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What is the purpose of setting a key in data.table?
I am using data.table and there are many functions which require me to set a key (e.g. X[Y] ). As such, I wish to understand what a key does in order to properly set keys in my data tables.
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Deploying my application at the root in Tomcat
...couple of options:
Remove the out-of-the-box ROOT/ directory from tomcat and rename your war file to ROOT.war before deploying it.
Deploy your war as (from your example) war_name.war and configure the context root in conf/server.xml to use your war file :
<Context path="" docBase="war_name" de...
Evaluating a mathematical expression in a string
...ppend(toks[0])
def pushUMinus(self, strg, loc, toks):
if toks and toks[0] == '-':
self.exprStack.append('unary -')
def __init__(self):
"""
expop :: '^'
multop :: '*' | '/'
addop :: '+' | '-'
integer :: ['+' | '-'] '0'..'9'+
...
Get url parameters from a string in .NET
...ng "google.com/…" doesn't detect the parameter q
– Andrew Shepherd
Jun 30 '09 at 4:26
@Andrew I confirm. It's strang...
How to handle code when app is killed by swiping in android?
If my app is running and i press home button, the app goes in background. Now if a long press the home button and kill the app by swiping it from the recent app list, none of the events like onPause() , onStop() or onDestroy() gets called rather the process is terminated. So if i want my servic...
Adding days to $Date in PHP
... ' + 1 days'));
echo date('Y-m-d', strtotime($Date. ' + 2 days'));
?>
And it outputs correctly:
2010-09-18
2010-09-19
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How to move files from one git repo to another (not a clone), preserving history
...ory, since you wanted to end up with only a (renamed) subset of the files, and this by definition changes the hashes. Since none of the standard commands (e.g. pull) rewrite history, there's no way you could use them to accomplish this.
You could refine the details, of course - some of your cloning...
Convert a binary NodeJS Buffer to JavaScript ArrayBuffer
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Instances of Buffer are also instances of Uint8Array in node.js 4.x and higher. Thus, the most efficient solution is to access the buf.buffer property directly, as per https://stackoverflow.com/a/31394257/1375574. The Buffer constructor also takes an ArrayBufferView argument if you need to ...
How can I see the size of files and directories in linux? [closed]
How can I see the size of files and directories in Linux? If use df -m , then it shows the size of all the directory at the top level, but, for the directories and files inside the directory, how do I check the size?
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C++ preprocessor __VA_ARGS__ number of arguments
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This is actually compiler dependent, and not supported by any standard.
Here however you have a macro implementation that does the count:
#define PP_NARG(...) \
PP_NARG_(__VA_ARGS__,PP_RSEQ_N())
#define PP_NARG_(...) \
PP_ARG_N(__VA_ARGS__)
#...