Percolation/Mean cluster density: Difference between revisions

</pre>

=={{header|Wren}}==

{{trans|Kotlin}}

{{libheader|Wren-fmt}}

<lang ecmascript>import "random" for Random

import "/fmt" for Fmt

var rand = Random.new()

var RAND_MAX = 32767

var list = []

var w = 0

var ww = 0

var ALPHA = "+.ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"

var ALEN = ALPHA.count - 3

var makeList = Fn.new { |p|

var thresh = (p * RAND_MAX).truncate

ww = w * w

var i = ww

list = List.filled(i, 0)

while (i != 0) {

i = i - 1

var r = rand.int(RAND_MAX+1)

if (r < thresh) list[i] = -1

}

}

var showCluster = Fn.new {

var k = 0

for (i in 0...w) {

for (j in 0...w) {

var s = list[k]

k = k + 1

var c = (s < ALEN) ? ALPHA[1 + s] : "?"

System.write(" %(c)")

}

System.print()

}

}

var recur // recursive

recur = Fn.new { |x, v|

if (x >= 0 && x < ww && list[x] == -1) {

list[x] = v

recur.call(x - w, v)

recur.call(x - 1, v)

recur.call(x + 1, v)

recur.call(x + w, v)

}

}

var countClusters = Fn.new {

var cls = 0

for (i in 0...ww) {

if (list[i] == -1) {

cls = cls + 1

recur.call(i, cls)

}

}

return cls

}

var tests = Fn.new { |n, p|

var k = 0

for (i in 0...n) {

makeList.call(p)

k = k + countClusters.call() / ww

}

return k / n

}

w = 15

makeList.call(0.5)

var cls = countClusters.call()

System.print("width = 15, p = 0.5, %(cls) clusters:")

showCluster.call()

System.print("\np = 0.5, iter = 5:")

w = 1 << 2

while (w <= (1 << 13)) {

var t = tests.call(5, 0.5)

Fmt.print("$5d $9.6f", w, t)

w = w << 1

}</lang>

{{out}}

Sample run:

<pre>

width = 15, p = 0.5, 28 clusters:

. A A . . B . C . D . . . . A

A A A . E . F . G . . A A A A

. A A A . F F . . . A A . . .

. A . . . . F . . H . A . A .

. A A . . . . . H H H . A A A

A A A . . I I . . H . J . . A

A . . K . . . . H H . . . A A

A . L . M M . N . . O . . . .

A A . P . . . N . Q . R . S .

. A A . T T . . U . R R R . .

A A . . T T T . . . . R . . .

. A . T T T . . . . . R R R R

. A . . . T . . V . W . R R .

A A . X . T T . . . W . . . .

. . Y . T T . Z . a . . . b b

p = 0.5, iter = 5:

4 0.125000

8 0.081250

16 0.094531

32 0.073242

64 0.067920

128 0.068567

256 0.067404

512 0.066401

1024 0.065870

2048 0.065885

4096 0.065812

8192 0.065795