On 7 November 2012 11:11, Oscar Benjamin <oscar.j.benja...@gmail.com> wrote:
> On Nov 7, 2012 5:41 AM, "Gregory Ewing" <greg.ew...@canterbury.ac.nz> > wrote: > > > > If anything is to be done in this area, it would be better > > as an extension of list comprehensions, e.g. > > > > [[None times 5] times 10] > > > > which would be equivalent to > > > > [[None for _i in xrange(5)] for _j in xrange(10)] > > I think you're right that the meaning of list-int multiplication > can't/shouldn't be changed if this way. > > A multidimensional list comprehension would be useful even for people who > are using numpy as it's common to use a list comprehension to initialise a > numpy array. > > A more modest addition for the limited case described in this thread could > be to use exponentiation: > > >>> [0] ** (2, 3) > [[0, 0, 0], [0, 0, 0]] > Hold on: why not just use multiplication? >>> [0] * (2, 3) is an error now, and it makes total sense. Additionally, it's not breaking the "no copy -- _ever_" rule because none of the lists existed before. The values inside the list would be by reference, as before, so lst * (x,) would be the same as lst * x if x is an integer. *I* would use this a lot. This is the first thing on this thread that makes a lot of sense to me. We do have to think of the potential problems, though. There are definitely some. For one, code that relies on lst * x throwing an error would break. It may confuse others - although I don't see how. But I don't see any big problems, so I really do like this idea.
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