Thanks! I was not aware of the padding vs. replicating behavior, but I
guess it is due to the possibility of pdl accepting non-ndarray
arguments.
Regards,
Luis
On Thu, Aug 21, 2025 at 11:36:29AM +0000, Jörg Sommrey wrote:
> The "pdl" constructor does not replicate values to match dimensions but pads
> them instead. In contrary, "cat" works as expected:
>
> pdl> do_print 1
> 1
>
> pdl> $v = sequence 2
> [0 1]
>
> pdl> cat $v(,*1), $v(*1,)
>
> [
> [
> [0 1]
> [0 1]
> ]
> [
> [0 0]
> [1 1]
> ]
> ]
>
> Best regards,
> -jo
>
> On Tue 19 Aug 2025 07:09:32 PM CEST, Luis Mochan <moc...@icf.unam.mx> wrote:
>
> > I'm confused by variations of the following program:
> > use v5.36;
> > use PDL;
> > use PDL::NiceSlice;
> > my $v=sequence(2);
> > my $m=pdl($v->slice(":,*2"), $v->slice("*2,:"));
> > say $m;
> >
> > The output is
> >
> > [
> > [
> > [0 1]
> > [0 1]
> > ]
> > [
> > [0 0]
> > [1 1]
> > ]
> > ]
> >
> > which is what I expected. But after a small change:
> >
> > use v5.36;
> > use PDL;
> > use PDL::NiceSlice;
> > my $v=sequence(2);
> > my $m=pdl($v->slice(":,*"), $v->slice("*,:"));
> > say $m;
> >
> > the output becomes
> >
> >
> > [
> > [
> > [0 1]
> > [0 0]
> > ]
> > [
> > [0 0]
> > [1 0]
> > ]
> > ]
> >
> > The same if I replace * by *1. Was I wrong to expect the same output?
> > I expected the dummy dimension of size 1 (or unspecified size) would
> > lead to the initial array [0 1] being replicated as many times as
> > required by the actual dimensions of the other arrays.
> >
> > Best regards,
> > Luis
>
>
>
--
o
W. Luis Mochán, | tel:(52)(777)329-1734 /<(*)
Instituto de Ciencias Físicas, UNAM | fax:(52)(777)317-5388 `>/ /\
Av. Universidad s/n CP 62210 | (*)/\/ \
Cuernavaca, Morelos, México | moc...@fis.unam.mx /\_/\__/
GPG: 791EB9EB, C949 3F81 6D9B 1191 9A16 C2DF 5F0A C52B 791E B9EB
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