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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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How do I empty an array in JavaScript?
Is there a way to empty an array and if so possibly with .remove() ?
18 Answers
18
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Can you use a trailing comma in a JSON object?
...ed to worry about all browsers.
In general I try turn the problem around, and add the comma before the actual value, so you end up with code that looks like this:
s.append("[");
for (i = 0; i < 5; ++i) {
if (i) s.append(","); // add the comma only if this isn't the first entry
s.appendF("\"...
How do I get the AM/PM value from a DateTime?
... answered Oct 24 '11 at 12:06
AndyAndy
6,97077 gold badges3939 silver badges6666 bronze badges
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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'+
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Convert SVG image to PNG with PHP
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That's funny you asked this, I just did this recently for my work's site and I was thinking I should write a tutorial... Here is how to do it with PHP/Imagick, which uses ImageMagick:
$usmap = '/path/to/blank/us-map.svg';
$im = new Imagick();
$svg = file_get_contents($usmap);
/*loop to color eac...
Is there an expression for an infinite generator?
...entinel. However, as int() will always return 0, we can call int() forever and never reach 1. This will in effect produce an infinite list of 0's
– Olsgaard
Apr 14 at 8:47
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What is content-type and datatype in an AJAX request?
What is content-type and datatype in a POST request? Suppose I have this:
3 Answers
3
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What should my Objective-C singleton look like? [closed]
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@Paul you can override the release method and make it empty. :)
– user142019
Mar 25 '11 at 22:20
4
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How can I suppress all output from a command using Bash?
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The following sends standard output to the null device (bit bucket).
scriptname >/dev/null
And if you also want error messages to be sent there, use one of (the first may not work in all shells):
scriptname &>/dev/null
scriptname >...