fastest way to find the intersection of n lists of sets
Alex Martelli
aleax at mac.com
Sun Apr 29 21:41:33 EDT 2007
Prateek <surekap at gmail.com> wrote:
> > For the above example, it's worth sorting lists_of_sets by the
> > length of the sets, and doing the short ones first.
>
> Thanks. I thought so - I'm doing just that using a simple Decorate-
> Sort-Undecorate idiom.
Use, instead, the DSU that is now build into Python:
listofsets.sort(key=len)
this will be faster (as well as more readable &c) than programming your
own DSU, and is exactly the reason the key= parameter was added.
I also suggest avoiding reduce in favor of a simple explicit loop.
Alex
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