trafficModeling.C

//
//  trafficModeling.C
////////////////////////////////////////////////////
//
//  Simple Monte Carlo for traffic modeling
//
///////////////////////////////////////////////////
//  Created by @visionlib.postach.io
void titleStyle(TH2* h1){
    h1->GetYaxis()->CenterTitle();
    h1->GetXaxis()->CenterTitle();
    h1->GetXaxis()->SetLabelSize(h1->GetXaxis()->GetTitleSize()*1.4);
    h1->GetYaxis()->SetLabelSize(h1->GetYaxis()->GetTitleSize()*1.4);
    h1->GetXaxis()->SetTitleSize(h1->GetXaxis()->GetLabelSize()*1.2);
    h1->GetYaxis()->SetTitleSize(h1->GetYaxis()->GetLabelSize()*1.2);
    h1->GetYaxis()->SetTitleOffset(0.9);
    h1->GetXaxis()->SetTitleOffset(0.9);
}
void trafficModeling(){
    const Int_t nVehicle = 100;
    const Int_t nSpace = 1000;
    const Int_t speedMax = 5;
    const Float_t probRandomSlow = 0.33;//1/3
    //initialize position and velocity
    Int_t pos_t0[nVehicle]={};
    Int_t vel_t0[nVehicle]={};
    Int_t disNext_t0[nVehicle]={};
    Int_t time_t0[nVehicle]={0};
    for (int ivehicle=0; ivehicle<nVehicle; ivehicle++) {
        pos_t0[ivehicle] = gRandom->Uniform(ivehicle*10,(ivehicle+1)*10);
        cout<<" postion "<<pos_t0[ivehicle]<<endl;
        vel_t0[ivehicle] = gRandom->Uniform(1,speedMax);
    }
    //reinitialize velocity to avoid collision
    for (int ivehicle=0; ivehicle<nVehicle; ivehicle++) {
        if (ivehicle<nVehicle-1) {
            disNext_t0[ivehicle] = (pos_t0[ivehicle+1] - pos_t0[ivehicle])%nSpace;
        }
        //circle condition
        else disNext_t0[ivehicle] = (pos_t0[0]+nSpace-pos_t0[ivehicle])%nSpace;
        //avoid collision at the beginning
        if (disNext_t0[ivehicle]<vel_t0[ivehicle]) {
            vel_t0[ivehicle] = disNext_t0[ivehicle]-1;
        }
        cout <<"vehical "<<ivehicle<<" pos "<<pos_t0[ivehicle]<<" dis "<<disNext_t0[ivehicle]<<" vel "<<vel_t0[ivehicle]<<endl;
    }//end for
    const Int_t kIteration =500;
    TH2F *hempty = new TH2F("hempty","hempty",nSpace,0,nSpace,kIteration,0,kIteration);
    hempty->GetXaxis()->SetTitle("Car position");
    hempty->GetYaxis()->SetTitle("Time evolution");
    titleStyle(hempty);
    TCanvas *c1 = new TCanvas("c1","c1",1250,1000);
    gStyle->SetOptStat(0);
    gStyle->SetLineWidth(2);
    hempty->SetTitle();
    hempty->Draw();
    TGraph *pgraph_t0 = new TGraph(nVehicle,pos_t0,time_t0);
    pgraph_t0->SetMarkerStyle(8);
    Int_t ci;
    //navy blue
    ci = TColor::GetColor("#0B3861");
    pgraph_t0->SetTitle("");
    pgraph_t0->SetMarkerColor(ci);
    pgraph_t0->SetMarkerSize(0.4);
    pgraph_t0->Draw("P");
    //time goes by
    Int_t time_i[nVehicle]={};
    TGraph *pgraph_i;
    for (Int_t i=1; i<kIteration;i++) {
        
        if (i%100==0) {
            cout<<"Processing  "<<i<<"/"<<kIteration<<endl;
        }
        //calculate speed
        for (int ivehicle=0; ivehicle<nVehicle; ivehicle++) {
             time_i[ivehicle]=i;
             //if velocity smaller than max, then increase by 1
             if (vel_t0[ivehicle]<speedMax) {
                 vel_t0[ivehicle] +=1;
             }
             //avoid collision
             if (vel_t0[ivehicle]>disNext_t0[ivehicle]) {
                 vel_t0[ivehicle] = disNext_t0[ivehicle]-1;
             }
             //reduce speed randomly
             double randomSpeedSlow = gRandom->Uniform(0.0,1.0);
             if (randomSpeedSlow<0.33) {
                 vel_t0[ivehicle] -=1;
             }
             //newlocation
             pos_t0[ivehicle] = (pos_t0[ivehicle]+vel_t0[ivehicle])%nSpace;
        }//end for ivehicle
        
        //recalculate distance, NOT so good way
        for (int ivehicle=0; ivehicle<nVehicle; ivehicle++) {
            if (ivehicle < (nVehicle-1)) {
                disNext_t0[ivehicle] = (pos_t0[ivehicle+1]+nSpace - pos_t0[ivehicle])%nSpace;
            }
            //circle condition
            else disNext_t0[ivehicle] = (pos_t0[0]+nSpace-pos_t0[ivehicle])%nSpace;
        }
        pgraph_i = new TGraph(nVehicle,pos_t0,time_i);
        pgraph_i->SetMarkerColor(ci);
        pgraph_i->SetMarkerSize(0.4);
        pgraph_i->SetTitle("");
        pgraph_i->Draw("P same");
        c1->Update();
    }//end for kIteration

    c1->Print("trafficModeling.png");
}