On 12 Jun 2013 01:36, "Roy Smith" <r...@panix.com> wrote: > > In article <mailman.3023.1370964449.3114.python-l...@python.org>, > Serhiy Storchaka <storch...@gmail.com> wrote: > > > 11.06.13 07:11, Roy Smith написав(ла): > > > In article <mailman.2992.1370904643.3114.python-l...@python.org>, > > > Roel Schroeven <r...@roelschroeven.net> wrote: > > > > > >> new_songs, old_songs = [], [] > > >> [(new_songs if s.is_new() else old_songs).append(s) for s in songs] > > > > > > Thanks kind of neat, thanks. > > > > > > I'm trying to figure out what list gets created and discarded. I think > > > it's [None] * len(songs). > > > > It is the same as your klunky code, but consumes more memory. > > Well, continuing down this somewhat bizarre path: > > new_songs, old_songs = [], [] > itertools.takewhile( > lambda x: True, > (new_songs if s.is_new() else old_songs).append(s) for s in songs) > ) > > I'm not sure I got the syntax exactly right, but the idea is anything > that will iterate over a generator expression. That at least gets rid > of the memory requirement to hold the throw-away list :-)
You could equivalently pass the generator to deque() with maxlen=0 - this consumes the iterator with constant memory usage. We are of course firmly in the twilight zone at this point (although this can be a useful technique in general). Cheers, Phil > > -- > http://mail.python.org/mailman/listinfo/python-list >
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