#include <iostream>
#include "TCanvas.h"
#include "TProfile.h"
#include "TROOT.h"
#include "TGraph.h"
#include "TH2.h"
#include "TGraphErrors.h"
#include "TStyle.h"
#include "TColor.h"
#include "TRandom3.h"


void rando()
{

    gStyle->SetPalette(53); 
    gStyle->SetErrorX(0.0001);
    gStyle->SetOptStat(0); 
    

    
    const int nbin = 30, n_entr = 1000;
    
    double xmin = -5., xmax = 5., y1 = 0., y2 =10., x[n_entr], y[n_entr], sum, sumSqr, xval, yval; // for filling TH2F and TPtofile
    int counts;
    double vx[nbin], vy[nbin], sigma2Y[nbin], errX[nbin], errY[nbin]; //necessary for my own averaging code for TGraphErrors 
    
    TRandom3 r;

    
    TH2F *hist = new TH2F("hist", "2D Hist", nbin, xmin, xmax, nbin, y1, y2); //2D hist
    TProfile *prof = new TProfile("prof", "Prof", nbin, xmin, xmax, y1, y2); //Profile
    TCanvas  *canv = new TCanvas("canv", "Hist and Prof", 0, 0, 1000, 500);   
    canv->Divide(3,1);
    

    double dx = (xmax - xmin)/n_entr; // step size
    double bin_width = (xmax-xmin)/nbin; // bin width needed for the last part (TGraphErrors) 

    for(int i = 0; i <= n_entr; ++i) // loop filling TH2F and TProfile
    {
        
        x[i] = xmin + i*dx + dx/2; //arrays were not necessary but I needed them for another purpose
        y[i] = 10-r.Exp(4);

        hist->Fill(x[i], y[i]); 
        prof->Fill(x[i], y[i]); 
    
    }


    // drawing TH2F------------------------------------------
    canv->cd(1);
    hist->SetTitle("TH2F");
    hist->Draw("ALP");
    hist->Draw("C");
    canv->Modified();
    canv->Update();

    //drawing TProfile---------------------------------------
    //Fails to connect poibts by smooth curve or even just "L"
    canv->cd(2);
    prof->SetTitle("TProfile");
    prof->Draw("e1");
    //prof->Draw("C");
    prof->Draw("L");
    prof->SetMarkerSize(0.5);
    prof->SetMarkerStyle(8);
    prof->SetLineStyle(1);
    prof->SetLineWidth(1);
    canv->Modified();
    canv->Update();


    
//THIS  PART  IS NECESSARY TO FILL A TGRAPHERROR TO SHOW THAT IN THIS CASE A
//SMOOTH CURVE OR ANY LINE WORKS JUST FINE
//my averaging code--------------------------------------------

            for(int j = 0; j < nbin; ++j)
            {
                
                counts = 0;
                sum = 0; //the y average
                sumSqr =0; //mean square for error calc
                
                errX[j] = 0; //setting X error to 0

                vx[j] = xmin + j*bin_width + bin_width/2.; //vx is my x variable now               
                xval = x[j];

                while ( xval < xmin + (j+1)*bin_width ) //looping inside each bin
                {
                    sum += y[counts+j];   // summing for mean 
                    sumSqr += pow(y[j+counts], 2); //summing for mean squared
                    
                    counts++;
                    xval = x[j+counts];

                }
                
                
                vy[j] = sum/counts;   // average of each bin
                sigma2Y[j] = (sumSqr/counts-pow(vy[j],2)); //stand. dev.
                errY[j] = sqrt(sigma2Y[j]/counts); //stand. err.
                
            }
    
            //feeding vx and vy to TGraphErrors and
            //drawing-----------------------------------------------------
            TGraphErrors *gr = new TGraphErrors(nbin, vx, vy, errX, errY);
            canv->cd(3);
            gr->SetTitle("TGraph");
            gr->Draw("AP");
            gr->Draw("C"); // notice in this case "C" works
            gr->SetMarkerSize(0.5);
            gr->SetMarkerStyle(8);
            gr->SetLineStyle(1);
            gr->SetLineWidth(1);
            canv->Modified();
            canv->Update();



}