Arnaud Delobelle: > Some people would write it as: > > def leniter(iterable): > if hasattr(iterable, '__len__'): > return len(iteratble) > return sum(1 for _ in iterable)
That's slower than my version. > > def xpairwise(iterable): > > return izip(iterable, islice(iterable, 1, None)) > > This doesn't work if the iterable is an iterator. I see. I think I have never used it with an iterator so far :-) I'll fix it. > Why not: > > def xpairs(seq): > for i, el in enumerate(seq): > for j in xrange(i): > yield seq[j], el Maybe because I was not smart enough to invent that :-) ------------------- Mark Dickinson: > 3) xpairs(seq) > >>> list(xpairs(range(5))) > [(0, 1), (0, 2), (0, 3), (0, 4), (1, 2), (1, 3), (1, 4), (2, 3), > (2, 4), (3, 4)] Doesn't itertools.combinations already do this for you? >>> list(itertools.combinations(range(5), 2)) I have written most of those functions when I have used Python 2.4, before itertools.combinations. But you are right, xpairs is now almost useless, just one line long :-) Combinatorics is so fun :-) Thank you very much to both. Bye, bearophile -- http://mail.python.org/mailman/listinfo/python-list
