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Remove empty elements from an array in Javascript
... to remove null or undefined values:
var array = [0, 1, null, 2, "", 3, undefined, 3,,,,,, 4,, 4,, 5,, 6,,,,];
var filtered = array.filter(function (el) {
return el != null;
});
console.log(filtered);
It will depend on what you consider to be "empty" for example, if you were d...
Can dplyr package be used for conditional mutating?
... 1 & b == 4), 2,
ifelse(a == 0 | a == 1 | a == 4 | a == 3 | c == 4, 3, NA)))
Added - if_else: Note that in dplyr 0.5 there is an if_else function defined so an alternative would be to replace ifelse with if_else; however, note that since if_else is stricter than ifelse (both leg...
Is there a Python function to determine which quarter of the year a date is in?
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13 Answers
13
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Find indices of elements equal to zero in a NumPy array
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numpy.where() is my favorite.
>>> x = numpy.array([1,0,2,0,3,0,4,5,6,7,8])
>>> numpy.where(x == 0)[0]
array([1, 3, 5])
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PHP Regex to check date is in YYYY-MM-DD format
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23 Answers
23
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Insert a line at specific line number with sed or awk
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243
sed -i '8i8 This is Line 8' FILE
inserts at line 8
8 This is Line 8
into file FILE
-i doe...
How to drop columns by name in a data frame
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389
You should use either indexing or the subset function. For example :
R> df <- data.fram...
How can I get nth element from a list?
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Look here, the operator used is !!.
I.e. [1,2,3]!!1 gives you 2, since lists are 0-indexed.
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How to get all subsets of a set? (powerset)
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137
The Python itertools page has exactly a powerset recipe for this:
from itertools import chain,...
Base64 length calculation?
...log2(64) = 6).
Therefore 4 chars are used to represent 4 * 6 = 24 bits = 3 bytes.
So you need 4*(n/3) chars to represent n bytes, and this needs to be rounded up to a multiple of 4.
The number of unused padding chars resulting from the rounding up to a multiple of 4 will obviously be 0, 1, 2 or...