From 70252c2ef37ddf974349fa092dce92782ffd302a Mon Sep 17 00:00:00 2001
From: sanine <sanine.not@pm.me>
Date: Mon, 30 Oct 2023 02:14:17 -0500
Subject: add genome creation & mutation trial

---
 src/genome/genome.js | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 86 insertions(+), 1 deletion(-)

(limited to 'src/genome/genome.js')

diff --git a/src/genome/genome.js b/src/genome/genome.js
index d2650b5..bc569ff 100644
--- a/src/genome/genome.js
+++ b/src/genome/genome.js
@@ -1,6 +1,7 @@
 'use strict';
 
-import { network } from '../mind/topology';
+import { random_choice } from '../util.js';
+import { network } from '../mind/topology.js';
 
 
 // check if a given genome is valid and compute its size
@@ -25,6 +26,7 @@ export function get_size(num_input, num_output, genome) {
 }
 
 
+// parse a genome into a useable neural net
 export function parse_genome(num_input, num_output, genome) {
   const size = get_size(num_input, num_output, genome);
   if (size < 0) {
@@ -49,6 +51,7 @@ function clamp(value, min, max) {
   return value;
 }
 
+// adjust the source input of a gene
 export function mut_gene_source(n_input, n_internal, n_output, gene, r) {
   const [source, sink, weight] = gene;
 
@@ -62,6 +65,7 @@ export function mut_gene_source(n_input, n_internal, n_output, gene, r) {
 }
 
 
+// adjust the sink target of a gene
 export function mut_gene_sink(n_input, n_internal, n_output, gene, r) {
   const [source, sink, weight] = gene;
 
@@ -75,6 +79,9 @@ export function mut_gene_sink(n_input, n_internal, n_output, gene, r) {
 }
 
 
+// modify a gene's weight
+// only adjusts the weight by performing a weighted average, so as to
+// more gently modify the generated net
 export function mut_gene_weight(weight_max, gene, r) {
   const [source, sink, weight] = gene;
   
@@ -90,6 +97,9 @@ export function mut_gene_weight(weight_max, gene, r) {
 }
 
 
+
+// expand the size of the neural net encoded by the genome
+// relabels internal indices so that there is one extra internal neuron
 export function mut_genome_expand(
   [n_input, n_internal, n_output, genome], r
 ) {
@@ -106,11 +116,16 @@ export function mut_genome_expand(
 }
 
 
+// contract the size of the neural net encoded by the genome
+// relabels internal indices so that there is one less internal neuron
 export function mut_genome_contract(
   [n_input, n_internal, n_output, genome], r
 ) {
   const contract_idx = Math.floor(n_internal * r) + n_input;
+
+  // decrement sources on the contract index too, to prevent invalid genomes
   const new_source = (source) => source >= contract_idx ? source-1 : source;
+  // decrement sinks only after the contract index
   const new_sink   = (sink)   => sink > contract_idx ? sink-1 : sink;
 
   const new_genome = genome.map(([source, sink, weight]) => [
@@ -125,6 +140,7 @@ export function mut_genome_contract(
 }
 
 
+// append a newly generated gene to the end of the genome
 export function mut_genome_insert(
   [n_input, n_internal, n_output, genome], 
   weight_max, 
@@ -141,6 +157,7 @@ export function mut_genome_insert(
 }
 
 
+// delete a gene from the genome
 export function mut_genome_delete(
   [n_input, n_internal, n_output, genome], r
 ) {
@@ -148,3 +165,71 @@ export function mut_genome_delete(
   const new_genome = genome.filter((_, idx) => idx != del_idx);
   return [n_input, n_internal, n_output, new_genome];
 }
+
+
+function mut_gene(
+  [n_input, n_internal, n_output, genome], 
+  weight_max, r1, r2, r3
+) {
+  const gene_idx = Math.floor(genome.length * r1);
+  const mod = random_choice(['source', 'sink', 'weight'], r2);
+  let new_gene;
+  if (mod == 'source') {
+    new_gene = mut_gene_source(
+      n_input, n_internal, n_output, 
+      genome[gene_idx],
+      r3
+    );
+  } else if (mod == 'sink') {
+    new_gene = mut_gene_sink(
+      n_input, n_internal, n_output, 
+      genome[gene_idx],
+      r3
+    );
+  } else {
+    new_gene = mut_gene_weight(
+      weight_max, genome[gene_idx], r3
+    );
+  }
+
+  const new_genome = genome.map((gene, idx) => {
+    if (idx == gene_idx) { return new_gene; }
+    return gene;
+  });
+
+  return [
+    n_input, n_internal, n_output, new_genome
+  ];
+}
+
+
+export function mutate_genome(obj, weight_max) {
+  const mut = random_choice([
+    'gene', 'gene', 'gene',
+    'gene', 'gene', 'gene',
+    'gene', 'gene', 'gene',
+    'insert', 'delete',
+    'insert', 'delete',
+    'expand', 'contract',
+  ], Math.random());
+
+  if (mut == 'gene') {
+    return mut_gene(
+      obj, weight_max, 
+      Math.random(), Math.random(), Math.random()
+    );
+  } else if (mut == 'insert') {
+    return mut_genome_insert(
+      obj, weight_max, 
+      Math.random(), Math.random(), Math.random()
+    );
+  } else if (mut == 'delete') {
+    return mut_genome_delete(obj, Math.random());
+  } else if (mut == 'expand') {
+    return mut_genome_expand(obj, Math.random());
+  } else if (mut == 'contract') {
+    return mut_genome_contract(obj, Math.random());
+  } else {
+    throw new Error(`bad mut value: ${mut}`);
+  }
+}
-- 
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