Best way to handle large lists?

Larry Bates larry.bates at
Tue Oct 3 16:54:10 CEST 2006

Chaz Ginger wrote:
> I have a system that has a few lists that are very large (thousands or
> tens of thousands of entries) and some that are rather small. Many times
> I have to produce the difference between a large list and a small one,
> without destroying the integrity of either list. I was wondering if
> anyone has any recommendations on how to do this and keep performance
> high? Is there a better way than
> [ i for i in bigList if i not in smallList ]
> Thanks.
> Chaz

IMHO the only way to speed things up is to know more about the
actual data in the lists (e.g are the elements unique, can they
be sorted, etc) and take advantage of all that information to
come up with a "faster" algorithm.  If they are unique, sets
might be a good choice.  If they are sorted, bisect module
might help.  The specifics about the list(s) may yield a faster


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