On May 13, 1:58 am, Jaime Fernandez del Rio <jaime.f...@gmail.com> wrote: > On Tue, May 12, 2009 at 5:02 PM, MRAB <goo...@mrabarnett.plus.com> wrote: > > John Machin wrote: > > >> MRAB <google <at> mrabarnett.plus.com> writes: > > >>> Sort the list, passing a function as the 'key' argument. The function > >>> should return an integer for the month, eg 0 for 'jan', 1 for 'feb'. If > >>> you want to have a different start month then add > > >> and if you don't like what that produces, try subtract :-) > > > Oops! > > >>> the appropriate > >>> integer for that month (eg 0 for 'jan', 1 for 'feb') and then modulo 12 > >>> to make it wrap around (there are only 12 months in a year), returning > >>> the result. > > > Actually, subtract the start month, add 12, and then modulo 12. > > Both on my Linux and my Windows pythons, modulos of negative numbers > are properly taken, returning always the correct positive number > between 0 and 11. I seem to recall, from my distant past, that Perl > took pride on this being a language feature. Anyone knows if that is > not the case with python, and so not adding 12 before taking the > modulo could result in wrong results in some implementations?
If that happens, it's a bug. http://docs.python.org/reference/expressions.html#binary-arithmetic-operations If you look at function i_divmod() in the 2.x branch's Objects/ intobject.c, you'll be reassured to see that it doesn't just take whatever C serves up :-) -- http://mail.python.org/mailman/listinfo/python-list
