How to iterate through a PDL piddle?

arrac has asked for the wisdom of the Perl Monks concerning the following question:

The closest I got to was something like

use PDL;
my $u = pdl [1,2,3,4];
my $dim = 4;
for(my $i=0; $i<$dim; $i++)
{
  print $u->flat->index($i), "\n";
}
[download]

Also as I convert the list [1,2,3,4] to the piddle $u, can I get back a list (or a list of lists for a matrix) from $u?

Comment on How to iterate through a PDL piddle? Select or Download Code

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Re: How to iterate through a PDL piddle? by zentara (Cardinal) on Mar 10, 2011 at 14:31 UTC
You need a dog, not puppies. :-) Does this work? `#!/usr/bin/perl use strict; use warnings; use PDL::LiteF; #dog dosn't work on huge values my $u = pdl [1,2,3,4]; my $dim = 4; print join "\t", $u->dog; print "\n";` [download] I'm not really a human, but I play one on earth. Old Perl Programmer Haiku ................... flash japh	[reply] [d/l]
Re^2: How to iterate through a PDL piddle? by arrac (Initiate) on Mar 11, 2011 at 07:36 UTC
Thanks @zentara. It works! I can't believe that it works though. There should be a more obvious way like `$u->list` which gives an array reference. Or a custom iterator on a piddle which can replace `foreach`.	[reply] [d/l] [select]
Re^3: How to iterate through a PDL piddle? by etj (Priest) on May 26, 2022 at 14:44 UTC
If you feel the urge to use an iterator in PDL, quite often that is a sign you could instead use "array programming" type constructs (see https://en.wikipedia.org/wiki/Array_programming), which lets all the processing be done inside the fast C loops, rather than going backwards and forwards between Perl and PDL.	[reply]
Re^3: How to iterate through a PDL piddle? by dkogan (Initiate) on Apr 22, 2011 at 07:47 UTC
Errr..... there IS a 'list' function $u->list acts the same as $u->dog except list breaks the piddle up into individual elements while dog breaks it up into N-1-dimensional slices. In this particular case, where $u is one-dimensional, $u->list is identical to $u->dog	[reply]
Re^4: How to iterate through a PDL piddle? by etj (Priest) on May 26, 2022 at 14:41 UTC
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