Abelian sandpile model: Difference between revisions
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[[Media:Abelian sandpile java.png]]
=={{header|jq}}==
''Adapted from [[#Wren|Wren]]''
'''Works with jq and gojq, the C and Go implementations of jq'''
For consistency with [[Abelian sandpile model/Identity#jq]], the
function for reducing a sandpile to its equilibrium position is called
`avalanche` here.
<syntaxhighlight lang=jq>
# Generic functions
def array($n): . as $in | [range(0;$n)|$in];
def when(filter; action): if filter // null then action else . end;
def lpad($len): tostring | ($len - length) as $l | (" " * $l) + .;
# module Sandpile
# 'a' is a list of integers in row order
def new($a):
($a|length) as $length
| ($length|sqrt|floor) as $rows
| if ($rows * $rows != $length) then "The matrix of values must be square." | error
else
{$a,
$rows,
neighbors:
(reduce range(0; $length) as $i (null;
.[$i] = []
| when($i % $rows > 0; .[$i] += [$i-1] )
| when(($i + 1) % $rows > 0; .[$i] += [$i+1] )
| when($i - $rows >= 0; .[$i] += [$i-$rows] )
| when($i + $rows < $length; .[$i] += [$i+$rows] ) ) )
}
end;
def isStable:
all(.a[]; . <= 3);
def tos:
. as $in
| .rows as $rows
| reduce range(0; $rows) as $i ("";
reduce range(0; $rows) as $j (.;
. + " \($in.a[$rows*$i + $j] | lpad(2))" )
| . +"\n" );
# just topple once so we can observe intermediate results
def topple:
last(
label $out
| foreach range(0; .a|length) as $i (.;
if .a[$i] > 3
then .a[$i] += -4
| reduce .neighbors[$i][] as $j (.; .a[$j] += 1)
| ., break $out
else .
end ) );
def avalanche:
until(isStable; topple);
# str1 and str2 should be strings representing a sandpile (i.e. .a)
def printAcross(str1; str2):
(str1|split("\n")) as $r1
| (str2|split("\n")) as $r2
| ($r1|length - 1) as $rows
| ($rows/2|floor) as $cr
| reduce range(0; $rows) as $i ("";
(if $i == $cr then "->" else " " end) as $symbol
| . + "\($r1[$i]) \($symbol) \($r2[$i])\n" ) ;
{ a1: (0|array(25))}
| .a2 = .a1
| .a3 = .a1
| .a1[12] = 4
| .a2[12] = 6
| .a3[12] = 16
| .a4 = (0|array(100))
| .a4[55] = 64
| (.a1, .a2, .a3, .a4) as $a
| .s = new($a)
| (.s|tos) as $str1
| .s |= avalanche
| (.s|tos) as $str2
| printAcross($str1; $str2)
</syntaxhighlight>
{{output}}
As for [[#Wren|Wren]]
=={{header|Julia}}==
| |||