John Machin wrote: > On 13/06/2006 6:28 PM, Paul McGuire wrote: > > >> (Oh, and I like groupby too! Combine it with sort to quickly create >> histograms.) >> >> # tally a histogram of a list of values from 1-10 >> dataValueRange = range(1,11) >> data = [random.choice(dataValueRange) for i in xrange(10000)] >> >> hist = [ (k,len(list(g))) for k,g in itertools.groupby(sorted(data)) ] >> > > That len(list(g)) looks like it uses O(N) memory just to find out what N > is :-( > Not at all! A python list *knows* its length at all times. len() is a constant time lookup of an internal attribute.
Gary Herron > The best I could come up with is sum(itertools.imap(lambda x: 1, g)) -- > but that does look a bit ugly ... > > -- http://mail.python.org/mailman/listinfo/python-list
