[Gretl-devel] Re: 'msplitby' quirks

Am 11.08.2021 um 20:44 schrieb Allin Cottrell: > On Wed, 11 Aug 2021, Sven Schreiber wrote: > > > Am 11.08.2021 um 17:29 schrieb Allin Cottrell: > > > > > > > matrices msplitby (matrix M, <vector-or-scalar> by, bool alt) > > > > > > where @alt would switch to column-wise splitting and scalar @by would > > > give the chunk size, provided the relevant dimension is divisible by > > > @by. > > Yes, that's what I had in mind, too. > > > > > > BTW splitting a matrix by columns will be much faster then by rows; > > > > Right, that's one reason why I found the current status a bit surprising. > > Maybe a feature request is not necessary. The signature given above is > now supported in git, available for testing. Excellent, thanks Allin! I tested a little bit, and mostly it works fine I think. Some minor observations: - If the rows (or cols) are not dividible by "by", I get an "invalid arg" error. Perhaps "Matrix not conformable" would be a more informative error? - (Probably not new behavior:) A scalar in place of M does not seem to be allowed, as in msplitby(2, {1}). Of course this operation does not look very useful, but it could arise in a corner case in a function or script. And my understanding is that gretl always tries to allow a scalar where a 1x1 matrix is valid, and msplitby({2}, {1}) already works.