From e6cfec79f6e95057e88040ae4fcd4442f734c49e Mon Sep 17 00:00:00 2001
From: Antonio De Luca <contact@antoniodeluca.info>
Date: Thu, 14 May 2015 19:26:17 +0200
Subject: [PATCH] Added a new training option that enable users to specify if
 the weights of the neural network have to be (re)initialized or not.

---
 lib/neuralnetwork.js   |  5 ++++-
 test/unit/trainopts.js | 14 ++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/lib/neuralnetwork.js b/lib/neuralnetwork.js
index 02fae0d..d7ff6ba 100644
--- a/lib/neuralnetwork.js
+++ b/lib/neuralnetwork.js
@@ -88,6 +88,7 @@ NeuralNetwork.prototype = {
     var learningRate = options.learningRate || this.learningRate || 0.3;
     var callback = options.callback;
     var callbackPeriod = options.callbackPeriod || 10;
+    var initialization = _.isUndefined(options.initialization) ? true : options.initialization;
 
     var inputSize = data[0].input.length;
     var outputSize = data[0].output.length;
@@ -97,7 +98,9 @@ NeuralNetwork.prototype = {
       hiddenSizes = [Math.max(3, Math.floor(inputSize / 2))];
     }
     var sizes = _([inputSize, hiddenSizes, outputSize]).flatten();
-    this.initialize(sizes);
+    if (initialization) {
+      this.initialize(sizes);
+    }    
 
     var error = 1;
     for (var i = 0; i < iterations && error > errorThresh; i++) {
diff --git a/test/unit/trainopts.js b/test/unit/trainopts.js
index 5ca84e7..9d09376 100644
--- a/test/unit/trainopts.js
+++ b/test/unit/trainopts.js
@@ -48,4 +48,18 @@ describe('train() options', function() {
       callbackPeriod: 20
     });
   });
+  
+  it('trains the neural network without (re)initializing the weights', function() {
+    var net = new brain.NeuralNetwork();
+    var firstTrainingError = net.train(data, {
+      errorThresh: 0.2,
+      iterations: 100000
+    }).error;
+    var secondTrainingError = net.train(data, {
+      errorThresh: 0.2,
+      iterations: 1,
+      initialization: false
+    }).error;   
+    assert.ok(secondTrainingError <= firstTrainingError);      
+  });  
 })