Sorry, I missed this the first time around. You might be better off
making an index array of your mask with which(), and then using that
to dice the input PDL explicitly, rather than reshaping the output
PDL. That will set up the data flow correctly.
On May 9, 2010, at 8:17 PM, David Mertens wrote:
I feel like I've seen some pp code that did this, but I don't
remember where it was. I'll muck around and see what I can find. I
think it can be done, but I'm not sure if you can do it with
standard Perl or if we'll need to figure out some sort of PDL::PP
trick for it.
David
On Sat, May 1, 2010 at 7:17 PM, Matthew Kenworthy <[email protected]
> wrote:
I've written a version of whereND that does 'the right thing' in
threading a mask over higher dimensions of an input piddle, and it
returns a sensible looking piddle back.
The trouble is that the reshape() breaks the threading back to the
original piddle. Can any other pdlers suggest a way to return back a
piddle with dataflow all the way back to $i?
Thanks,
Matt
sub whereND {
use strict;
my ($i, $w) = @_;
# w is a mask 0 = false, 1 = true
# i is M dimensional
# w is N < M dimensional
# dims(i) 1..N == dims(i) 1..N
# thread over N+1 to M dimensions
my $n = sum($w);
my $sub_i = $w * ones($i);
my $where_sub_i = $i->where($sub_i);
# count the number of dims in w and i
# w = a b c d e f.....
my @idims = dims($i);
# ...and pop off the number of dims in w
foreach(dims($w)){shift(@idims)};
$where_sub_i->reshape($n, @idims);
return ($where_sub_i);
}
--
Matthew Kenworthy / Assistant Professor / Leiden Observatory
Niels Bohrweg 2 (#463) / P.O. Box 9513 / 2300 RA Leiden / NL
_______________________________________________
Perldl mailing list
[email protected]
http://mailman.jach.hawaii.edu/mailman/listinfo/perldl
_______________________________________________
Perldl mailing list
[email protected]
http://mailman.jach.hawaii.edu/mailman/listinfo/perldl
_______________________________________________
Perldl mailing list
[email protected]
http://mailman.jach.hawaii.edu/mailman/listinfo/perldl
