Percolation/Bond percolation: Difference between revisions
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p=0.90, 0.000
</pre>
=={{header|Perl 6}}==
{{works with|Rakudo|2017.02}}
Starts "filling" from the top left. Fluid flow favours directions in Down, Left, Right, Up order. I interpreted p to be porosity, so small p mean low permeability, large p means high permeability.
<lang perl6>my @bond;
my $grid = 10;
my $geom = $grid - 1;
my $prob;
my $water = '▒';
enum Direction <DeadEnd Up Right Down Left>;
say 'Sample percolation at .6';
percolate(.6);
.join.say for @bond;
say "\n";
my $tests = 100;
say "Doing $tests trials at each porosity:";
for .1, .2 ... 1 -> $p {
printf "p = %0.1f: %0.2f\n", $p, (sum percolate($p) xx $tests) / $tests
}
sub percolate ( $prob = .6 ) {
generate ( $prob );
my @stack;
my $current = [1;0];
$current.&fill;
loop {
if my $dir = direction( $current ) {
@stack.push: $current;
$current = move( $dir, $current )
}
else {
return 0 unless @stack;
$current = @stack.pop
}
return 1 if $current[1] == +@bond - 1
}
sub direction( [$x, $y] ) {
(Down if @bond[$y + 1][$x].contains: ' ' ) ||
(Left if @bond[$y][$x - 1].contains: ' ' ) ||
(Right if @bond[$y][$x + 1].contains: ' ' ) ||
(Up if @bond[$y - 1][$x].defined && @bond[$y - 1][$x].contains: ' ' ) ||
DeadEnd
}
sub move ( $dir, @cur ) {
my ( $x, $y ) = @cur;
given $dir {
when Up { fill([$x,--$y]); fill([$x,--$y]) }
when Down { fill([$x,++$y]); fill([$x,++$y]) }
when Left { fill([--$x,$y]); fill([--$x,$y]) }
when Right { fill([++$x,$y]); fill([++$x,$y]) }
}
[$x, $y]
}
sub fill ([$x, $y]) { @bond[$y;$x].=subst(' ', $water, :g) }
}
sub generate ( $prob = .5 ) {
@bond = ();
my $sp = ' ';
append @bond, [flat '│', ($sp, ' ') xx $geom, $sp, '│'],
[flat '├', (h(), '┬') xx $geom, h(), '┤'];
append @bond, [flat '│', ($sp, v()) xx $geom, $sp, '│'],
[flat '├', (h(), '┼') xx $geom, h(), '┤'] for ^$geom;
append @bond, [flat '│', ($sp, v()) xx $geom, $sp, '│'],
[flat '├', (h(), '┴') xx $geom, h(), '┤'],
[flat '│', ($sp, ' ') xx $geom, $sp, '│'];
sub h () { rand < $prob ?? $sp !! '───' }
sub v () { rand < $prob ?? ' ' !! '│' }
}</lang>
{{out}}
<pre>Sample percolation at .6
│▒▒▒ │
├▒▒▒┬ ┬───┬ ┬ ┬ ┬ ┬ ┬───┬ ┤
│▒▒▒▒▒▒▒ │ │ │
├───┼▒▒▒┼ ┼ ┼ ┼ ┼ ┼───┼ ┼ ┤
│▒▒▒▒▒▒▒▒▒▒▒│ │ │ │ │ │ │
├▒▒▒┼───┼▒▒▒┼ ┼───┼ ┼───┼ ┼ ┼ ┤
│▒▒▒│▒▒▒▒▒▒▒▒▒▒▒ │ │ │
├▒▒▒┼───┼───┼▒▒▒┼ ┼ ┼───┼ ┼ ┼ ┤
│▒▒▒│ ▒▒▒│ │ │ │ │
├───┼ ┼ ┼▒▒▒┼───┼ ┼ ┼ ┼ ┼───┤
│ │▒▒▒ │ │
├ ┼───┼ ┼▒▒▒┼───┼───┼───┼───┼ ┼───┤
│ │▒▒▒│ │
├───┼ ┼───┼▒▒▒┼───┼───┼───┼───┼ ┼───┤
│▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ │ │ │
├▒▒▒┼▒▒▒┼───┼▒▒▒┼───┼ ┼───┼ ┼ ┼ ┤
│▒▒▒│▒▒▒▒▒▒▒│▒▒▒▒▒▒▒│ │
├▒▒▒┼───┼───┼───┼───┼───┼ ┼ ┼ ┼ ┤
│▒▒▒▒▒▒▒ │ │ │ │
├▒▒▒┼▒▒▒┼───┼───┼ ┼───┼───┼ ┼ ┼ ┤
│▒▒▒│▒▒▒ │ │ │
├───┴▒▒▒┴ ┴ ┴ ┴───┴ ┴ ┴ ┴───┤
│ ▒▒▒ │
Doing 100 trials at each porosity:
p = 0.1: 0.00
p = 0.2: 0.00
p = 0.3: 0.00
p = 0.4: 0.05
p = 0.5: 0.42
p = 0.6: 0.92
p = 0.7: 1.00
p = 0.8: 1.00
p = 0.9: 1.00
p = 1.0: 1.00</pre>
=={{header|Python}}==
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