[Python-Dev] Retrieve an arbitrary element from a set without removing it (original) (raw)

Terry Reedy 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.

tjr

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