Re: [Gretl-devel] Preserve row and col names of a matrix after functions
On Wed, 2 Nov 2016, Sven Schreiber wrote:
Am 02.11.2016 um 14:47 schrieb Riccardo (Jack) Lucchetti:
> While we're on the subject:
You recently have a tendency to use this "speaking of which"
phrase to actually do a Monty-Python-esque "and now for something
completely different" ...
> brouht up the fact that it's not immediate, in Hansl, to delete
> certain row/columns from a matrix.
Yeah, by coincidence I just answered this (old) question yesterday on
Stackexchange
(http://stackoverflow.com/questions/37242922/deleting-a-column-in-hansl).
> but I wouldn't be averse to introducing a function pair like
> killcol(X, e) and killrow(X, e). Opinions?
First, it would be an improvement. Second, if at all possible, I
would favor some clever extension of the matrix indexing
apparatus. For example (just an example, no claim of optimality),
X[-3, -2] might return the matrix X without the 3rd row and the
2nd column.
I appreciate that you said "no claim of optimality", but I don't
think we should use negative indices for the purpose you indicate.
Seems to me the de facto standard regarding negative indices in
matrix-oriented languages is that they mean, "count from the end,
not the beginning", not "drop these rows or columns".
Allin