On Wed, 08 Feb 2012 01:10:28 +0000, 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?
PythonWin 2.7.2 (default, Jun 12 2011, 15:08:59) [MSC v.1500 32 bit
(Intel)] on win32.
Portions Copyright 1994-2008 Mark Hammond - see 'Help/About PythonWin'
for further copyright information.
from itertools import chain
a=range(10)
g = chain((a[i] for i in xrange(4, 10, 1)), (a[i] for i in xrange(4)))
for x in g: print x,
...
4 5 6 7 8 9 0 1 2 3
How large a sequence and, more important, is it fully known at the
start...
a = range(20)
a
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
a_shift = a[5:] + a[:5]
a_shift
[5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 0, 1, 2, 3, 4]
IOWs, just slice and join: tail first, then front-end.
