I have two lists in Python:
temp1 = ['One', 'Two', 'Three', 'Four'] temp2 = ['One', 'Two']
Assuming the elements in each list are unique, I want to create a third list with items from the first list which are not in the second list:
temp3 = ['Three', 'Four']
Are there any fast ways without cycles and checking?
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Answer
To get elements which are in temp1 but not in temp2 (assuming uniqueness of the elements in each list):
In [5]: list(set(temp1) - set(temp2)) Out[5]: ['Four', 'Three']
Beware that it is asymmetric :
In [5]: set([1, 2]) - set([2, 3]) Out[5]: set([1])
where you might expect/want it to equal set([1, 3]). If you do want set([1, 3]) as your answer, you can use set([1, 2]).symmetric_difference(set([2, 3])).