Percolation/Site percolation: Difference between revisions

</pre>

=={{header|Perl 6}}==

{{works with|Rakudo|2017.02}}

<lang perl6>my $block = '▒';

my $water = '+';

my $pore = ' ';

my $grid = 15;

my @site;

enum Direction <DeadEnd Up Right Down Left>;

sub infix:<deq> ($a, $b) { $a.defined && ($a eq $b) }

percolate(.6);

say 'Sample percolation at .6';

.join.say for @site;

say "\n";

my $tests = 1000;

for .1, .2 ... 1.0 -> $p {

printf "p = %0.1f: %0.3f\n" , $p, (sum percolate($p) xx $tests) / $tests;

}

sub percolate ( $prob = .6 ) {

@site[0] = [$pore xx $grid];

@site[$grid+1] = [$pore xx $grid];

for 0..^$grid X 1..$grid -> ($x, $y) {

@site[$y][$x] = rand < $prob ?? $pore !! $block;

}

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

my @stack;

my $current = [0;0];

loop {

if my $dir = direction( $current ) {

@stack.push: $current;

$current = move( $dir, $current )

}

else {

return 0 unless @stack;

$current = @stack.pop

}

return 1 if $current[1] > $grid;

}

sub direction([$x,$y]) {

my @neighbors =

(Down if @site[$y + 1][$x] deq $pore),

(Left if @site[$y][$x - 1] deq $pore),

(Right if @site[$y][$x + 1] deq $pore),

(Up if @site[$y - 1][$x] deq $pore);

@neighbors.shift or DeadEnd

}

sub move ($dir, @cur) {

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

given $dir {

when Up { @site[--$y][$x] = $water }

when Down { @site[++$y][$x] = $water }

when Left { @site[$y][--$x] = $water }

when Right { @site[$y][++$x] = $water }

}

[$x,$y];

}

}</lang>

{{out}}

<pre>Sample percolation at .6

++++

▒▒▒+ ▒ ▒ ▒ ▒ ▒▒

▒▒++ ▒▒ ▒▒

▒+ ▒▒ ▒ ▒▒

▒▒ ▒++++▒ ▒▒

▒ ▒+▒▒+▒ ▒

▒++▒++ ▒▒▒ ▒

▒▒▒ +▒

▒▒ ▒ ▒++ ▒ ▒▒

▒▒▒▒▒▒▒+▒▒▒

▒ ▒ + ▒

▒▒ ▒+ ▒ ▒ ▒

▒ ▒ ▒▒+ ▒

▒▒ ▒ ▒++▒ ▒

▒ +▒ ▒▒ ▒▒

▒ ▒▒▒+ ▒▒ ▒

+

p = 0.1: 0.000

p = 0.2: 0.000

p = 0.3: 0.000

p = 0.4: 0.005

p = 0.5: 0.096

p = 0.6: 0.573

p = 0.7: 0.959

p = 0.8: 0.999

p = 0.9: 1.000

p = 1.0: 1.000