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Filtering a list based on a list of booleans
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>>> from itertools import compress
>>> list_a = [1, 2, 4, 6]
>>> fil = [True, False, True, False]
>>> list(compress(list_a, fil))
[1, 4]
Timing comparisons(py3.x):
>>> list_a = [1, 2, 4, 6]
>>> fil = [True, False, True, False]
>>> %...
regex for zip-code
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^\d{5}(?:[-\s]\d{4})?$
^ = Start of the string.
\d{5} = Match 5 digits (for condition 1, 2, 3)
(?:…) = Grouping
[-\s] = Match a space (for condition 3) or a hyphen (for condition 2)
\d{4} = Match 4 digits (for condition 2, 3)
…? = The ...
Mean per group in a data.frame [duplicate]
... 12 23
Aira 2 18 73
Aira 3 19 45
Ben 1 53 19
Ben 2 22 87
Ben 3 19 45
Cat 1 22 87
Cat 2 67 43
Cat 3 45 32', header=TRUE)
aggregate(d[, 3:4], ...
What does the star operator mean, in a function call?
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s = sum(1, 2, c=10, d=15)
Also see section 4.7.4 - Unpacking Argument Lists of the Python documentation.
Additionally you can define functions to take *x and **y arguments, this allows a function to accept any number of positional and/or named arguments that aren't...
Specify custom Date format for colClasses argument in read.table/read.csv
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4 Answers
4
Active
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NPM - How to fix “No readme data”
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edited Oct 23 '14 at 16:22
answered Aug 6 '13 at 17:29
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sed: print only matching group
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140
Match the whole line, so add a .* at the beginning of your regex. This causes the entire line t...
PHP Pass by reference in foreach [duplicate]
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146
Because on the second loop, $v is still a reference to the last array item, so it's overwritten...
What does the slash mean in help() output?
What does the / mean in Python 3.4's help output for range before the closing parenthesis?
3 Answers
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What does “%” (percent) do in PowerShell?
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146
When used in the context of a cmdlet (such as your example), it's an alias for ForEach-Object:
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