On 2012-02-08, Mark Lawrence <breamore...@yahoo.co.uk> wrote:
> I'm looking at a way of cycling around a sequence i.e. starting
> at some given location in the middle of a sequence and running
> to the end before coming back to the beginning and running to
> the start place. About the best I could come up with is the
> following, any better ideas for some definition of better?
Python's indices were designed for these kinds of shenanigans.
def rotated(seq, n):
"""Iterate through all of seq, but starting from index n.
>>> ", ".join(str(n) for n in rotated(range(5), 3))
'3, 4, 0, 1, 2'
"""
i = n - len(seq)
while i < n:
yield seq[i]
i += 1
if __name__ == "__main__":
import doctest
doctest.testmod()
If you have merely an iterable instead of a sequence, then look
to some of the other clever stuff already posted.
--
Neil Cerutti
--
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