I have list like this:
a = [1,2,3,4,5,6,7]
b = [10,11,13,2,14,7]
I want output like this:
b = [10,11,13,14]
if an element of a is in b then it has been discarded. please, anyone can tell me how to do this?
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Using list comprehension:
b = [x for x in b if x not in a]
Works like this:
a = [1,2,3,4,5,6,7]
b = [10,11,13,2,14,7]
b = [x for x in b if x not in a]
print b
>> [10, 11, 13, 14]
Re: @DeepSpace's suggestion, looking for elements of a set in a list will go significantly faster than looking for elements of a list in another list, so declare a as a set()
a = set([1,2,3,4,5,6,7])
b = [10,11,13,2,14,7]
b = [x for x in b if x not in a]
kamses
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1This is `O(len(a) * len(b))`. Make `a` a set and this will become `O(len(b))` as set lookup is `O(1)` rather than list lookup which is `O(n)` – DeepSpace Dec 02 '18 at 17:29
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Thank you for pointing this out! Added to answer. – kamses Dec 02 '18 at 17:37