[Serhiy] > Isn't everyone expect that x*2 == x + x? Isn't this the definition of > multiplication?
Note: in my first message in this thread, I made the same objection. And that, e.g., it would also be weird if x*-1 is not the same as -x. Obviously, I don't care enough about those to make up a meaning for "multiset * scalar" that preserves those in all cases. And we have to make up a meaning, because there is no generally accepted _mathematical_ meaning for what "multiset times a scalar" should do. It's not that there's controversy about what it should do, it's that nobody asks the question. It's like asking "what should the logarithm of matrix to a base that's a string mean?" This isn't Perl ;-) For a scalar that's a non-negative integer, I agree repeated addition makes _most_ sense. But, as I also noted in my first message, Peter's "obvious" implementation satisfies that! Provided that the Counter represents a legit (all values are strictly positive integers) multiset to begin with, `Counter * n` is the same as adding the Counter n times. If the Counter doesn't represent a legit multiset to begin with, who cares? It's not "a multiset operation" at all then. Or if the scalar isn't a non-negative integer. What on Earth is "multiset * math.pi" supposed to do that gives a legit multiset result? For each value v, return math.floor(v * math.pi)? That's just nuts - _any_ answer to that would be nuts, utterly arbitrary just to preserve a useless notion of "consistency". The use cases Peter have in mind appear to do with manipulating discrete probability distributions represented as Counters, which really have nothing to do with multisets. Has values will always be non-negative, but almost never integers, so almost never _sanely_ viewed as being multisets. Counter doesn't care. And I don't want to get in his way by insisting on some notion of formal consistency in new operations that have nothing to do with multisets except by accident, or by artificially forced contrivance. I've used Counters to represent multisets a fair bit, but have never had the slightest desire to use "times an integer" as a shorthand for repeated addition, and can't even dream up a meaning for what dividing a multiset by an integer (let alone a float!) could return that would make a lick of sense. "Scalar broadcast" makes instant sense in both cases, though, just by dropping the illusion that people using Counters _as multisets_ are interested in these operations at all. _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
