Python analogue for Ruby Enumerable .partition method

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python equivalent of filter() getting two output lists (i.e. partition of a list)

Is there any built-in function or maybe some module in python standard library, that simulates Enumerable.partition behaviour from Ruby and iterates over an object just once to get two lists/tuples based on a predicate function passed?

it's here: http://docs.python.org/dev/library/itertools.html#itertools-recipes. And this has been asked a number of times. http://stackoverflow.com/questions/4578590/python-equivalent-of-filter-getting-two-output-lists-i-e-partition-of-a-list — tokland, Sep 12 '12 at 12:00

score 1 · Answer 1 · edited May 23 '17 at 11:49

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Stolen shamelessly from this question - you can use the tee function from itertools:

from itertools import tee

def split_on_condition(seq, condition):
    l1,l2 = tee((condition(item),item) for item in seq)
    return (i for p, i in l1 if p), (i for p, i in l2 if not p)

edited May 23 '17 at 11:49

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answered Sep 12 '12 at 12:00

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no need to copy and paste, we can close the question for being an exact duplicate – tokland Sep 12 '12 at 12:01

Python analogue for Ruby Enumerable .partition method

1 Answers1