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What is the purpose of setting a key in data.table?
...e other vignettes that we plan to.
I've updated this answer again (Feb 2016) in light of the new on= feature that allows ad-hoc joins as well. See history for earlier (outdated) answers.
What exactly does setkey(DT, a, b) do?
It does two things:
reorders the rows of the data.table DT by the...
Bootstrap: Open Another Modal in Modal
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How to make part of the text Bold in android at runtime?
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Say you have a TextView called etx. You would then use the following code:
final SpannableStrin...
Exact time measurement for performance testing [duplicate]
...Stopwatch();
sw.Start();
// ...
sw.Stop();
Console.WriteLine("Elapsed={0}",sw.Elapsed);
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Upgrade python packages from requirements.txt using pip command
...ch to unpinned versions in your requirements file.
Example:
lxml>=2.2.0
This would upgrade lxml to any version newer than 2.2.0
lxml>=2.2.0,<2.3.0
This would upgrade lxml to the most recent version between 2.2.0 and 2.3.0.
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How to get a microtime in Node.js?
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new Date().getTime()? This gives you a timestamp in milliseconds, which is the most accurate th...
Can Visual Studio 2012 be installed side-by-side w/ Visual Studio 2010?
Will Visual Studio 2012 interfere/break .NET 4 and/or Visual Studio 2010 if installed side-by-side on the same instance of Windows?
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Force unmount of NFS-mounted directory [closed]
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answered Sep 2 '08 at 19:05
tesseintessein
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Turn off deprecated errors in PHP 5.3
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You can do it in code by calling the following functions.
error_reporting(E_ERROR | E_WARNING ...
Invalid argument supplied for foreach()
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Personally I find this to be the most clean - not sure if it's the most efficient, mind!
if (is...