1 files changed, 49 insertions, 50 deletions
diff --git a/src/genome/genome.js b/src/genome/genome.js
index 0f7275f..c288d02 100644
--- a/src/genome/genome.js
+++ b/src/genome/genome.js
@@ -3,56 +3,6 @@
 import { network } from '../mind/topology';
 
 
-export const mutation_type = Object.freeze({
-  none: 'none',
-  source: 'source',
-  sink: 'sink',
-  weight: 'weight',
-});
-
-
-// clamp a number in the range [0, infinity)
-function nonneg(x) {
-  if (x < 0) { 
-    return 0; 
-  } else {
-    return x;
-  }
-}
-
-
-// mutate a gene
-export function mutate(gene, type, value) {
-  const [ source, sink, weight ] = gene;
-
-  switch(type) {
-    case mutation_type.none:
-      return [...gene];
-
-    case mutation_type.source:
-      if (value <= 0.5) {
-        return [ nonneg(source-1), sink, weight ];
-      } else {
-        return [ source+1, sink, weight ];
-      }
-
-    case mutation_type.sink:
-      if (value <= 0.5) {
-        return [ source, nonneg(sink-1), weight ];
-      } else {
-        return [ source, sink+1, weight ];
-      }
-
-    case mutation_type.weight:
-      const w = (8*value) - 4;
-      return [ source, sink, 0.5*(w + weight) ];
-
-    default:
-      throw new Error(`unknown mutation type: '${type}'`);
-  };
-}
-
-
 // check if a given genome is valid and compute its size
 export function get_size(num_input, num_output, genome) {
   const [ max_index, max_weight ] = genome.reduce(
@@ -89,3 +39,52 @@ export function parse_genome(num_input, num_output, genome) {
 
   return n;
 }
+
+
+// --===== mutations =====--
+
+function clamp(value, min, max) {
+  if (value > max) { return max; }
+  if (value < min) { return min; }
+  return value;
+}
+
+export function mut_gene_source(n_input, n_internal, n_output, gene, r) {
+  const [source, sink, weight] = gene;
+
+  const new_source = r < 0.5 ? source-1 : source+1;
+
+  return [
+    clamp(new_source, 0, n_input+n_internal-1), 
+    sink, 
+    weight,
+  ];
+}
+
+
+export function mut_gene_sink(n_input, n_internal, n_output, gene, r) {
+  const [source, sink, weight] = gene;
+
+  const new_sink = r < 0.5 ? sink-1 : sink+1;
+
+  return [
+    source, 
+    clamp(new_sink,  n_input+n_internal, n_input+n_internal+n_output-1), 
+    weight,
+  ];
+}
+
+
+export function mut_gene_weight(weight_max, gene, r) {
+  const [source, sink, weight] = gene;
+  
+  const rr = (2*r)-1;
+  const move = weight_max * rr;
+  const new_weight = (2*weight + move)/3;
+
+  return [
+    source,
+    sink,
+    clamp(new_weight, -weight_max, weight_max),
+  ];
+}