Paul Rudin wrote: > Steven D'Aprano <st...@remove-this-cybersource.com.au> writes: > > >> I'm sympathetic to your request for list views. I've often wanted some >> way to cleanly and neatly do this: >> >> for item in seq[1:]: >> process(item) >> >> without making an unnecessary copy of almost all of seq. >> > > I don't know how it's implemented - but presumably itertools.islice > could provide what you're asking for?
For skipping just a few items islice() is perfect, for big offsets its O(N) behaviour may get annoying: $ python -m timeit -s"from itertools import islice; N=10**5; r = range(N)" "for i in islice(r, N, N): pass" 100 loops, best of 3: 1.93 msec per loop $ python -m timeit -s"from itertools import islice; N=10**6; r = range(N)" "for i in islice(r, N, N): pass" 10 loops, best of 3: 18.9 msec per loop $ python -m timeit -s"from itertools import islice; N=10**7; r = range(N)" "for i in islice(r, N, N): pass" 10 loops, best of 3: 188 msec per loop islice() could be changed to special-case lists and tuples, but that feels a bit unclean. -- http://mail.python.org/mailman/listinfo/python-list
