[Python-Dev] Retrieve an arbitrary element from a set without removing it
tjreedy at udel.edu
Fri Oct 23 21:04:12 CEST 2009
John Arbash Meinel wrote:
> So 'for x in s: break' is about 2x faster than next(iter(s)) and 3x
> faster than (iter(s).next()).
> I was pretty surprised that it was 30% faster than "for x in s: pass". I
> assume it has something to do with a potential "else:" statement?
for x in s: pass
iterates through *all* the elements in s and leaves x bound to the
arbritrary *last* one instead of the arbitrary *first* one. For a large
set, this would be a lot slower, not just a little.
fwiw, I think the use case for this is sufficiently rare that it does
not need a separate method just for this purpose.
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