从零开始的CPP（36）—

现有一个Excel A1.csv。

其表格第一列为：生物样本的名称；其他列为：生物样本的含量。表格第一行第一列是空格，第一行其他列为:受试者名称。

需求

如下：设计一个程序，可以指定受试者名称（某列），对该列所有生物样本含量进行排序，保留含量前X名的生物样本，其余生物样本含量合并，命名为others。

设计思路：

1.如何根据受试者名称（第一行），读取csv中指定某列数据？

vector<string> getRownames() {ifstream file("A1.csv");string line;string rowname;vector<string> rownames;getline(file, line);for (int i = 0; i < line.length();) {if (line[i] == ',') {rowname = line.substr(0, i);rownames.push_back(rowname);line = line.substr(i + 1, line.length());i = 0;}else i++;}for (auto i : rownames) {cout << i << " ";}return rownames;
}

通过这段代码，就可以得到一个储存每列名称的vector了。

int findRowname(vector<string> rownames,string aim) {for (int i = 0; i < rownames.size(); i++) {if (rownames[i] == aim) {return i;}}
}

通过这段代码，就可以得到目标受试者所在列了。

2.如何获得目标受试者所在列的数据及其对应样本名称？

vector<pair<string, double>> getNameAndData(int row) {vector<pair<string, double>> NameAndData;ifstream file("A1.csv");string line;string rowdata;double value;getline(file, line);while (getline(file, line)) {vector<string> rowdatas;for (int i = 0; i < line.length();) {if (line[i] == ',') {rowdata = line.substr(0, i);rowdatas.push_back(rowdata);line = line.substr(i + 1, line.length());i = 0;}else i++;}            value = stod(rowdatas[row]);NameAndData.push_back({ rowdatas[0], value });}for (auto i : NameAndData) {cout << i.first << " " << i.second << endl;}return NameAndData;
}

循环读取文件每一行，把每一行都存进vector，找到vector的0列（样本名）与row列（受试者所在列），将其pair，存入新vector。

这里有代码重复了，就是从line转换为vector的代码，可以将其封装。

void split(string line, vector<string>& linedatas) {string linedata;for (int i = 0; i < line.length();) {if (line[i] == ',') {linedata = line.substr(0, i);linedatas.push_back(linedata);line = line.substr(i + 1, line.length());i = 0;}else i++;}return;
}

需要时直接传入line和vector就可以啦。

3. 排序，并保留前X行，剩余行合并为others

复习了lambda表达式与sort函数结合的用法

vector<pair<string, double>> getNewNameAndData(vector<pair<string, double>> NameAndData,int reserve) {sort(NameAndData.begin(), NameAndData.end(), [](const auto& a, const auto& b) {return a.second > b.second;});vector<pair<string, double>> NewNameAndData(reserve + 1);for (int i = 0; i < reserve; i++) {NewNameAndData[i] = NameAndData[i];}double reservesum = 0;for (int i = reserve; i < NameAndData.size(); i++) {reservesum = reservesum + NameAndData[i].second;}NewNameAndData[reserve] = { "Others",reservesum };for (auto i : NewNameAndData) {cout << i.first << " " << i.second << endl;}return NewNameAndData;
}

4.将new vector写入新文件

void getNewCsv(vector<pair<string, double>> NewNameAndData,int row) {ofstream file("newA.csv");ifstream file1("A1.csv");string line;getline(file1, line);vector<string> data0;split(line, data0);file << data0[0] << "," << data0[row] << endl;for (int i = 0; i < NewNameAndData.size(); i++) {file << NewNameAndData[i].first << "," << NewNameAndData[i].second << endl;}return;
}

5.完整代码

#include <iostream>
#include <fstream>
#include <sstream>
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <vector>
#include <algorithm>
#include <cassert>
using namespace std;
class Solution {
public:vector<string> getRownames() {ifstream file("A1.csv");string line;string rowname;vector<string> rownames;getline(file, line);split(line, rownames);/*for (auto i : rownames) {cout << i << " ";}*/return rownames;}int findRowname(vector<string> rownames,string aim) {for (int i = 0; i < rownames.size(); i++) {if (rownames[i] == aim) {return i;}}return 0;}vector<pair<string, double>> getNameAndData(int row) {vector<pair<string, double>> NameAndData;ifstream file("A1.csv");string line;string rowdata;double value;getline(file, line);while (getline(file, line)) {vector<string> rowdatas;split(line, rowdatas);value = stod(rowdatas[row]);NameAndData.push_back({ rowdatas[0], value });}/*for (auto i : NameAndData) {cout << i.first << " " << i.second << endl;}*/return NameAndData;}vector<pair<string, double>> getNewNameAndData(vector<pair<string, double>> NameAndData,int reserve) {sort(NameAndData.begin(), NameAndData.end(), [](const auto& a, const auto& b) {return a.second > b.second;});vector<pair<string, double>> NewNameAndData(reserve + 1);for (int i = 0; i < reserve; i++) {NewNameAndData[i] = NameAndData[i];}double reservesum = 0;for (int i = reserve; i < NameAndData.size(); i++) {reservesum = reservesum + NameAndData[i].second;}NewNameAndData[reserve] = { "Others",reservesum };/*for (auto i : NewNameAndData) {cout << i.first << " " << i.second << endl;}*/return NewNameAndData;}void getNewCsv(vector<pair<string, double>> NewNameAndData,int row,string aim, int reverse) {stringstream ss;ss << reverse;string s1 = ss.str();string str = aim + "_"+s1+"_newA.csv";ofstream file(str);ifstream file1("A1.csv");string line;getline(file1, line);vector<string> data0;split(line, data0);file << data0[0] << "," << data0[row] << endl;for (int i = 0; i < NewNameAndData.size(); i++) {file << NewNameAndData[i].first << "," << NewNameAndData[i].second << endl;}cout << "文件已经保存在"<< str <<"中。";return;}private:void split(string line, vector<string>& linedatas) {string linedata;for (int i = 0; i < line.length();) {if (line[i] == ',') {linedata = line.substr(0, i);linedatas.push_back(linedata);line = line.substr(i + 1, line.length());i = 0;}else i++;}return;}
};int main()
{Solution solution;vector<string> rownames=solution.getRownames();// 用户输入目标名string aim;cout << "请输入目标名: ";cin >> aim;int row=solution.findRowname(rownames, aim);//cout << row;vector<pair<string, double>> NameAndData = solution.getNameAndData(row);// 用户输入保留行数int reverse;cout << "请输入保留行数: ";cin >> reverse;vector<pair<string, double>> NewNameAndData = solution.getNewNameAndData(NameAndData, reverse);solution.getNewCsv(NewNameAndData,row,aim,reverse);return 0;
}