一阶HMM词性标注
手头的语料库依然是msr_training.utf8和msr_test.utf8，它来自于自于SIGHAN Bakeoff 2005的 icwb2-data.rar
1.rmspace.cpp研究院的训练文档是已经分好词，但我们并不需要这个结果，我们要使用计算所有分词系统重新进行分词并进行词性标注，所以第一步要把训练文档中行内的空格去掉。
#include<iostream>
#include<fstream>
#include<sstream>
#include<string>
using namespace std;
int main(int argc,char *argv[]){
if(argc<3){
cerr<<"Usage:"<<argv[0]<<" inputfile outputfile"<<endl;
return 1;
}
ifstream ifs(argv[1]);
ofstream ofs(argv[2]);
if(!(ifs && ofs)){
cerr<<"open file failed."<<endl;
return 1;
}
string line,word,line_out;
while(getline(ifs,line)){
line_out.clear();
istringstream strstm(line);
while(strstm>>word)
line_out+=word;
ofs<<line_out<<endl;
}
ifs.close();
ofs.close();
return 0;
}
2.对第1步得到的输出文件还需要稍作修善，即把每行句首和句尾的双引号去掉。这个可以用vim来完成：1,$s/^“//g 1,$s/”$//g
3.wordseg.cpp对第2步得到的输出文件进行分词。g++ wordseg.cpp -o wordseg -I/home/orisun/master/ICTCLAS50_Linux_RHAS_32_C/API -lICTCLAS50运行命令时注意要把libICTCLAS50.so拷贝到当前目录下。
#include <string>
#include <iostream>
#define OS_LINUX
#include "ICTCLAS50.h"
using namespace std;
int main(int argc, char *argv[])
{
if (argc < 2) { //命令行中需要给定要处理的文件名
cout << "Usage:command filename" << endl;
return 1;
}
string filename = argv[1];
string outfile = filename + ".ws";
string initPath = "/home/orisun/master/ICTCLAS50_Linux_RHAS_32_C/API";
if (!ICTCLAS_Init(initPath.c_str())) {
cout << "Init fails" << endl;
return -1;
}
ICTCLAS_FileProcess(filename.c_str(), outfile.c_str(), CODE_TYPE_UTF8,1);
ICTCLAS_Exit();
return 0;
}
4.由于我们要做的是词性标注，所以先要对测试文档进行分词。仍然使用wordseg.cpp。
5.rmpos.cpp计算所的分词系统在分词的同时也做了词性标注（修改配置文件Configure.xml是不起作用的）,所以现在还得把测试文本中标注好的词性去掉。
#include<iostream>
#include<fstream>
#include<sstream>
#include<string>
using namespace std;
int main(int argc,char *argv[]){
if(argc<3){
cerr<<"Usage:"<<argv[0]<<" inputfile outputfile"<<endl;
return 1;
}
ifstream ifs(argv[1]);
ofstream ofs(argv[2]);
if(!(ifs && ofs)){
cerr<<"open file failed."<<endl;
return 1;
}
string line,word,line_out,chinese;
while(getline(ifs,line)){
line_out.clear();
istringstream strstm(line);
while(strstm>>word){
string::size_type pos=word.find("/");
chinese=word.substr(0,pos);
line_out+=chinese+" ";
}
ofs<<line_out<<endl;
}
ifs.close();
ofs.close();
return 0;
}
6.对训练文本（即第3步的输出）也实行rmpos.cpp。
7.createdict.cpp第5步和第6步生成了训练集和测试集中出现的所有词语和标点符号，现在要把它们都存入GDBM数据库。
#include<sys/stat.h>
#include<gdbm.h>
#include<iostream>
#include<string>
#include<fstream>
#include<sstream>
using namespace std;
int main(int argc,char *argv[]){
if(argc<2){
cerr<<"Usage: "<<argv[0]<<" inputfile";
return 1;
}
ifstream ifs(argv[1]);
if(!ifs){
cerr<<"open file failed."<<endl;
return 1;
}
GDBM_FILE dbm_ptr;
dbm_ptr = gdbm_open("dict_db",0,GDBM_WRCREAT,S_IRUSR | S_IWUSR,NULL);
char v='w';
datum key,value;
value.dptr=&v;
value.dsize=1;
string line,word;
while(getline(ifs,line)){
istringstream strstm(line);
while(strstm>>word){
char *chinese=const_cast<char*>(word.c_str());
key.dptr=chinese;
key.dsize=word.size();
//cout<<chinese<<"\t"<<word.size()<<endl;
gdbm_store(dbm_ptr,key,value,GDBM_REPLACE);
}
}
ifs.close();
gdbm_close(dbm_ptr);
return 0;
}
8.indexword.cpp对数据库中所有的词语（包含标点）进行序号的标记。
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<sys/stat.h>
#include<gdbm.h>
#include<ctype.h>
#define DB_FILE_BLOCK "dict_db"
int main(int argc,char* argv[]){
GDBM_FILE dbm_ptr;
dbm_ptr = gdbm_open(DB_FILE_BLOCK,0,GDBM_WRCREAT,S_IRUSR | S_IWUSR,NULL);
datum key,data;
long index=0; //从0开始编号
char index_str[10]={0};
for(key=gdbm_firstkey(dbm_ptr);key.dptr;key=gdbm_nextkey(dbm_ptr,key)){
data=gdbm_fetch(dbm_ptr,key);
bzero(index_str,sizeof(index_str));
sprintf(index_str,"%ld",index++);
data.dptr=index_str;
data.dsize=sizeof(index_str);
gdbm_store(dbm_ptr,key,data,GDBM_REPLACE);
}
gdbm_close(dbm_ptr);
return 0;
}
9.query.c和lookup.c（可选辅助）前者打印输出数据库中的所有数据，后者根据用户输出的key去GDBM中查询对应的value。
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<sys/stat.h>
#include<gdbm.h>
#include<ctype.h>
#define DB_FILE_BLOCK "dict_db"
int main(int argc,char* argv[]){
GDBM_FILE dbm_ptr;
dbm_ptr = gdbm_open(DB_FILE_BLOCK,0,GDBM_READER,S_IRUSR | S_IWUSR,NULL);
datum key,data;
for(key=gdbm_firstkey(dbm_ptr);key.dptr;key=gdbm_nextkey(dbm_ptr,key)){
data=gdbm_fetch(dbm_ptr,key);
printf("%s--%s\t",key.dptr,data.dptr);
}
printf("\n");
gdbm_close(dbm_ptr);
return 0;
}
#include<sys/stat.h>
#include<gdbm.h>
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int main(int argc,char *argv[]){
char *word=(char*)malloc(50);
GDBM_FILE dbm_ptr;
dbm_ptr=gdbm_open("dict_db",0,GDBM_WRCREAT,S_IRUSR | S_IWUSR,NULL);
datum key,value;
while(1){
printf("please input a word.\n");
bzero(word,50);
scanf("%s",word);
if(strcmp(word,"exit")==0)
break;
key.dptr=word;
key.dsize=strlen(word);
value=gdbm_fetch(dbm_ptr,key);
if(value.dsize==0){
printf("%s not exist in dict.\n",word);
}
else{
printf("%s--%s\n",key.dptr,value.dptr);
}
}
gdbm_close(dbm_ptr);
return 0;
}
10.AMatrix.cpp统计训练文本（当然是第3步的输出）生成状态转移矩阵和初始状态概率矩阵，分别写入A.mat和PI.mat。
header.h头文件中主要包含ICTCLAS的词性标注集和Good-Turing平滑算法。
#ifndef _HEADER_H
#define _HEADER_H
#include<vector>
#include<list>
#include<map>
using namespace std;
const int POS_NUM=97; //计算所汉语词性标记集去掉标点符号共有POS_NUM个元素
/*POS_NUM种词性，即POS_NUM种状态*/
string posarr[POS_NUM]={"n","nr","nr1","nr2","nrj","nrf","ns","nsf","nt","nz",
"nl","ng","t","tg","s","f","v","vd","vn","vshi",
"vyou","vf","vx","vi","vl","vg","a","ad","an","ag",
"al","b","bl","z","r","rr","rz","rzt","rzs","rzv",
"ry","ryt","rys","ryv","Rg","m","mq","Mg","q","qv",
"qt","d","dl","dg","p","pba","pbei","c","cc","u",
"uzhe","ule","uguo","ude1","ude2","ude3","usuo","udeng","uyy","udh",
"uls","uzhi","ulian","e","y","o","h","k","x","xx",
"xu","w","wkz","wky","wyz","wyy","wj","ww","wd","wf",
"wn","wm","ws","wp","wb","wh","wt"};
void goodturing(const int count[],double prob[],int len){
map<int, list<int> > count_map; //map可以自动按key排好序
int N=0;
for(int i=0;i<len;++i){
int c=count[i];
N+=c;
map<int, list<int> >::const_iterator itr;
itr=count_map.find(c);
if(itr==count_map.end()){
list<int> l;
l.push_back(i);
count_map[c]=l;
}
else{
count_map[c].push_back(i);
}
}
map<int, list<int> >::const_iterator iter=count_map.begin();
while(iter!=count_map.end()){
double pr;
int r=iter->first;
int nr=iter->second.size();
if(++iter!=count_map.end()){
int r_new=iter->first;
if(r_new=r+1){
int nr_1=iter->second.size();
pr=(1.0+r)*nr_1/(N*nr);
}
else{
pr=1.0*r/N;
}
}
else{
pr=1.0*r/N;
}
list<int> l=(--iter)->second;
list<int>::const_iterator itr1=l.begin();
while(itr1!=l.end()){
int index=*itr1;
itr1++;
prob[index]=pr;
}
++iter;
}
//概率归一化
double sum=0;
for(int i=0;i<len;++i)
sum+=prob[i];
for(int i=0;i<len;++i)
prob[i]/=sum;
}
#endif
#include<iostream>
#include<string>
#include<fstream>
#include<sstream>
#include<vector>
#include<algorithm>
#include<iomanip>
#include<iterator>
#include<cassert>
#include"header.h"
int A[POS_NUM][POS_NUM]; //记录状态间转移的次数
int PI[POS_NUM]; //记录各种状态出现的次数
inline int indexof(string search){
for(int i=0;i<POS_NUM;++i){
if(search==posarr[i]){
return i;
}
}
return -1;
}
int main(int argc,char *argv[]){
if(argc<2){
cout<<"Usage:"<<argv[0]<<" pos_tagged_file"<<endl;
return 1;
}
//打开输入文件
ifstream ifs(argv[1]);
if(!ifs){
cerr<<"open file "<<argv[1]<<" failed."<<endl;
return 1;
}
string line,word;
while(getline(ifs,line)){
istringstream strstm(line);
string pre,post; //pre是前一个状态，post是后一个状态
strstm>>word;
string::size_type pos=word.find("/");
post=word.substr(pos+1);
int index1,index2;
index2=indexof(post);
if(index2<0){
cout<<post<<" not exist"<<endl;
return 1;
}
PI[index2]++;
while(strstm>>word){
pre=post;
pos=word.find("/");
post=word.substr(pos+1);
//cout<<"pre="<<pre<<"\tpost="<<post<<endl;
index1=indexof(pre);
//if(index1<0){
// cout<<pre<<" not exist"<<endl;
// return 1;
//}
index2=indexof(post);
//if(index2<0){
// cout<<post<<" not exist"<<endl;
// return 1;
//}
A[index1][index2]++;
PI[index2]++;
}
}
ifs.close();
ofstream ofs1("A.mat");
ofstream ofs2("PI.mat");
if(!(ofs1 && ofs2)){
cerr<<"create file failed."<<endl;
return 1;
}
ofs1<<setprecision(8);
ofs2<<setprecision(8);
double arr_out[POS_NUM]={0.0};
for(int i=0;i<POS_NUM;++i){
goodturing(A[i],arr_out,POS_NUM);
for(int j=0;j<POS_NUM;++j){
ofs1<<arr_out[j]<<"\t";
}
ofs1<<endl;
}
goodturing(PI,arr_out,POS_NUM);
for(int j=0;j<POS_NUM;++j){
ofs2<<arr_out[j]<<"\t";
}
ofs2<<endl;
ofs1.close();
ofs2.close();
return 0;
}
11.BMatrix.cpp统计训练文本（当然是第3步的输出）生成发射矩阵，写入B.mat。
#include<iostream>
#include<fstream>
#include<sstream>
#include<string>
#include<iomanip>
#include<cassert>
#include<cstdlib>
#include<gdbm.h>
#include<sys/stat.h>
#include"header.h"
const int TERM_NUM=70000;
int matrix[POS_NUM][TERM_NUM]={0.0}; //混淆矩阵（或称发射矩阵）
inline int indexof(string search){
for(int i=0;i<POS_NUM;++i){
if(search==posarr[i]){
return i;
}
}
return -1;
}
int main(int argc,char *argv[]){
if(argc<2){
cout<<"Usage: "<<argv[0]<<" pos_tagged_file"<<endl;
return 1;
}
ifstream ifs(argv[1]);
if(!ifs){
cerr<<"open file "<<argv[1]<<" failed."<<endl;
return 1;
}
GDBM_FILE dbm_ptr;
dbm_ptr=gdbm_open("dict_db",0,GDBM_READER,S_IRUSR|S_IWUSR,NULL);
datum key,value;
string line,word,term,pos;
string slash="/";
while(getline(ifs,line)){
istringstream strstm(line);
while(strstm>>word){
string::size_type loc=word.find(slash);
assert(loc!=string::npos);
term=word.substr(0,loc); //词语
pos=word.substr(loc+1); //词性
//cout<<term<<"\t"<<pos<<endl;
int rowindex=indexof(pos);
assert(rowindex>=0);
key.dsize=term.size();
key.dptr=const_cast<char*>(term.c_str());
value=gdbm_fetch(dbm_ptr,key);
int colindex=atoi(value.dptr);
//cout<<rowindex<<"\t"<<colindex<<endl;
matrix[rowindex][colindex]++;
}
}
ifs.close();
gdbm_close(dbm_ptr);
//将发射矩阵写入文件
ofstream ofs("B.mat");
if(!ofs){
cerr<<"create file B.mat failed."<<endl;
return 1;
}
ofs<<setprecision(8);
double arr_out[TERM_NUM]={0.0};
for(int i=0;i<POS_NUM;++i){
goodturing(matrix[i],arr_out,TERM_NUM);
for(int j=0;j<TERM_NUM;++j){
ofs<<arr_out[j]<<"\t";
}
ofs<<endl;
}
ofs.close();
return 0;
}
12.postag.cpp对测试文本（第5步的输出）进行词性标注。
#include<sys/stat.h>
#include<ctype.h>
#include<gdbm.h>
#include<iostream>
#include<sstream>
#include<fstream>
#include<string>
#include<cstring>
#include<cstdlib>
#include<stack>
#include<vector>
#include"header.h"
const string DB_FILE_BLOCK="dict_db";
const int TERM_NUM=70000;
const int TERM_MAXLEN=100;
GDBM_FILE dbm_ptr;
double PI[POS_NUM]; //初始状态概率矩阵
double A[POS_NUM][POS_NUM]; //状态转移矩阵
double B[POS_NUM][TERM_NUM]; //发射矩阵
/*从文件中读出HMM模型参数*/
void initHMM(string f1,string f2,string f3){
ifstream ifs1(f1.c_str());
ifstream ifs2(f2.c_str());
ifstream ifs3(f3.c_str());
if(!(ifs1 && ifs2 && ifs3)){
cerr<<"Open file failed!"<<endl;
exit(1);
}
//读取PI
string line;
if(getline(ifs1,line)){
istringstream strstm(line);
string word;
for(int i=0;i<POS_NUM;++i){
strstm>>word;
PI[i]=atof(word.c_str());
}
}else{
cerr<<"Read PI failed!"<<endl;
exit(1);
}
//读取A
for(int i=0;i<POS_NUM;++i){
getline(ifs2,line);
istringstream strstm(line);
string word;
for(int j=0;j<POS_NUM;++j){
strstm>>word;
A[i][j]=atof(word.c_str());
}
}
//读取B
for(int i=0;i<POS_NUM;++i){
getline(ifs3,line);
istringstream strstm(line);
string word;
for(int j=0;j<TERM_NUM;++j){
strstm>>word;
B[i][j]=atof(word.c_str());
}
}
ifs1.close();
ifs2.close();
ifs3.close();
}
/*Viterbi算法进行词性标注*/
void viterbi(vector<string> terms,string &result){
if(terms.size()==0)
return;
result.clear();
int row=terms.size(); //观察序列的长度
double **Q=new double*[row]; //初始化Q矩阵
for(int i=0;i<row;++i)
Q[i]=new double[POS_NUM]();
int **Path=new int*[row]; //初始化Path矩阵
for(int i=0;i<row;++i)
Path[i]=new int[POS_NUM]();
//给Q和Path矩阵的第1行赋值
datum key,data;
char chinese[TERM_MAXLEN]={0};
char *bp=const_cast<char*>(terms[0].c_str());
strncpy(chinese,bp,terms[0].size()); //读取句子中的第1个词
key.dptr=chinese;
key.dsize=terms[0].size();
data=gdbm_fetch(dbm_ptr,key); //从数据库中获取汉字对应的index，该index对应发射矩阵的列
int colindex=atoi(data.dptr);
for(int i=0;i<POS_NUM;++i){
Path[0][i]=-1;
Q[0][i]=PI[i]*B[i][colindex];
}
//给Q和Path矩阵的后续行赋值
for(int i=1;i<row;++i){
bp=const_cast<char*>(terms[i].c_str());
strncpy(chinese,bp,terms[i].size()); //读取句子中的下一个汉字
key.dptr=chinese;
key.dsize=terms[i].size();
data=gdbm_fetch(dbm_ptr,key);
colindex=atoi(data.dptr);
for(int j=0;j<POS_NUM;++j){
double max=-1.0;
int maxindex=-1;
for(int k=0;k<POS_NUM;++k){
double product=Q[i-1][k]*A[k][j];
if(product>max){
max=product;
maxindex=k;
}
}
Q[i][j]=max*B[j][colindex];
Path[i][j]=maxindex;
}
}
//找Q矩阵最后一行的最大值
double max=-1.0;
int maxindex=-1;
for(int i=0;i<POS_NUM;++i){
if(Q[row-1][i]>max){
max=Q[row-1][i];
maxindex=i;
}
}
//从maxindex出发，根据Path矩阵找出最可能的状态序列
stack<int> st;
st.push(maxindex);
for(int i=row-1;i>0;--i){
maxindex=Path[i][maxindex];
st.push(maxindex);
}
//释放二维数组
for(int i=0;i<row;++i){
delete []Q[i];
delete []Path[i];
}
delete []Q;
delete []Path;
//根据标记好的状态序列分词
int mark=-1;
for(int i=0;i<terms.size();++i){
mark=st.top();
st.pop();
result+=terms[i]+"/"+posarr[mark]+"\t";
}
}
int main(int argc,char *argv[]){
if(argc<3){
cout<<"Usage: "<<argv[0]<<" inputfile outputfile"<<endl;
return 1;
}
dbm_ptr = gdbm_open(DB_FILE_BLOCK.c_str(),0,GDBM_READER,S_IRUSR | S_IWUSR,NULL);
initHMM("PI.mat","A.mat","B.mat");
ifstream ifs(argv[1]);
ofstream ofs(argv[2]);
if(!(ifs&&ofs)){
cerr<<"Open file failed!"<<endl;
return 1;
}
string line;
//循环读取每一行
while(getline(ifs,line)){
istringstream strstm(line);
string term;
vector<string> term_vec;
string result;
while(strstm>>term){
term_vec.push_back(term);
}
viterbi(term_vec,result);
ofs<<result<<endl;
}
ifs.close();
ofs.close();
gdbm_close(dbm_ptr);
return 0;
}
看一下效果吧，左边是ICTCLAS的pos-tagging结果，作为标准答案，右边是我用一阶HMM词性标注的结果。
使用简单的加1平滑：
可以看到词性标注准确度还很低，并且"mq"贡献了大部分的错误率。
使用Good-Turing平滑后的效果，大体上已经看不出有什么错误：
本文来自博客园，作者：张朝阳，转载请注明原文链接：https://www.cnblogs.com/zhangchaoyang/articles/2567610.html
