Imager::Heatmap - Perl extension for drawing Heatmap using 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 ); # Add point datas to construct density matrix $hmap->insert_datas(@piont_datas); # @point_datas should be: ( [ x1, y1, 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 images. $base_img->rubthrough( src => $hmap->img ); # Overlay on other images(see Imager::Transformations) # 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 assigned to color of heatmap and its value. $hmap->matrix;
Imager::Heatmap is a module to draw heatmap using Imager.
This module calculates probability density matrix from input data and map a color for each pixels to represent density of input data.
Create a blessed object of Imager::Heatmap. You can specify some options as follows. See the accessors description for more details about each parameters.
$hmap = Imager::Heatmap->new(xsize => 300, ysize => 300);
X-direction size of heatmap image.
Y-direction size of heatmap image.
Sigma value of X-direction.
Sigma value of Y-direction.
Correlation between X and Y.
Set/Get the X-direction size of heatmap image. Constructed matrix will invalidated after call this method as "Setter".
$hmap->xsize(100); $xsize = $hmap->xsize;
Set/Get the Y-direction size of heatmap image. Constructed matrix will invalidated after call this method as "Setter".
$hmap->ysize(100); $ysize = $hmap->ysize;
Set/Get the Sigma value of X-direction. This value represents the standard deviation of X-direction. This value should be positive number. You will see the heatmap that amplicifed for X-direction if you increment this number.
$hmap->xsigma(10.0); $xsigma = $hmap->xsigma;
Set/Get the Sigma value of Y-direction. This value represents the standard deviation of Y-direction. This value should be positive number. You will see the heatmap that amplicifed for Y-direction if you increment this number.
$hmap->ysigma(10.0); $ysigma = $hmap->ysigma;
Set/Get the correlation coefficient of XY; This value represents correlation between X and Y. This value should be the number between -1 and 1. (includeing -1 and 1)
$hmap->correlation(0.5); $correlation = $hmap->correlation;
Construct the matrix that represents probability density of each pixels of image. This method may be take a while if the datas are large.
$hmap->insert_datas([ $x1, $y1, $weight1 ], [ $x2, $y2 ], ...);
Each element of array should contain x(), y(), and optionally weight() as follows:
@insert_datas = ( [ x1, y1, weight1 ], [ x2, y2, weight2 ] ... );
The default value of weight is 1.
x and y will implicitly cast to integer in XS, so it doesn't make any sense specifying real numbers to these parameters.
weight can be a real number.
Draw a heatmap from a constructed probability density matrix and return it.
my $img = $hmap->draw;
Rerturn value is blessed object of Imager. It is created as following options($self is blessed object of Imager::Heatmap)
my $img = Imager->new( xsize => $self->xsize, ysize => $self->ysize, channels => 4, );
Get the processed probability density matrix.
$matrix = $hmap->matrix;
Return value is flat array. You can access the value of pixel(x,y) as follows:
$pixel_value = $matrix->[$y * $hmap->xsize + $x];
Imager::Heatmap calculates probability density matrix of input datas.
You can find the equation used to calculate 2-dimensional probability density matrix at following location:
The equation used to calculate 2-dimensional probability density matrix: Multivariate normal distribution - Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/Multivariate_normal_distribution#Bivariate_case
Yuto KAWAMURA(kawamuray), <firstname.lastname@example.org>
Copyright (C) 2012 by Yuto KAWAMURA(kawamuray)
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.12.3 or, at your option, any later version of Perl 5 you may have available.