On Mon, Jun 10, 2013 at 1:34 PM, Roy Smith <r...@panix.com> wrote: > I have a list, songs, which I want to divide into two groups. > Essentially, I want: > > new_songs = [s for s in songs if s.is_new()] > old_songs = [s for s in songs if not s.is_new()] > > but I don't want to make two passes over the list. I could do: > > new_songs = [] > old_songs = [] > for s in songs: > if s.is_new(): > new_songs.append(s) > else: > old_songs.append(s) > > Which works, but is klunky compared to the two-liner above. This > seems like a common enough thing that I was expecting to find > something in itertools which did this. I'm thinking something along > the lines of: > > matches, non_matches = isplit(lambda s: s.is_new, songs) > > Does such a thing exist?
itertools.groupby() is kinda similar, but unfortunately doesn't fit the bill due to its sorting requirement. There is regrettably no itertools.partition(). And given how dead-set Raymond seems to be against adding things to the itertools module, there will likely never be. Maybe more-itertools (https://pypi.python.org/pypi/more-itertools ) would accept a patch? Cheers, Chris -- http://mail.python.org/mailman/listinfo/python-list
