[Football score] illustration football score #tutorials #MC #ROOT

football_score.C

//
//  football_score.C
////////////////////////////////////////////////////
//
//  Simple Monte Carlo
//
///////////////////////////////////////////////////
//  Created by @visionlib.postach.io
{
    const Int_t nteam = 4;
    //number of match (combination)
    Int_t nmatch = TMath::Factorial(nteam)/(TMath::Factorial(nteam-2)*TMath::Factorial(2));
    cout<<"Number of match "<<nmatch<<endl;//should be six if 4 teams per group
    Int_t nwin=0;//number win = number lost
    Int_t ndraw=0;
    //number of iterations
    const Int_t kIteration = 10000;
    //floating from 2 to 4 with 100 steps
    const Float_t winPointMin = 1.5;//or 3 for later change
    const Float_t winPointMax = 3.5;
    Float_t winPoint;
    const Int_t nstep = 100;
    //match 0: team1 - team2
    //match 1: team3 - team4
    //match 2: team1 - team3
    //match 3: team2 - team4
    //match 4: team1 - team4
    //match 5: team2 - team3
    Float_t ipoint1[nmatch];//point of match for 1st team
    Float_t ipoint2[nmatch];// point of match for 2nd team
    

    Float_t arrayPointTeam[4];//to store total point of four teams
    Int_t arraySortIndex[4];//for sorting
    
    Int_t numTeamEqualPoint;//number of team have equal point
    Int_t numberTieBreaker=0;//number of trial require tie breaker
    Float_t tieBreakerPercentage;
    TH2F* hwinpoint_vs_tiebreaker = new TH2F("hwinpoint_vs_tiebreaker","",100,winPointMin,winPointMax,100,20,40);
    gRandom->SetSeed();
    //loop over nstep (different winner point)
    for (Int_t istep = 0; istep<=nstep; istep++){
        winPoint = winPointMin+istep*(winPointMax-winPointMin)/float(nstep);
        numberTieBreaker = 0;
        //loop over iterations
        for (Int_t iIter = 0; iIter<kIteration; iIter++ ){
            //reset number of team has equal point
            //if (iIter%1000==0) printf("Processing %d/%d\n",iIter,kIteration);
            numTeamEqualPoint=0;
            //loop over nmatch to randomize result
            for (Int_t imatch = 0; imatch<nmatch; imatch++){
                int valueRandom = (int)(gRandom->Uniform(0.0,1.0)*3);
                
                if (valueRandom==0) {//win
                    ipoint1[imatch] = winPoint;
                    ipoint2[imatch] = 0;
                }
                else if (valueRandom==1) {//draw
                    ipoint1[imatch] = 1;
                    ipoint2[imatch] = 1;
                }
                else {//lose
                    ipoint1[imatch] = 0;
                    ipoint2[imatch] = winPoint;
                }
            }//end for imatch
            //calculate total point for each team
            //TODO: this mapping can be done in better way
            
            arrayPointTeam[0] = ipoint1[0]+ipoint1[2]+ipoint1[4];
            arrayPointTeam[1] = ipoint2[0]+ipoint1[3]+ipoint1[5];
            arrayPointTeam[2] = ipoint1[1]+ipoint2[2]+ipoint2[5];
            arrayPointTeam[3] = ipoint2[1]+ipoint2[3]+ipoint2[4];
            
            TMath::Sort(4,arrayPointTeam,arraySortIndex);
            
            //tie breaker
            //happen when the 2nd and 3rd team have same point
            if (arrayPointTeam[arraySortIndex[1]] == arrayPointTeam[arraySortIndex[2]]){
                ++numTeamEqualPoint;
            }
            //count number of trial with tie-breaker requirement
            if (numTeamEqualPoint>0) ++numberTieBreaker;
            
        }//end for iIter
        //printf("%d times per %d require tie breaker, i.e %.3g percentage\n",numberTieBreaker,kIteration,numberTieBreaker*100/kIteration);
        tieBreakerPercentage = numberTieBreaker*100/float(kIteration);
        hwinpoint_vs_tiebreaker->Fill(winPoint,tieBreakerPercentage);
        cout<<" win/draw "<<winPoint<<" tiebreak "<<tieBreakerPercentage<<endl;
    }//end for istep
    
    new TCanvas;
    gStyle->SetOptStat(0);
    gStyle->SetLineWidth(2);
    hwinpoint_vs_tiebreaker->GetXaxis()->SetTitle("Winner point / Draw point");
    hwinpoint_vs_tiebreaker->GetYaxis()->SetTitle("Percentage of Tie Breaker");
    hwinpoint_vs_tiebreaker->GetYaxis()->CenterTitle();
    hwinpoint_vs_tiebreaker->GetXaxis()->CenterTitle();
    hwinpoint_vs_tiebreaker->GetXaxis()->SetLabelSize(hwinpoint_vs_tiebreaker->GetXaxis()->GetTitleSize()*1.2);
    hwinpoint_vs_tiebreaker->GetYaxis()->SetLabelSize(hwinpoint_vs_tiebreaker->GetYaxis()->GetTitleSize()*1.2);
    hwinpoint_vs_tiebreaker->GetXaxis()->SetTitleSize(hwinpoint_vs_tiebreaker->GetXaxis()->GetLabelSize()*1.2);
    hwinpoint_vs_tiebreaker->GetYaxis()->SetTitleSize(hwinpoint_vs_tiebreaker->GetYaxis()->GetLabelSize()*1.2);
    hwinpoint_vs_tiebreaker->GetYaxis()->SetTitleOffset(0.9);
    hwinpoint_vs_tiebreaker->GetXaxis()->SetTitleOffset(0.9);
    
    hwinpoint_vs_tiebreaker->SetMarkerStyle(8);
    hwinpoint_vs_tiebreaker->SetMarkerSize(1.2);
    Int_t ci;
     ci = TColor::GetColor("#B45F04");
    hwinpoint_vs_tiebreaker->SetMarkerColor(ci);
    hwinpoint_vs_tiebreaker->Draw();
    gPad->Print("football_score.png");

}