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package dut.ir.CRFJava;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import riso.numerical.LBFGS;
/**
* FileName: CRFTrainer.java <br/>
* package:dut.ir.CRFJava <br/>
* author:zmz <br/>
* date:2014-7-11 <br/>
* time:下午8:46:42 <br/>
* email: [email protected] <br/>
* 功能:训练CRF参数,并将训练得到的参数写入文件 <br/>
* CRF的理论推导可参考李航老师的《统计学习方法》 <br/>
* CRFJava使用LBFGS来优化目标函数,使用RISO Project中的LBFGS.java文件,感谢作者的工作。<br/><br/>
*
* 如发现问题,请发送email至 [email protected],谢谢!
*/
public class CRFTrainer extends AbstractCRF {
/**
* delta * delta,负对数似然函数与权重的调和参数,该值越大,越拟合训练数据
*/
private double delta2;
/**
* 状态特征的个数
*/
private int uFeatureNum;
/**
* 转移特征的函数
*/
private int bFeatureNum;
public CRFTrainer(String trainFile, String templateFile, String modelFile,
int threshold, double delta) throws IOException {
this.delta2 = delta * delta;
this.modelFile = modelFile;
crfParams = new CRFParams();
// 初始化templates
initTemplates(templateFile);
System.out.println("模板:" + crfParams.templates.size());
// 初始化:sentences,sentenceLabels,labels
initSentencesAndLabels(trainFile);
crfParams.K = crfParams.labels.size();
System.out.println("句子:" + sentences.size());
System.out.println("标签数:" + crfParams.K);
// 初始化:crfParams.uFeatureAddr,crfParams.bFeatureAddr,uFunWeight,bFunWeight,
initFeatureInfo(threshold);
System.out.println("状态特征:" + crfParams.uFeatureAddr.size());
System.out.println("转移特征:" + crfParams.bFeatureAddr.size());
System.out.println("特征函数:" + (crfParams.bFeatureAddr.size() * crfParams.K * crfParams.K + crfParams.uFeatureAddr.size()*crfParams.K));
//初始化:uFeatureArray,bFeatureArray
initFeatureArray(this.sentences, this.sentenceLabels);
// 初始化:uFeatureArray,bFeatureArray,uFeatureStart,uFeatureEnd,bFeatureStart,bFeatureEnd
initWordFeatureInfo(this.sentences, this.sentenceLabels);
}
public static void main(String[] args) throws IOException {
CRFTrainer crf = new CRFTrainer("data/train.data", "data/template", "data/model",1, 1);
crf.train();
//MyTool.showMap(crfParams.uFeatureAddr);
}
/**
* 使用LBFGS算法进行训练
*/
public void train(){
double diag1[];
double f, eps, xtol, gtol, t1, t2, stpmin, stpmax;
int iprint[], iflag[] = new int[1], iter, n, m, mp, lp, j;
iprint = new int[2];
boolean diagco;
iprint[0] = -1;
iprint[1] = 0;
diagco = false;
eps = 1.0e-10;
xtol = 1.0e-16;
iter = 0;
iflag[0] = 0;
m = 7;
diag1 = new double[crfParams.funWeight.length];
double preLoss = 0;//前一次的损失值
double relLoss = 0;//与前一次损失值的相对差别
do {
double[] gradient = new double[crfParams.funWeight.length];
double loss = loss(gradient);
double[] p = this.checkAllaccuracy();
if(iter == 0){
relLoss = 1;
}
else{
relLoss = (preLoss - loss) / preLoss;
}
preLoss = loss;
System.out.printf("iter=%d loss=%f 句子准确率:%f 单词准确率:%f 相对损失:%f\n",iter,loss,p[0],p[1],relLoss);
//System.out.println("iter=" + iter + "\tloss=" + loss + "\t句子准确率:" + p[0] + "\t单词准确率:" + p[1]);
try {
LBFGS.lbfgs(crfParams.funWeight.length, m, crfParams.funWeight, loss, gradient, diagco, diag1, iprint, eps, xtol,
iflag);
} catch (LBFGS.ExceptionWithIflag e) {
System.err.println("Sdrive: lbfgs failed.\n" + e);
return;
}
iter += 1;
} while (iflag[0] != 0 && iter <= 100 && relLoss > 0.00001);
this.writeModel();
}
/**
* 计算句子级别和单词级别的准确率
* @return 句子级别的准确率和单词级别的准确率
*/
private double[] checkAllaccuracy(){
double[] p = new double[2];
int corS = 0;//正确的句子数
int corT = 0;//正确的单词数
int tokens = 0;//所有的单词数
boolean right = true;
for(int i = 0; i < sentences.size(); i++){
int[] tags = new int[sentences.get(i).length];
Integer[] sLabels = sentenceLabels.get(i);
int[] pLabels = this.viterbi(i);//预测值
right = true;//句子是否完全正确
for(int j = 0; j < pLabels.length; j++){
if(sLabels[j] == pLabels[j]){
corT++;
}
else{
right = false;
}
}
tokens += pLabels.length;
}
p[0] = 1.0 * corS / sentences.size();
p[1] = 1.0 * corT / tokens;
return p;
}
/**
* 根据当前参数,计算训练损失函数的值,并计算参数的梯度向量
* @param gradient 梯度向量
* @return 损失函数的值
*/
public double loss(double[] gradient) {
int iter = 0;
Integer[] uStart;
Integer[] uEnd;
Integer[] bStart;
Integer[] bEnd;
int addr;
double loss = 0;
for (int s = 0; s < sentences.size(); s++) {// 遍历所有句子
uStart = uFeatureStart.get(s);
uEnd = uFeatureEnd.get(s);
bStart = bFeatureStart.get(s);
bEnd = bFeatureStart.get(s);
ArrayList<double[][]> Ms = this.computeMs(s);
Integer[] sLabels = sentenceLabels.get(s);
double[][] alpha = this.alpha(Ms);
double[][] beta = this.beta(Ms);
double zeta1 = this.zetaByAlpha(alpha);
if(Double.isInfinite(zeta1)//如果句子太长,归一化参数容易变为无穷大,所以句子应该尽可能的短
continue;
loss += Math.log(zeta1);
for (int i = 0; i < Ms.size(); i++) {// 遍历每个单词
double[][] M = Ms.get(i);
for(int j = uStart[i]; j >=0 && j <= uEnd[i]; j++){//更新状态特征函数的梯度
addr = uFeatureArray[j];//特征索引
loss = loss - crfParams.funWeight[addr + sLabels[i]];
gradient[addr + + sLabels[i]] -= 1;
for(int k = 0; k < crfParams.K; k++){//addr处,第k个特征函数
gradient[addr + k] += alpha[k][i]*beta[k][i] / zeta1;
//gradient[addr + k] += crfParams.funWeight[addr + k] * alpha[k][i]*beta[k][i] / zeta1;
}
}
if(i > 0){
for(int j = bStart[i]; j >=0 && j <= bEnd[i]; j++){//更新转移特征函数的梯度
addr = bFeatureArray[j];//特征索引
loss -= crfParams.funWeight[addr + sLabels[i-1] * crfParams.K + sLabels[i]];
gradient[addr + sLabels[i-1] * crfParams.K + sLabels[i]] -= 1;
for(int preK = 0; preK < crfParams.K; preK++){
for(int k = 0; k < crfParams.K;k++){
gradient[addr + preK * crfParams.K + k] += alpha[preK][i-1]*beta[k][i] * M[preK][k] / zeta1;
//gradient[addr + preK * crfParams.K + k] += crfParams.funWeight[addr + preK * crfParams.K + k] * alpha[preK][i-1]*beta[k][i] * M[preK][k] / zeta1;
}
}
}
}
}
}// 遍历句子完成
for(int k = 0; k < crfParams.funWeight.length; k++){
loss += 0.5 * crfParams.funWeight[k] * crfParams.funWeight[k] / delta2;
gradient[k] = gradient[k] + crfParams.funWeight[k] / delta2;
}
return loss;
}
/**
* 通过alpha矩阵计算zeta
* @param alpha alpha矩阵
* @return 归一化因子zeta
*/
public double zetaByAlpha(double[][] alpha) {
double zeta = 0;
int length = alpha[0].length;
for (int i = 0; i < crfParams.K; i++) {
zeta += alpha[i][length - 1];
}
return zeta;
}
/**
* 计算前向后向算法中的alpha矩阵
*
* @param Ms 句子每个单词的M矩阵组成的列表
* @return alpha矩阵
*/
public double[][] alpha(ArrayList<double[][]> Ms) {
double[][] alpha = new double[crfParams.K][Ms.size()];
for (int i = 0; i < Ms.size(); i++) {// 依此求取每个位置的alpha
double[][] M = Ms.get(i);// i处的M矩阵
if (i == 0) {
for (int k = 0; k < crfParams.K; k++) {
alpha[k][i] = M[0][k];
}
} else {
for (int k = 0; k < crfParams.K; k++) {
for (int preK = 0; preK < crfParams.K; preK++) {
alpha[k][i] += alpha[preK][i - 1] * M[preK][k];
}
}
}
}
return alpha;
}
/**
* 计算前向后向算法中的beta矩阵
* @param Ms 句子每个单词的M矩阵组成的列表
* @return beta矩阵
*/
public double[][] beta(ArrayList<double[][]> Ms) {
double[][] beta = new double[crfParams.K][Ms.size()];
for (int i = Ms.size() - 1; i >= 0; i--) {
if (i == Ms.size() - 1) {
for (int k = 0; k < crfParams.K; k++)
beta[k][i] = 1;
} else {
double[][] M = Ms.get(i + 1);
for (int k = 0; k < crfParams.K; k++) {
for (int nextK = 0; nextK < crfParams.K; nextK++) {
beta[k][i] += beta[nextK][i + 1] * M[k][nextK];
}
}
}
}
return beta;
}
/**
* 将crfParmas写入文件
*/
private void writeModel(){
FileOutputStream fos;
ObjectOutputStream oos;
try {
fos = new FileOutputStream(this.modelFile);
oos = new ObjectOutputStream(fos);
oos.writeObject(crfParams);
oos.close();
}catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/**
* 根据当前sentences中存储的句子,初始化:crfParams.uFeatureAddr,crfParams.bFeatureAddr,crfParams.funWeight<br/>
*
* @param threshold 特征频次阈值,出现次数小于该阈值的特征被删除
*/
public void initFeatureInfo(int threshold) {
// 首先:crfParams.uFeatureAddr和crfParams.bFeatureAddr中存储每个特征出现的次数,
crfParams.uFeatureAddr = new HashMap<String, Integer>();
crfParams.bFeatureAddr = new HashMap<String, Integer>();
String feature;
// Entry<String,Integer[]> temps = templates.;
for (int i = 0; i < sentences.size(); i++) {
String[][] sentence = sentences.get(i);
for (int m = 0; m < sentence.length; m++) {
Iterator<Entry<String, Integer[]>> it = crfParams.templates.entrySet()
.iterator();
while (it.hasNext()) {
Entry<String, Integer[]> entry = it.next();
feature = entry.getKey() + ":";
Integer[] numbers = entry.getValue();
for (int k = 0; k < numbers.length; k = k + 2) {
if (numbers[k] + m < 0|| numbers[k] + m >= sentence.length)
continue;
feature += sentence[numbers[k] + m][numbers[k + 1]];
}
if (feature.startsWith("U")) {// 状态特征模板
if (crfParams.uFeatureAddr.containsKey(feature))
crfParams.uFeatureAddr.put(feature,
1 + crfParams.uFeatureAddr.get(feature));
else
crfParams.uFeatureAddr.put(feature, 1);
} else {// 转移特征模板
if (crfParams.bFeatureAddr.containsKey(feature))
crfParams.bFeatureAddr.put(feature,
1 + crfParams.bFeatureAddr.get(feature));
else
crfParams.bFeatureAddr.put(feature, 1);
}
}
}
}
// 精简特征
Iterator<String> it = crfParams.uFeatureAddr.keySet().iterator();
while (it.hasNext()) {
feature = it.next();
if (crfParams.uFeatureAddr.get(feature) < threshold) {
it.remove();
crfParams.uFeatureAddr.remove(feature);
}
}
it = crfParams.bFeatureAddr.keySet().iterator();
while (it.hasNext()) {
feature = it.next();
if (crfParams.bFeatureAddr.get(feature) <= threshold) {
it.remove();
crfParams.bFeatureAddr.remove(feature);
}
}
uFeatureNum = crfParams.uFeatureAddr.size();
bFeatureNum = crfParams.bFeatureAddr.size();
crfParams.funWeight = new double[uFeatureNum * crfParams.K + bFeatureNum * crfParams.K * crfParams.K];
it = crfParams.uFeatureAddr.keySet().iterator();
int index = 0;
while (it.hasNext()) {
crfParams.uFeatureAddr.put(it.next(), index);
index = index + crfParams.K;
}
it = crfParams.bFeatureAddr.keySet().iterator();
while (it.hasNext()) {
crfParams.bFeatureAddr.put(it.next(), index);
index = index + crfParams.K * crfParams.K;
}
}
/**
* 读取所有训练句子,并初始化每个句子对应的标签数组
* @param trainFile
*/
public void initSentencesAndLabels(String trainFile){
sentences = new ArrayList<String[][]>();
sentenceLabels = new ArrayList<Integer[]>();
crfParams.labels = new ArrayList<String>();
try {
BufferedReader in = new BufferedReader(new FileReader(trainFile));
while(true){
String[][] tem = this.readSingleSentence(in);
if(tem.length == 0)
break;
sentences.add(tem);
sentenceLabels.add(this.mapSentenceLabelToNum(tem));
}
in.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//return sentences;
}
/**
* 初始化模板列表,模板格式详见CRFParams.templates
* @param templateFile
* @throws FileNotFoundException
*/
private void initTemplates(String templateFile) throws IOException {
BufferedReader in = new BufferedReader(new FileReader(templateFile));
crfParams.templates = new HashMap<String, Integer[]>();
String line = "";
int row = -1;// 行号
int col = -1; // 列号
Pattern p = Pattern.compile("\\[(-*\\d+),(\\d+)\\]");// 匹配[-2,1]
while (null != (line = in.readLine())) {
if (line.startsWith("U") || line.startsWith("B")) {
String[] tem = line.split(":");
ArrayList<Integer> numbers = new ArrayList<Integer>();
if (tem.length == 2) {
Matcher m = p.matcher(tem[1]);
while (m.find()) {
row = Integer.valueOf(m.group(1));
col = Integer.valueOf(m.group(2));
numbers.add(row);
numbers.add(col);
}
crfParams.templates.put(tem[0], numbers.toArray(new Integer[0]));
}
else {// 特征模板: B
crfParams.templates.put(tem[0], new Integer[0]);
}
}
}
in.close();
}
}