Re^5: Interpolating data using pdl

use strict;
use warnings;
use PDL;
use PDL::IO::Image;

# data
my $x = sequence( 100, 100 );

# ranges
my $range1 = $x < 3000;
my $range2 = ( $x >= 3000 ) * ( $x <= 7000 );
my $range3 = $x > 7000;

my $bytes = (     $range1 
            + 2 * $range2
            + 3 * $range3 )-> byte;

my $palette = byte [ 
    [  0,   0,    0 ],
    [ 255,  50,  50 ],
    [ 128, 255,   0 ],
    [ 255, 215,   0 ]
];

$bytes-> wimage( 'test.png', { palette => $palette });
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Not sure if I understand what you need, but, "from the top of my head", this code produces rather dull looking image with three colorful stripes (no time to invent some "smart" data). You have your conditions, combine them, associate with palette of the same length + 1.

Comment on Re^5: Interpolating data using pdl Download Code

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Re^6: Interpolating data using pdl by karthik248 (Acolyte) on Mar 16, 2017 at 05:22 UTC
I'm able to use your solution. When I try to initiate a piddle with `zeroes(5400,2700)` it works fine, but `zeroes(21600,10800)` doesn't work. It shows an error as `Probably false alloc of over 1Gb PDL! (set $PDL::BIGPDL = 1 to enable)`. I tried setting `$PDL::BIGPDL=1`, but then it crashes. How can we solve this?	[reply] [d/l] [select]
Re^7: Interpolating data using pdl by vr (Curate) on Mar 16, 2017 at 08:43 UTC
`zeroes(21600,10800)` works for me. Are you on 32-bit OS? Then use 64-bit. If your data is going to finish as 8 bits per channel image anyway, then work with `byte` piddles. P.S. BTW, you understand, that your image will be 700 MB (uncompressed), don't you?	[reply] [d/l] [select]
Re^8: Interpolating data using pdl by etj (Priest) on May 10, 2022 at 15:23 UTC
PDL 2.067 removed the `$PDL::BIGPDL` check, because 1GB isn't big anymore. `zeroes(21600,10800)` has about 200,000 elements in, which for `double` (the default) at 8 bytes each would be about 1.6GB. `float` would be half that. `byte` would naturally be an eighth. Which to use depends on both available resources, and the needs of your application.	[reply] [d/l] [select]