#include <xtensor/xarray.hpp>
#include <xtensor/xio.hpp>
#include <xtensor/xview.hpp>
#include <cstdio>
#include <iostream>
#include <fstream>
#include <TH1F.h>
#include <TH1D.h>
#include <TH2F.h>
#include <TH2D.h>
#include <TROOT.h>
#include <TRandom.h>
#include <TTree.h>
#include <TFile.h>


void correlation(){
    //Open the file
    f = new TFile("insurance.root");
    t = (TTree*) f->Get("insurance");
 
    //Variable
    Int_t age, sex, children, smoker, north, east;
    Float_t bmi, charges;
 
    //Bind variables
    t->SetBranchAddress("age", &age);
    t->SetBranchAddress("sex", &sex);
    t->SetBranchAddress("children", &children);
    t->SetBranchAddress("smoker", &smoker);
    t->SetBranchAddress("north", &north);
    t->SetBranchAddress("east", &east);
    t->SetBranchAddress("age", &age);
    t->SetBranchAddress("bmi", &bmi);
    t->SetBranchAddress("charges", &charges);
 
    values = xt::xarray<float>::from_shape({8});
 
    mat = xt::xarray<float>::from_shape({(size_t)t->GetEntries(), 8});
 
    for (Int_t i = 0; i < t->GetEntries(); i++) {
        t->GetEntry(i);
 
        //Append variables to matrix
        values[0] = age;
        values[1] = sex;
        values[2] = children;
        values[3] = smoker;
        values[4] = north;
        values[5] = east;
        values[6] = bmi;
        values[7] = charges;
 
        xt::view(mat, i) = values;
         
    }
 
    //Calculate the corrilation
    cor = xt::eval(xt::zeros<float>({8,8}));
 
    float means[8];
    float stds[8];
    for(int i=0;i<8;i++)
        means[i] = xt::mean(xt::view(mat, xt::all(), i))[0];
    for(int i=0;i<8;i++)
        stds[i] = xt::stddev(xt::eval(xt::view(mat, xt::all(), i)))[0];
    for(int i=0;i<8;i++) {
        auto a = xt::view(mat, xt::all(), i);
        for(int j=0;j<8;j++) {
            auto b = xt::view(mat, xt::all(), j);
 
            xt::view(cor, i, j) = xt::mean((a-means[i])*(b-means[j]))
                /(stds[i]*stds[j]);
        }
    }
    cout << cor << endl;
}