Ian Kelly wrote: > On Wed, Nov 25, 2015 at 10:44 AM, Ian Kelly <ian.g.ke...@gmail.com> wrote: >> On Wed, Nov 25, 2015 at 3:07 AM, Peter Otten <__pete...@web.de> wrote: >>>> elif name in METRICS_AVG: >>> # writing a function that calculates the average without >>> # materialising the list left as an exercise ;) >> >> metrics = itertools.tee(metrics) >> return int(sum(metrics[0]) / len(metrics[1])) > > Actually, don't do that. It does effectively materialize the list, > just not as a list.
Not just that, it will also complain >>> a, b = itertools.tee([1,2,3]) >>> sum(a), len(b) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: object of type 'itertools._tee' has no len() -- https://mail.python.org/mailman/listinfo/python-list
