Python Remove the repeat element

Question

I have two lists. How can I define a function "remove_repeat_element" to remove repeat elements from them ? ?

def remove_repeat_element(a, b):
    ... ...

a = ['bd09fdf7-918e-4a5e-8338-0f6fe78fd238']
b = ['bd09fdf7-918e-4a5e-8338-0f6fe78fd238', '3c26f383-da50-446c-8613-64e1068bd57e']

result = remove_repeat_element(a, b)
print result
>>> ['3c26f383-da50-446c-8613-64e1068bd57e']

Could someone give me some advice ?? Thanks a lot!

See this [post](http://stackoverflow.com/a/15188973/1982962) — Kobi K, Dec 05 '13 at 10:48

score 10 · Accepted Answer · answered Dec 05 '13 at 10:48

10

You can use sets :

>>> a = ['bd09fdf7-918e-4a5e-8338-0f6fe78fd238']
>>> b = ['bd09fdf7-918e-4a5e-8338-0f6fe78fd238', '3c26f383-da50-446c-8613-64e1068bd57e']
>>> list(set(b) - set(a))
['3c26f383-da50-446c-8613-64e1068bd57e']

answered Dec 05 '13 at 10:48

Faruk Sahin

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Ray · Answer 2 · 2013-12-05T11:02:21.707

2

My suggestion:

c = [x for x in b if x not in a]

It is pretty straight forward to write and efficient enough as a list comprehension.

Hope this helps!

Update:

For more efficient membership checking, use set instead of list.

a = set(a)
c = [x for x in b if x not in a]

This would be even faster and not to mention the improvement when the list is large.

edited Dec 05 '13 at 11:02

answered Dec 05 '13 at 10:50

Ray

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score 0 · Answer 3 · answered Dec 05 '13 at 10:51

0

return [el for el in b if el not in a]

answered Dec 05 '13 at 10:51

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Python Remove the repeat element

3 Answers3