advanced lab code

#include <iostream>
#include <fstream>
#include <filesystem>
#include <string>
#include <strstream>
#include <vector>

using namespace std;
namespace fs = std::experimental::filesystem;

void calcReg(vector<double>&, vector<double>&, double &, double&);

int main(int argc, char** argv) {


    //return 0;

    vector<double> I;
    vector<double> V;

    vector<double> x;
    vector<double> y;

    string path = ".";
    string avg = " averged.csv";

    ifstream in;
    ofstream out;
    double iTemp = 0, vTemp = 0, iTempOld = 0, vTempOld = 0, dTemp=0;
    bool first = true;
    int i = 0, j = 0;

    int n = 0;

    double a = 0, b = 0;

    int tail = 2000;

    int numToAvg = 12;
    int shift = numToAvg;

    std::cout << "How many do I average?  >>";
    std::cin >> numToAvg;

    std::cout << "How much to shift the average? >>";
    std::cin >> shift;

    double threshold = .15;
    for (auto & p : fs::directory_iterator(path)) {


        if (fs::is_directory(p))
            continue;
        if (fs::path(p).extension() != ".csv")
            continue;
        first = false;
        in.open(p.path(), ios::in);
        std::cout << in.is_open() << "\t\tbegin reading data from " << p.path() << std::endl;
        out.open(path + "\\ average\\" + p.path().filename().string(), ios::out | ios::trunc);
        std::cout << out.is_open() << "\t\tout file dir " << path + "average\\" + p.path().filename().string() << std::endl;
        while (!in.eof()) {
            in >> iTemp; in.get();
            in >> vTemp; in.get();
            if (vTemp > 0) {
                I.push_back(iTemp);
                V.push_back(vTemp);
            }
        }
        /*
        //Calcualte lin reg of the tail end, then decide what the turning point is
        n = V.size();
        for (i = 0; i < n; i++) {
            if (V[i] > 1.2) {
                x.push_back(V[i]);
                y.push_back(I[i]);
            }
        }
        calcReg(x, y, a, b);

        for (int i = 0; i < n; i++) {
            vTempOld = a + b*V[i];
            vTemp = I[i] - vTempOld;

            iTemp = vTemp/vTempOld;
            out << I[i] << "," << V[i] << ", ," <<vTemp<< ","<< iTemp*100<<"," << vTempOld << endl;
        }
        */
        //-------------------------------------------------------------

        //Do some averaging to use with GNUPlot for final figures.
        for (i = 0; i < I.size() && j < I.size()-i; i+=shift) {
            iTemp = vTemp = 0;
            for (j = 0; j < numToAvg && j < I.size()-i; j += 1) {
                iTemp += I[i+j];
                vTemp += V[i+j];
                //std::cout<<i+j<<"\t" << I[i+j] << "\t" << V[i+j] << std::endl
            }
            if(i==0)
                out << vTemp / numToAvg << "," << iTemp / numToAvg << ","<< 0 << std::endl;
            else {
                dTemp = (iTempOld - iTemp) / (vTempOld - vTemp);
                if (abs(dTemp) > 1)
                    dTemp = 0;
                out << vTemp / numToAvg << "," << iTemp / numToAvg << "," << dTemp << std::endl;
            }
            vTempOld = vTemp;
            iTempOld = iTemp;
        }//*/
        I.clear();
        V.clear();
        in.close();
        out.close();
    }




    return 0;
}


void calcReg(vector<double>& x, vector<double>& y, double & a, double& b) {

    int n = x.size();

    double xi = 0, xi2 = 0, yi = 0, xiyi = 0;
    for (int i = 0; i < n; i++) {
        xi += x[i];
        xi2 += x[i] * x[i];
        yi += y[i];
        xiyi += x[i] * y[i];
    }

    double det = (n*xi2 - xi*xi);

    a = yi*xi2 - xi*xiyi;
    b = n*xiyi - xi*yi;

    a = a / det;
    b = b / det;

}