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dplyr summarise: Equivalent of “.drop=FALSE” to keep groups with zero length in output
...g summarise with plyr 's ddply function, empty categories are dropped by default. You can change this behavior by adding .drop = FALSE . However, this doesn't work when using summarise with dplyr . Is there another way to keep empty categories in the result?
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How can I join elements of an array in Bash?
If I have an array like this in Bash:
30 Answers
30
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Pandas groupby: How to get a union of strings
... df = read_csv(StringIO(data),sep='\s+')
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: obj...
What's the difference between HEAD^ and HEAD~ in Git?
When I specify an ancestor commit object in Git, I'm confused between HEAD^ and HEAD~ .
15 Answers
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Easy way to concatenate two byte arrays
What is the easy way to concatenate two byte arrays?
12 Answers
12
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C++ equivalent of java's instanceof
...>doSomething();
}
This requires your compiler to have rtti support enabled.
EDIT:
I've had some good comments on this answer!
Every time you need to use a dynamic_cast (or instanceof) you'd better ask yourself whether it's a necessary thing. It's generally a sign of poor design.
Typical wor...
What's the difference between array_merge and array + array?
A fairly simple question. What's the difference between:
9 Answers
9
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Combine the first two commits of a Git repository?
Suppose you have a history containing the three commits A, B and C :
8 Answers
8
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Relationship between SciPy and NumPy
SciPy appears to provide most (but not all [1]) of NumPy's functions in its own namespace. In other words, if there's a function named numpy.foo , there's almost certainly a scipy.foo . Most of the time, the two appear to be exactly the same, oftentimes even pointing to the same function object.
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Why do I need 'b' to encode a string with Base64?
Following this python example , I encode a string as Base64 with:
5 Answers
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