C++读入"N,X,Y,Z"格式文本文件到Eigen3 Matrix

C++读入"N,X,Y,Z"格式文本文件到Eigen3 Matrix，以及相同格式输出方法

很多数据资料的格式类似这样：

1,-2085738.7757,5503702.8697,2892977.6829
2,-2071267.5135,5520926.7235,2883341.8135
3,-2079412.5535,5512450.8800,2879771.2119
4,-2093693.1744,5511218.2651,2869861.8947
5,-2113681.5062,5491864.0382,2896934.4852
6,-2100573.2849,5496675.0138,2894377.6030

其中数据按照N(点号），X，Y，Z（三维坐标）排序。
这里提供一种C++读入"N,X,Y,Z"格式文本文件到Eigen3 Matrix的方法，以及对应的同格式输出方法

`

#pragma once
#include <fstream>
#include <iostream>
#include <string>
#include <Eigen/Dense>
#include <vector>
#include <cmath>
#include <iomanip>

using namespace std;
using namespace Eigen;

// 字符串分割
void SplitString(const std::string& s, std::vector<std::string>& v, const std::string& c)
{
	std::string::size_type pos1, pos2;
	pos2 = s.find(c);
	pos1 = 0;
	while (std::string::npos != pos2)
	{
		v.push_back(s.substr(pos1, pos2 - pos1));

		pos1 = pos2 + c.size();
		pos2 = s.find(c, pos1);
	}
	if (pos1 != s.length())
		v.push_back(s.substr(pos1));
}
// 读入相应格式的xyz文件
void ReadXYZFile(string filepath, MatrixXd& origin_data)
{
	ifstream infile;
	infile.open(filepath);
	cout << "Reading XYZ File: " << filepath << endl;
	if (!infile.is_open())
	{
		cout << "File Cannot Open" << endl;
		exit(1);
	}

	int r = 0; // 逐行加载数据
	char buffer[100];
	while (!infile.eof())
	{
		// getline只能读成char*，
		// 而SplitString只能切割string,
		// 而atof又只能转化char*到double
		infile.getline(buffer, 100);
		// cout << buffer << endl;
		string line = buffer;
		if (line == "")
		{
			continue;
		}
		vector<string> vector_data;
		SplitString(line, vector_data, ",");
		for (int c = 0; c < origin_data.cols(); c++)
		{
			origin_data(r, c) = atof(vector_data[c].c_str());
		}
		r++;

	}
	return;


}
// 将矩阵按读入的相同格式保存至相应路径
void WriteXYZFile(string filepath, MatrixXd& trans_data)
{
	ofstream outfile;
	outfile.open(filepath, ios::out | ios::trunc);
	for (int r = 0; r < trans_data.rows(); r++)
	{
		for (int c = 0; c < trans_data.cols(); c++)
		{
			if (c < trans_data.cols() - 1)
			{
				outfile << trans_data(r, c) << ',';
			}
			if (c == trans_data.cols() - 1)
			{
				outfile << trans_data(r, c);
			}

		}
		outfile << endl;
	}
	cout << "Write XYZ File: " << filepath << endl;
	outfile.close();
	return;
}