayOffset + buffer.position(),
                              arrayOffset + buffer.limit());
// do something else

UNION with WHERE clause

I would make sure you have an index on ColA, and then run both of them and time them. That would give you the best answer.

How to specify jdk path in eclipse.ini on windows 8 when path contains space

Add the entry of vm above the vm args else it will not work..! i.e `

    C:\Program Files\Java\jdk1.7.0_75\bin\javaw.exe

facet label font size

This should get you started:

R> qplot(hwy, cty, data = mpg) + 
       facet_grid(. ~ manufacturer) + 
       theme(strip.text.x = element_text(size = 8, colour = "orange", angle = 90))

See also this question: How can I manipulate the strip text of facet plots in ggplot2?

How to run a maven created jar file using just the command line

Use this command.

mvn package

to make the package jar file. Then, run this command.

java -cp target/artifactId-version-SNAPSHOT.jar package.Java-Main-File-Name

after mvn package command. Target folder with classes, test classes, jar file and other resources folder and files will be created.

type your own artifactId, version and package and java main file.

Server Error in '/' Application. ASP.NET

This wont necessarily fix the problem...but it will tell you what the real problem is.
Its currently trying to use a custom error page that doesn't exist.
If you add this line to Web.config (under system.web tag) it should give you the real error.

    <!-- added line -->
    <customErrors mode="Off"/>
    <!-- added  line -->

Can you remove elements from a std::list while iterating through it?

Removal invalidates only the iterators that point to the elements that are removed.

So in this case after removing *i , i is invalidated and you cannot do increment on it.

What you can do is first save the iterator of element that is to be removed , then increment the iterator and then remove the saved one.

Change onclick action with a Javascript function

Do not invoke the method when assigning the new onclick handler.

Simply remove the parenthesis:

document.getElementById("a").onclick = Foo;

UPDATE (due to new information):

document.getElementById("a").onclick = function () { Foo(param); };

Is div inside list allowed?

I'm starting in the webdesign universe and i used DIVs inside LIs with no problem with the semantics. I think that DIVs aren't allowed on lists, that means you can't put a DIV inside an UL, but it has no problem inserting it on a LI (because LI are just list items haha) The problem that i have been encountering is that sometimes the DIV behaves somewhat different from usual, but nothing that our good CSS can't handle haha. Anyway, sorry for my bad english and if my response wasn't helpful haha good luck!

How to remove specific object from ArrayList in Java?

If you want to remove multiple objects that are matching to the property try this.

I have used following code to remove element from object array it helped me.

In general an object can be removed in two ways from an ArrayList (or generally any List), by index (remove(int)) and by object (remove(Object)).

some time for you arrayList.remove(index)or arrayList.remove(obj.get(index)) using these lines may not work try to use following code.

for (Iterator<DetailInbox> iter = detailInboxArray.iterator(); iter.hasNext(); ) {
    DetailInbox element =;
   if (element.isSelected()) {

PHP unable to load php_curl.dll extension

Make sure to have your apache SSH dlls loading correctly. On a fresh install I had to download and load into my apache bin directory the following dll "libssh2.dll"

After ssl dll was loaded cURL was able to load with no issues.

You can download it from the link below:

CSS-moving text from left to right

Hi you can achieve your result with use of <marquee behavior="alternate"></marquee>


<div class="wrapper">
<marquee behavior="alternate"><span class="marquee">This is a marquee!</span></marquee>


    max-width: 400px;
    background: green;
    height: 40px;
    text-align: right;

.marquee {
    background: red;
    white-space: nowrap;
    -webkit-animation: rightThenLeft 4s linear;

see the demo:-

Clear ComboBox selected text

comboBox1.Text = " ";

This is the best and easiest way to set your combo box back to default settings without erasing the contents of the combo box.

no module named urllib.parse (How should I install it?)

The urlparse in Python 2.7.11 was renamed to urllib.parse in Python 3. So, if you have a code such from urlparse import urlparse, I suggest you change it to from urllib.parse import urlparse Since you are using python 2.7.5, using the below will solve your poblem

from urlparse import urlparse

Instead of from urllib.parse import urlparse

C++: Rounding up to the nearest multiple of a number

This is what I would do:

#include <cmath>

int roundUp(int numToRound, int multiple)
    // if our number is zero, return immediately
   if (numToRound == 0)
        return multiple;

    // if multiplier is zero, return immediately
    if (multiple == 0)
        return numToRound;

    // how many times are number greater than multiple
    float rounds = static_cast<float>(numToRound) / static_cast<float>(multiple);

    // determine, whether if number is multiplier of multiple
    int floorRounds = static_cast<int>(floor(rounds));

    if (rounds - floorRounds > 0)
        // multiple is not multiplier of number -> advance to the next multiplier
        return (floorRounds+1) * multiple;
        // multiple is multiplier of number -> return actual multiplier
        return (floorRounds) * multiple;

The code might not be optimal, but I prefer clean code than dry performance.

Android ListView with Checkbox and all clickable



holder.checkbox.setOnClickListener( new OnClickListener() {

                public void onClick(View v) {
                    CheckBox c = (CheckBox) v;

                    int row_id = (Integer) v.getTag();

                    checkboxes.put(row_id, c.isChecked());


How to sleep for five seconds in a batch file/cmd

Two answers:

Firstly, to delay in a batch file, simply without all the obtuse methods people have been proposing:

timeout /t <TimeoutInSeconds> [/nobreak]

Secondly, worth mentioning that while it may not do exactly what you want, using the inbuilt Windows snipping tool, you can trigger a snip on it without using the mouse. Run the snipping tool, escape out of the current snip but leave the tool running, and hit Control + Print Screen when you want the snip to occur. This shouldn't interfere with whatever it is you're trying to snip.

data type not understood


mmatrix = np.zeros((nrows, ncols))

Since the shape parameter has to be an int or sequence of ints

Otherwise you are passing ncols to np.zeros as the dtype.

How to render pdfs using C#

The easiest lib I have used is Paolo Gios's library. It's basically

Create GiosPDFDocument object
Create TextArea object
Add text, images, etc to TextArea object
Add TextArea object to PDFDocument object
Write to stream

This is a great tutorial to get you started.

How to access my localhost from another PC in LAN?

You have to edit httpd.conf and find this line: Listen

Then write down your desired IP you set for LAN. Don't use automatic IP.
e.g.: Listen

I used as my LAN IP of Windows 7. Restart Apache and enjoy sharing.

DB2 SQL error sqlcode=-104 sqlstate=42601

You miss the from clause


Load JSON text into class object in c#

I recommend you to use JSON.NET. it is an open source library to serialize and deserialize your c# objects into json and Json objects into .net objects ...

Serialization Example:

Product product = new Product();
product.Name = "Apple";
product.Expiry = new DateTime(2008, 12, 28);
product.Price = 3.99M;
product.Sizes = new string[] { "Small", "Medium", "Large" };

string json = JsonConvert.SerializeObject(product);
//  "Name": "Apple",
//  "Expiry": new Date(1230422400000),
//  "Price": 3.99,
//  "Sizes": [
//    "Small",
//    "Medium",
//    "Large"
//  ]

Product deserializedProduct = JsonConvert.DeserializeObject<Product>(json);

Performance Comparison To Other JSON serializiation Techniques enter image description here

Onclick javascript to make browser go back to previous page?

<input name="action" type="submit" value="Cancel" onclick="window.history.back();"/> 

Converting HTML string into DOM elements?

You can do it like this:

  var d=document
  return b;

var foo="<img src='//'>foo<i>bar</i>".toDOM();

node.js hash string?

function md5(a) {
    var r = 0,
        c = "";
    return h(a);

    function h(t) {
        return u(l(m(t)))

    function l(t) {
        return p(g(f(t), 8 * t.length))

    function u(t) {
        for (var e, i = r ? "0123456789ABCDEF" : "0123456789abcdef", n = "", o = 0; o < t.length; o++)
            e = t.charCodeAt(o),
            n += i.charAt(e >>> 4 & 15) + i.charAt(15 & e);
        return n

    function m(t) {
        for (var e, i, n = "", o = -1; ++o < t.length;)
            e = t.charCodeAt(o),
            i = o + 1 < t.length ? t.charCodeAt(o + 1) : 0,
            55296 <= e && e <= 56319 && 56320 <= i && i <= 57343 && (e = 65536 + ((1023 & e) << 10) + (1023 & i),
            e <= 127 ? n += String.fromCharCode(e) : e <= 2047 ? n += String.fromCharCode(192 | e >>> 6 & 31, 128 | 63 & e) : e <= 65535 ? n += String.fromCharCode(224 | e >>> 12 & 15, 128 | e >>> 6 & 63, 128 | 63 & e) : e <= 2097151 && (n += String.fromCharCode(240 | e >>> 18 & 7, 128 | e >>> 12 & 63, 128 | e >>> 6 & 63, 128 | 63 & e));
        return n

    function f(t) {
        for (var e = Array(t.length >> 2), i = 0; i < e.length; i++)
            e[i] = 0;
        for (i = 0; i < 8 * t.length; i += 8)
            e[i >> 5] |= (255 & t.charCodeAt(i / 8)) << i % 32;
        return e

    function p(t) {
        for (var e = "", i = 0; i < 32 * t.length; i += 8)
            e += String.fromCharCode(t[i >> 5] >>> i % 32 & 255);
        return e

    function g(t, e) {
        t[e >> 5] |= 128 << e % 32,
            t[14 + (e + 64 >>> 9 << 4)] = e;
        for (var i = 1732584193, n = -271733879, o = -1732584194, s = 271733878, a = 0; a < t.length; a += 16) {
            var r = i,
                c = n,
                h = o,
                l = s;
            n = E(n = E(n = E(n = E(n = N(n = N(n = N(n = N(n = C(n = C(n = C(n = C(n = S(n = S(n = S(n = S(n, o = S(o, s = S(s, i = S(i, n, o, s, t[a + 0], 7, -680876936), n, o, t[a + 1], 12, -389564586), i, n, t[a + 2], 17, 606105819), s, i, t[a + 3], 22, -1044525330), o = S(o, s = S(s, i = S(i, n, o, s, t[a + 4], 7, -176418897), n, o, t[a + 5], 12, 1200080426), i, n, t[a + 6], 17, -1473231341), s, i, t[a + 7], 22, -45705983), o = S(o, s = S(s, i = S(i, n, o, s, t[a + 8], 7, 1770035416), n, o, t[a + 9], 12, -1958414417), i, n, t[a + 10], 17, -42063), s, i, t[a + 11], 22, -1990404162), o = S(o, s = S(s, i = S(i, n, o, s, t[a + 12], 7, 1804603682), n, o, t[a + 13], 12, -40341101), i, n, t[a + 14], 17, -1502002290), s, i, t[a + 15], 22, 1236535329), o = C(o, s = C(s, i = C(i, n, o, s, t[a + 1], 5, -165796510), n, o, t[a + 6], 9, -1069501632), i, n, t[a + 11], 14, 643717713), s, i, t[a + 0], 20, -373897302), o = C(o, s = C(s, i = C(i, n, o, s, t[a + 5], 5, -701558691), n, o, t[a + 10], 9, 38016083), i, n, t[a + 15], 14, -660478335), s, i, t[a + 4], 20, -405537848), o = C(o, s = C(s, i = C(i, n, o, s, t[a + 9], 5, 568446438), n, o, t[a + 14], 9, -1019803690), i, n, t[a + 3], 14, -187363961), s, i, t[a + 8], 20, 1163531501), o = C(o, s = C(s, i = C(i, n, o, s, t[a + 13], 5, -1444681467), n, o, t[a + 2], 9, -51403784), i, n, t[a + 7], 14, 1735328473), s, i, t[a + 12], 20, -1926607734), o = N(o, s = N(s, i = N(i, n, o, s, t[a + 5], 4, -378558), n, o, t[a + 8], 11, -2022574463), i, n, t[a + 11], 16, 1839030562), s, i, t[a + 14], 23, -35309556), o = N(o, s = N(s, i = N(i, n, o, s, t[a + 1], 4, -1530992060), n, o, t[a + 4], 11, 1272893353), i, n, t[a + 7], 16, -155497632), s, i, t[a + 10], 23, -1094730640), o = N(o, s = N(s, i = N(i, n, o, s, t[a + 13], 4, 681279174), n, o, t[a + 0], 11, -358537222), i, n, t[a + 3], 16, -722521979), s, i, t[a + 6], 23, 76029189), o = N(o, s = N(s, i = N(i, n, o, s, t[a + 9], 4, -640364487), n, o, t[a + 12], 11, -421815835), i, n, t[a + 15], 16, 530742520), s, i, t[a + 2], 23, -995338651), o = E(o, s = E(s, i = E(i, n, o, s, t[a + 0], 6, -198630844), n, o, t[a + 7], 10, 1126891415), i, n, t[a + 14], 15, -1416354905), s, i, t[a + 5], 21, -57434055), o = E(o, s = E(s, i = E(i, n, o, s, t[a + 12], 6, 1700485571), n, o, t[a + 3], 10, -1894986606), i, n, t[a + 10], 15, -1051523), s, i, t[a + 1], 21, -2054922799), o = E(o, s = E(s, i = E(i, n, o, s, t[a + 8], 6, 1873313359), n, o, t[a + 15], 10, -30611744), i, n, t[a + 6], 15, -1560198380), s, i, t[a + 13], 21, 1309151649), o = E(o, s = E(s, i = E(i, n, o, s, t[a + 4], 6, -145523070), n, o, t[a + 11], 10, -1120210379), i, n, t[a + 2], 15, 718787259), s, i, t[a + 9], 21, -343485551),
                i = v(i, r),
                n = v(n, c),
                o = v(o, h),
                s = v(s, l)
        return [i, n, o, s]

    function _(t, e, i, n, o, s) {
        return v((a = v(v(e, t), v(n, s))) << (r = o) | a >>> 32 - r, i);
        var a, r

    function S(t, e, i, n, o, s, a) {
        return _(e & i | ~e & n, t, e, o, s, a)

    function C(t, e, i, n, o, s, a) {
        return _(e & n | i & ~n, t, e, o, s, a)

    function N(t, e, i, n, o, s, a) {
        return _(e ^ i ^ n, t, e, o, s, a)

    function E(t, e, i, n, o, s, a) {
        return _(i ^ (e | ~n), t, e, o, s, a)

    function v(t, e) {
        var i = (65535 & t) + (65535 & e);
        return (t >> 16) + (e >> 16) + (i >> 16) << 16 | 65535 & i
string = 'hello';

Youtube iframe wmode issue

If you are using the new asynchronous API, you will need to add the parameter like so:

<!-- YOUTUBE -->
// 2. This code loads the IFrame Player API code asynchronously.
var tag = document.createElement('script');
tag.src = "";
var firstScriptTag = document.getElementsByTagName('script')[0];
firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);

// 3. This function creates an <iframe> (and YouTube player)
//    after the API code downloads.
var player;
var initialVideo = 'ApkM4t9L5jE'; // YOUR YOUTUBE VIDEO ID
function onYouTubePlayerAPIReady() {
    console.log("onYouTubePlayerAPIReady" + initialVideo);
    player = new YT.Player('player', {
      height: '381',
      width: '681',
      wmode: 'transparent', // SECRET SAUCE HERE
      videoId: initialVideo,      
       playerVars: { 'autoplay': 1, 'rel': 0, 'wmode':'transparent' },
      events: {
        'onReady': onPlayerReady,
        'onStateChange': onPlayerStateChange

This is based on the google documentation and example here:

Symbolicating iPhone App Crash Reports

Here's another issue I have with symbolicatecrash – it won't work with Apps that have spaces in their bundle (i.e. 'Test'). Note I don't think you can have spaces in their name when submitting so you should remove these anyway, but if you already have crashes that need analysing, patch symbolicatecrash (4.3 GM) as such:

<         my $cmd = "mdfind \"kMDItemContentType == && kMDItemFSName == $\"";
>         my $cmd = "mdfind \"kMDItemContentType == && kMDItemFSName == '$'\"";
<             my $cmd = "find \"$archive_path/Products\" -name $";
>             my $cmd = "find \"$archive_path/Products\" -name \"$\"";

What is Python Whitespace and how does it work?

Whitespace just means characters which are used for spacing, and have an "empty" representation. In the context of python, it means tabs and spaces (it probably also includes exotic unicode spaces, but don't use them). The definitive reference is here:

I'm not sure exactly how to use it.

Put it at the front of the line you want to indent. If you mix spaces and tabs, you'll likely see funky results, so stick with one or the other. (The python community usually follows PEP8 style, which prescribes indentation of four spaces).

You need to create a new indent level after each colon:

for x in range(0, 50):
    print x
    print 2*x

print x

In this code, the first two print statements are "inside" the body of the for statement because they are indented more than the line containing the for. The third print is outside because it is indented less than the previous (nonblank) line.

If you don't indent/unindent consistently, you will get indentation errors. In addition, all compound statements (i.e. those with a colon) can have the body supplied on the same line, so no indentation is required, but the body must be composed of a single statement.

Finally, certain statements, like lambda feature a colon, but cannot have a multiline block as the body.

Getting request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource

Basically, to make a cross domain AJAX requests, the requested server should allow the cross origin sharing of resources (CORS). You can read more about that from here:

In your scenario, you are setting the headers in the client which in fact needs to be set into http://localhost:8080/app server side code.

If you are using PHP Apache server, then you will need to add following in your .htaccess file:

Header set Access-Control-Allow-Origin "*"

How do CORS and Access-Control-Allow-Headers work?

Yes, you need to have the header Access-Control-Allow-Origin: or Access-Control-Allow-Origin: * on both the OPTIONS response and the POST response. You should include the header Access-Control-Allow-Credentials: true on the POST response as well.

Your OPTIONS response should also include the header Access-Control-Allow-Headers: origin, content-type, accept to match the requested header.

Equal height rows in CSS Grid Layout

Short Answer

If the goal is to create a grid with equal height rows, where the tallest cell in the grid sets the height for all rows, here's a quick and simple solution:

  • Set the container to grid-auto-rows: 1fr

How it works

Grid Layout provides a unit for establishing flexible lengths in a grid container. This is the fr unit. It is designed to distribute free space in the container and is somewhat analogous to the flex-grow property in flexbox.

If you set all rows in a grid container to 1fr, let's say like this:

grid-auto-rows: 1fr;

... then all rows will be equal height.

It doesn't really make sense off-the-bat because fr is supposed to distribute free space. And if several rows have content with different heights, then when the space is distributed, some rows would be proportionally smaller and taller.

Except, buried deep in the grid spec is this little nugget:

7.2.3. Flexible Lengths: the fr unit


When the available space is infinite (which happens when the grid container’s width or height is indefinite), flex-sized (fr) grid tracks are sized to their contents while retaining their respective proportions.

The used size of each flex-sized grid track is computed by determining the max-content size of each flex-sized grid track and dividing that size by the respective flex factor to determine a “hypothetical 1fr size”.

The maximum of those is used as the resolved 1fr length (the flex fraction), which is then multiplied by each grid track’s flex factor to determine its final size.

So, if I'm reading this correctly, when dealing with a dynamically-sized grid (e.g., the height is indefinite), grid tracks (rows, in this case) are sized to their contents.

The height of each row is determined by the tallest (max-content) grid item.

The maximum height of those rows becomes the length of 1fr.

That's how 1fr creates equal height rows in a grid container.

Why flexbox isn't an option

As noted in the question, equal height rows are not possible with flexbox.

Flex items can be equal height on the same row, but not across multiple rows.

This behavior is defined in the flexbox spec:

6. Flex Lines

In a multi-line flex container, the cross size of each line is the minimum size necessary to contain the flex items on the line.

In other words, when there are multiple lines in a row-based flex container, the height of each line (the "cross size") is the minimum height necessary to contain the flex items on the line.

How to parse JSON array in jQuery?

Your data is a string of '[{}]' at that point in time, you can eval it like so:

function(data) {
    data = eval( '(' + data + ')' )

However this method is far from secure, this will be a bit more work but the best practice is to parse it with Crockford's JSON parser:

Another method would be $.getJSON and you'll need to set the dataType to json for a pure jQuery reliant method.

How to simulate a mouse click using JavaScript?

Here's a pure JavaScript function which will simulate a click (or any mouse event) on a target element:

function simulatedClick(target, options) {

  var event = target.ownerDocument.createEvent('MouseEvents'),
      options = options || {},
      opts = { // These are the default values, set up for un-modified left clicks
        type: 'click',
        canBubble: true,
        cancelable: true,
        view: target.ownerDocument.defaultView,
        detail: 1,
        screenX: 0, //The coordinates within the entire page
        screenY: 0,
        clientX: 0, //The coordinates within the viewport
        clientY: 0,
        ctrlKey: false,
        altKey: false,
        shiftKey: false,
        metaKey: false, //I *think* 'meta' is 'Cmd/Apple' on Mac, and 'Windows key' on Win. Not sure, though!
        button: 0, //0 = left, 1 = middle, 2 = right
        relatedTarget: null,

  //Merge the options with the defaults
  for (var key in options) {
    if (options.hasOwnProperty(key)) {
      opts[key] = options[key];

  //Pass in the options

  //Fire the event

Here's a working example:

You can simulate a click on any element in the DOM. Something like simulatedClick(document.getElementById('yourButtonId')) would work.

You can pass in an object into options to override the defaults (to simulate which mouse button you want, whether Shift/Alt/Ctrl are held, etc. The options it accepts are based on the MouseEvents API.

I've tested in Firefox, Safari and Chrome. Internet Explorer might need special treatment, I'm not sure.

Java Initialize an int array in a constructor

in your constructor you are creating another int array:

 public Date(){
  int[] data = {0,0,0};

Try this:

 data = {0,0,0};

NOTE: By the way you do NOT need to initialize your array elements if it is declared as an instance variable. Instance variables automatically get their default values, which for an integer array, the default values are all zeroes.

If you had locally declared array though they you would need to initialize each element.

How to create large PDF files (10MB, 50MB, 100MB, 200MB, 500MB, 1GB, etc.) for testing purposes?

Have you tried using cat to combine the files?

cat 10MB.pdf 10MB.pdf > 20MB.pdf

That should result in a 20MB file.

How to construct a set out of list items in python?

The most direct solution is this:

s = set(filelist)

The issue in your original code is that the values weren't being assigned to the set. Here's the fixed-up version of your code:

s = set()
for filename in filelist:

Sql script to find invalid email addresses

Here is a quick and easy solution:

CREATE FUNCTION dbo.vaValidEmail(@EMAIL varchar(100))

RETURNS bit as
  DECLARE @bitRetVal as Bit
  IF (@EMAIL <> '' AND @EMAIL NOT LIKE '_%@__%.__%')
     SET @bitRetVal = 0  -- Invalid
    SET @bitRetVal = 1   -- Valid
  RETURN @bitRetVal

Then you can find all rows by using the function:

SELECT * FROM users WHERE dbo.vaValidEmail(email) = 0

If you are not happy with creating a function in your database, you can use the LIKE-clause directly in your query:

SELECT * FROM users WHERE email NOT LIKE '_%@__%.__%'


remove table row with specific id


Might not work with numeric id's though.

Convert stdClass object to array in PHP

You can convert an std object to array like this:

$objectToArray = (array)$object;

Interpreting segfault messages

Let's go to the source -- 2.6.32, for example. The message is printed by show_signal_msg() function in arch/x86/mm/fault.c if the show_unhandled_signals sysctl is set.

"error" is not an errno nor a signal number, it's a "page fault error code" -- see definition of enum x86_pf_error_code.

"[7fa44d2f8000+f6f000]" is starting address and size of virtual memory area where offending object was mapped at the time of crash. Value of "ip" should fit in this region. With this info in hand, it should be easy to find offending code in gdb.

JavaScript validation for empty input field

Add an id "question" to your input element and then try this:

   if( document.getElementById('question').value === '' ){

The reason your current code doesn't work is because you don't have a FORM tag in there. Also, lookup using "name" is not recommended as its deprecated.

See @Paul Dixon's answer in this post : Is the 'name' attribute considered outdated for <a> anchor tags?

error: passing xxx as 'this' argument of xxx discards qualifiers

Let's me give a more detail example. As to the below struct:

struct Count{
    uint32_t c;

    Count(uint32_t i=0):c(i){}

    uint32_t getCount(){
        return c;

    uint32_t add(const Count& count){
        uint32_t total = c + count.getCount();
        return total;

enter image description here

As you see the above, the IDE(CLion), will give tips Non-const function 'getCount' is called on the const object. In the method add count is declared as const object, but the method getCount is not const method, so count.getCount() may change the members in count.

Compile error as below(core message in my compiler):

error: passing 'const xy_stl::Count' as 'this' argument discards qualifiers [-fpermissive]

To solve the above problem, you can:

  1. change the method uint32_t getCount(){...} to uint32_t getCount() const {...}. So count.getCount() won't change the members in count.


  1. change uint32_t add(const Count& count){...} to uint32_t add(Count& count){...}. So count don't care about changing members in it.

As to you problem, objects in the std::set are stored as const StudentT, but the method getId and getName are not const, so you give the above error.

You can also see this question Meaning of 'const' last in a function declaration of a class? for more detail.

Better/Faster to Loop through set or list?

set is what you want, so you should use set. Trying to be clever introduces subtle bugs like forgetting to add one tomax(mylist)! Code defensively. Worry about what's faster when you determine that it is too slow.

range(min(mylist), max(mylist) + 1)  # <-- don't forget to add 1

how to get domain name from URL


usage of this javascript regex ignores www and following dot, while retaining the domain intact. also properly matches no www and cc tld

Database Structure for Tree Data Structure

If you have to use Relational DataBase to organize tree data structure then Postgresql has cool ltree module that provides data type for representing labels of data stored in a hierarchical tree-like structure. You can get the idea from there.(For more information see:

In common LDAP is used to organize records in hierarchical structure.

Import error No module named skimage

Hey this is pretty simple to solve this error.Just follow this steps:

First uninstall any existing installation:

pip uninstall scikit-image

or, on conda-based systems:

conda uninstall scikit-image

Now, clone scikit-image on your local computer, and install:

git clone
cd scikit-image
pip install -e .

To update the installation:

git pull  # Grab latest source
pip install -e .  # Reinstall

For other os and manual process please check this Link.

Re-render React component when prop changes

componentWillReceiveProps(nextProps) { // your code here}

I think that is the event you need. componentWillReceiveProps triggers whenever your component receive something through props. From there you can have your checking then do whatever you want to do.

Object passed as parameter to another class, by value or reference?

I found the other examples unclear, so I did my own test which confirmed that a class instance is passed by reference and as such actions done to the class will affect the source instance.

In other words, my Increment method modifies its parameter myClass everytime its called.

class Program
    static void Main(string[] args)
        MyClass myClass = new MyClass();
        Console.WriteLine(myClass.Value);  // Displays 1
        Console.WriteLine(myClass.Value);  // Displays 2
        Console.WriteLine(myClass.Value);  // Displays 3           
        Console.WriteLine(myClass.Value);  // Displays 4
        Console.WriteLine("Hit Enter to exit.");

    public static void Increment(MyClass myClassRef)

public class MyClass
    public int Value {get;set;}
    public MyClass()
        Value = 1;

WebForms UnobtrusiveValidationMode requires a ScriptResourceMapping for 'jquery'. Please add a ScriptResourceMapping named jquery(case-sensitive)

You need a web.config key to enable the pre 4.5 validation mode.

More Info on ValidationSettings:UnobtrusiveValidationMode:

Specifies how ASP.NET globally enables the built-in validator controls to use unobtrusive JavaScript for client-side validation logic.

Type: UnobtrusiveValidationMode

Default value: None

Remarks: If this key value is set to "None" [default], the ASP.NET application will use the pre-4.5 behavior (JavaScript inline in the pages) for client-side validation logic. If this key value is set to "WebForms", ASP.NET uses HTML5 data-attributes and late bound JavaScript from an added script reference for client-side validation logic.


      <add key="ValidationSettings:UnobtrusiveValidationMode" value="None" />

file_get_contents() how to fix error "Failed to open stream", "No such file"

I hope below solution will work for you all as I was having the same problem with my websites...

For : $json = json_decode(file_get_contents('http://...'));

Replace with below query

$Details= unserialize(file_get_contents('http://......'));

Python string prints as [u'String']

import json, ast
r = {u'name': u'A', u'primary_key': 1}

will print

{'name': 'A', 'primary_key': 1}

What is the proper way to check and uncheck a checkbox in HTML5?

<input type="checkbox" checked />

HTML5 does not require attributes to have values

Difference between style = "position:absolute" and style = "position:relative"

OK, very obvious answer here... basically relative position is relative to previous element or window, while absolute don't care about the other elements unless it's a parent if you using top and left...

Look at the example I create for you to show the differences...

enter image description here

Also you can see it in action, using the css I create for you, you can see how absolute and relative positions behave:

.parent {_x000D_
  display: inline-block;_x000D_
  width: 180px;_x000D_
  height: 160px;_x000D_
  border: 1px solid black;_x000D_
.black {_x000D_
  position: relative;_x000D_
  width: 100px;_x000D_
  height: 30px;_x000D_
  margin: 5px;_x000D_
  border: 1px solid black;_x000D_
.red {_x000D_
  width: 100px;_x000D_
  height: 30px;_x000D_
  margin: 5px;_x000D_
  top: 16px;_x000D_
  background: red;_x000D_
  border: 1px solid red;_x000D_
.red-1 {_x000D_
  position: relative;_x000D_
.red-2 {_x000D_
  position: absolute;_x000D_
<div class="parent">_x000D_
  <div class="black">_x000D_
  <div class="red red-1">_x000D_
<div class="parent">_x000D_
  <div class="black">_x000D_
  <div class="red red-2">_x000D_

Create html documentation for C# code

In 2017, the thing closest to Javadoc would probably DocFx which was developed by Microsoft and comes as a Commmand-Line-Tool as well as a VS2017 plugin.

It's still a little rough around the edges but it looks promising.

Another alternative would be Wyam which has a documentation recipe suitable for net aplications. Look at the cake documentation for an example.

Modifying list while iterating

This slice syntax makes a copy of the list and does what you want:

l  = range(100)  
for i in l[:]:  
    print i,  
    print l.pop(0),  
    print l.pop(0)

How to use FormData for AJAX file upload?

$('#form-withdraw').submit(function(event) {

    //prevent the form from submitting by default

    var formData = new FormData($(this)[0]);

        url: 'function/ajax/topup.php',
        type: 'POST',
        data: formData,
        async: false,
        cache: false,
        contentType: false,
        processData: false,
        success: function (returndata) {
          if(returndata == 'success')
              title: "Great",
              text: "Your Form has Been Transfer, We will comfirm the amount you reload in 3 hours",
              type: "success",
              showCancelButton: false,
              confirmButtonColor: "#DD6B55",
              confirmButtonText: "OK",
              closeOnConfirm: false
              window.location.href = '/transaction.php';

          else if(returndata == 'Offline')
              sweetAlert("Offline", "Please use other payment method", "error");


How can I put CSS and HTML code in the same file?

You can include CSS styles in an html document with <style></style> tags.


  .myClass { background: #f00; }

  .myOtherClass { font-size: 12px; }

How to reference a file for variables using Bash?

Converting parameter file to Environment variables

Usually I go about parsing instead of sourcing, to avoid complexities of certain artifacts in my file. It also offers me ways to specially handle quotes and other things. My main aim is to keep whatever comes after the '=' as a literal, even the double quotes and spaces.


function cntpars() {
  echo "  > Count: $#"
  echo "  > Pars : $*"
  echo "  > par1 : $1"
  echo "  > par2 : $2"

  if [[ $# = 1 && $1 = "value content" ]]; then
    echo "  > PASS"
    echo "  > FAIL"
    return 1

function readpars() {
  while read -r line ; do
    key=$(echo "${line}" | sed -e 's/^\([^=]*\)=\(.*\)$/\1/')
    val=$(echo "${line}" | sed -e 's/^\([^=]*\)=\(.*\)$/\2/' -e 's/"/\\"/g')
    eval "${key}=\"${val}\""
  done << EOF
var1="value content"
var2=value content

# Option 1: Will Pass
echo "eval \"cntpars \$var1\""
eval "cntpars $var1"

# Option 2: Will Fail
echo "cntpars \$var1"
cntpars $var1

# Option 3: Will Fail
echo "cntpars \"\$var1\""
cntpars "$var1"

# Option 4: Will Pass
echo "cntpars \"\$var2\""
cntpars "$var2"

Note the little trick I had to do to consider my quoted text as a single parameter with space to my cntpars function. There was one extra level of evaluation required. If I wouldn't do this, as in Option 2, I would have passed 2 parameters as follows:

  • "value
  • content"

Double quoting during command execution causes the double quotes from the parameter file to be kept. Hence the 3rd Option also fails.

The other option would be of course to just simply not provide variables in double quotes, as in Option 4, and then just to make sure that you quote them when needed.

Just something to keep in mind.

Real-time lookup

Another thing I like to do is to do a real-time lookup, avoiding the use of environment variables:

lookup() {
if [[ -z "$1" ]] ; then
  echo ""
  ${AWK} -v "id=$1" 'BEGIN { FS = "=" } $1 == id { print $2 ; exit }' $2

MY_LOCAL_VAR=$(lookup CONFIG_VAR filename.cfg)
echo "${MY_LOCAL_VAR}"

Not the most efficient, but with smaller files works very cleanly.

How to "scan" a website (or page) for info, and bring it into my program?

You may use an html parser (many useful links here: java html parser).

The process is called 'grabbing website content'. Search 'grab website content java' for further invertigation.

Is there a splice method for strings?


This is of course not the best way to "splice" a string, I had given this as an example of how the implementation would be, which is flawed and very evident from a split(), splice() and join(). For a far better implementation, see Louis's method.

No, there is no such thing as a String.splice, but you can try this:

newStr = str.split(''); // or newStr = [...str];
newStr = newStr.join('');

I realise there is no splice function as in Arrays, so you have to convert the string into an array. Hard luck...

How to define relative paths in Visual Studio Project?

I have used a syntax like this before:




As other have pointed out, the starting directory is the one your project file is in(vcproj or vcxproj), not where your main code is located.

Download files from server php

Here is the code that will not download courpt files

$filename = "myfile.jpg";
$file = "/uploads/images/".$filename;

header('Content-type: application/octet-stream');
header("Content-Type: ".mime_content_type($file));
header("Content-Disposition: attachment; filename=".$filename);
while (ob_get_level()) {

I have included mime_content_type which will return content type of file .

To prevent from corrupt file download i have added ob_get_level() and ob_end_clean();

How to convert an ArrayList containing Integers to primitive int array?

Java 8:

int[] intArr =>i).toArray();

caching JavaScript files

or in the .htaccess file

AddOutputFilter DEFLATE css js
ExpiresActive On
ExpiresByType application/x-javascript A2592000

How can I fix WebStorm warning "Unresolved function or method" for "require" (Firefox Add-on SDK)

Disable JetBrains Inspections and get the ESLint plugin.

The only thing that File | Invalidate caches and restart does for me is reset it long enough to trick me into thinking the error is gone. Once the inspections run again the error comes back like a gift that keeps on giving.

I saved myself all that frustration by disabling all JetBrains inspections (Editor > Inspections > uncheck JavaScript) Then I installed the ESLint plugin.

The inspection that causes "Unresolved function method" can be turned off by going to JetBrains inspections (Editor > Inspections > JavaScript) and searching for "Unresolved Javascript" and turning off "Unresolved Javascript function" and "Unresolved Javascript variable"

I killed them all and have edited my code hassle free ever since.

Android camera android.hardware.Camera deprecated

Answers provided here as which camera api to use are wrong. Or better to say they are insufficient.

Some phones (for example Samsung Galaxy S6) could be above api level 21 but still may not support Camera2 api.

CameraCharacteristics mCameraCharacteristics = mCameraManager.getCameraCharacteristics(mCameraId);
Integer level = mCameraCharacteristics.get(CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL);
if (level == null || level == CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_LEGACY) {
    return false;

CameraManager class in Camera2Api has a method to read camera characteristics. You should check if hardware wise device is supporting Camera2 Api or not.

But there are more issues to handle if you really want to make it work for a serious application: Like, auto-flash option may not work for some devices or battery level of the phone might create a RuntimeException on Camera or phone could return an invalid camera id and etc.

So best approach is to have a fallback mechanism as for some reason Camera2 fails to start you can try Camera1 and if this fails as well you can make a call to Android to open default Camera for you.

java.sql.SQLException: Missing IN or OUT parameter at index:: 1

In your INSERT statements:

INSERT INTO employee(hans,germany) values(?,?)

You've got your values where your field names belong. Change it to be:

INSERT INTO employee(emp_name,emp_address) values(?,?)

If you were to run that statement from a SQL prompt, it would look like this:

INSERT INTO employee(emp_name,emp_address) values('hans','germany');

Note that you'd need to put single quotes around the string/varchar values.

Additionally, you are also not adding any parameters to your prepared statement. That is what's actually causing the error you're seeing. Try this:

PreparedStatement ps = con.prepareStatement(inserting); 
ps.setString(1, "hans");
ps.setString(2, "germany");

Also (according to Oracle), you can use "execute" for any SQL statement. Using "executeUpdate" would also be valid in this situation, which would return an integer to indicate the number of rows affected.

Download JSON object as a file from browser

This is how I solved it for my application:

HTML: <a id="downloadAnchorElem" style="display:none"></a>

JS (pure JS, not jQuery here):

var dataStr = "data:text/json;charset=utf-8," + encodeURIComponent(JSON.stringify(storageObj));
var dlAnchorElem = document.getElementById('downloadAnchorElem');
dlAnchorElem.setAttribute("href",     dataStr     );
dlAnchorElem.setAttribute("download", "scene.json");;

In this case, storageObj is the js object you want to store, and "scene.json" is just an example name for the resulting file.

This approach has the following advantages over other proposed ones:

  • No HTML element needs to be clicked
  • Result will be named as you want it
  • no jQuery needed

I needed this behavior without explicit clicking since I want to trigger the download automatically at some point from js.

JS solution (no HTML required):

  function downloadObjectAsJson(exportObj, exportName){
    var dataStr = "data:text/json;charset=utf-8," + encodeURIComponent(JSON.stringify(exportObj));
    var downloadAnchorNode = document.createElement('a');
    downloadAnchorNode.setAttribute("href",     dataStr);
    downloadAnchorNode.setAttribute("download", exportName + ".json");
    document.body.appendChild(downloadAnchorNode); // required for firefox;

jQuery Get Selected Option From Dropdown

If you are in event context, in jQuery, you can retrieve the selected option element using :
$(this).find('option:selected') like this :

$('dropdown_selector').change(function() {
    //Use $option (with the "$") to see that the variable is a jQuery object
    var $option = $(this).find('option:selected');
    //Added with the EDIT
    var value = $option.val();//to get content of "value" attrib
    var text = $option.text();//to get <option>Text</option> content


As mentioned by PossessWithin, My answer just answer to the question : How to select selected "Option".

Next, to get the option value, use option.val().

extract the date part from DateTime in C#

DateTime d = DateTime.Today.Date;
Console.WriteLine(d.ToShortDateString()); // outputs just date

if you want to compare dates, ignoring the time part, make an use of DateTime.Year and DateTime.DayOfYear properties.

code snippet

DateTime d1 = DateTime.Today;
DateTime d2 = DateTime.Today.AddDays(3);
if (d1.Year < d2.Year)
    Console.WriteLine("d1 < d2");
    if (d1.DayOfYear < d2.DayOfYear)
        Console.WriteLine("d1 < d2");

PHP Fatal error: Call to undefined function mssql_connect()

I am using IIS and mysql (directly downloaded, without wamp or xampp) My php was installed in c:\php I was getting the error of "call to undefined function mysql_connect()" For me the change of extension_dir worked. This is what I did. In the php.ini, Originally, I had this line

; On windows: extension_dir = "ext"

I changed it to:

; On windows: extension_dir = "C:\php\ext"

And it worked. Of course, I did the other things also like uncommenting the dll extensions etc, as explained in others remarks.

How to do a simple file search in cmd

dir /s *foo* searches in current folder and sub folders.

It finds directories as well as files.

where /s means(documentation):

/s Lists every occurrence of the specified file name within the specified directory and all subdirectories.

Assign output of os.system to a variable and prevent it from being displayed on the screen

The commands module is a reasonably high-level way to do this:

import commands
status, output = commands.getstatusoutput("cat /etc/services")

status is 0, output is the contents of /etc/services.

How To Upload Files on GitHub

To upload files to your repo without using the command-line, simply type this after your repository name in the browser:

and then drag and drop your files.(provided you are on github and the repository has been created beforehand)

How do I concatenate two arrays in C#?

This is it:

using System.Linq;

int[] array1 = { 1, 3, 5 };
int[] array2 = { 0, 2, 4 };

// Concatenate array1 and array2.
var result1 = array1.Concat(array2);

How to pass arguments and redirect stdin from a file to program run in gdb?

Start GDB on your project.

  1. Go to project directory, where you've already compiled the project executable. Issue the command gdb and the name of the executable as below:

    gdb projectExecutablename

This starts up gdb, prints the following: GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.04) 7.11.1 Copyright (C) 2016 Free Software Foundation, Inc. ................................................. Type "apropos word" to search for commands related to "word"... Reading symbols from projectExecutablename...done. (gdb)

  1. Before you start your program running, you want to set up your breakpoints. The break command allows you to do so. To set a breakpoint at the beginning of the function named main:

    (gdb) b main

  2. Once you've have the (gdb) prompt, the run command starts the executable running. If the program you are debugging requires any command-line arguments, you specify them to the run command. If you wanted to run my program on the "xfiles" file (which is in a folder "mulder" in the project directory), you'd do the following:

    (gdb) r mulder/xfiles

Hope this helps.

Disclaimer: This solution is not mine, it is adapted from This short guide to gdb was, most probably, developed at Stanford University.

Switch statement for string matching in JavaScript

Might be too late and all, but I liked this in case assignment :)

function extractParameters(args) {
    function getCase(arg, key) {
        return arg.match(new RegExp(`${key}=(.*)`)) || {};

    args.forEach((arg) => {
        console.log("arg: " + arg);
        let match;
        switch (arg) {
            case (match = getCase(arg, "--user")).input:
            case (match = getCase(arg, "-u")).input:
                userName = match[1];

            case (match = getCase(arg, "--password")).input:
            case (match = getCase(arg, "-p")).input:
                password = match[1];

            case (match = getCase(arg, "--branch")).input:
            case (match = getCase(arg, "-b")).input:
                branch = match[1];

you could event take it further, and pass a list of option and handle the regex with |

Insert line after first match using sed

The awk variant :

awk '1;/CLIENTSCRIPT=/{print "CLIENTSCRIPT2=\"hello\""}' file

How do I find the location of Python module sources?

In an IDE like Spyder, import the module and then run the module individually. enter image description here

How can the Euclidean distance be calculated with NumPy?

I want to expound on the simple answer with various performance notes. np.linalg.norm will do perhaps more than you need:

dist = numpy.linalg.norm(a-b)

Firstly - this function is designed to work over a list and return all of the values, e.g. to compare the distance from pA to the set of points sP:

sP = set(points)
pA = point
distances = np.linalg.norm(sP - pA, ord=2, axis=1.)  # 'distances' is a list

Remember several things:

  • Python function calls are expensive.
  • [Regular] Python doesn't cache name lookups.


def distance(pointA, pointB):
    dist = np.linalg.norm(pointA - pointB)
    return dist

isn't as innocent as it looks.

>>> dis.dis(distance)
  2           0 LOAD_GLOBAL              0 (np)
              2 LOAD_ATTR                1 (linalg)
              4 LOAD_ATTR                2 (norm)
              6 LOAD_FAST                0 (pointA)
              8 LOAD_FAST                1 (pointB)
             10 BINARY_SUBTRACT
             12 CALL_FUNCTION            1
             14 STORE_FAST               2 (dist)

  3          16 LOAD_FAST                2 (dist)
             18 RETURN_VALUE

Firstly - every time we call it, we have to do a global lookup for "np", a scoped lookup for "linalg" and a scoped lookup for "norm", and the overhead of merely calling the function can equate to dozens of python instructions.

Lastly, we wasted two operations on to store the result and reload it for return...

First pass at improvement: make the lookup faster, skip the store

def distance(pointA, pointB, _norm=np.linalg.norm):
    return _norm(pointA - pointB)

We get the far more streamlined:

>>> dis.dis(distance)
  2           0 LOAD_FAST                2 (_norm)
              2 LOAD_FAST                0 (pointA)
              4 LOAD_FAST                1 (pointB)
              6 BINARY_SUBTRACT
              8 CALL_FUNCTION            1
             10 RETURN_VALUE

The function call overhead still amounts to some work, though. And you'll want to do benchmarks to determine whether you might be better doing the math yourself:

def distance(pointA, pointB):
    return (
        ((pointA.x - pointB.x) ** 2) +
        ((pointA.y - pointB.y) ** 2) +
        ((pointA.z - pointB.z) ** 2)
    ) ** 0.5  # fast sqrt

On some platforms, **0.5 is faster than math.sqrt. Your mileage may vary.

**** Advanced performance notes.

Why are you calculating distance? If the sole purpose is to display it,

 print("The target is %.2fm away" % (distance(a, b)))

move along. But if you're comparing distances, doing range checks, etc., I'd like to add some useful performance observations.

Let’s take two cases: sorting by distance or culling a list to items that meet a range constraint.

# Ultra naive implementations. Hold onto your hat.

def sort_things_by_distance(origin, things):
    return things.sort(key=lambda thing: distance(origin, thing))

def in_range(origin, range, things):
    things_in_range = []
    for thing in things:
        if distance(origin, thing) <= range:

The first thing we need to remember is that we are using Pythagoras to calculate the distance (dist = sqrt(x^2 + y^2 + z^2)) so we're making a lot of sqrt calls. Math 101:

dist = root ( x^2 + y^2 + z^2 )
dist^2 = x^2 + y^2 + z^2
sq(N) < sq(M) iff M > N
sq(N) > sq(M) iff N > M
sq(N) = sq(M) iff N == M

In short: until we actually require the distance in a unit of X rather than X^2, we can eliminate the hardest part of the calculations.

# Still naive, but much faster.

def distance_sq(left, right):
    """ Returns the square of the distance between left and right. """
    return (
        ((left.x - right.x) ** 2) +
        ((left.y - right.y) ** 2) +
        ((left.z - right.z) ** 2)

def sort_things_by_distance(origin, things):
    return things.sort(key=lambda thing: distance_sq(origin, thing))

def in_range(origin, range, things):
    things_in_range = []

    # Remember that sqrt(N)**2 == N, so if we square
    # range, we don't need to root the distances.
    range_sq = range**2

    for thing in things:
        if distance_sq(origin, thing) <= range_sq:

Great, both functions no-longer do any expensive square roots. That'll be much faster. We can also improve in_range by converting it to a generator:

def in_range(origin, range, things):
    range_sq = range**2
    yield from (thing for thing in things
                if distance_sq(origin, thing) <= range_sq)

This especially has benefits if you are doing something like:

if any(in_range(origin, max_dist, things)):

But if the very next thing you are going to do requires a distance,

for nearby in in_range(origin, walking_distance, hotdog_stands):
    print("%s %.2fm" % (, distance(origin, nearby)))

consider yielding tuples:

def in_range_with_dist_sq(origin, range, things):
    range_sq = range**2
    for thing in things:
        dist_sq = distance_sq(origin, thing)
        if dist_sq <= range_sq: yield (thing, dist_sq)

This can be especially useful if you might chain range checks ('find things that are near X and within Nm of Y', since you don't have to calculate the distance again).

But what about if we're searching a really large list of things and we anticipate a lot of them not being worth consideration?

There is actually a very simple optimization:

def in_range_all_the_things(origin, range, things):
    range_sq = range**2
    for thing in things:
        dist_sq = (origin.x - thing.x) ** 2
        if dist_sq <= range_sq:
            dist_sq += (origin.y - thing.y) ** 2
            if dist_sq <= range_sq:
                dist_sq += (origin.z - thing.z) ** 2
                if dist_sq <= range_sq:
                    yield thing

Whether this is useful will depend on the size of 'things'.

def in_range_all_the_things(origin, range, things):
    range_sq = range**2
    if len(things) >= 4096:
        for thing in things:
            dist_sq = (origin.x - thing.x) ** 2
            if dist_sq <= range_sq:
                dist_sq += (origin.y - thing.y) ** 2
                if dist_sq <= range_sq:
                    dist_sq += (origin.z - thing.z) ** 2
                    if dist_sq <= range_sq:
                        yield thing
    elif len(things) > 32:
        for things in things:
            dist_sq = (origin.x - thing.x) ** 2
            if dist_sq <= range_sq:
                dist_sq += (origin.y - thing.y) ** 2 + (origin.z - thing.z) ** 2
                if dist_sq <= range_sq:
                    yield thing
        ... just calculate distance and range-check it ...

And again, consider yielding the dist_sq. Our hotdog example then becomes:

# Chaining generators
info = in_range_with_dist_sq(origin, walking_distance, hotdog_stands)
info = (stand, dist_sq**0.5 for stand, dist_sq in info)
for stand, dist in info:
    print("%s %.2fm" % (stand, dist))

How to check if all inputs are not empty with jQuery

$('input').each(function() {
    if ($(this).val() != '') {
        console.log('all inputs filled');
        console.log('theres an empty input');
        return false

you might want to wrap this in a keyup function

Adding JPanel to JFrame

public class Test{

Test2 test = new Test2();
JFrame frame = new JFrame();

frame.setLayout(new BorderLayout());
frame.add(test, BorderLayout.CENTER);


//public class Test2{
public class Test2 extends JPanel {

//JPanel test2 = new JPanel();


How to inject window into a service?

There is an opportunity for direct access to the object of window through the document

document.defaultView == window

how to pass data in an hidden field from one jsp page to another?

To pass the value you must included the hidden value value="hiddenValue" in the <input> statement like so:

<input type="hidden" id="thisField" name="inputName" value="hiddenValue">

Then you recuperate the hidden form value in the same way that you recuperate the value of visible input fields, by accessing the parameter of the request object. Here is an example:

This code goes on the page where you want to hide the value.

<form action="anotherPage.jsp" method="GET">
    <input type="hidden" id="thisField" name="inputName" value="hiddenValue">
<input type="submit">   

Then on the 'anotherPage.jsp' page you recuperate the value by calling the getParameter(String name) method of the implicit request object, as so:

<% String hidden = request.getParameter("inputName"); %>
The Hidden Value is <%=hidden %>

The output of the above script will be:

The Hidden Value is hiddenValue 

Updating a dataframe column in spark

DataFrames are based on RDDs. RDDs are immutable structures and do not allow updating elements on-site. To change values, you will need to create a new DataFrame by transforming the original one either using the SQL-like DSL or RDD operations like map.

A highly recommended slide deck: Introducing DataFrames in Spark for Large Scale Data Science.

Finding version of Microsoft C++ compiler from command-line (for makefiles)

Have a look at C++11 Features (Modern C++)

and section "Quick Reference Guide to Visual C++ Version Numbers" ...

IIS: Idle Timeout vs Recycle

From here:

One way to conserve system resources is to configure idle time-out settings for the worker processes in an application pool. When these settings are configured, a worker process will shut down after a specified period of inactivity. The default value for idle time-out is 20 minutes.

Also check Why is the IIS default app pool recycle set to 1740 minutes?

If you have a just a few sites on your server and you want them to always load fast then set this to zero. Otherwise, when you have 20 minutes without any traffic then the app pool will terminate so that it can start up again on the next visit. The problem is that the first visit to an app pool needs to create a new w3wp.exe worker process which is slow because the app pool needs to be created, ASP.NET or another framework needs to be loaded, and then your application needs to be loaded. That can take a few seconds. Therefore I set that to 0 every chance I have, unless it’s for a server that hosts a lot of sites that don’t always need to be running.

Unit test naming best practices

I use Given-When-Then concept. Take a look at this short article Article describes this concept in terms of BDD, but you can use it in TDD as well without any changes.

How to list all dates between two dates

I made a calendar using:

then a Store procedure passing two dates and thats all:


@FEC_FIN date

How to make android listview scrollable?

This is my working code. you may try with this.


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout  xmlns:android=""

        <TextView android:id="@+id/tvEmpId"
            <TextView android:id="@+id/tvNameEmp"


<RelativeLayout xmlns:android=""
    android:orientation="vertical" >
        android:orientation="vertical" >

        ................... others components here............................


Adapter class :

import java.util.List;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

public class ListViewAdapter extends BaseAdapter {
    private Context context;
    private List<EmployeeBean> employeeList; 

    publicListViewAdapter(Context context, List<EmployeeBean> employeeList) {
            this.context = context;
            this.employeeList = employeeList;

    public View getView(int position, View convertView, ViewGroup parent) {
            View row = convertView;
            EmployeeBeanHolder holder = null;
            LayoutInflater inflater = ((Activity) context).getLayoutInflater();
            row = inflater.inflate(R.layout.row, parent, false);

            holder = new EmployeeBeanHolder();
            holder.employeeBean = employeeList.get(position);
            holder.tvEmpId = (TextView) row.findViewById(;
            holder.tvName = (TextView) row.findViewById(;
            holder.tvStatus = (TextView) row.findViewById(;


             if (position % 2 == 0) {
                    row.setBackgroundColor(Color.rgb(213, 229, 241));
                } else {                    
                    row.setBackgroundColor(Color.rgb(255, 255, 255));

            return row;

   public static class EmployeeBeanHolder {
        EmployeeBean employeeBean;
        TextView tvEmpId;
        TextView tvName;
        TextView tvStatus;

    public int getCount() {
            return employeeList.size();

    public Object getItem(int position) {
            return null;

    public long getItemId(int position) {
            return 0;

employee bean class:

public class EmployeeBean {
    private String empId;
    private String name;
    private String status;

    public EmployeeBean(){      

    public EmployeeBean(String empId, String name, String status) {
        this.empId= empId; = name;
        this.status = status;

    public String getEmpId() {
        return empId;

    public void setEmpId(String empId) {
        this.empId= empId;

    public String getName() {
        return name;

    public void setName(String name) { = name;

    public String getStatus() {
        return status;

    public void setStatus(String status) {
        this.status =status;

in Activity class:

onCreate method:

public static List<EmployeeBean> EMPLOYEE_LIST = new ArrayList<EmployeeBean>();

//create emplyee data
for(int i=0;i<=10;i++) {
  EmployeeBean emplyee = new EmployeeBean("EmpId"+i,"Name "+i, "Active");
  EMPLOYEE_LIST .add(emplyee );

ListView listView;
listView = (ListView) findViewById(;
listView.setAdapter(new ListViewAdapter(this, EMPLOYEE_LIST));

How to make a rest post call from ReactJS code?

I think this way also a normal way. But sorry, I can't describe in English ((

    submitHandler = e => {_x000D_
        method: 'POST',_x000D_
        headers: {_x000D_
            Accept: 'application/json',_x000D_
                    'Content-Type': 'application/json',_x000D_
        body: JSON.stringify(this.state)_x000D_
    }).then(response => {_x000D_
        .catch(error =>{_x000D_

fetch('url/questions',{ method: 'POST', headers: { Accept: 'application/json', 'Content-Type': 'application/json', }, body: JSON.stringify(this.state) }).then(response => { console.log(response) }) .catch(error =>{ console.log(error) })

How do I ignore files in a directory in Git?


  • A blank line matches no files, so it can serve as a separator for readability.

  • A line starting with # serves as a comment.

  • An optional prefix ! which negates the pattern; any matching file excluded by a previous pattern will become included again. If a negated pattern matches, this will override lower precedence patterns sources.

  • If the pattern ends with a slash, it is removed for the purpose of the following description, but it would only find a match with a directory. In other words, foo/ will match a directory foo and paths underneath it, but will not match a regular file or a symbolic link foo (this is consistent with the way how pathspec works in general in git).

  • If the pattern does not contain a slash /, git treats it as a shell glob pattern and checks for a match against the pathname relative to the location of the .gitignore file (relative to the toplevel of the work tree if not from a .gitignore file).

  • Otherwise, git treats the pattern as a shell glob suitable for consumption by fnmatch(3) with the FNM_PATHNAME flag: wildcards in the pattern will not match a / in the pathname. For example, Documentation/*.html matches Documentation/git.html but not Documentation/ppc/ppc.html or tools/perf/Documentation/perf.html.

  • A leading slash matches the beginning of the pathname. For example, /*.c matches cat-file.c but not mozilla-sha1/sha1.c.

You can find more here

git help gitignore
man gitignore

Check if an element is present in a Bash array

If array elements don't contain spaces, another (perhaps more readable) solution would be:

if echo ${arr[@]} | grep -q -w "d"; then 
    echo "is in array"
    echo "is not in array"

How to change the button text for 'Yes' and 'No' buttons in the MessageBox.Show dialog?

Just add a new form and add buttons and a label. Give the value to be shown and the text of the button, etc. in its constructor, and call it from anywhere you want in the project.

In project -> Add Component -> Windows Form and select a form

Add some label and buttons.

Initialize the value in constructor and call it from anywhere.

public class form1:System.Windows.Forms.Form
    public form1()

    public form1(string message,string buttonText1,string buttonText2)
       lblMessage.Text = message;
       button1.Text = buttonText1;
       button2.Text = buttonText2;

// Write code for button1 and button2 's click event in order to call 
// from any where in your current project.

// Calling

Form1 frm = new Form1("message to show", "buttontext1", "buttontext2");

error: expected declaration or statement at end of input in c

For me this problem was caused by a missing ) at the end of an if statement in a function called by the function the error was reported as from. Try scrolling up in the output to find the first error reported by the compiler. Fixing that error may fix this error.

Html code as IFRAME source rather than a URL

You can do this with a data URL. This includes the entire document in a single string of HTML. For example, the following HTML:


can be encoded as this:


and then set as the src attribute of the iframe. Example.

Edit: The other alternative is to do this with Javascript. This is almost certainly the technique I'd choose. You can't guarantee how long a data URL the browser will accept. The Javascript technique would look something like this:

var iframe = document.getElementById('foo'),
    iframedoc = iframe.contentDocument || iframe.contentWindow.document;

iframedoc.body.innerHTML = 'Hello world';


Edit 2 (December 2017): use the Html5's srcdoc attribute, just like in Saurabh Chandra Patel's answer, who now should be the accepted answer! If you can detect IE/Edge efficiently, a tip is to use srcdoc-polyfill library only for them and the "pure" srcdoc attribute in all non-IE/Edge browsers (check to be sure).

<iframe srcdoc="<html><body>Hello, <b>world</b>.</body></html>"></iframe>

Throwing multiple exceptions in a method of an interface in java

You need to specify it on the methods that can throw the exceptions. You just seperate them with a ',' if it can throw more than 1 type of exception. e.g.

public interface MyInterface {
  public MyObject find(int x) throws MyExceptionA,MyExceptionB;

Get current date in milliseconds

Cconvert NSTimeInterval milisecondedDate value to nsstring and after that convert into int.

Python division

You need to change it to a float BEFORE you do the division. That is:

float(20 - 10) / (100 - 10)

Wordpress keeps redirecting to install-php after migration

I experienced this issue today and started searching on internet. In my case there was no table in my DB. I forgot to import the tables on the online server. I did it and all works fine.

Unsetting array values in a foreach loop

One solution would be to use the key of your items to remove them -- you can both the keys and the values, when looping using foreach.

For instance :

$arr = array(
    'a' => 123,
    'b' => 456,
    'c' => 789, 

foreach ($arr as $key => $item) {
    if ($item == 456) {


Will give you this array, in the end :

  'a' => int 123
  'c' => int 789

Which means that, in your case, something like this should do the trick :

foreach($images as $key => $image)
    if($image == '' ||
    $image == '' ||
    $image == '')

How to configure port for a Spring Boot application

Hope this one help> 




How to read/write from/to file using Go?

With newer Go versions, reading/writing to/from file is easy. To read from a file:

package main

import (

func main() {
    data, err := ioutil.ReadFile("text.txt")
    if err != nil {

To write to a file:

package main

import "os"

func main() {
    file, err := os.Create("text.txt")
    if err != nil {
    defer file.Close()


This will overwrite the content of a file (create a new file if it was not there).

continuous page numbering through section breaks

You can check out this post on SuperUser.

Word starts page numbering over for each new section by default.

I do it slightly differently than the post above that goes through the ribbon menus, but in both methods you have to go through the document to each section's beginning.

My method:

  • open up the footer (or header if that's where your page number is)
  • drag-select the page number
  • right-click on it
  • hit Format Page Numbers
  • click on the Continue from Previous Section radio button under Page numbering

I find this right-click method to be a little faster. Also, usually if I insert the page numbers first before I start making any new sections, this problem doesn't happen in the first place.

function to return a string in java

Your code is fine. There's no problem with returning Strings in this manner.

In Java, a String is a reference to an immutable object. This, coupled with garbage collection, takes care of much of the potential complexity: you can simply pass a String around without worrying that it would disapper on you, or that someone somewhere would modify it.

If you don't mind me making a couple of stylistic suggestions, I'd modify the code like so:

public String time_to_string(long t) // time in milliseconds
    if (t < 0)
        return "-";
        int secs = (int)(t/1000);
        int mins = secs/60;
        secs = secs - (mins * 60);
        return String.format("%d:%02d", mins, secs);

As you can see, I've pushed the variable declarations as far down as I could (this is the preferred style in C++ and Java). I've also eliminated ans and have replaced the mix of string concatenation and String.format() with a single call to String.format().

What is is used for python programs in zip files. The file will be executed when the zip file in run. For example, if the zip file was as such:

and the contents of was

import sys
print "hello %s" % sys.argv[1]

Then if we were to run python world we would get hello world out.

So the file run when python is called on a zip file.

Which UUID version to use?

There are two different ways of generating a UUID.

If you just need a unique ID, you want a version 1 or version 4.

  • Version 1: This generates a unique ID based on a network card MAC address and a timer. These IDs are easy to predict (given one, I might be able to guess another one) and can be traced back to your network card. It's not recommended to create these.

  • Version 4: These are generated from random (or pseudo-random) numbers. If you just need to generate a UUID, this is probably what you want.

If you need to always generate the same UUID from a given name, you want a version 3 or version 5.

  • Version 3: This generates a unique ID from an MD5 hash of a namespace and name. If you need backwards compatibility (with another system that generates UUIDs from names), use this.

  • Version 5: This generates a unique ID from an SHA-1 hash of a namespace and name. This is the preferred version.

How to plot two columns of a pandas data frame using points?

Now in latest pandas you can directly use df.plot.scatter function

df = pd.DataFrame([[5.1, 3.5, 0], [4.9, 3.0, 0], [7.0, 3.2, 1],
                   [6.4, 3.2, 1], [5.9, 3.0, 2]],
                  columns=['length', 'width', 'species'])
ax1 = df.plot.scatter(x='length',

UnsupportedClassVersionError unsupported major.minor version 51.0 unable to load class

Even though your JDK in eclipse is 1.7, you need to make sure eclipse compilance level also set to 1.7. You can check compilance level--> Window-->Preferences--> Java--Compiler--compilance level.

Unsupported major minor error happens in cases where compilance level doesn't match with runtime.

Can't open config file: /usr/local/ssl/openssl.cnf on Windows


just set -config parameter location correctly, i.e :

openssl ....................  -config C:\bin\apache\apache2.4.9\conf\openssl.cnf

How can I replace newlines using PowerShell?

A CRLF is two characters, of course, the CR and the LF. However, `n consists of both. For example:

PS C:\> $x = "Hello
>> World"

PS C:\> $x
PS C:\> $x.contains("`n")
PS C:\> $x.contains("`r")
PS C:\> $x.replace("o`nW","o There`nThe W")
Hello There
The World
PS C:\>

I think you're running into problems with the `r. I was able to remove the `r from your example, use only `n, and it worked. Of course, I don't know exactly how you generated the original string so I don't know what's in there.

How do I get PHP errors to display?

You can add your own custom error handler, which can provide extra debug information. Furthermore, you can set it up to send you the information via email.

function ERR_HANDLER($errno, $errstr, $errfile, $errline){
    $msg = "<b>Something bad happened.</b> [$errno] $errstr <br><br>
    <b>File:</b> $errfile <br>
    <b>Line:</b> $errline <br>
    <pre>".json_encode(debug_backtrace(), JSON_PRETTY_PRINT)."</pre> <br>";

    echo $msg;

    return false;

function EXC_HANDLER($exception){
    ERR_HANDLER(0, $exception->getMessage(), $exception->getFile(), $exception->getLine());

function shutDownFunction() {
    $error = error_get_last();
    if ($error["type"] == 1) {
        ERR_HANDLER($error["type"], $error["message"], $error["file"], $error["line"]);

set_error_handler ("ERR_HANDLER", E_ALL & ~E_NOTICE & ~E_STRICT & ~E_DEPRECATED);

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

Assuming that c++ code (c++11) is okay as well and the interface is known.

#include <cstdint>
#include <fstream>
#include <streambuf>
#include <regex>

using namespace std;

uint64_t getIFMAC(const string &ifname) {
  ifstream iface("/sys/class/net/" + ifname + "/address");
  string str((istreambuf_iterator<char>(iface)), istreambuf_iterator<char>());
  if (str.length() > 0) {
    string hex = regex_replace(str, std::regex(":"), "");
    return stoull(hex, 0, 16);
  } else {
    return 0;
int main()
  string iface = "eth0";
  printf("%s: mac=%016llX\n", iface.c_str(), getIFMAC(iface));

Updating records codeigniter

In your Controller

public function updtitle() 
    $data = array(
        'table_name' => 'your_table_name_to_update', // pass the real table name
        'id' => $this->input->post('id'),
        'title' => $this->input->post('title')

    $this->load->model('Updmodel'); // load the model first
    if($this->Updmodel->upddata($data)) // call the method from the model
        // update successful
        // update not successful


In Your Model

public function upddata($data) {
    $this->db->where('emp_no', $id);
    $this->db->update($table_name, array('title' => $title));
    return true;

The active record query is similar to

"update $table_name set title='$title' where emp_no=$id"

Converting a String to DateTime

Since you are handling 24-hour based time and you have a comma separating the seconds fraction, I recommend that you specify a custom format:

DateTime myDate = DateTime.ParseExact("2009-05-08 14:40:52,531", "yyyy-MM-dd HH:mm:ss,fff",

[INSTALL_FAILED_NO_MATCHING_ABIS: Failed to extract native libraries, res=-113]

Android 9 and Android 11 emulators have support for arm binaries.

I had the same issue while using x86 emulator with API level 29, trying to install an apk targeting arm ABI.

I tried x86 emulator with API level 30 and it worked fine.

Resolving require paths with webpack

For future reference, webpack 2 removed everything but modules as a way to resolve paths. This means root will not work.

The example configuration starts with:

  modules: [path.resolve(__dirname, "app"), "node_modules"]
  // (was split into `root`, `modulesDirectories` and `fallback` in the old options)

How to copy a directory structure but only include certain files (using windows batch files)

For those using Altap Salamander (2 panels file manager) : in the Options of the Copy popup, just specify the file names or masks. Easy.

Java how to sort a Linked List?

I wouldn't. I would use an ArrayList or a sorted collection with a Comparator. Sorting a LinkedList is about the most inefficient procedure I can think of.

Html- how to disable <a href>?

I created a button...

This is where you've gone wrong. You haven't created a button, you've created an anchor element. If you had used a button element instead, you wouldn't have this problem:

<button type="button" data-toggle="modal" data-target="#myModal" data-role="disabled">

If you are going to continue using an a element instead, at the very least you should give it a role attribute set to "button" and drop the href attribute altogether:

<a role="button" ...>

Once you've done that you can introduce a piece of JavaScript which calls event.preventDefault() - here with event being your click event.

How to find the extension of a file in C#?

At the server you can check the MIME type, lookup flv mime type here or on google.

You should be checking that the mime type is


If you were using a FileUpload in C# for instance, you could do

FileUpload.PostedFile.ContentType == "video/x-flv"

Measure the time it takes to execute a t-sql query

One simplistic approach to measuring the "elapsed time" between events is to just grab the current date and time.

In SQL Server Management Studio

SELECT /* query one */ 1 ;
SELECT /* query two */ 2 ; 

To calculate elapsed times, you could grab those date values into variables, and use the DATEDIFF function:


SET @t1 = GETDATE();
SELECT /* query one */ 1 ;
SET @t2 = GETDATE();
SELECT DATEDIFF(millisecond,@t1,@t2) AS elapsed_ms;

SET @t1 = GETDATE();
SELECT /* query two */ 2 ;
SET @t2 = GETDATE();
SELECT DATEDIFF(millisecond,@t1,@t2) AS elapsed_ms;

That's just one approach. You can also get elapsed times for queries using SQL Profiler.

How can I throw a general exception in Java?

You could use IllegalArgumentException:

public void speedDown(int decrement)
    if(speed - decrement < 0){
        throw new IllegalArgumentException("Final speed can not be less than zero");
        speed -= decrement;

Is it possible to import a whole directory in sass using @import?

With defining the file to import it's possible to use all folders common definitions.

So, @import "style/*" will compile all the files in the style folder.

More about import feature in Sass you can find here.

Android Closing Activity Programmatically

What about the Activity.finish() method (quoting) :

Call this when your activity is done and should be closed.

console.log not working in Angular2 Component (Typescript)

The console.log should be wrapped in a function , the "default" function for every class is its constructor so it should be declared there.

import { Component } from '@angular/core';

  selector: 'hello-console',
    export class App {
     s: string = "Hello2";


How do I create a round cornered UILabel on the iPhone?

xCode 7.3.1 iOS 9.3.2

 _siteLabel.layer.masksToBounds = true;
  _siteLabel.layer.cornerRadius = 8;

When to use: Java 8+ interface default method, vs. abstract method

Remi Forax rule is You don't design with Abstract classes. You design your app with interfaces. Watever is the version of Java, whatever is the language. It is backed by the Interface segregation principle in SOLID principles.

You can later use Abstract classes to factorize code. Now with Java 8 you can do it directly in the interface. This is a facility, not more.

Using StringWriter for XML Serialization

First of all, beware of finding old examples. You've found one that uses XmlTextWriter, which is deprecated as of .NET 2.0. XmlWriter.Create should be used instead.

Here's an example of serializing an object into an XML column:

public void SerializeToXmlColumn(object obj)
    using (var outputStream = new MemoryStream())
        using (var writer = XmlWriter.Create(outputStream))
            var serializer = new XmlSerializer(obj.GetType());
            serializer.Serialize(writer, obj);

        outputStream.Position = 0;
        using (var conn = new SqlConnection(Settings.Default.ConnectionString))

            const string INSERT_COMMAND = @"INSERT INTO XmlStore (Data) VALUES (@Data)";
            using (var cmd = new SqlCommand(INSERT_COMMAND, conn))
                using (var reader = XmlReader.Create(outputStream))
                    var xml = new SqlXml(reader);

                    cmd.Parameters.AddWithValue("@Data", xml);

H.264 file size for 1 hr of HD video

For a good quality x264 encoding of 1060i, done by a computer, not a mobile device, not in real time, you could use a bitrate at about 5 MBps. That means 2250 MB/hour of encoded material. Recommend you deinterlace the footage and compress as progressive.

numpy max vs amax vs maximum

np.maximum not only compares elementwise but also compares array elementwise with single value

>>>np.maximum([23, 14, 16, 20, 25], 18)
array([23, 18, 18, 20, 25])

How can I pretty-print JSON using node.js?

JSON.stringify's third parameter defines white-space insertion for pretty-printing. It can be a string or a number (number of spaces). Node can write to your filesystem with fs. Example:

var fs = require('fs');

fs.writeFile('test.json', JSON.stringify({ a:1, b:2, c:3 }, null, 4));
/* test.json:
     "a": 1,
     "b": 2,
     "c": 3,

See the JSON.stringify() docs at MDN, Node fs docs

How to create a multi line body in C# System.Net.Mail.MailMessage

You need to enable IsBodyHTML

message.IsBodyHtml = true; //This will enable using HTML elements in email body
message.Body ="First Line <br /> second line";

How to correctly implement custom iterators and const_iterators?

Boost has something to help: the Boost.Iterator library.

More precisely this page: boost::iterator_adaptor.

What's very interesting is the Tutorial Example which shows a complete implementation, from scratch, for a custom type.

template <class Value>
class node_iter
  : public boost::iterator_adaptor<
        node_iter<Value>                // Derived
      , Value*                          // Base
      , boost::use_default              // Value
      , boost::forward_traversal_tag    // CategoryOrTraversal
    struct enabler {};  // a private type avoids misuse

      : node_iter::iterator_adaptor_(0) {}

    explicit node_iter(Value* p)
      : node_iter::iterator_adaptor_(p) {}

    // iterator convertible to const_iterator, not vice-versa
    template <class OtherValue>
        node_iter<OtherValue> const& other
      , typename boost::enable_if<
          , enabler
        >::type = enabler()
      : node_iter::iterator_adaptor_(other.base()) {}

    friend class boost::iterator_core_access;
    void increment() { this->base_reference() = this->base()->next(); }

The main point, as has been cited already, is to use a single template implementation and typedef it.

How can I sanitize user input with PHP?

Never trust user data.

function clean_input($data) {
  $data = trim($data);
  $data = stripslashes($data);
  $data = htmlspecialchars($data);
  return $data;

The trim() function removes whitespace and other predefined characters from both sides of a string.

The stripslashes() function removes backslashes

The htmlspecialchars() function converts some predefined characters to HTML entities.

The predefined characters are:

& (ampersand) becomes &amp;
" (double quote) becomes &quot;
' (single quote) becomes &#039;
< (less than) becomes &lt;
> (greater than) becomes &gt;

Switch android x86 screen resolution

Set resolution in android x86



  • Add nomodeset and vga=ask to android x86 grub entry's kernel loading options;
  • Find your best resolution and note the code you used.


  • Convert that code to decimal from hex;
  • Add vga=decimal_code to your preferred entry in /mnt/grub/menu.lst (mounted if android is started in debug mode).

What are the options for storing hierarchical data in a relational database?

My favorite answer is as what the first sentence in this thread suggested. Use an Adjacency List to maintain the hierarchy and use Nested Sets to query the hierarchy.

The problem up until now has been that the coversion method from an Adjacecy List to Nested Sets has been frightfully slow because most people use the extreme RBAR method known as a "Push Stack" to do the conversion and has been considered to be way to expensive to reach the Nirvana of the simplicity of maintenance by the Adjacency List and the awesome performance of Nested Sets. As a result, most people end up having to settle for one or the other especially if there are more than, say, a lousy 100,000 nodes or so. Using the push stack method can take a whole day to do the conversion on what MLM'ers would consider to be a small million node hierarchy.

I thought I'd give Celko a bit of competition by coming up with a method to convert an Adjacency List to Nested sets at speeds that just seem impossible. Here's the performance of the push stack method on my i5 laptop.

Duration for     1,000 Nodes = 00:00:00:870 
Duration for    10,000 Nodes = 00:01:01:783 (70 times slower instead of just 10)
Duration for   100,000 Nodes = 00:49:59:730 (3,446 times slower instead of just 100) 
Duration for 1,000,000 Nodes = 'Didn't even try this'

And here's the duration for the new method (with the push stack method in parenthesis).

Duration for     1,000 Nodes = 00:00:00:053 (compared to 00:00:00:870)
Duration for    10,000 Nodes = 00:00:00:323 (compared to 00:01:01:783)
Duration for   100,000 Nodes = 00:00:03:867 (compared to 00:49:59:730)
Duration for 1,000,000 Nodes = 00:00:54:283 (compared to something like 2 days!!!)

Yes, that's correct. 1 million nodes converted in less than a minute and 100,000 nodes in under 4 seconds.

You can read about the new method and get a copy of the code at the following URL.

I also developed a "pre-aggregated" hierarchy using similar methods. MLM'ers and people making bills of materials will be particularly interested in this article.

If you do stop by to take a look at either article, jump into the "Join the discussion" link and let me know what you think.

How does the @property decorator work in Python?

The first part is simple:

def x(self): ...

is the same as

def x(self): ...
x = property(x)
  • which, in turn, is the simplified syntax for creating a property with just a getter.

The next step would be to extend this property with a setter and a deleter. And this happens with the appropriate methods:

def x(self, value): ...

returns a new property which inherits everything from the old x plus the given setter.

x.deleter works the same way.

iPhone SDK:How do you play video inside a view? Rather than fullscreen

The best way is to use layers insted of views:

AVPlayer *player = [AVPlayer playerWithURL:[NSURL url...]]; // 

AVPlayerLayer *layer = [AVPlayerLayer layer];

[layer setPlayer:player];
[layer setFrame:CGRectMake(10, 10, 300, 200)];
[layer setBackgroundColor:[UIColor redColor].CGColor];
[layer setVideoGravity:AVLayerVideoGravityResizeAspectFill];

[self.view.layer addSublayer:layer];

[player play];

Don't forget to add frameworks:

#import <QuartzCore/QuartzCore.h>
#import "AVFoundation/AVFoundation.h"

download file using an ajax request

Update April 27, 2015

Up and coming to the HTML5 scene is the download attribute. It's supported in Firefox and Chrome, and soon to come to IE11. Depending on your needs, you could use it instead of an AJAX request (or using window.location) so long as the file you want to download is on the same origin as your site.

You could always make the AJAX request/window.location a fallback by using some JavaScript to test if download is supported and if not, switching it to call window.location.

Original answer

You can't have an AJAX request open the download prompt since you physically have to navigate to the file to prompt for download. Instead, you could use a success function to navigate to download.php. This will open the download prompt but won't change the current page.

    url: 'download.php',
    type: 'POST',
    success: function() {
        window.location = 'download.php';

Even though this answers the question, it's better to just use window.location and avoid the AJAX request entirely.

Is there a .NET/C# wrapper for SQLite?

The folks from have taken over the development of the ADO.NET provider:

From their homepage:

This is a fork of the popular ADO.NET 4.0 adaptor for SQLite known as System.Data.SQLite. The originator of System.Data.SQLite, Robert Simpson, is aware of this fork, has expressed his approval, and has commit privileges on the new Fossil repository. The SQLite development team intends to maintain System.Data.SQLite moving forward.

Historical versions, as well as the original support forums, may still be found at, though there have been no updates to this version since April of 2010.

The complete list of features can be found at on their wiki. Highlights include

  • ADO.NET 2.0 support
  • Full Entity Framework support
  • Full Mono support
  • Visual Studio 2005/2008 Design-Time support
  • Compact Framework, C/C++ support

Released DLLs can be downloaded directly from the site.

C/C++ include header file order

Include from the most specific to the least specific, starting with the corresponding .hpp for the .cpp, if one such exists. That way, any hidden dependencies in header files that are not self-sufficient will be revealed.

This is complicated by the use of pre-compiled headers. One way around this is, without making your project compiler-specific, is to use one of the project headers as the precompiled header include file.

support FragmentPagerAdapter holds reference to old fragments

I solved the problem by saving the fragments in SparceArray:

public abstract class SaveFragmentsPagerAdapter extends FragmentPagerAdapter {

    SparseArray<Fragment> fragments = new SparseArray<>();

    public SaveFragmentsPagerAdapter(FragmentManager fm) {

    public Object instantiateItem(ViewGroup container, int position) {
        Fragment fragment = (Fragment) super.instantiateItem(container, position);
        fragments.append(position, fragment);
        return fragment;

    public Fragment getFragmentByPosition(int position){
        return fragments.get(position);


Guid is all 0's (zeros)?

In the spirit of being complete, the answers that instruct you to use Guid.NewGuid() are correct.

In addressing your subsequent edit, you'll need to post the code for your RequestObject class. I'm suspecting that your guid property is not marked as a DataMember, and thus is not being serialized over the wire. Since default(Guid) is the same as new Guid() (i.e. all 0's), this would explain the behavior you're seeing.

Django Cookies, how can I set them?

You could manually set the cookie, but depending on your use case (and if you might want to add more types of persistent/session data in future) it might make more sense to use Django's sessions feature. This will let you get and set variables tied internally to the user's session cookie. Cool thing about this is that if you want to store a lot of data tied to a user's session, storing it all in cookies will add a lot of weight to HTTP requests and responses. With sessions the session cookie is all that is sent back and forth (though there is the overhead on Django's end of storing the session data to keep in mind).

Limiting floats to two decimal points

You can modify the output format:

>>> a = 13.95
>>> a
>>> print "%.2f" % a

CSS Cell Margin

I realize this is quite belated, but for the record, you can also use CSS selectors to do this (eliminating the need for inline styles.) This CSS applies padding to the first column of every row:

table > tr > td:first-child { padding-right:10px }

And this would be your HTML, sans CSS!:

<table><tr><td>data</td><td>more data</td></tr></table>

This allows for much more elegant markup, especially in cases where you need to do lots of specific formatting with CSS.

Iptables setting multiple multiports in one rule

As far as i know, writing multiple matches is logical AND operation; so what your rule means is if the destination port is "59100" AND "3000" then reject connection with tcp-reset; Workaround is using -mport option. Look out for the man page.

Calculate Pandas DataFrame Time Difference Between Two Columns in Hours and Minutes

This was driving me bonkers as the .astype() solution above didn't work for me. But I found another way. Haven't timed it or anything, but might work for others out there:

t1 = pd.to_datetime('1/1/2015 01:00')
t2 = pd.to_datetime('1/1/2015 03:30')

print pd.Timedelta(t2 - t1).seconds / 3600.0

...if you want hours. Or:

print pd.Timedelta(t2 - t1).seconds / 60.0

...if you want minutes.

How to change xampp localhost to another folder ( outside xampp folder)?

Please follow @Sourav's advice.

If after restarting the server you get errors, you may need to set your directory options as well. This is done in the <Directory> tag in httpd.conf. Make sure the final config looks like this:

DocumentRoot "C:\alan"
<Directory "C:\alan">
    Options Indexes FollowSymLinks
    AllowOverride All
    Order allow,deny
    Allow from all

Default value to a parameter while passing by reference in C++

No, it's not possible.

Passing by reference implies that the function might change the value of the parameter. If the parameter is not provided by the caller and comes from the default constant, what is the function supposed to change?

printing a value of a variable in postgresql

You can raise a notice in Postgres as follows:

raise notice 'Value: %', deletedContactId;

Read here

JQuery find first parent element with specific class prefix

Use .closest() with a selector:

var $div = $('#divid').closest('div[class^="div-a"]');

System.Net.Http: missing from namespace? (using .net 4.5)

just go to add reference then add

enter image description here

How to rotate the background image in the container?


.reverse {
  transform: rotate(180deg);

.rotate {
  animation-duration: .5s;
  animation-iteration-count: 1;
  animation-name: yoyo;
  animation-timing-function: linear;

@keyframes yoyo {
  from { transform: rotate(  0deg); }
  to   { transform: rotate(360deg); }


$(buttonElement).click(function () {

  return false

$(buttonElement).hover(function () {
}, function() {

PS: I've found this somewhere else but don't remember the source

AssertNull should be used or AssertNotNull

Use assertNotNull(obj). assert means must be.

Rails Model find where not equal

The only way you can get it fancier is with MetaWhere.

MetaWhere has a newer cousin which is called Squeel which allows code like this:

GroupUser.where{user_id != me}

It goes without saying, that if this is the only refactor you are going to make, it is not worth using a gem and I would just stick with what you got. Squeel is useful in situations where you have many complex queries interacting with Ruby code.

Spring MVC: difference between <context:component-scan> and <annotation-driven /> tags?

<context:component-scan base-package="" /> 

tells Spring to scan those packages for Annotations.


registers a RequestMappingHanderMapping, a RequestMappingHandlerAdapter, and an ExceptionHandlerExceptionResolver to support the annotated controller methods like @RequestMapping, @ExceptionHandler, etc. that come with MVC.

This also enables a ConversionService that supports Annotation driven formatting of outputs as well as Annotation driven validation for inputs. It also enables support for @ResponseBody which you can use to return JSON data.

You can accomplish the same things using Java-based Configuration using @ComponentScan(basePackages={"...", "..."} and @EnableWebMvc in a @Configuration class.

Check out the 3.1 documentation to learn more.

Creating an empty list in Python

Here is how you can test which piece of code is faster:

% python -mtimeit  "l=[]"
10000000 loops, best of 3: 0.0711 usec per loop

% python -mtimeit  "l=list()"
1000000 loops, best of 3: 0.297 usec per loop

However, in practice, this initialization is most likely an extremely small part of your program, so worrying about this is probably wrong-headed.

Readability is very subjective. I prefer [], but some very knowledgable people, like Alex Martelli, prefer list() because it is pronounceable.

Count textarea characters

textarea.addEventListener("keypress", textareaLengthCheck(textarea), false);

You are calling textareaLengthCheck and then assigning its return value to the event listener. This is why it doesn't update or do anything after loading. Try this:


Aside from that:

var length = textarea.length;

textarea is the actual textarea, not the value. Try this instead:

var length = textarea.value.length;

Combined with the previous suggestion, your function should be:

function textareaLengthCheck() {
    var length = this.value.length;
    // rest of code

How to create a directory using Ansible

you can create using:

Latest version 2<

- name: Create Folder
    path: /srv/www/
    owner: user 
    group: user 
    mode: 0755 
    state: directory

Older version

- name: Create Folder

Refer -

jQuery .live() vs .on() method for adding a click event after loading dynamic html

I know it's a little late for an answer, but I've created a polyfill for the .live() method. I've tested it in jQuery 1.11, and it seems to work pretty well. I know that we're supposed to implement the .on() method wherever possible, but in big projects, where it's not possible to convert all .live() calls to the equivalent .on() calls for whatever reason, the following might work:

if(jQuery && ! { = function(evt, func) {
        $('body').on(evt, this.selector, func);

Just include it after you load jQuery and before you call live().

Node.js: Difference between req.query[] and req.params

req.params contains route parameters (in the path portion of the URL), and req.query contains the URL query parameters (after the ? in the URL).

You can also use req.param(name) to look up a parameter in both places (as well as req.body), but this method is now deprecated.

Export table to file with column headers (column names) using the bcp utility and SQL Server 2008

This method automatically outputs column names with your row data using BCP.

The script writes one file for the column headers (read from INFORMATION_SCHEMA.COLUMNS table) then appends another file with the table data.

The final output is combined into TableData.csv which has the headers and row data. Just replace the environment variables at the top to specify the Server, Database and Table name.

set BCP_EXPORT_SERVER=put_my_server_name_here
set BCP_EXPORT_DB=put_my_db_name_here
set BCP_EXPORT_TABLE=put_my_table_name_here

BCP "DECLARE @colnames VARCHAR(max);SELECT @colnames = COALESCE(@colnames + ',', '') + column_name from %BCP_EXPORT_DB%.INFORMATION_SCHEMA.COLUMNS where TABLE_NAME='%BCP_EXPORT_TABLE%'; select @colnames;" queryout HeadersOnly.csv -c -T -S%BCP_EXPORT_SERVER%

BCP %BCP_EXPORT_DB%.dbo.%BCP_EXPORT_TABLE% out TableDataWithoutHeaders.csv -c -t, -T -S%BCP_EXPORT_SERVER%


copy /b HeadersOnly.csv+TableDataWithoutHeaders.csv TableData.csv

del HeadersOnly.csv
del TableDataWithoutHeaders.csv

Note that if you need to supply credentials, replace the -T option with -U my_username -P my_password

This method has the advantage of always having the column names in sync with the table by using INFORMATION_SCHEMA.COLUMNS. The downside is that it creates temporary files. Microsoft should really fix the bcp utility to support this.

This solution uses the SQL row concatenation trick from here combined with bcp ideas from here

Spring RestTemplate timeout

Here are my 2 cents. Nothing new, but some explanations, improvements and newer code.

By default, RestTemplate has infinite timeout. There are two kinds of timeouts: connection timeout and read time out. For instance, I could connect to the server but I could not read data. The application was hanging and you have no clue what's going on.

I am going to use annotations, which these days are preferred over XML.

public class AppConfig {

    public RestTemplate restTemplate() {

        var factory = new SimpleClientHttpRequestFactory();


        return new RestTemplate(factory);

Here we use SimpleClientHttpRequestFactory to set the connection and read time outs. It is then passed to the constructor of RestTemplate.

public class AppConfig {

    public RestTemplate restTemplate(RestTemplateBuilder builder) {

        return builder

In the second solution, we use the RestTemplateBuilder. Also notice the parameters of the two methods: they take Duration. The overloaded methods that take directly milliseconds are now deprecated.

Edit Tested with Spring Boot 2.1.0 and Java 11.

How to update specific key's value in an associative array in PHP?

This a single solution, in where your_field is a field that will set and new_value is a new value field, that can a function or a single value

foreach ($array as $key => $item) {
   $item["your_field"] = "new_value";
   $array[$key] = $item;

In your case new_value will be a date() function

Angular 2 Date Input not binding to date value

Angular 2 completely ignores type=date. If you change type to text you'll see that your input has two-way binding.

<input type='text' #myDate [(ngModel)]=''/><br>

Here is pretty bad advise with better one to follow:

My project originally used jQuery. So, I'm using jQuery datepicker for now, hoping that angular team will fix the original issue. Also it's a better replacement because it has cross-browser support. FYI, input=date doesn't work in Firefox.

Good advise: There are few pretty good Angular2 datepickers:

C++ vector's insert & push_back difference

Beside the fact, that push_back(x) does the same as insert(x, end()) (maybe with slightly better performance), there are several important thing to know about these functions:

  1. push_back exists only on BackInsertionSequence containers - so, for example, it doesn't exist on set. It couldn't because push_back() grants you that it will always add at the end.
  2. Some containers can also satisfy FrontInsertionSequence and they have push_front. This is satisfied by deque, but not by vector.
  3. The insert(x, ITERATOR) is from InsertionSequence, which is common for set and vector. This way you can use either set or vector as a target for multiple insertions. However, set has additionally insert(x), which does practically the same thing (this first insert in set means only to speed up searching for appropriate place by starting from a different iterator - a feature not used in this case).

Note about the last case that if you are going to add elements in the loop, then doing container.push_back(x) and container.insert(x, container.end()) will do effectively the same thing. However this won't be true if you get this container.end() first and then use it in the whole loop.

For example, you could risk the following code:

auto pe = v.end();
for (auto& s: a)
    v.insert(pe, v);

This will effectively copy whole a into v vector, in reverse order, and only if you are lucky enough to not get the vector reallocated for extension (you can prevent this by calling reserve() first); if you are not so lucky, you'll get so-called UndefinedBehavior(tm). Theoretically this isn't allowed because vector's iterators are considered invalidated every time a new element is added.

If you do it this way:

copy(a.begin(), a.end(), back_inserter(v);

it will copy a at the end of v in the original order, and this doesn't carry a risk of iterator invalidation.

[EDIT] I made previously this code look this way, and it was a mistake because inserter actually maintains the validity and advancement of the iterator:

copy(a.begin(), a.end(), inserter(v, v.end());

So this code will also add all elements in the original order without any risk.

Insert a string at a specific index

UPDATE 2016: Here is another just-for-fun (but more serious!) prototype function based on one-liner RegExp approach (with prepend support on undefined or negative index):

 * Insert `what` to string at position `index`.
String.prototype.insert = function(what, index) {
    return index > 0
        ? this.replace(new RegExp('.{' + index + '}'), '$&' + what)
        : what + this;

console.log( 'foo baz'.insert('bar ', 4) );  // "foo bar baz"
console.log( 'foo baz'.insert('bar ')    );  // "bar foo baz"

Previous (back to 2012) just-for-fun solution:

var index = 4,
    what  = 'bar ';

'foo baz'.replace(/./g, function(v, i) {
    return i === index - 1 ? v + what : v;
});  // "foo bar baz"

Remove all of x axis labels in ggplot

You have to set to element_blank() in theme() elements you need to remove

ggplot(data = diamonds, mapping = aes(x = clarity)) + geom_bar(aes(fill = cut))+

Bootstrap 3 Align Text To Bottom of Div

The easiest way I have tested just add a <br> as in the following:

<div class="col-sm-6">
    <br><h3><p class="text-center">Some Text</p></h3>

The only problem is that a extra line break (generated by that <br>) is generated when the screen gets smaller and it stacks. But it is quick and simple.

Function pointer as a member of a C struct

My guess is that part of your problem is the parameter lists not matching.

int (* length)();


int length(PString * self)

are not the same. It should be int (* length)(PString *);.

...woah, it's Jon!

Edit: and, as mentioned below, your struct pointer is never set to point to anything. The way you're doing it would only work if you were declaring a plain struct, not a pointer.

str = (PString *)malloc(sizeof(PString));

How to count the NaN values in a column in pandas DataFrame

Suppose you want to get the number of missing values(NaN) in a column(series) known as price in a dataframe called reviews

#import the dataframe
import pandas as pd

reviews = pd.read_csv("../input/wine-reviews/winemag-data-130k-v2.csv", index_col=0)

To get the missing values, with n_missing_prices as the variable, simple do

n_missing_prices = sum(reviews.price.isnull())

sum is the key method here, was trying to use count before i realized sum is the right method to use in this context

Increment a Integer's int value?


Maybe this is of some worth also: there is a Java class called AtomicInteger.

This class has some useful methods like addAndGet(int delta) or incrementAndGet() (and their counterparts) which allow you to increment/decrement the value of the same instance. Though the class is designed to be used in the context of concurrency, it's also quite useful in other scenarios and probably fits your need.

final AtomicInteger count = new AtomicInteger( 0 ) ;
count.incrementAndGet();  // Ignoring the return value. 

How does strtok() split the string into tokens in C?

To understand how strtok() works, one first need to know what a static variable is. This link explains it quite well....

The key to the operation of strtok() is preserving the location of the last seperator between seccessive calls (that's why strtok() continues to parse the very original string that is passed to it when it is invoked with a null pointer in successive calls)..

Have a look at my own strtok() implementation, called zStrtok(), which has a sligtly different functionality than the one provided by strtok()

char *zStrtok(char *str, const char *delim) {
    static char *static_str=0;      /* var to store last address */
    int index=0, strlength=0;           /* integers for indexes */
    int found = 0;                  /* check if delim is found */

    /* delimiter cannot be NULL
    * if no more char left, return NULL as well
    if (delim==0 || (str == 0 && static_str == 0))
        return 0;

    if (str == 0)
        str = static_str;

    /* get length of string */

    /* find the first occurance of delim */
    for (index=0;index<strlength;index++)
        if (str[index]==delim[0]) {

    /* if delim is not contained in str, return str */
    if (!found) {
        static_str = 0;
        return str;

    /* check for consecutive delimiters
    *if first char is delim, return delim
    if (str[0]==delim[0]) {
        static_str = (str + 1);
        return (char *)delim;

    /* terminate the string
    * this assignmetn requires char[], so str has to
    * be char[] rather than *char
    str[index] = '\0';

    /* save the rest of the string */
    if ((str + index + 1)!=0)
        static_str = (str + index + 1);
        static_str = 0;

        return str;

And here is an example usage

  Example Usage
      char str[] = "A,B,,,C";
      printf("1 %s\n",zStrtok(s,","));
      printf("2 %s\n",zStrtok(NULL,","));
      printf("3 %s\n",zStrtok(NULL,","));
      printf("4 %s\n",zStrtok(NULL,","));
      printf("5 %s\n",zStrtok(NULL,","));
      printf("6 %s\n",zStrtok(NULL,","));

  Example Output
      1 A
      2 B
      3 ,
      4 ,
      5 C
      6 (null)

The code is from a string processing library I maintain on Github, called zString. Have a look at the code, or even contribute :)

Delete many rows from a table using id in Mysql

If you have some 'condition' in your data to figure out the 254 ids, you could use:

delete from tablename
where id in 
(select id from tablename where <your-condition>)

or simply:

delete from tablename where <your-condition>

Simply hard coding the 254 values of id column would be very tough in any case.

Font scaling based on width of container

Artistically, if you need to fit two or more lines of text within the same width regardless of their character count then you have nice options.

It's best to find a dynamical solution so whatever text is entered we end up with a nice display.

Let's see how we may approach.

var els     = document.querySelectorAll(".divtext"),_x000D_
refWidth    = els[0].clientWidth,_x000D_
refFontSize = parseFloat(window.getComputedStyle(els[0],null)_x000D_
els.forEach((el,i) => = refFontSize * refWidth / els[i].clientWidth + "px")
#container {_x000D_
  display: inline-block;_x000D_
  background-color: black;_x000D_
  padding: 0.6vw 1.2vw;_x000D_
.divtext {_x000D_
  display: table;_x000D_
  color: white;_x000D_
  font-family: impact;_x000D_
  font-size: 4.5vw;_x000D_
<div id="container">_x000D_
  <div class="divtext">THIS IS JUST AN</div>_x000D_
  <div class="divtext">EXAMPLE</div>_x000D_
  <div class="divtext">TO SHOW YOU WHAT</div>_x000D_
  <div class="divtext">YOU WANT</div>_x000D_

All we do is to get the width (els[0].clientWidth) and the font size (parseFloat(window.getComputedStyle(els[0],null).getPropertyValue("font-size"))) of the first line as a reference and then just calculate the subsequent lines font size accordingly.

Is it possible to execute multiple _addItem calls asynchronously using Google Analytics?

From the docs:

_trackTrans() Sends both the transaction and item data to the Google Analytics server. This method should be called after _trackPageview(), and used in conjunction with the _addItem() and addTrans() methods. It should be called after items and transaction elements have been set up.

So, according to the docs, the items get sent when you call trackTrans(). Until you do, you can add items, but the transaction will not be sent.

Edit: Further reading led me here:

Where it clearly says you can start another transaction with an existing ID. When you commit it, the new items you listed will be added to that transaction.

Missing visible-** and hidden-** in Bootstrap v4

Bootstrap v4.1 uses new classnames for hiding columns on their grid system.

For hiding columns depending on the screen width, use d-none class or any of the d-{sm,md,lg,xl}-none classes. To show columns on certain screen sizes, combine the above mentioned classes with d-block or d-{sm,md,lg,xl}-block classes.

Examples are:

<div class="d-lg-none">hide on screens wider than lg</div>_x000D_
<div class="d-none d-lg-block">hide on screens smaller than lg</div>

More of these here.

Print all key/value pairs in a Java ConcurrentHashMap

The HashMap has forEach as part of its structure. You can use that with a lambda expression to print out the contents in a one liner such as:

map.forEach((k,v)-> System.out.println(k+", "+v));


map.forEach((k,v)-> System.out.println("key: "+k+", value: "+v));

Starting Docker as Daemon on Ubuntu

There are multiple popular repositories offering docker packages for Ubuntu. The package is (most likely) from the Ubuntu repository. Another popular one is which offers a package lxc-docker (I am running the latter because it ships updates faster). Make sure only one package is installed. Not quite sure if removal of the packages cleans up properly. If sudo service docker restart still does not work, you may have to clean up manually in /etc/.

How to present popover properly in iOS 8

I found a complete example of how to get this all to work so that you can always display a popover no matter the device/orientation

The key is to implement UIAdaptivePresentationControllerDelegate

func adaptivePresentationStyleForPresentationController(PC: UIPresentationController!) -> UIModalPresentationStyle {
    // This *forces* a popover to be displayed on the iPhone
    return .None

Then extend the example above (from Imagine Digital):

nav.popoverPresentationController!.delegate = implOfUIAPCDelegate

How can I search Git branches for a file or directory?

git log + git branch will find it for you:

% git log --all -- somefile

commit 55d2069a092e07c56a6b4d321509ba7620664c63
Author: Dustin Sallings <[email protected]>
Date:   Tue Dec 16 14:16:22 2008 -0800

    added somefile

% git branch -a --contains 55d2069

Supports globbing, too:

% git log --all -- '**/my_file.png'

The single quotes are necessary (at least if using the Bash shell) so the shell passes the glob pattern to git unchanged, instead of expanding it (just like with Unix find).

MVC DateTime binding with incorrect date format

It going to be slightly different in MVC 3.

Suppose we have a controller and a view with Get method

public ActionResult DoSomething(DateTime dateTime)
    return View();

We should add ModelBinder

public class DateTimeBinder : IModelBinder
    #region IModelBinder Members
    public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
        DateTime dateTime;
        if (DateTime.TryParse(controllerContext.HttpContext.Request.QueryString["dateTime"], CultureInfo.GetCultureInfo("en-GB"), DateTimeStyles.None, out dateTime))
            return dateTime;
        return new DateTime();//or another appropriate default ;

and the command in Application_Start() of Global.asax

ModelBinders.Binders.Add(typeof(DateTime), new DateTimeBinder());

Override intranet compatibility mode IE8

For anyone else reading this looking to disable this via GPO for all users, this is the setting:

Computer Configuration/Administrative Templates/Windows Components/Internet Explorer/Compatibility View/Turn on Internet Explorer Standards Mode for Local Intranet

although the web.config edit fixed it for me.

How to increase the distance between table columns in HTML?

If you need to give a distance between two rows use this tag

margin-top: 10px !important;

Adding an .env file to React Project

So I'm myself new to React and I found a way to do it.

This solution does not require any extra packages.

Step 1 ReactDocs

In the above docs they mention export in Shell and other options, the one I'll attempt to explain is using .env file

1.1 create Root/.env

#.env file

Important notes it MUST start with REACT_APP_

1.2 Access ENV variable

#App.js file or the file you need to access ENV
<p>print env secret to HTML</p>

handleFetchData() { // access in API call
    .then((res) => res.json())
    .then((data) => console.log(data))

1.3 Build Env Issue

So after I did step 1.1|2 it was not working, then I found the above issue/solution. React read/creates env when is built so you need to npm run start every time you modify the .env file so the variables get updated.

JavaScript Loading Screen while page loads

To build further upon the ajax part which you may or may not use (from the comments)

a simple way to load another page and replace it with your current one is:

    $(document).ready( function() {
            type: 'get',
            url: 'http://pageToLoad.from',
            success: function(response) {
                // response = data which has been received and passed on to the 'success' function.

How to send custom headers with requests in Swagger UI?

I ended up here because I was trying to conditionally add header parameters in Swagger UI, based on my own [Authentication] attribute I added to my API method. Following the hint that @Corcus listed in a comment, I was able to derive my solution, and hopefully it will help others.

Using Reflection, it's checking if the method nested down in apiDescription has the desired attribute (MyApiKeyAuthenticationAttribute, in my case). If it does, I can append my desired header parameters.

public void Apply(Operation operation, SchemaRegistry schemaRegistry, ApiDescription apiDescription) {
    if (operation.parameters == null)
        operation.parameters = new List<Parameter>();

    var attributes = ((System.Web.Http.Controllers.ReflectedHttpActionDescriptor)
    if(attributes != null && attributes.Any()) {
        if(attributes.Where(x => x.GetType() 
            == typeof(MyApiKeyAuthenticationAttribute)).Any()) {

            operation.parameters.Add(new Parameter {
                name = "MyApiKey",
                @in = "header",
                type = "string",
                description = "My API Key",
                required = true
            operation.parameters.Add(new Parameter {
                name = "EID",
                @in = "header",
                type = "string",
                description = "Employee ID",
                required = true


Redirecting new tab on button click.(Response.Redirect) in C#

You can use Rout redirecting.

protected void btnNewEntry_Click(object sender, EventArgs e)

which requires to define your routing logic in Global.asax file that could be like that:

routes.MapPageRoute("CMS_1", "CMS_1", "~/CMS_1.aspx");

where any request by CMS_1 pattern in application scope will be redirecting to CMS_1.aspx, but in URL shows like

Can we overload the main method in Java?

Yes,u can overload main method but the interpreter will always search for the correct main method syntax to begin the execution.. And yes u have to call the overloaded main method with the help of object.

class Sample{
public void main(int a,int b){
System.out.println("The value of a is "  +a);
public static void main(String args[]){
System.out.println("We r in main method");
Sample obj=new Sample();
public static void main(int c){
System.out.println("The value of c  is"  +c);

The output of the program is:
We r in main method
The value of a is 5
The value of c is 3

How to avoid 'undefined index' errors?

Same idea as Michael Waterfall

From CodeIgniter

// Lets you determine whether an array index is set and whether it has a value.
// If the element is empty it returns FALSE (or whatever you specify as the default value.)
function element($item, $array, $default = FALSE)
    if ( ! isset($array[$item]) OR $array[$item] == "")
        return $default;

    return $array[$item];

Fitting a density curve to a histogram in R

Here's the way I do it:

foo <- rnorm(100, mean=1, sd=2)
hist(foo, prob=TRUE)
curve(dnorm(x, mean=mean(foo), sd=sd(foo)), add=TRUE)

A bonus exercise is to do this with ggplot2 package ...

memcpy() vs memmove()

I have tried to run same program using eclipse and it shows clear difference between memcpy and memmove. memcpy() doesn't care about overlapping of memory location which results in corruption of data, while memmove() will copy data to temporary variable first and then copy into actual memory location.

While trying to copy data from location str1 to str1+2, output of memcpy is "aaaaaa". The question would be how? memcpy() will copy one byte at a time from left to right. As shown in your program "aabbcc" then all copying will take place as below,

  1. aabbcc -> aaabcc

  2. aaabcc -> aaaacc

  3. aaaacc -> aaaaac

  4. aaaaac -> aaaaaa

memmove() will copy data to temporary variable first and then copy to actual memory location.

  1. aabbcc(actual) -> aabbcc(temp)

  2. aabbcc(temp) -> aaabcc(act)

  3. aabbcc(temp) -> aaaacc(act)

  4. aabbcc(temp) -> aaaabc(act)

  5. aabbcc(temp) -> aaaabb(act)

Output is

memcpy : aaaaaa

memmove : aaaabb

What are best practices for multi-language database design?

What we do, is to create two tables for each multilingual object.

E.g. the first table contains only language-neutral data (primary key, etc.) and the second table contains one record per language, containing the localized data plus the ISO code of the language.

In some cases we add a DefaultLanguage field, so that we can fall-back to that language if no localized data is available for a specified language.


Table "Product":
ID                 : int
<any other language-neutral fields>

Table "ProductTranslations"
ID                 : int      (foreign key referencing the Product)
Language           : varchar  (e.g. "en-US", "de-CH")
IsDefault          : bit
ProductDescription : nvarchar
<any other localized data>

With this approach, you can handle as many languages as needed (without having to add additional fields for each new language).

Update (2014-12-14): please have a look at this answer, for some additional information about the implementation used to load multilingual data into an application.