Gerard Flanagan a écrit : > Alex Martelli wrote: > >>Gerard Flanagan <[EMAIL PROTECTED]> wrote: >> ... >> >>>a = [ '+', 'tag1', '+', 'tag2', '-', 'tag3', '+', 'tag4' ] >>> >>>import itertools >>> >>>b = list(itertools.islice(a,0,8,2)) >>>c = list(itertools.islice(a,1,8,2)) >> >>Much as I love itertools, this specific task would be best expressed ad >> >>b = a[::2] >>c = a[1::2] >> > > > Yes, I thought that when I saw bruno's solution - I can't say that I've > never seen that syntax before, but I never really understood that this > is what it did.
It's in fact pretty simple. The full slice syntax is [start:end:step], with default values of start=0, end=len(seq), step=1. So a[::2] will retrieve a[0], a[2], a[4] etc, and a[1::2] -> a[1], a[3], a[5] etc. (snip) -- http://mail.python.org/mailman/listinfo/python-list
