public void Train()
{
RNN <T> rnn;
if (ModelSettings.ModelDirection == 0)
{
int sparseFeatureSize = TrainingSet.SparseFeatureSize;
if (ModelSettings.IsSeq2SeqTraining)
{
//[Sparse feature set of each state in target sequence][Sparse feature set of entire source sequence]
sparseFeatureSize += Featurizer.AutoEncoder.Featurizer.SparseFeatureSize;
Logger.WriteLine("Sparse Feature Format: [{0}][{1}] = {2}",
TrainingSet.SparseFeatureSize, Featurizer.AutoEncoder.Featurizer.SparseFeatureSize, sparseFeatureSize);
}
List <SimpleLayer> hiddenLayers = new List <SimpleLayer>();
for (int i = 0; i < ModelSettings.HiddenLayerSizeList.Count; i++)
{
SimpleLayer layer = null;
if (ModelSettings.ModelType == LayerType.BPTT)
{
BPTTLayer bpttLayer = new BPTTLayer(ModelSettings.HiddenLayerSizeList[i], ModelSettings);
layer = bpttLayer;
}
else if (ModelSettings.ModelType == LayerType.LSTM)
{
LSTMLayer lstmLayer = new LSTMLayer(ModelSettings.HiddenLayerSizeList[i], ModelSettings);
layer = lstmLayer;
}
else
{
throw new System.Exception(string.Format("Invalidate hidden layer type: {0}", ModelSettings.ModelType.ToString()));
}
if (i == 0)
{
Logger.WriteLine("Create hidden layer {0}: size = {1}, sparse feature size = {2}, dense feature size = {3}",
i, ModelSettings.HiddenLayerSizeList[i], sparseFeatureSize, TrainingSet.DenseFeatureSize);
if (ModelSettings.IsSeq2SeqTraining)
{
Logger.WriteLine("For seq2seq training, we have {0} sprase feature and {1} dense feature from source sequence.",
Featurizer.AutoEncoder.Featurizer.SparseFeatureSize, Featurizer.AutoEncoder.GetTopHiddenLayerSize());
}
layer.InitializeWeights(sparseFeatureSize, GetCurrentLayerDenseFeatureSize(TrainingSet.DenseFeatureSize));
}
else
{
Logger.WriteLine("Create hidden layer {0}: size = {1}, sparse feature size = {2}, dense feature size = {3}",
i, ModelSettings.HiddenLayerSizeList[i], sparseFeatureSize, hiddenLayers[i - 1].LayerSize);
layer.InitializeWeights(sparseFeatureSize, GetCurrentLayerDenseFeatureSize(hiddenLayers[i - 1].LayerSize));
}
hiddenLayers.Add(layer);
}
if (ModelSettings.Dropout > 0)
{
Logger.WriteLine("Adding dropout layer");
DropoutLayer dropoutLayer = new DropoutLayer(hiddenLayers[hiddenLayers.Count - 1].LayerSize, ModelSettings);
dropoutLayer.InitializeWeights(0, GetCurrentLayerDenseFeatureSize(hiddenLayers[hiddenLayers.Count - 1].LayerSize));
hiddenLayers.Add(dropoutLayer);
}
SimpleLayer outputLayer;
if (ModelSettings.OutputLayerType == LayerType.NCESoftmax)
{
Logger.WriteLine("Create NCESoftmax layer as output layer");
NCEOutputLayer nceOutputLayer = new NCEOutputLayer(TrainingSet.TagSize, ModelSettings);
nceOutputLayer.BuildStatisticData <T>(TrainingSet);
nceOutputLayer.InitializeWeights(0, GetCurrentLayerDenseFeatureSize(hiddenLayers[hiddenLayers.Count - 1].LayerSize));
outputLayer = nceOutputLayer;
}
else if (ModelSettings.OutputLayerType == LayerType.Softmax)
{
Logger.WriteLine("Create Softmax layer as output layer.");
outputLayer = new SimpleLayer(TrainingSet.TagSize);
outputLayer.InitializeWeights(sparseFeatureSize, GetCurrentLayerDenseFeatureSize(hiddenLayers[hiddenLayers.Count - 1].LayerSize));
}
else
{
throw new System.Exception(string.Format("Invalidate output layer type: {0}", ModelSettings.OutputLayerType.ToString()));
}
rnn = new ForwardRNN <T>(hiddenLayers, outputLayer);
}
else
{
List <SimpleLayer> forwardHiddenLayers = new List <SimpleLayer>();
List <SimpleLayer> backwardHiddenLayers = new List <SimpleLayer>();
for (int i = 0; i < ModelSettings.HiddenLayerSizeList.Count; i++)
{
SimpleLayer forwardLayer = null;
SimpleLayer backwardLayer = null;
if (ModelSettings.ModelType == LayerType.BPTT)
{
//For BPTT layer
BPTTLayer forwardBPTTLayer = new BPTTLayer(ModelSettings.HiddenLayerSizeList[i], ModelSettings);
forwardLayer = forwardBPTTLayer;
BPTTLayer backwardBPTTLayer = new BPTTLayer(ModelSettings.HiddenLayerSizeList[i], ModelSettings);
backwardLayer = backwardBPTTLayer;
}
else if (ModelSettings.ModelType == LayerType.LSTM)
{
//For LSTM layer
LSTMLayer forwardLSTMLayer = new LSTMLayer(ModelSettings.HiddenLayerSizeList[i], ModelSettings);
forwardLayer = forwardLSTMLayer;
LSTMLayer backwardLSTMLayer = new LSTMLayer(ModelSettings.HiddenLayerSizeList[i], ModelSettings);
backwardLayer = backwardLSTMLayer;
}
else
{
throw new System.Exception(string.Format("Invalidate hidden layer type: {0}", ModelSettings.ModelType.ToString()));
}
if (i == 0)
{
Logger.WriteLine("Create hidden layer {0}: size = {1}, sparse feature size = {2}, dense feature size = {3}",
i, ModelSettings.HiddenLayerSizeList[i], TrainingSet.SparseFeatureSize, TrainingSet.DenseFeatureSize);
forwardLayer.InitializeWeights(TrainingSet.SparseFeatureSize, TrainingSet.DenseFeatureSize);
backwardLayer.InitializeWeights(TrainingSet.SparseFeatureSize, TrainingSet.DenseFeatureSize);
}
else
{
Logger.WriteLine("Create hidden layer {0}: size = {1}, sparse feature size = {2}, dense feature size = {3}",
i, ModelSettings.HiddenLayerSizeList[i], TrainingSet.SparseFeatureSize, forwardHiddenLayers[i - 1].LayerSize);
forwardLayer.InitializeWeights(TrainingSet.SparseFeatureSize, forwardHiddenLayers[i - 1].LayerSize);
backwardLayer.InitializeWeights(TrainingSet.SparseFeatureSize, backwardHiddenLayers[i - 1].LayerSize);
}
forwardHiddenLayers.Add(forwardLayer);
backwardHiddenLayers.Add(backwardLayer);
}
if (ModelSettings.Dropout > 0)
{
Logger.WriteLine("Adding dropout layers");
DropoutLayer forwardDropoutLayer = new DropoutLayer(forwardHiddenLayers[forwardHiddenLayers.Count - 1].LayerSize, ModelSettings);
DropoutLayer backwardDropoutLayer = new DropoutLayer(backwardHiddenLayers[backwardHiddenLayers.Count - 1].LayerSize, ModelSettings);
forwardDropoutLayer.InitializeWeights(0, forwardHiddenLayers[forwardHiddenLayers.Count - 1].LayerSize);
backwardDropoutLayer.InitializeWeights(0, backwardHiddenLayers[backwardHiddenLayers.Count - 1].LayerSize);
forwardHiddenLayers.Add(forwardDropoutLayer);
backwardHiddenLayers.Add(backwardDropoutLayer);
}
SimpleLayer outputLayer;
if (ModelSettings.OutputLayerType == LayerType.NCESoftmax)
{
Logger.WriteLine("Create NCESoftmax layer as output layer.");
NCEOutputLayer nceOutputLayer = new NCEOutputLayer(TrainingSet.TagSize, ModelSettings);
nceOutputLayer.BuildStatisticData <T>(TrainingSet);
nceOutputLayer.InitializeWeights(0, forwardHiddenLayers[forwardHiddenLayers.Count - 1].LayerSize);
outputLayer = nceOutputLayer;
}
else if (ModelSettings.OutputLayerType == LayerType.Softmax)
{
Logger.WriteLine("Create Softmax layer as output layer.");
outputLayer = new SimpleLayer(TrainingSet.TagSize);
outputLayer.InitializeWeights(TrainingSet.SparseFeatureSize, forwardHiddenLayers[forwardHiddenLayers.Count - 1].LayerSize);
}
else
{
throw new System.Exception(string.Format("Invalidate output layer type: {0}", ModelSettings.OutputLayerType.ToString()));
}
rnn = new BiRNN <T>(forwardHiddenLayers, backwardHiddenLayers, outputLayer);
}
rnn.ModelDirection = (MODELDIRECTION)ModelSettings.ModelDirection;
rnn.bVQ = (ModelSettings.VQ != 0) ? true : false;
rnn.ModelFile = ModelSettings.ModelFile;
rnn.SaveStep = ModelSettings.SaveStep;
rnn.MaxIter = ModelSettings.MaxIteration;
rnn.IsCRFTraining = ModelSettings.IsCRFTraining;
rnn.ModelType = ModelSettings.IsSeq2SeqTraining ? MODELTYPE.SEQ2SEQ : MODELTYPE.SEQLABEL;
if (rnn.ModelDirection == MODELDIRECTION.BI_DIRECTIONAL && rnn.ModelType == MODELTYPE.SEQ2SEQ)
{
throw new System.Exception("Bi-directional RNN model doesn't support sequence-to-sequence model.");
}
RNNHelper.LearningRate = ModelSettings.LearningRate;
RNNHelper.GradientCutoff = ModelSettings.GradientCutoff;
RNNHelper.IsConstAlpha = ModelSettings.IsConstAlpha;
//Create tag-bigram transition probability matrix only for sequence RNN mode
if (ModelSettings.IsCRFTraining)
{
rnn.setTagBigramTransition(TrainingSet.CRFLabelBigramTransition);
}
Logger.WriteLine("");
Logger.WriteLine("Iterative training begins ...");
double lastPPL = double.MaxValue;
double lastAlpha = RNNHelper.LearningRate;
int iter = 0;
while (true)
{
Logger.WriteLine("Cleaning training status...");
rnn.CleanStatus();
if (rnn.MaxIter > 0 && iter > rnn.MaxIter)
{
Logger.WriteLine("We have trained this model {0} iteration, exit.");
break;
}
//Start to train model
double ppl = rnn.TrainNet(TrainingSet, iter);
if (ppl >= lastPPL && lastAlpha != RNNHelper.LearningRate)
{
//Although we reduce alpha value, we still cannot get better result.
Logger.WriteLine("Current perplexity({0}) is larger than the previous one({1}). End training early.", ppl, lastPPL);
Logger.WriteLine("Current alpha: {0}, the previous alpha: {1}", RNNHelper.LearningRate, lastAlpha);
break;
}
lastAlpha = RNNHelper.LearningRate;
//Validate the model by validated corpus
if (ValidationSet != null)
{
Logger.WriteLine("Verify model on validated corpus.");
if (rnn.ValidateNet(ValidationSet, iter) == true)
{
//We got better result on validated corpus, save this model
Logger.WriteLine("Saving better model into file {0}...", ModelSettings.ModelFile);
rnn.SaveModel(ModelSettings.ModelFile);
}
}
else if (ppl < lastPPL)
{
//We don't have validate corpus, but we get a better result on training corpus
//We got better result on validated corpus, save this model
Logger.WriteLine("Saving better model into file {0}...", ModelSettings.ModelFile);
rnn.SaveModel(ModelSettings.ModelFile);
}
if (ppl >= lastPPL)
{
//We cannot get a better result on training corpus, so reduce learning rate
RNNHelper.LearningRate = RNNHelper.LearningRate / 2.0f;
}
lastPPL = ppl;
iter++;
}
}