Re^2: Creating Heat Map in perl

[huzefa52]

Hi, Thanks for the reply, I am using below code, it is giving me following error. Can't locate object method "Imager=HASH(0xfeeb4d0)" via package "Imager::Heatmap" at heatmap.pl line 28.

#!/usr/bin/perl -w
use strict;
#use warnings;
use utf8;
use XSLoader;
use Carp;
use Imager;
use List::Util qw/ max /;
use Imager;
use Imager::Heatmap;
my $hmap = Imager::Heatmap->new(
    xsize  => 640,        # Image width
    ysize  => 480,        # Image height
    xsigma => 10,         # Sigma value of X-direction
    ysigma => 10,         # Sigma value of Y-direction
);
 
my @piont_datas = ( [ 10, 20, 50 ], [ 20, 40, 70 ] );
# Add point datas to construct density matrix
$hmap->insert_datas(@piont_datas); # @point_datas should be: ( [ x1, y
+1, weight1 ], [ x2, y2, weight2 ] ... )
 
#$hmap->insert_datas(...); # You can call multiple times to add large 
+data that cannot process at a time.
 
# After adding datas, you could get heatmap as Imager instance.
my $img = $hmap->draw;
 
# Returned image is 4-channels image. So you can overlay it on other i
+mages.
my $base_img->rubthrough( src => $hmap->$img );  # Overlay on other im
+ages(see Imager::Transformations)

$img = Imager->new(
        xsize    => $hmap->xsize,
        ysize    => $hmap->ysize,
        channels => 4,
    );
# And you can access probability density matrix using matrix method if
+ you like.
# In case, maybe you would like to create some graduations which be as
+signed to color of heatmap and its value.
$hmap->matrix;

[Corion]

So, what is in line 28? Have you looked at it and checked it that it means what you intend?

my $base_img->rubthrough( src => $hmap->$img );  # Overlay on other im
+ages(see Imager::Transformations)

Please explain for every item in English what it is supposed to mean. Especially, explain the construct $hmap->$img.

[space_monk]

Very minor thing s/piont_datas/point_datas/g;. The only reason the code doesn't generate an error is because you made this spelling mistake consistently.
What is the last line doing? $hmap->matrix simply returns a reference to the density matrix - on its own it does nothing.

[huzefa52]

Thanks for finding my mistake. Now, I am getting the heatmap image in my $img variable i.e $img = $hmap->draw; But how to use this $img value to get image in gif/png format. Because there is no plot option defined in Imager::Heatmap module.

[Mr. Muskrat]

The synopsis for Imager::Heatmap can not be run as is. It doesn't create $base_img, it doesn't show how to properly use matrix, etc. So it is no surprise that what you ended up with didn't work.

Try this as a starting point. It uses your data and creates a png file in the current directory.

#!/bin/env perl
use strict;
use warnings;

use Imager::Heatmap;

my $hmap = Imager::Heatmap->new(
    xsize  => 640,        # Image width
    ysize  => 480,        # Image height
    xsigma => 10,         # Sigma value of X-direction
    ysigma => 10,         # Sigma value of Y-direction
);

# @point_datas should be: ( [ x1, y1, weight1 ], [ x2, y2, weight2 ] .
+.. )
my @point_datas = ( [ 10, 20, 50 ], [ 20, 40, 70 ] );

# Add point datas to construct density matrix
$hmap->insert_datas(@point_datas); 

# After adding datas, get heatmap as Imager instance.
my $img = $hmap->draw;

# create png file in current directory
$img->write( file => './hm.png' );

Here's the generated heatmap image.