package edu.stanford.nlp.neural;
import java.io.File;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.Random;
import java.util.function.Predicate;
import org.ejml.simple.SimpleMatrix;
import edu.stanford.nlp.io.IOUtils;
import edu.stanford.nlp.util.CollectionUtils;
/**
* Includes a bunch of utility methods usable by projects which use
* RNN, such as the parser and sentiment models. Some methods convert
* iterators of SimpleMatrix objects to and from a vector. Others are
* general utility methods on SimpleMatrix objects.
*
* @author John Bauer
* @author Richard Socher
* @author Thang Luong
*/
public class NeuralUtils {
private NeuralUtils() {} // static methods only
/**
* Convert a file into a text matrix. The expected format one row
* per line, one entry per column. Not too efficient for large
* matrices, but you shouldn't store large matrices in text files
* anyway. This specific format is not supported by ejml, which
* expects the number of rows and columns in its text matrices.
*/
public static SimpleMatrix loadTextMatrix(String path) {
return convertTextMatrix(IOUtils.slurpFileNoExceptions(path));
}
/**
* Convert a file into a text matrix. The expected format one row
* per line, one entry per column. Not too efficient for large
* matrices, but you shouldn't store large matrices in text files
* anyway. This specific format is not supported by ejml, which
* expects the number of rows and columns in its text matrices.
*/
public static SimpleMatrix loadTextMatrix(File file) {
return convertTextMatrix(IOUtils.slurpFileNoExceptions(file));
}
public static SimpleMatrix convertTextMatrix(String text) {
List<String> lines = CollectionUtils.filterAsList(Arrays.asList(text.split("\n")), new Predicate<String>() {
public boolean test(String s) {
return s.trim().length() > 0;
}
private static final long serialVersionUID = 1;
});
int numRows = lines.size();
int numCols = lines.get(0).trim().split("\\s+").length;
double[][] data = new double[numRows][numCols];
for (int row = 0; row < numRows; ++row) {
String line = lines.get(row);
String[] pieces = line.trim().split("\\s+");
if (pieces.length != numCols) {
throw new RuntimeException("Unexpected row length in line " + row);
}
for (int col = 0; col < numCols; ++col) {
data[row][col] = Double.valueOf(pieces[col]);
}
}
return new SimpleMatrix(data);
}
/**
* Compute cosine distance between two column vectors.
*/
public static double cosine(SimpleMatrix vector1, SimpleMatrix vector2){
return dot(vector1, vector2)/(vector1.normF()*vector2.normF());
}
/**
* Compute dot product between two vectors.
*/
public static double dot(SimpleMatrix vector1, SimpleMatrix vector2){
if(vector1.numRows()==1){ // vector1: row vector, assume that vector2 is a row vector too
return vector1.mult(vector2.transpose()).get(0);
} else if (vector1.numCols()==1){ // vector1: col vector, assume that vector2 is also a column vector.
return vector1.transpose().mult(vector2).get(0);
} else {
throw new AssertionError("Error in neural.Utils.dot: vector1 is a matrix " + vector1.numRows() + " x " + vector1.numCols());
}
}
/**
* Given a sequence of Iterators over SimpleMatrix, fill in all of
* the matrices with the entries in the theta vector. Errors are
* thrown if the theta vector does not exactly fill the matrices.
*/
@SafeVarargs
public static void vectorToParams(double[] theta, Iterator<SimpleMatrix> ... matrices) {
int index = 0;
for (Iterator<SimpleMatrix> matrixIterator : matrices) {
while (matrixIterator.hasNext()) {
SimpleMatrix matrix = matrixIterator.next();
int numElements = matrix.getNumElements();
for (int i = 0; i < numElements; ++i) {
matrix.set(i, theta[index]);
++index;
}
}
}
if (index != theta.length) {
throw new AssertionError("Did not entirely use the theta vector");
}
}
/**
* Given a sequence of iterators over the matrices, builds a vector
* out of those matrices in the order given. Asks for an expected
* total size as a time savings. AssertionError thrown if the
* vector sizes do not exactly match.
*/
@SafeVarargs
public static double[] paramsToVector(int totalSize, Iterator<SimpleMatrix> ... matrices) {
double[] theta = new double[totalSize];
int index = 0;
for (Iterator<SimpleMatrix> matrixIterator : matrices) {
while (matrixIterator.hasNext()) {
SimpleMatrix matrix = matrixIterator.next();
int numElements = matrix.getNumElements();
//System.out.println(Integer.toString(numElements)); // to know what matrices are
for (int i = 0; i < numElements; ++i) {
theta[index] = matrix.get(i);
++index;
}
}
}
if (index != totalSize) {
throw new AssertionError("Did not entirely fill the theta vector: expected " + totalSize + " used " + index);
}
return theta;
}
/**
* Given a sequence of iterators over the matrices, builds a vector
* out of those matrices in the order given. The vector is scaled
* according to the <code>scale</code> parameter. Asks for an
* expected total size as a time savings. AssertionError thrown if
* the vector sizes do not exactly match.
*/
@SafeVarargs
public static double[] paramsToVector(double scale, int totalSize, Iterator<SimpleMatrix> ... matrices) {
double[] theta = new double[totalSize];
int index = 0;
for (Iterator<SimpleMatrix> matrixIterator : matrices) {
while (matrixIterator.hasNext()) {
SimpleMatrix matrix = matrixIterator.next();
int numElements = matrix.getNumElements();
for (int i = 0; i < numElements; ++i) {
theta[index] = matrix.get(i) * scale;
++index;
}
}
}
if (index != totalSize) {
throw new AssertionError("Did not entirely fill the theta vector: expected " + totalSize + " used " + index);
}
return theta;
}
/**
* Returns a sigmoid applied to the input <code>x</code>.
*/
public static double sigmoid(double x) {
return 1.0 / (1.0 + Math.exp(-x));
}
/**
* Applies softmax to all of the elements of the matrix. The return
* matrix will have all of its elements sum to 1. If your matrix is
* not already a vector, be sure this is what you actually want.
*/
public static SimpleMatrix softmax(SimpleMatrix input) {
SimpleMatrix output = new SimpleMatrix(input);
for (int i = 0; i < output.numRows(); ++i) {
for (int j = 0; j < output.numCols(); ++j) {
output.set(i, j, Math.exp(output.get(i, j)));
}
}
double sum = output.elementSum();
// will be safe, since exp should never return 0
return output.scale(1.0 / sum);
}
/**
* Applies log to each of the entries in the matrix. Returns a new matrix.
*/
public static SimpleMatrix elementwiseApplyLog(SimpleMatrix input) {
SimpleMatrix output = new SimpleMatrix(input);
for (int i = 0; i < output.numRows(); ++i) {
for (int j = 0; j < output.numCols(); ++j) {
output.set(i, j, Math.log(output.get(i, j)));
}
}
return output;
}
/**
* Applies tanh to each of the entries in the matrix. Returns a new matrix.
*/
public static SimpleMatrix elementwiseApplyTanh(SimpleMatrix input) {
SimpleMatrix output = new SimpleMatrix(input);
for (int i = 0; i < output.numRows(); ++i) {
for (int j = 0; j < output.numCols(); ++j) {
output.set(i, j, Math.tanh(output.get(i, j)));
}
}
return output;
}
/**
* Applies the derivative of tanh to each of the elements in the vector. Returns a new matrix.
*/
public static SimpleMatrix elementwiseApplyTanhDerivative(SimpleMatrix input) {
SimpleMatrix output = new SimpleMatrix(input.numRows(), input.numCols());
output.set(1.0);
output = output.minus(input.elementMult(input));
return output;
}
/**
* Concatenates several column vectors into one large column
* vector, adds a 1.0 at the end as a bias term
*/
public static SimpleMatrix concatenateWithBias(SimpleMatrix ... vectors) {
int size = 0;
for (SimpleMatrix vector : vectors) {
size += vector.numRows();
}
// one extra for the bias
size++;
SimpleMatrix result = new SimpleMatrix(size, 1);
int index = 0;
for (SimpleMatrix vector : vectors) {
result.insertIntoThis(index, 0, vector);
index += vector.numRows();
}
result.set(index, 0, 1.0);
return result;
}
/**
* Concatenates several column vectors into one large column vector
*/
public static SimpleMatrix concatenate(SimpleMatrix ... vectors) {
int size = 0;
for (SimpleMatrix vector : vectors) {
size += vector.numRows();
}
SimpleMatrix result = new SimpleMatrix(size, 1);
int index = 0;
for (SimpleMatrix vector : vectors) {
result.insertIntoThis(index, 0, vector);
index += vector.numRows();
}
return result;
}
/**
* Returns a vector with random Gaussian values, mean 0, std 1
*/
public static SimpleMatrix randomGaussian(int numRows, int numCols, Random rand) {
SimpleMatrix result = new SimpleMatrix(numRows, numCols);
for (int i = 0; i < numRows; ++i) {
for (int j = 0; j < numCols; ++j) {
result.set(i, j, rand.nextGaussian());
}
}
return result;
}
/**
* Returns true iff every element of matrix is 0
*/
public static boolean isZero(SimpleMatrix matrix) {
int size = matrix.getNumElements();
for (int i = 0; i < size; ++i) {
if (matrix.get(i) != 0.0) {
return false;
}
}
return true;
}
}