2 files changed, 67 insertions, 0 deletions
diff --git a/src/genome/genome.js b/src/genome/genome.js
index c288d02..7688b32 100644
--- a/src/genome/genome.js
+++ b/src/genome/genome.js
@@ -88,3 +88,19 @@ export function mut_gene_weight(weight_max, gene, r) {
     clamp(new_weight, -weight_max, weight_max),
   ];
 }
+
+
+export function mut_genome_expand(
+  [n_input, n_internal, n_output, genome], r
+) {
+  const expand_index = Math.floor(n_internal * r) + n_input;
+  const new_genome = genome.map(([source, sink, weight]) => [
+    source >= expand_index ? source+1 : source,
+    sink >= expand_index ? sink+1 : sink,
+    weight,
+  ]);
+
+  return [
+    n_input, n_internal+1, n_output, new_genome,
+  ];
+}
diff --git a/src/genome/genome.test.js b/src/genome/genome.test.js
index e1c8711..11b2d31 100644
--- a/src/genome/genome.test.js
+++ b/src/genome/genome.test.js
@@ -6,6 +6,7 @@ import {
   mut_gene_source,
   mut_gene_sink,
   mut_gene_weight,
+  mut_genome_expand,
 } from './genome';
 
 
@@ -110,3 +111,53 @@ test('mutate gene weight', () => {
     weight_max, [0, 0, 3], 0.5
   )).toEqual([0, 0, (6+0)/3]);
 });
+
+
+test('expand genome', () => {
+  const n_input = 1;
+  const n_internal = 3;
+  const n_output = 1;
+
+  const genome = [
+    [0, 1, 0],
+    [1, 2, 0],
+    [2, 3, 0],
+    [3, 4, 0],
+  ];
+
+  expect(mut_genome_expand([
+    n_input, n_internal, n_output, genome
+  ], 0.0)).toEqual([
+    n_input, n_internal+1, n_output,
+    [
+      [0, 2, 0],
+      [2, 3, 0],
+      [3, 4, 0],
+      [4, 5, 0],
+    ],
+  ]);
+
+  expect(mut_genome_expand([
+    n_input, n_internal, n_output, genome
+  ], 0.5)).toEqual([
+    n_input, n_internal+1, n_output,
+    [
+      [0, 1, 0],
+      [1, 3, 0],
+      [3, 4, 0],
+      [4, 5, 0],
+    ],
+  ]);
+
+  expect(mut_genome_expand([
+    n_input, n_internal, n_output, genome
+  ], 0.99)).toEqual([
+    n_input, n_internal+1, n_output,
+    [
+      [0, 1, 0],
+      [1, 2, 0],
+      [2, 4, 0],
+      [4, 5, 0],
+    ],
+  ]);
+});