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Pandas: create two new columns in a dataframe with values calculated from a pre-existing column
... return x*2, x*3
...:
In [3]: df = DataFrame({'a': [1,2,3], 'b': [2,3,4]})
In [4]: df
Out[4]:
a b
0 1 2
1 2 3
2 3 4
In [5]: df["A1"], df["A2"] = zip(*df["a"].map(calculate))
In [6]: df
Out[6]:
a b A1 A2
0 1 2 2 3
1 2 3 4 6
2 3 4 6 9
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Bootstrap 3 - Why is row class is wider than its container?
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edited Feb 4 '16 at 14:50
Seonghyeon Cho
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answered Sep ...
Reloading module giving NameError: name 'reload' is not defined
...module in Python 3, you should use either:
importlib.reload for Python 3.4 and above
imp.reload for Python 3.0 to 3.3 (deprecated since Python 3.4 in favour of importlib)
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What's the difference between tilde(~) and caret(^) in package.json?
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4053
See the NPM docs and semver docs:
~version “Approximately equivalent to version”, will u...
Remove all occurrences of a value from a list?
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524
Functional approach:
Python 3.x
>>> x = [1,2,3,2,2,2,3,4]
>>> list(filter((2...
What is sys.maxint in Python 3?
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martineau
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answered Dec 10 '12 at 5:58
Diego BaschDiego Basch
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Pass a data.frame column name to a function
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edited Apr 11 '16 at 21:42
joran
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while (1) vs. while(True) — Why is there a difference (in python 2 bytecode)?
...True is reassignable:
Python 2.7 (r27:82508, Jul 3 2010, 21:12:11)
[GCC 4.0.1 (Apple Inc. build 5493)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> True = 4
>>> True
4
In Python 3.x it truly becomes a keyword and a real constant:
Pyth...
dplyr summarise: Equivalent of “.drop=FALSE” to keep groups with zero length in output
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4 Answers
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Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.
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Update
data.table v1.9.6+ now supports OP's original attempt and the following answer is no lon...