On Monday, January 8, 2018 at 12:02:09 AM UTC, Ethan Furman wrote: > On 01/07/2018 12:33 PM, Chris Angelico wrote: > > On Mon, Jan 8, 2018 at 7:13 AM, Thomas Jollans wrote: > >> On 07/01/18 20:55, Chris Angelico wrote: > >>> Under what circumstances would you want "x != y" to be different from > >>> "not (x == y)" ? > >> > >> In numpy, __eq__ and __ne__ do not, in general, return bools. > >> > >>>>> a = np.array([1,2,3,4]) > >>>>> b = np.array([0,2,0,4]) > >>>>> a == b > >> array([False, True, False, True], dtype=bool) > >>>>> a != b > >> array([ True, False, True, False], dtype=bool) > > > > Thanks, that's the kind of example I was looking for. Though numpy > > doesn't drive the core language development much, so the obvious next > > question is: was this why __ne__ was implemented, or was there some > > other reason? This example shows how it can be useful, but not why it > > exists. > > Actually, I think it is why it exists. If I recall correctly, the addition > of the six comparative operators* was added > at the behest of the scientific/numerical community. > > -- > ~Ethan~ > > * Yeah, I can't remember the cool name for those six operators at the moment. > :(
The six rich comparison methods were added to 2.1 as a result of PEP 207, which confirms that you're correct, they were added at the request of the numpyites. -- Kindest regards. Mark Lawrence. -- https://mail.python.org/mailman/listinfo/python-list
