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How does one reorder columns in a data frame?
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354
Your dataframe has four columns like so df[,c(1,2,3,4)].
Note the first comma means keep all the...
Remove insignificant trailing zeros from a number?
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143
If you convert it to a string it will not display any trailing zeros, which aren't stored in th...
Mysql order by specific ID values
...rder by" using predefined set of column values (ID) like: order by (ID=1,5,4,3) so I would get record 1, 5, 4, 3 in that order out?
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Get a pixel from HTML Canvas?
...pixel and invert the color.
for (var i = 0, n = pix.length; i < n; i += 4) {
pix[i ] = 255 - pix[i ]; // red
pix[i+1] = 255 - pix[i+1]; // green
pix[i+2] = 255 - pix[i+2]; // blue
// i+3 is alpha (the fourth element)
}
// Draw the ImageData at the given (x,y) coordinates.
conte...
How can I convert tabs to spaces in every file of a directory?
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answered Jun 19 '12 at 4:35
Martin BeckettMartin Beckett
88.4k2323 gold badges175175 silver badges248248 bronze badges
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How does PHP 'foreach' actually work?
...on iterate($arr) {
foreach ($arr as $v) {}
}
$outerArr = [0, 1, 2, 3, 4];
iterate($outerArr);
Here, $arr will be duplicated to prevent IAP changes on $arr from leaking to $outerArr. In terms of the conditions above, the array is not a reference (is_ref=0) and is used in two places (refcount=2...
Why isn't std::initializer_list a language built-in?
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48
There were already examples of "core" language features that returned types defined in the std ...
Assigning code to a variable
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edited Apr 17 '14 at 19:38
answered Apr 16 '14 at 20:42
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__lt__ instead of __cmp__
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Alex MartelliAlex Martelli
725k148148 gold badges11261126 silver badges13241324 bronze badges
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How do I commit only some files?
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wjandrea
12.3k55 gold badges2424 silver badges4747 bronze badges
answered Aug 30 '11 at 6:28
AlexAlex
19k11...