94 lines
2.4 KiB
PHP
94 lines
2.4 KiB
PHP
<?php
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/*
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Random boolean network in PHP (7.4+).
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Inspired by the Computerphile Video: https://www.youtube.com/watch?v=mCML2B94rUg
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The use of random_int combined with modulo leads to better randomness entropy.
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Formally correct as the relations with other cells are bitshifted in the right order.
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Not that it matters, as it's randomly chosen, but done anyway for the sake of repeatability.
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Joop Schilder
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Sat 14 Nov 01:30
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One of the nights that I shall remember as if it were me who was in control of my brain.
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*/
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const NUM_NODES = 20;
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const NUM_CONNECTIONS = 3;
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const NUM_GENERATIONS = 20;
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const CHAR_ON_ZERO = '0';
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const CHAR_ON_ONE = ' ';
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const TRUTH_TABLE_SIZE = (1 << NUM_CONNECTIONS);
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$truth_table = [];
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for ($i = 0; $i < TRUTH_TABLE_SIZE; $i++) {
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$truth_table[$i] = random_int(0, 100) % 2;
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}
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$nodes = [];
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for ($i = 0; $i < NUM_NODES; $i++) {
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$nodes[$i] = random_int(0, 100) % 2;
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}
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$connections = [];
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for ($i = 0; $i < NUM_NODES; $i++) {
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for ($j = 0; $j < NUM_CONNECTIONS; $j++) {
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$connections[$i][$j] = random_int(0, 2000) % 20;
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}
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}
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function print_generation(int $g, array $nodes): void
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{
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printf("G%5d %s\n", $g, format_nodes($nodes));
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}
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function print_truth_table(array $truth_table): void
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{
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print("Truth table:\n");
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for($i = 0; $i < TRUTH_TABLE_SIZE; $i++) {
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printf("[%s] => %d\n", str_pad(decbin($i), NUM_CONNECTIONS, '0', STR_PAD_LEFT), $truth_table[$i]);
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}
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}
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function print_connections(array $connections): void
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{
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print("Connections:\n");
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for ($i = 0; $i < NUM_NODES; $i++) {
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printf("[%3d] => [%s]\n", $i, implode(', ', $connections[$i]));
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}
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}
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function format_nodes(array $nodes): string
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{
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return implode(' ', array_map(fn($i): string => $i == 0 ? CHAR_ON_ZERO : CHAR_ON_ONE, $nodes));
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}
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function propagate(array $nodes, array &$connections, array &$truth_table): array
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{
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$next_nodes = [];
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for ($i = 0; $i < NUM_NODES; $i++) {
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$tt_index = 0;
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for ($j = 0; $j < NUM_CONNECTIONS; $j++) {
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$tt_index += $nodes[$connections[$i][$j]] << (NUM_CONNECTIONS - 1 - $j);
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}
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$next_nodes[$i] = $truth_table[$tt_index];
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}
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return $next_nodes;
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}
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print_truth_table($truth_table);
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print("\n");
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print_connections($connections);
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print("\n");
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print_generation(0, $nodes);
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for ($i = 0; $i < NUM_GENERATIONS; $i++) {
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$nodes = propagate($nodes, $connections, $truth_table);
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print_generation($i, $nodes);
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}
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