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How to join (merge) data frames (inner, outer, left, right)
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Why do you need to convert CustomerId to numeric? I don't see any mentioning in documentation (for both plyr and dplyr) about this type of restriction. Would your code work incorrectly, if the merge column would be of character type (especially...
When should I use C++ private inheritance?
Unlike protected inheritance, C++ private inheritance found its way into mainstream C++ development. However, I still haven't found a good use for it.
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How to 'insert if not exists' in MySQL?
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use INSERT IGNORE INTO table
see http://bogdan.org.ua/2007/10/18/mysql-insert-if-not-exists-syntax.html
there's also INSERT … ON DUPLICATE KEY UPDATE syntax, you can find explanations on dev.mysql.com
Post from bogdan.org.ua according t...
Explanation of JSONB introduced by PostgreSQL
...o a json column postgres doesn't have to actually run the functionality to convert the text to json on every row which will likely save a vast amount of time alone.
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What is the purpose of the “final” keyword in C++11 for functions?
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Thanks! this is the point I was missing : ie that even your "leaf" classes need to mark their function as virtual even if they intend to override functions, and not to be overridden themselves
– lezebulon
Jan...
JavaScript: Check if mouse button down?
...garding Pax' solution: it doesn't work if user clicks more than one button intentionally or accidentally. Don't ask me how I know :-(.
The correct code should be like that:
var mouseDown = 0;
document.body.onmousedown = function() {
++mouseDown;
}
document.body.onmouseup = function() {
--mous...
How to know user has clicked “X” or the “Close” button?
...MMAND
public bool ClosedByXButtonOrAltF4 {get; private set;}
private const int SC_CLOSE = 0xF060;
private const int WM_SYSCOMMAND = 0x0112;
protected override void WndProc(ref Message msg)
{
if (msg.Msg == WM_SYSCOMMAND && msg.WParam.ToInt32() == SC_CLOSE)
ClosedByXButtonOrAltF4 ...
What are allowed characters in cookies?
...Utility to safely encode the cookie value before writing to the cookie and convert it back to its original form on reading it out.
// Encode
HttpUtility.UrlEncode(cookieData);
// Decode
HttpUtility.UrlDecode(encodedCookieData);
This will stop ampersands and equals signs spliting a value into a b...
Hash function that produces short hashes?
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If you don't need an algorithm that's strong against intentional modification, I've found an algorithm called adler32 that produces pretty short (~8 character) results. Choose it from the dropdown here to try it out:
http://www.sha1-online.com/
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How to urlencode data for curl command?
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@ColinFraizer the single quote serves to convert the following character into its numeric value. ref. pubs.opengroup.org/onlinepubs/9699919799/utilities/…
– Sam
Nov 22 '18 at 22:37
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