#!/usr/bin/perl 
use strict; 
use warnings;
use Storable;
use Statistics::Descriptive;

my @grid = @{ retrieve('grid.dat') };
my %param = %{ retrieve('param.dat') }; # rows and cols parameters

my @contaminated_walks;

for (1 .. 100) {
	my $num_walks = 100;
	my ($x, $y) = (int(rand $param{range_contx}), int(rand $param{range_conty}));
	my @walks;
	
	for (1 .. $num_walks) {
		my $steps = 100;
		my $infected;
		my $total_steps;
		
	 	#Inner loop to perform each step of a random walk  
		for (1 .. $steps) {		  
			$total_steps += my $rand_steps = (1 + int( rand 6 ));
			last if $total_steps > $steps;
			
			my $random_num = rand;
			if($random_num < 0.25) {
				for (1 .. $rand_steps) {
					$x = ($x - 1) % $param{range_contx};
					$infected += $grid[$x][$y] || 0;
				} 
			} 
			elsif ($random_num < 0.5) { 
				for (1 .. $rand_steps) {
					$x = ($x + 1) % $param{range_contx};
					$infected += $grid[$x][$y] || 0;
				} 
			} 
			elsif ($random_num < 0.75) { 
				for (1 .. $rand_steps) {
					$y = ($y - 1) % $param{range_conty};
					$infected += $grid[$x][$y] || 0;
				}  
			} 
			else { 
				for (1 .. $rand_steps) {
					$y = ($y + 1) % $param{range_conty};
					$infected += $grid[$x][$y] || 0;
				}   
			} 
		}
		push @walks, $infected;
	}
	push @contaminated_walks, scalar grep $_, @walks;
}
my $stat = Statistics::Descriptive::Sparse->new();
$stat->add_data(@contaminated_walks);

printf "min-max %d-%d mean: %.1f std. deviation: %.1f count: %d\n",
	$stat->min, $stat->max, $stat->mean, $stat->standard_deviation, $stat->count;

__END__
C:\Old_Data\perlp>perl t33.pl
min-max 34-61 mean: 50.7 std. deviation: 5.6 count: 100