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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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Remove a character from the end of a variable
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And it is POSIX, so is pretty much portable.
– go2null
Nov 9 '15 at 4:13
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How to run two jQuery animations simultaneously?
... @pilau It will be executed when the document is ready. This is a shorthand for $(document).ready(function(){}); and enables you to put your javascript code before your element definition.
– Raphael Michel
May 8 '13 at 17:31
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How to search for a string in text files?
...suggestion:
If your file is not too large, you can read it into a string, and just use that (easier and often faster than reading and checking line per line):
with open('example.txt') as f:
if 'blabla' in f.read():
print("true")
Another trick: you can alleviate the possible memory pr...
Standard alternative to GCC's ##__VA_ARGS__ trick?
...preprocessor features; you must use some extension to the language. clang and icc have adopted this GCC extension, but MSVC has not.
Back in 2001 I wrote up the GCC extension for standardization (and the related extension that lets you use a name other than __VA_ARGS__ for the rest-parameter) in ...
Java: PrintStream to String?
I have a function that takes an object of a certain type, and a PrintStream to which to print, and outputs a representation of that object. How can I capture this function's output in a String? Specifically, I want to use it as in a toString method.
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When should I use ugettext_lazy?
I have a question about using ugettext and ugettext_lazy for translations.
I learned that in models I should use ugettext_lazy , while in views ugettext.
But are there any other places, where I should use ugettext_lazy too? What about form definitions?
Are there any performance diffrences betwe...
PostgreSQL disable more output
...t, run it with -q or set QUIET=1 in the environment.
To produce results and throw them away you can redirect stdout to /dev/null with:
psql db -f sql.sql >/dev/null
You can redirect both stdout and stderr with:
psql db -f sql.sql >&/dev/null
but I don't recommend that, as it'll th...
Is it possible to use global variables in Rust?
...t spawn. The upside is that unlike truly global state, it is entirely safe and is not a pain to use - true global state is a massive pain in any language. Here's an example:
extern mod sqlite;
use std::cell::RefCell;
thread_local!(static ODB: RefCell<sqlite::database::Database> = RefCell::n...
How do I show a MySQL warning that just happened?
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You can also set the command line to always display warnings after a query using \W
You can switch them off again with \w
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