[Python-Dev] Getting values stored inside sets
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.
- Sebastian
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