This is my howto file for comparing pdls:
use Test::More 'no_plan';
use PDL;
use PDL::NiceSlice;
use PDL::IO::SndFile;
my $a = pdl(2,3,4);
my $b = pdl(2,3,4);
my $cmp = which($a - $b);
ok (($cmp =~ m/Empty/), 'the two pdls match');
my $e = pdl(3,4,5);
$cmp = which($a - $e);
ok (not ($cmp =~ m/Empty/), 'the two pdls do not match');
print "$cmp\n";
my $them = pdl(0,1,2);
my $cmpcmp = which($cmp - $them);
ok (($cmpcmp =~ m/Empty/), 'all three did not compare');
$c = pdl(2,3,10);
$cmp = which($a - $c);
print "$cmp\n";
$them = pdl(2);
$cmpcmp = which($cmp - $them);
ok (($cmpcmp =~ m/Empty/), 'just the third did not compare');
Hope that helps!
Judy
On Friday, September 26, 2014 2:30 PM, Vikas N Kumar <[email protected]> wrote:
Hi
I am stumped by the problems I face with simple conditionals in using
the which() function. I have tried many different ways in trying to
solve it but none of them give me the result I want.
Here is a sample:
use PDL;
# a random list of values that are above and below 0
my $a = randsym(100) - 0.5;
# create a lag of 1
my $idx = xvals($a->dims) - 1;
$i = $i->setbadif($i < 0)->setbadtoval(0); # can this be more elegant ?
# find all the positions where $a[i] > 0 and $a[i - 1] < 0
# in essence where $a crosses the zero line
my $b = zeroes($a->dims);
my $b_idx = which($a > 0 && $a->index($i) < 0);
# set those points as 1
$b->index($b_idx) .= 1;
Everytime I run this I get "multielement piddle in conditional
expression" errors.
I have not been able to find an elegant solution to this problem. I
cannot seem to create a mask that has more than 1 piddle comparisons.
Please help.
Thanks
Vikas
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