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The tilde operator in Python
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204
It is a unary operator (taking a single argument) that is borrowed from C, where all data type...
How do I get indices of N maximum values in a NumPy array?
...mplest I've been able to come up with is:
In [1]: import numpy as np
In [2]: arr = np.array([1, 3, 2, 4, 5])
In [3]: arr.argsort()[-3:][::-1]
Out[3]: array([4, 3, 1])
This involves a complete sort of the array. I wonder if numpy provides a built-in way to do a partial sort; so far I haven't bee...
Is it possible to have multiple statements in a python lambda expression?
...found in the heapq module.
>>> import heapq
>>> l = [5,2,6,8,3,5]
>>> heapq.nsmallest(l, 2)
[2, 3]
So just use:
map(lambda x: heapq.nsmallest(x,2)[1], list_of_lists)
It's also usually considered clearer to use a list comprehension, which avoids the lambda altogethe...
pandas DataFrame: replace nan values with average of columns
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283
You can simply use DataFrame.fillna to fill the nan's directly:
In [27]: df
Out[27]:
...
How to count the number of set bits in a 32-bit integer?
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How to find all occurrences of an element in a list?
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123
While not a solution for lists directly, numpy really shines for this sort of thing:
import nu...
Mapping a function on the values of a map in Clojure
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answered Nov 5 '09 at 2:16
Brian CarperBrian Carper
64.9k2525 gold badges154154 silver badges164164 bronze badges
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How to find my Subversion server version number?
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211
To find the version of the subversion REPOSITORY you can:
Look to the repository on the web ...
How to implement a queue using two stacks?
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20 Answers
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How to split a sequence into two pieces by predicate?
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By using partition method:
scala> List(1,2,3,4).partition(x => x % 2 == 0)
res0: (List[Int], List[Int]) = (List(2, 4),List(1, 3))
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