James Stroud wrote: groupby() is "all you can eat", but "no doggy bag".
> def serialize(table, keyer=_keyer, > selector=_selector, > keyfunc=_keyfunc, > series_keyfunc=_series_keyfunc): > keyed = izip(imap(keyer, table), table) > filtered = ifilter(selector, keyed) > serialized = groupby(filtered, series_keyfunc) > serieses = [] > for s_name, series in serialized: > grouped = groupby(series, keyfunc) > regrouped = ((k, (v[1] for v in g)) for (k,g) in grouped) > serieses.append((s_name, regrouped)) You are trying to store a group for later consumption here. > for s in serieses: > yield s That doesn't work: >>> groups = [g for k, g in groupby(range(10), lambda x: x//3)] >>> for g in groups: ... print list(g) ... [] [] [] [9] You cannot work around that because what invalidates a group is the call of groups.next(): >>> groups = groupby(range(10), lambda x: x//3) >>> g = groups.next()[1] >>> g.next() 0 >>> groups.next() (1, <itertools._grouper object at 0x2b3bd1f300f0>) >>> g.next() Traceback (most recent call last): File "<stdin>", line 1, in <module> StopIteration Perhaps Python should throw an out-of-band exception for an invalid group instead of yielding bogus data. Peter -- http://mail.python.org/mailman/listinfo/python-list
