[Python-Dev] Getting values stored inside sets (original) (raw)

Sebastian Rittau srittau at jroger.in-berlin.de
Fri Apr 3 17:45:42 CEST 2009

Hello,

On Fri, Apr 03, 2009 at 02:07:02PM +0200, Hrvoje Niksic wrote:

But I can't seem to find a way to retrieve the element corresponding to 'foo', at least not without iterating over the entire set. Is this an oversight or an intentional feature? Or am I just missing an obvious way to do this?

I am missing a simple way to retrieve the "first" element of any iterable in python that matches a certain condition anyway. Something like this:

def first(iter, cb): for el in iter: if cb(el): return el raise IndexError()

Or (shorter, but potentially slower):

def first(iter, cb): return [el for el in iter if cb(el)][0]

To be used like this:

my_el = first(my_set, lambda el: el == "foobar")

This is something I need from time to time and this also seems to solve your problem.

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