Re: [ROOTDEV] THStack doesnt like GetXaxis()

Hi Christian,

The TAxis object is generated only when painting the stack. After your first hs->Draw(); statement add the two lines

    hs->GetXaxis()->SetTitle("Test X-Title"); // <-- NEW     gPad->Modified();

Rene brun

Christian Hansen wrote:
> Dear Rooters,
>
> when I use GetXaxis() from a THStack I get
> segmentation fault with root version 4.00/04.
>
> For example, I have addes one line to
> $ROOTSYS/tutorials/hstack.C, this line:
> hs->GetXaxis()->SetTitle("Test X-Title");
> (see attachement)
> And I get segmentation fault.
> Why?
>
> Thanks
> / Christian Hansen
>
> ===============================================
> Box 535 Office: +46-(0)18-471 32 57
> S-751 21 Uppsala Office: 82104
> Sweden
> -----------------------------------------------
> Mobile : +46-(0)708-887617
> Home Page : http://welcome.to/Christian_Hansen
> http://www.cern.ch/Christian.Hansen
>
>
> ------------------------------------------------------------------------
>
> void hstack() {
> // Example of stacked histograms: class THStack
> //
> // Author: Rene Brun
>
> THStack *hs = new THStack("hs","test stacked histograms");
> //create three 1-d histograms
> TH1F *h1 = new TH1F("h1","test hstack",100,-4,4);
> h1->FillRandom("gaus",20000);
> h1->SetFillColor(kRed);
> h1->SetMarkerStyle(21);
> h1->SetMarkerColor(kRed);
> hs->Add(h1);
> TH1F *h2 = new TH1F("h2","test hstack",100,-4,4);
> h2->FillRandom("gaus",15000);
> h2->SetFillColor(kBlue);
> h2->SetMarkerStyle(21);
> h2->SetMarkerColor(kBlue);
> hs->Add(h2);
> TH1F *h3 = new TH1F("h3","test hstack",100,-4,4);
> h3->FillRandom("gaus",10000);
> h3->SetFillColor(kGreen);
> h3->SetMarkerStyle(21);
> h3->SetMarkerColor(kGreen);
> hs->Add(h3);
>
> TCanvas *c1 = new TCanvas("c1","stacked hists",10,10,1000,800);
> hs->GetXaxis()->SetTitle("Test X-Title"); // <-- NEW
> c1->SetFillColor(41);
> c1->Divide(2,2);
> // in top left pad, draw the stack with defaults
> c1->cd(1);
> hs->Draw();
> // in top right pad, draw the stack in non-stack mode and errors option
> c1->cd(2);
> gPad->SetGrid();
> hs->Draw("nostack,e1p");
> //in bottom left, draw in stack mode with "lego1" option
> c1->cd(3);
> gPad->SetFrameFillColor(17);
> gPad->SetTheta(3.77);
> gPad->SetPhi(2.9);
> hs->Draw("lego1");
>
> c1->cd(4);
> //create two 2-D histograms and draw them in stack mode
> gPad->SetFrameFillColor(17);
> THStack *a = new THStack("a","test legos");
> TF2 *f1 = new TF2("f1","xygaus + xygaus(5) + xylandau(10)",-4,4,-4,4);
> Double_t params[] = {130,-1.4,1.8,1.5,1, 150,2,0.5,-2,0.5, 3600,-2,0.7,-3,0.3};
> f1->SetParameters(params);
> TH2F *h2a = new TH2F("h2a","h2a",20,-4,4,20,-4,4);
> h2a->SetFillColor(38);
> h2a->FillRandom("f1",4000);
> TF2 *f2 = new TF2("f2","xygaus + xygaus(5)",-4,4,-4,4);
> Double_t params[] = {100,-1.4,1.9,1.1,2, 80,2,0.7,-2,0.5};
> f2->SetParameters(params);
> TH2F *h2b = new TH2F("h2b","h2b",20,-4,4,20,-4,4);
> h2b->SetFillColor(46);
> h2b->FillRandom("f2",3000);
> a->Add(h2a);
> a->Add(h2b);
> a->Draw();
>
> c1->Print("stackTest.eps");
>
> }
Received on Tue Mar 08 2005 - 08:12:22 MET