com.expleague.ml.methods.seq.nn.LSTMLayer Maven / Gradle / Ivy
package com.expleague.ml.methods.seq.nn;
import com.expleague.commons.math.vectors.Mx;
import com.expleague.commons.math.vectors.Vec;
import com.expleague.commons.math.vectors.VecTools;
import com.expleague.commons.math.vectors.impl.vectors.ArrayVec;
import com.expleague.commons.math.vectors.impl.mx.VecBasedMx;
import com.expleague.commons.random.FastRandom;
public class LSTMLayer implements NetworkLayer {
private final LSTMNode[] nodes;
private Vec[][] nodeInputs;
public LSTMLayer(int nodeCount, int inputDim, FastRandom random) {
nodes = new LSTMNode[nodeCount];
for (int i = 0; i < nodeCount; i++) {
nodes[i] = new LSTMNode(inputDim, random);
}
}
/**
*
* @param x i-th row of x is a signal value at the moment i
* @return output.get(i, j) is a signal value of j-th node at the moment i
*/
@Override
public Mx value(Mx x) {
Mx result = new VecBasedMx(x.rows(), nodes.length);
nodeInputs = new Vec[nodes.length][x.rows()];
for (int node = 0; node < nodes.length; node++) {
Vec lastNodeOutput = new ArrayVec(2);
for (int moment = 0; moment < x.rows(); moment++) {
nodeInputs[node][moment] = VecTools.concat(x.row(moment), lastNodeOutput);
lastNodeOutput = nodes[node].value(nodeInputs[node][moment]);
result.set(moment, node, lastNodeOutput.get(0));
}
}
return result;
}
//Fixme: for now assuming that this is the first layer in the network
@Override
public LayerGrad gradient(Mx x, Mx outputGrad, boolean isAfterValue) {
if (!isAfterValue) {
value(x);
}
final int paramCount = nodes[0].params().dim();
Vec gradByParams = new ArrayVec(nodes.length * paramCount);
Mx gradByInput = new VecBasedMx(x.rows(), x.columns());
for (int node = 0; node < nodes.length; node++) {
Vec nodeOutputGrad = new ArrayVec(2);
for (int moment = x.rows() - 1; moment >= 0; moment--) {
nodeOutputGrad.adjust(0, outputGrad.get(moment, node));
NetworkNode.NodeGrad grad = nodes[node].grad(nodeInputs[node][moment], nodeOutputGrad);
nodeOutputGrad = grad.gradByInput;
VecTools.incscale(gradByParams.sub(node * paramCount, paramCount), grad.gradByParams, 1);
}
}
return new LayerGrad(gradByParams, gradByInput);
}
@Override
public void adjustParams(Vec dW) {
final int nodeParamCount = nodes[0].params().dim();
for (int i = 0; i < nodes.length; i++) {
VecTools.append(nodes[i].params(), dW.sub(i * nodeParamCount, nodeParamCount));
}
}
@Override
public void setParams(Vec newW) {
final int nodeParamCount = nodes[0].params().dim();
for (int i = 0; i < nodes.length; i++) {
VecTools.assign(nodes[i].params(), newW.sub(i * nodeParamCount, nodeParamCount));
}
}
@Override
public int paramCount() {
return nodes.length * nodes[0].params().dim();
}
@Override
public Vec paramsView() {
Vec[] params = new Vec[nodes.length];
for (int i =0; i < nodes.length; i++) {
params[i] = nodes[i].params();
}
return VecTools.join(params);
}
}
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