Hi again,
By the way, I made a small package which may be useful (unless its
functionality is already part of PDL and I missed it): PDL::ApplyDim.
The idea is to factor out a common shuffling and unshuffling of
indices before calling pdl functions/methods that act only on the
first dimension(s). So, instead of
$pdl->mv($dim,0)->function($some, $extra, $args)->mv(0, $dim);
one may write
$pdl->apply_to(\&function, $dim, $some, $extra, $args);
$pdl->apply_to("function", $dim, $some, $extra, $args);
apply_to($pdl, \&function", $dim, $some, $extra, $args);
or
apply_to($pdl, "function", $dim, $some, $extra, $args);
...
For example, a scalar time dependent field, f(x,y,z,t) may be
represented by a 4D ndarray $f. We have $f->xvals, $f->yvals,
$f->zvals, but no $f->tvals. We could define
sub tvals($pdl){$pdl->apply_to(3, \&xvals)
Similarly, instead of
$pdl->reorder(3,2,0,1)->function(@otherargs)->reorder(2,3,1,0);
to move dimensions 3 and 2 to the front and shift the rest towards the
end, apply the function and then recover the original order, one may
write
$pdl->apply_to(\&function, [3,2], @otherargs);
or more generally
$pdl->apply_to(\&function, [$d0, $d1, $d2...], @otherargs);
The converse function is apply_not_to, to move the given dimensions to
the end, applying the function and then restoring them back to the front.
For example, to make a D-dimensional Fourier transform of
a rank 3 tensor field, represented by a (D+3)-dimensional ndarray, one
would have to move the first three dimensions (the tesorial indices)
to the end, perform the D-dimensional Fourier transform over the first
D indices and then bring the tensorial indices back to the front.
Regards,
Luis
On Sat, Jan 11, 2025 at 11:52:53AM -0600, Luis Mochan wrote:
> I didn't know (or had forgotten) about the pptemplate; I'll try it, thanks.
--
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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