Issue
Is there a built-in function that works like zip()
but that will pad the results so that the length of the resultant list is the length of the longest input rather than the shortest input?
>>> a = ['a1']
>>> b = ['b1', 'b2', 'b3']
>>> c = ['c1', 'c2']
>>> zip(a, b, c)
[('a1', 'b1', 'c1')]
>>> What command goes here?
[('a1', 'b1', 'c1'), (None, 'b2', 'c2'), (None, 'b3', None)]
Solution
In Python 3 you can use itertools.zip_longest
>>> list(itertools.zip_longest(a, b, c))
[('a1', 'b1', 'c1'), (None, 'b2', 'c2'), (None, 'b3', None)]
You can pad with a different value than None
by using the fillvalue
parameter:
>>> list(itertools.zip_longest(a, b, c, fillvalue='foo'))
[('a1', 'b1', 'c1'), ('foo', 'b2', 'c2'), ('foo', 'b3', 'foo')]
With Python 2 you can either use itertools.izip_longest
(Python 2.6+), or you can use map
with None
. It is a little known feature of map
(but map
changed in Python 3.x, so this only works in Python 2.x).
>>> map(None, a, b, c)
[('a1', 'b1', 'c1'), (None, 'b2', 'c2'), (None, 'b3', None)]
Answered By - Nadia Alramli
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