On Fri, Dec 6, 2013 at 2:59 PM, Nathaniel Smith <n...@pobox.com> wrote: > On Fri, Dec 6, 2013 at 11:55 AM, Alexander Belopolsky <ndar...@mac.com> wrote: >> >> >> >> On Fri, Dec 6, 2013 at 1:46 PM, Alan G Isaac <alan.is...@gmail.com> wrote: >>> >>> On 12/6/2013 1:35 PM, josef.p...@gmail.com wrote: >>> > unary versus binary minus >>> >>> Oh right; I consider binary `-` broken for >>> Boolean arrays. (Sorry Alexander; I did not >>> see your entire issue.) >>> >>> >>> > I'd rather write ~ than unary - if that's what it is. >>> >>> I agree. So I have no objection to elimination >>> of the `-`. >> >> >> It looks like we are close to reaching a consensus on the following points: >> >> 1. * is well-defined on boolean arrays and may be used in preference of & in >> code that is designed to handle 1s and 0s of any dtype in addition to >> booleans. >> >> 2. + is defined consistently with * and the only issue is the absence of >> additive inverse. This is not a problem as long as presence of - does not >> suggest otherwise. >> >> 3. binary and unary minus should be deprecated because its use in >> expressions where variables can be either boolean or numeric would lead to >> subtle bugs. For example -x*y would produce different results from -(x*y) >> depending on whether x is boolean or not. In all situations, ^ is >> preferable to binary - and ~ is preferable to unary -. >> >> 4. changing boolean arithmetics to auto-promotion to int is precluded by a >> significant use-case of boolean matrices. > > +1
+0.5 (I would still prefer a different binary minus, but it would be inconsistent with a logical unary minus that negates.) 5. `/` is useless 6 `**` follows from 1. Josef > > -- > Nathaniel J. Smith > Postdoctoral researcher - Informatics - University of Edinburgh > http://vorpus.org > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
