2/02/10 @ 00:01 (-0700), thus spake Charles R Harris: > On Mon, Feb 1, 2010 at 10:57 PM, <josef.p...@gmail.com> wrote: > > > On Tue, Feb 2, 2010 at 12:31 AM, Charles R Harris > > <charlesr.har...@gmail.com> wrote: > > > > > > > > > On Mon, Feb 1, 2010 at 10:02 PM, <josef.p...@gmail.com> wrote: > > >> > > >> On Mon, Feb 1, 2010 at 11:45 PM, Charles R Harris > > >> <charlesr.har...@gmail.com> wrote: > > >> > > > >> > > > >> > On Mon, Feb 1, 2010 at 9:36 PM, David Cournapeau <courn...@gmail.com> > > >> > wrote: > > >> >> > > >> >> On Tue, Feb 2, 2010 at 1:05 PM, <josef.p...@gmail.com> wrote: > > >> >> > > >> >> > I think this could be considered as a correct answer, the count of > > >> >> > any > > >> >> > integer is zero. > > >> >> > > >> >> Maybe, but this shape is random - it would be different in different > > >> >> conditions, as the length of the returned array is just some random > > >> >> memory location. > > >> >> > > >> >> > > > >> >> > Returning an array with one zero, or the empty array or raising an > > >> >> > exception? I don't see much of a pattern > > >> >> > > >> >> Since there is no obvious solution, the only rationale for not > > raising > > >> >> an exception I could see is to accommodate often-encountered special > > >> >> cases. I find returning [0] more confusing than returning empty > > >> >> arrays, though - maybe there is a usecase I don't know about. > > >> >> > > >> > > > >> > In this case I would expect an empty input to be a programming error > > and > > >> > raising an error to be the right thing. > > >> > > >> Not necessarily, if you run the bincount over groups in a dataset and > > >> your not sure if every group is actually observed. The main question, > > >> is whether the user needs or wants to check for empty groups before or > > >> after the loop over bincount. > > >> > > > > > > How would they know which bin to check? This seems like an unlikely way > > to > > > check for an empty input. > > > > # grade (e.g. SAT) distribution by school and race > > for s in schools: > > for r in race: > > print s, r, np.bincount(allstudentgrades[(sch==s)*(ra==r)]) > > > > allwhite schools and allblack schools raise an exception. > > > > I just made up the story, my first attempt was: all sectors, all > > firmsize groups, bincount something, will have empty cells for some > > size groups, e.g. nuclear power in family business. > > > > > OK, point taken. What do you think would be the best thing to do?
In my opinion, returning an empty array makes more sense than array([0]). An empty arrays means "there are no bins", whereas an array of length 1 implies that there is one. Cheers. Ernest _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
