[Gretl-devel] Re: accessing named matrix columns
On 16/04/2026 02:16, Cottrell, Allin wrote:
OK, for those working with gretl git here's a little test script
for
new functionality. Rownames are also supported, but not yet arrays of
matrices. This is not yet in the snapshots but that should happen
tomorrow.
<hansl>
set seed 765545431
matrix M = mnormal(4,3)
cnameset(M, "one two three")
print M
matrix c = M[,"two"]
print M c
rnameset(M, "a b c d")
eval M["c","two"]
matrices MM = defarray(M, I(3))
eval MM[1][,"three"]
bundle b = _(M)
eval b.M[,"three"]
matrix a = {1.5}
cnameset(a, "c1")
rnameset(a, "r1")
a
eval a["c1"]
eval a["r1"]
# and write mode
M[,"three"] = seq(1,4)'
M
MM[1][,"three"] = seq(1,4)'
eval MM[1][,"three"]
</hansl>
Thanks, Allin, this is very nice.
There is a more general point that IMO is worth considering. Suppose
we're slicing a matrix with row/column names (via traditional methods or
via this cool new feature). Should names be carried over to the
resulting objects? To be more explicit (quoting from above):
<hansl>
set seed 765545431
matrix M = mnormal(4,3)
cnameset(M, "one two three")
matrix c = M[,"two"]
</hansl>
should the "c" vector be endowed with the column name "two" too? My
spontaneous reaction would be "no" (on the grounds of efficiency), but
others may disagree.
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Riccardo (Jack) Lucchetti
Dipartimento di Scienze Economiche e Sociali (DiSES)
Università Politecnica delle Marche
(formerly known as Università di Ancona)
r.lucchetti(a)univpm.it
http://www2.econ.univpm.it/servizi/hpp/lucchetti
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