统计单词出现频率及排序从单机到多机合作

来源：互联网发布：淘宝品质退款率编辑：程序博客网时间：2024/06/06 01:07

本文是学习多线程服务端编程的练习

书籍作者陈硕的博客也有提到这个题目

http://blog.csdn.net/solstice/article/details/8497475

第一个层次很简单单机一个小文件读进来进行处理然后对每个单词进行统计排序记录每个单词出现频率

#include <algorithm>#include <iostream>#include <unordered_map>#include <vector>#include <sstream>#include <fstream> using namespace std; std::unordered_map<std::string, int> mapStringFrequent;  void SplitStrig(std::string& line, std::vector<std::string>& vecString) {    typedef std::string::size_type strSize;    strSize i = 0;    while (i != line.size()) {        while (i != line.size() && isspace(line[i]))            ++i;        strSize j = i;        while (j != line.size() && !isspace(line[j]))            ++j;        if (i != j) {            vecString.push_back(line.substr(i, j - i));            i = j;        }    }} bool CheckWord(std::string s) {    typedef std::string::size_type strSize;    strSize i = 0;    while (i != s.size()) {        if (isalpha(s[i])) {            i++;        }        else {            return false;        }    }    return true;}   void VecInputMap(std::vector<std::string>& vecString, std::unordered_map<std::string, int>& mapStringFrequent) {    for (auto it : vecString) {        if (CheckWord(it)) {            transform(it.begin(), it.end(), it.begin(), ::tolower);            mapStringFrequent[it]++;        }    }}  bool ReadFile(const string& fileName) {    bool ret = false;    std::ifstream in(fileName);    if (in.bad() || !in) {        return ret;    }    std::string line;    std::vector<std::string> vecString;    try {        while (getline(in, line))        {            //std::cout << line <<  std::endl;            SplitStrig(line, vecString);        }         VecInputMap(vecString, mapStringFrequent);    }    catch (std::exception& e) {        std::cout << line << std::endl;        in.close();        std::cerr << e.what() << std::endl;        return ret;    }     in.close();    ret = true;    return ret;}  void WriteToFile(const string& fileName, std::vector<std::pair<int, std::string>>& vecWordFreq) {    std::ofstream out(fileName);    if (out.bad() || !out) {        return;    }     for (auto& it : vecWordFreq) {        out << it.second << '\t' << it.first << std::endl;    }    out.close(); }//============================================================ int main(){    bool ret = ReadFile("1.txt");    if (!ret)        return -1;     //ret = ReadFile("2.txt");    //if (!ret)    //  return -1;    //ret = ReadFile("3.txt");    //if (!ret)    //  return -1;    //ret = ReadFile("4.txt");    //if (!ret)    //  return -1;     //ret = ReadFile("5.txt");    //if (!ret)    //  return -1;     //ret = ReadFile("6.txt");    //if (!ret)    //  return -1;     //ret = ReadFile("7.txt");    //if (!ret)    //  return -1;     //ret = ReadFile("8.txt");    //if (!ret)    //  return -1;     //ret = ReadFile("9.txt");    //if (!ret)    //  return -1;     //ret = ReadFile("10.txt");    //if (!ret)    //  return -1;     std::vector<std::pair<int, std::string>> freq;    freq.reserve(mapStringFrequent.size());     for (auto& it : mapStringFrequent){        freq.push_back(make_pair(it.second, it.first));    }     std::sort(freq.begin(), freq.end(), [](const std::pair<int, std::string>& lhs,  // const auto& lhs in C++14            const std::pair<int, std::string>& rhs) {        return lhs.first > rhs.first;    });     //for (auto it : freq) {    //  std::cout << it.first << '\t' << it.second << '\n';    //}     WriteToFile("freqResult.txt", freq);    return 0;}

第二个层次就是文件较大单词量较多如果一次性读入并使用vector容器存放以及使用hash容器进行统计频率会出现内存等资源不足现象

那么就依次读取进内存将解析的单词存放进vector中，当vector中的容量到达一个阈值将vector中的单词放进map容器中统计单词出现频率 vector容器清空

但是map容器有多个各个单词存放进那个map容器根据hash函数决定

当map容器的容量达到阈值后写入文件 map容器清空

这样我们就得到多个记录单词出现频率的文本供后继步骤分析合并但是一个单词的出现频率肯定只出现在一个记录文本中(因为相同的单词具有相同的hash值对应同一个记录文本)

如图

代码如下(记录合并代码后继完成)

#include <algorithm>#include <iostream>#include <unordered_map>#include <vector>#include <sstream>#include <fstream> using namespace std; #define BUCKET_NUM  10std::unordered_map<std::string, int> mapStringFrequent[BUCKET_NUM];std::ofstream out[BUCKET_NUM];  #define MAX_WORD_SIZE   1024*1024  void SplitStrig(std::string& line, std::vector<std::string>& vecString) {    typedef std::string::size_type strSize;    strSize i = 0;    while (i != line.size()) {        while (i != line.size() && isspace(line[i]))            ++i;        strSize j = i;        while (j != line.size() && !isspace(line[j]))            ++j;        if (i != j) {            vecString.push_back(line.substr(i, j - i));            i = j;        }    }} bool CheckWord(std::string s) {    typedef std::string::size_type strSize;    strSize i = 0;    while (i != s.size()) {        if (isalpha(s[i])) {            i++;        }        else {            return false;        }    }    return true;} void VecInputMap(std::vector<std::string>& vecString, std::unordered_map<std::string, int> mapStringFrequent[]) {    for (auto it : vecString) {        if (CheckWord(it)) {            transform(it.begin(), it.end(), it.begin(), ::tolower);            int idx = std::hash<string>()(it) % BUCKET_NUM;            mapStringFrequent[idx][it]++;            if (mapStringFrequent[idx].size() >= MAX_WORD_SIZE) {                for (auto& it : mapStringFrequent[idx]) {                    out[idx] << it.second << '\t' << it.first << std::endl;                }                mapStringFrequent[idx].clear();            }        }    }} bool ReadFile(const string& fileName) {    bool ret = false;    std::ifstream in(fileName);    if (in.bad() || !in) {        return ret;    }    std::string line;    std::vector<std::string> vecString;     try {        while (getline(in, line))        {            SplitStrig(line, vecString);            //std::cout << line << std::endl;            if (vecString.size() >= MAX_WORD_SIZE) {                //std::cout << "too many words" << std::endl;                VecInputMap(vecString, mapStringFrequent);                vecString.clear();            }        }         for (int i = 0; i < BUCKET_NUM; i++) {            for (auto& it : mapStringFrequent[i]) {                out[i] << it.second << '\t' << it.first << std::endl;            }            mapStringFrequent[i].clear();        }     }    catch (std::exception& e) {        in.close();        std::cerr << e.what() << std::endl;        return ret;    }     std::cout << vecString.size() << std::endl;    ret = true;    return ret;} int main(){    std::string fileName = "0bucket.txt";    for (int i = 0; i < BUCKET_NUM; i++) {        out[i].close();        out[i].open(fileName);        fileName[0]++;    }     ReadFile("LargeFile.txt");          return 0;}

运行效果如图

运行前

运行后

合并步骤如图:

合并代码如下

// WordFrequentMerge.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include <algorithm>#include <iostream>#include <unordered_map>#include <deque>#include <vector>#include <sstream>#include <fstream>using namespace std;#define DEFAULT_FILE_NAME"0bucket.txt"#define BUCKET_NUM10std::ifstream in[BUCKET_NUM];std::deque<std::pair<int, std::string>> deqFreqRecord[BUCKET_NUM];void OpenFile() {std::string fileName = "0bucket.txt";for (int i = 0; i < BUCKET_NUM; i++) {in[i].close();in[i].open(fileName);if (in[i].bad() || !in[i]) {std::cerr << "open file error.exit!!" << std::endl;return;}fileName[0]++;}}void ReadSortEle_(std::ifstream& in, std::deque<std::pair<int, std::string>>& d) {std::string line,word;int freq;try {while (getline(in, line)) {std::string::size_type pos = line.find('\t');if (pos != std::string::npos) {freq = std::stoi(line.substr(0, pos));word = line.substr(pos + 1);//std::cout << word << "\t" << freq << std::endl;d.push_back(std::make_pair(freq, word));}}}catch (std::exception& e) {std::cout << e.what() << std::endl;return;}std::sort(d.begin(),d.end(), [](const std::pair<int, std::string>& lhs,  const std::pair<int, std::string>& rhs) {return lhs.first > rhs.first;});}void ReadSortEle(std::ifstream in[], std::deque<std::pair<int, std::string>> d[]) {for (int i = 0; i < BUCKET_NUM; i++) {ReadSortEle_(in[i],d[i]);}}bool HeapCompareFunc(std::pair<int, std::string>& l,std::pair<int, std::string>& r) {return l.first < r.first;}void MergeFrequent(std::deque<std::pair<int, std::string>> d[]) {vector<std::pair<int, std::string>> vecHeap;for (int i = 0; i < BUCKET_NUM; i++) {if (!d[i].empty()) {vecHeap.push_back(d[i].front());d[i].pop_front();}}std::make_heap(vecHeap.begin(), vecHeap.end(), HeapCompareFunc);while (!vecHeap.empty()) {std::pop_heap(vecHeap.begin(), vecHeap.end(), HeapCompareFunc);std::pair<int, std::string> p = vecHeap.back();vecHeap.pop_back();std::cout << p.second << "\t" << p.first << std::endl;int idx = std::hash<string>()(p.second) % BUCKET_NUM;if (!d[idx].empty()) {vecHeap.push_back(d[idx].front());std::push_heap(vecHeap.begin(), vecHeap.end(), HeapCompareFunc);d[idx].pop_front();}}}int main(){OpenFile();ReadSortEle(in, deqFreqRecord);MergeFrequent(deqFreqRecord);    return 0;}

代码还有诸多待优化地方

比如读入单词后另开线程处理而不是等待处理完毕后再读取单词

比如数据的传递考虑传递指针和起始位置而不是传递拷贝

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统计单词出现频率及排序 从单机到多机合作

统计单词出现频率及排序从单机到多机合作