Drawing logarithmic scale using TGraph

[Javier_Galan]

ROOT Version: 6.20/00

Hi,

I am trying to plot a graph using logarithmic scale, I have seen few related posts, but I cannot find the problem.

I would like to Draw pad1->cd(1) in logarithmic and pad1->cd(2) linear.

It is strange, I cannot upload the file, it tells me the file contents are empty. So I copy/paste it here.

TCanvas* GraphLogTest() {
    TCanvas* canv = new TCanvas("canv", "", 1600, 600);
    canv->SetLogy(1);

    TPad* pad1 = new TPad("pad1", "This is pad1", 0.01, 0.02, 0.99, 0.97);
    pad1->Divide(3, 1);
    pad1->Draw();

    std::vector<TGraph*> graphs;

    std::vector<double> aRange = {0, 5};
    std::vector<double> lambdas = {0.3, 1, 2};
    for (int n = 0; n < lambdas.size(); n++) {
        TGraph* gr = new TGraph();
        for (double a = aRange[0]; a <= aRange[1]; a += (aRange[1] - aRange[0]) / 100.) {
            gr->SetPoint(gr->GetN(), a, TMath::Exp(-lambdas[n] * a));
        }
        graphs.push_back(gr);
    }


    graphs[0]->GetXaxis()->SetLimits(aRange[0], aRange[1]);
    graphs[0]->GetHistogram()->SetMaximum(1);
    graphs[0]->GetHistogram()->SetMinimum(1.e-3);

    graphs[0]->GetXaxis()->SetTitle("X-label");
    graphs[0]->GetXaxis()->SetTitleSize(0.05);
    graphs[0]->GetXaxis()->SetLabelSize(0.05);
    graphs[0]->GetYaxis()->SetTitle("Y-label");
    graphs[0]->GetYaxis()->SetTitleOffset(1.3);
    graphs[0]->GetYaxis()->SetTitleSize(0.05);
    graphs[0]->GetYaxis()->SetLabelSize(0.05);

    pad1->cd(1);
    pad1->SetLogy(1);
    graphs[0]->SetLineColor(33);
    graphs[0]->SetLineWidth(4);
    graphs[0]->Draw("AL");
    for (int n = 1; n < lambdas.size(); n++) {
        graphs[n]->SetLineWidth(4);
        graphs[n]->SetLineColor(33 + 2 * n);
        graphs[n]->Draw("L");
    }
    
    pad1->cd(2);
    pad1->SetLogy(0); 
    graphs[0]->SetLineColor(33);
    graphs[0]->SetLineWidth(4);
    graphs[0]->Draw("AL");
    for (int n = 1; n < lambdas.size(); n++) {
        graphs[n]->SetLineWidth(4);
        graphs[n]->SetLineColor(33 + 2 * n);
        graphs[n]->Draw("L");
    }

    return canv;
}

Any idea is welcome. Thank you!

[Javier_Galan]

Just found out the solution. I had to do pad1->cd(1)->SetLogy()