Data exploration

#include <iostream>
#include <string>
#include <vector>
#include <fstream>
#include <algorithm>
#include <iterator>
#include <cmath>

using namespace std;

// TODO: Convert double vectors to taking in (explicitly) any numeric value
// Reference: - Iterators: https://www.geeksforgeeks.org/iterators-c-stl/
//            - What get's passed into sort: https://cplusplus.com/reference/iterator/RandomAccessIterator/

class Explore
{
public:
    // Calculate the sum of the vector
    double sum_vector(vector<double> vect)
    {
        double sum = 0;
        for (int i = 0; i < vect.size(); i++)
        {
            sum += vect[i];
        }
        return sum;
    }

    // Calculate the mean of a vector
    double mean_vector(vector<double> vect)
    {
        double mean = sum_vector(vect) / vect.size();
        return mean;
    }

    // Calculate the median of a vector
    double median_vector(vector<double> vect)
    {
        double median;
        // Use an iterator because it is probably better -internet
        vector<double>::iterator it;
        // Find the center if it is even or odd
        sort(vect.begin(), vect.end());
        if (vect.size() % 2 == 0) // If there is an even number of elements
        {
            it = vect.begin() + vect.size() / 2 - 1;
            median = (*it + *(it + 1)) / 2;
        }
        else // if there is an odd number of elements
        {
            it = vect.begin() + vect.size() / 2;
            median = *it;
        }
        return median;
    }

    // Calculate the range of a vector
    vector<double> range_vector(vector<double> vect)
    {
        vector<double> range = {max_vector(vect), min_vector(vect)};
        return range;
    }

    // Calculate the max of a vector (Just for range)
    double max_vector(vector<double> vect)
    {
        double max;
        vector<double>::iterator it;
        sort(vect.begin(), vect.end());
        it = vect.end() - 1;
        max = *it;
        return max;
    }

    // Calculate the min of a vector (Just for range) just with a loop
    double min_vector(vector<double> vect)
    {
        double min;
        vector<double>::iterator it;
        sort(vect.begin(), vect.end());
        it = vect.begin();
        min = *it;
        return min;
    }

    // Calculate the covariance of two vectors
    // Cov(x,y) = E((x-x_mean)(y-y_mean)))/n-1
    double covar_vector(vector<double> x, vector<double> y)
    {
        double sum = 0;
        double mean_x = mean_vector(x);
        double mean_y = mean_vector(y);
        for (int i = 0; i < x.size(); i++)
        {
            float x_i_diff = x[i] - mean_x;
            float y_i_diff = y[i] - mean_y;
            float y_times_x_diff = x_i_diff * y_i_diff;
            // cout << x_i_diff << " * " << y_i_diff << " = " << y_times_x_diff << endl;
            sum = sum + y_times_x_diff;
        }
        return sum / (x.size() - 1);
    }

    // Calculate the correlation of two vectors
    // Cor(x,y) = Cov(x,y)/(standard_devation(x)*standard_devation(y))
    // Using the hint from the assignment:
    // "sigma of a vector can be calculated as the square root of variance(v,v)"
    double cor_vector(vector<double> x, vector<double> y)
    {
        double covar = covar_vector(x, y);
        double sigma_x = sqrt(covar_vector(x, x));
        double sigma_y = sqrt(covar_vector(y, y));
        return covar / (sigma_x * sigma_y);
    }

    // Run suite of statistcal functions on a vector
    void print_stats(vector<double> vect)
    {
        cout << "Sum:    " << sum_vector(vect) << endl;
        cout << "Mean:   " << mean_vector(vect) << endl;
        cout << "Median: " << median_vector(vect) << endl;
        vector<double> range = range_vector(vect);
        cout << "Range:  " << range[1] << ", " << range[0] << endl;
    }
};

int main(int argc, char **argv)
{
    ifstream inFS;
    string line;
    string rm_in, medv_in;
    const int MAX_LEN = 1000;
    vector<double> rm(MAX_LEN), medv(MAX_LEN);

    cout << "Opening file Boston.csv." << endl;

    inFS.open("Boston.csv");
    if (!inFS.is_open())
    {
        cout << "Error opening file Boston.csv." << endl;
        return 1;
    }

    cout << "Reading line 1 of Boston.csv." << endl;
    getline(inFS, line);

    // echo heading
    cout << "Headings: " << line << endl;

    // read data
    int numObservations = 0;
    while (inFS.good())
    {
        getline(inFS, rm_in, ',');
        getline(inFS, medv_in, '\n');
        rm.at(numObservations) = stof(rm_in);
        medv.at(numObservations) = stof(medv_in);

        numObservations++;
    }

    rm.resize(numObservations);
    medv.resize(numObservations);

    cout << "New Length: " << rm.size() << endl;

    cout << "Closing file Boston.csv." << endl;
    inFS.close(); // Done

    cout << "Number of records: " << numObservations << endl;

    // Create an Explore object to use stats functions
    Explore explore;

    cout << "\nStats for rm" << endl;
    explore.print_stats(rm);

    cout << "\nStats for medv" << endl;
    explore.print_stats(medv);

    cout << "\n Covariance = " << explore.covar_vector(rm, medv) << endl;

    cout << "\n Correlation = " << explore.cor_vector(rm, medv) << endl;

    cout << "\nProgram terminated." << endl;
}

Opening file Boston.csv.
Reading line 1 of Boston.csv.
Headings: rm,medv
New Length: 506
Closing file Boston.csv.
Number of records: 506

Stats for rm
Sum:    3180.03
Mean:   6.28463
Median: 6.2085
Range:  3.561, 8.78

Stats for medv
Sum:    11401.6
Mean:   22.5328
Median: 21.2
Range:  5, 50

 Covariance = 4.49345

 Correlation = 0.69536

Program terminated.