Percolation/Site percolation: Difference between revisions

=={{header|Perl}}==

{{trans|Perl 6}}

<lang perl>my $block = '▒';

my $water = '+';

my $pore = ' ';

my $grid = 15;

my @site;

$D{$_} = $i++ for qw<DeadEnd Up Right Down Left>;

sub deq { defined $_[0] && $_[0] eq $_[1] }

sub percolate {

my($prob) = shift || 0.6;

$site[0] = [($pore) x $grid];

for my $y (1..$grid) {

for my $x (0..$grid-1) {

$site[$y][$x] = rand() < $prob ? $pore : $block;

}

}

$site[$grid + 1] = [($pore) x $grid];

$site[0][0] = $water;

my $x = 0;

my $y = 0;

my @stack;

while () {

if (my $dir = direction($x,$y)) {

push @stack, [$x,$y];

($x,$y) = move($dir, $x, $y)

} else {

return 0 unless @stack;

($x,$y) = @{pop @stack}

}

return 1 if $y > $grid;

}

}

sub direction {

my($x, $y) = @_;

return $D{Down} if deq($site[$y+1][$x ], $pore);

return $D{Right} if deq($site[$y ][$x+1], $pore);

return $D{Left} if deq($site[$y ][$x-1], $pore);

return $D{Up} if deq($site[$y-1][$x ], $pore);

return $D{DeadEnd};

}

sub move {

my($dir,$x,$y) = @_;

$site[--$y][ $x] = $water if $dir == $D{Up};

$site[++$y][ $x] = $water if $dir == $D{Down};

$site[ $y][ --$x] = $water if $dir == $D{Left};

$site[ $y][ ++$x] = $water if $dir == $D{Right};

$x, $y

}

my $prob = 0.65;

percolate($prob);

print "Sample percolation at $prob\n";

print join '', @$_, "\n" for @site;

print "\n";

my $tests = 100;

print "Doing $tests trials at each porosity:\n";

my @table;

for my $p (1 .. 10) {

$p = $p/10;

my $total = 0;

$total += percolate($p) for 1..$tests;

push @table, sprintf "p = %0.1f: %0.2f", $p, $total / $tests

}

print "$_\n" for @table;</lang>

{{out}}

<pre>Sample percolation at 0.65

+++

▒▒+ ▒ ▒

▒+▒▒▒ ▒▒ ▒▒ ▒

+ ▒▒▒▒▒▒

▒▒++▒ ▒▒ ▒

▒ ▒++ ▒ ▒

▒▒▒+++▒ ▒ ▒

▒ ▒▒+▒ ▒ ▒

▒ ▒+ ▒

▒ ▒++▒▒

▒ ▒+ ▒ ▒

▒▒ ▒ ++ ▒

▒ ▒▒▒▒▒++ ▒

▒ ▒ ▒ ▒▒+ ▒

▒ ▒▒▒ + ▒▒

▒ ▒ + ▒▒

+

Doing 100 trials at each porosity:

p = 0.1: 0.00

p = 0.2: 0.00

p = 0.3: 0.00

p = 0.4: 0.01

p = 0.5: 0.10

p = 0.6: 0.51

p = 0.7: 0.89

p = 0.8: 1.00

p = 0.9: 1.00

p = 1.0: 1.00</pre>