c++读写csv

由于人脸测试需要，我计划通过csv文件来保存人脸的特征向量

每一个人脸的特征向量有128维，测试存放5000个，所以csv是5000*128的浮点数

先随机生成数据，每一维都落在（-1.0，1.0）之间

#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <algorithm>
#include <random>
using namespace std;

int main(){
    std::random_device rd; //obtain a seed
    std::mt19937 gen(rd()); //mersenne_twister_engine 
    std::uniform_real_distribution<> dist(-1.0, 1.0);
    
    ofstream outFile;
    outFile.open("test5000.csv", ios::out); 
    // 5000*128
    for(int i=1;i<=5000;i++){
        for(int j=1;j<=127;j++){
            outFile << dist(gen) << ',';
        }
        outFile <<dist(gen) <<endl;
    }
    outFile.close();
}    

读取数据到二维向量a:

#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include<algorithm>
using namespace std;
 
vector<vector<float> >a;  //二维数组存储读入变量
vector<float>b;
 
inline void file_to_string(vector<string> &record, const string& line, char delimiter);
inline float string_to_float(string str);
 
void read()
{
    vector<string> row;
    string line;
    string filename;
    ifstream in("test5000.csv");  
    if (in.fail())  { cout << "File not found" <<endl; return ; } 
    while(getline(in, line)  && in.good() )
    {
        file_to_string(row, line, ',');  //把line里的单元格数字字符提取出来，“,”为单元格分隔符
        for(int i=0, leng=row.size(); i<leng; i++){
            b.push_back(string_to_float(row[i]));
        }
        a.push_back(b);
        b.clear();
    }
    in.close();
    return ;
}
 
inline void file_to_string(vector<string> &record, const string& line, char delimiter)
{
    int linepos=0;
    char c;
    int linemax=line.length();
    string curstring;
    record.clear();
    while(linepos<linemax)
    {
        c = line[linepos];
        if(isdigit(c)||c=='.'){
            curstring+=c;
        }
        else if(c==delimiter&&curstring.size()){
            record.push_back(curstring);
            curstring="";
        }
        ++linepos;
    }
    if(curstring.size())
        record.push_back(curstring);
    return;
}
 
inline float string_to_float(string str){
    int i=0,len=str.length();
    float sum=0;
    while(i<len){
        if(str[i]=='.') break;
        sum=sum*10+str[i]-'0';
        ++i;
    }
    ++i;
    float t=1,d=1;
    while(i<len){
        d*=0.1;
        t=str[i]-'0';
        sum+=t*d;
        ++i;
    }
    return sum;
}

int main(){
    read();
    printf("total numbers of people: %d\n",a.size());
    cout<<"top 5dims of person 1:"<<endl;
    for(int i=0;i<=4;i++)
        cout<<a[0][i]<<" ";
    return 0;
}