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Pandas groupby: How to get a union of strings
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In [5]: df
Out[5]:
A B C
0 1 0.749065 This
1 2 0.301084 is
2 3 0.463468 a
3 4 0.643961 random
4 1 0.866521 string
5 2 0.120737 !
In [6]: df.dtypes
Out[6]:
A int64
B float64
C object
dtype: object
When you apply your own function, t...
What's the difference between lists enclosed by square brackets and parentheses in Python?
...you can change its contents:
>>> x = [1,2]
>>> x.append(3)
>>> x
[1, 2, 3]
while tuples are not:
>>> x = (1,2)
>>> x
(1, 2)
>>> x.append(3)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: '...
Numbering rows within groups in a data frame
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answered Oct 16 '12 at 23:41
mnelmnel
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The modulo operation on negative numbers in Python
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134
Unlike C or C++, Python's modulo operator (%) always return a number having the same sign as th...
Is there a 'foreach' function in Python 3?
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user 451
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answered Aug 18 '13 at 0:33
Jo Are ByJo Are By
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Does .asSet(…) exist in any API?
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answered Dec 23 '16 at 16:46
Mr. AndersonMr. Anderson
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pandas read_csv and filter columns with usecols
...mport StringIO
csv = r"""dummy,date,loc,x
bar,20090101,a,1
bar,20090102,a,3
bar,20090103,a,5
bar,20090101,b,1
bar,20090102,b,3
bar,20090103,b,5"""
df = pd.read_csv(StringIO(csv),
header=0,
index_col=["date", "loc"],
usecols=["date", "loc", "x"],
parse_dates=["date"...
Iterating over dictionaries using 'for' loops
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13 Answers
13
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Should I use encoding declaration in Python 3?
Python 3 uses UTF-8 encoding for source-code files by default. Should I still use the encoding declaration at the beginning of every source file? Like # -*- coding: utf-8 -*-
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const char* concatenation
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answered Jan 3 '10 at 14:05
codaddictcodaddict
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