On Wed, Nov 18, 2009, GoodPotatoes wrote:
>I'm dealing with bigger lists than I have been, and noticed this is getting
>really slow. Is there a faster way to do this?
>
>for x in list1:
> if x not in list2:
> list3.append(x)
>
>My search is taking up to 5 minutes to complete.
When I have had to deal with large lists, I have found that using
an intermediate dictionary can save huge amounts of time.
Something like:
dict2 = {}.fromkeys(list2)
for x in list1:
if x not in dist2:
dict2[x] = True
list2 = dict2.keys()
Bill
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