[ROOT] list contour problem

From: Gabriel Tabacaru (tabacaru@comp.tamu.edu)
Date: Mon Mar 08 2004 - 16:46:52 MET


Hi everbody!

I have a 2-d histogram and I'd like to get the graphs corresponding to 
the contour lines. According to the documentation , making 
h2->Draw("cont list") should save me these objects (contours) into 
Specials. 
The browser can see the Specials "contours" but double click on one of the 
graphs break(Segmentation violation) the root. 
Trying to get the graphs objects via macro look like impossible for the 
moment. Does anybody have a solution for this ?   
      
I think that this problem was reported before but I can't figure out a 
good answer. I have root 4.00/02 CVS on PC Pentium 4 RedHat 9.

Regards, 
Gabi 
-- 
===============================================
Dr. Gabriel Tabacaru                          =
Cyclotron Institute - Texas A&M University    =
Univ. Drive                                   =
MS 3366, College Station, Texas 77843-3366    = 
USA                                           =
Tel.  : ++ 979 845 1411                       =
e-mail: tabacaru@comp.tamu.edu                =
        tabacaru@tamu.edu                     =
===============================================
=================================================================
MACRO test_contour.C 
{
gROOT->Reset();

TH2F *h2=new TH2F("h2","h2",30,-0.5,0.5,30,-0.5,0.5);
for(Int_t i=0;i<1000;i++){
  Float_t x=gRandom->Gaus(0,0.2);
  Float_t y=gRandom->Gaus(0.2,0.2);
  h2->Fill(x,y);
}
TCanvas *c1=new TCanvas("c1","c1",600,600);
h2->Draw("list cont");

TObjArray *contours= 
(TObjArray*)gROOT->GetListOfSpecials()->FindObject("contours");
Int_t nc=contours->GetSize();
cout<<nc<<endl;
//TList *list=(TList*)contours->At(3);
//TGraph *gr1=(TGraph*)list->First();
}
root [0] .x test_contour.C
Processing test_contour.C...
Error: illegal pointer to class object contours 0x0 85  FILE:test_contour.C 
LINE:16
*** Interpreter error recovered ***
root [1] TBrowser b
	Double click on root->Specials->Contours->TList->Graph
root [2]
 *** Break *** segmentation violation
 Generating stack trace...
 0x41275054 in TRootBrowser::ProcessMessage(long, long, long) + 0xe66 from 
/opt/root/root/lib/libGui.so
 0x412065a0 in TGFrame::HandleClientMessage(Event_t*) + 0x36 from 
/opt/root/root/lib/libGui.so
 0x4120914e in TGMainFrame::HandleClientMessage(Event_t*) + 0x22 from 
/opt/root/root/lib/libGui.so
 0x41206331 in TGFrame::HandleEvent(Event_t*) + 0x1fd from 
/opt/root/root/lib/libGui.so
 0x411eddd3 in TGClient::HandleEvent(Event_t*) + 0xd1 from 
/opt/root/root/lib/libGui.so
 0x411edac7 in TGClient::ProcessOneEvent() + 0x71 from 
/opt/root/root/lib/libGui.so
 0x411edb59 in TGClient::HandleInput() + 0x2d from 
/opt/root/root/lib/libGui.so
 0x411ec65a in TGInputHandler::Notify() + 0x1e from 
/opt/root/root/lib/libGui.so 0x401c6909 in 
TUnixSystem::DispatchOneEvent(bool) + 0x3b from 
/opt/root/root/lib/libCore.so
 0x4013553c in TSystem::InnerLoop() + 0x18 from 
/opt/root/root/lib/libCore.so
 0x401354e1 in TSystem::Run() + 0x6f from /opt/root/root/lib/libCore.so
 0x400e630d in TApplication::Run(bool) + 0x2d from 
/opt/root/root/lib/libCore.so 0x40dd9697 in TRint::Run(bool) + 0x31d from 
/opt/root/root/lib/libRint.so
 0x08048861 in main + 0x71 from /opt/root/root/bin/root.exe
 0x42015574 in __libc_start_main + 0xe4 from /lib/tls/libc.so.6
 0x08048761 in _Unwind_Resume + 0x31 from /opt/root/root/bin/root.exe
Root >
 *** Break *** segmentation violation
 Generating stack trace...
 0x412065a0 in TGFrame::HandleClientMessage(Event_t*) + 0x36 from 
/opt/root/root/lib/libGui.so
 0x4120914e in TGMainFrame::HandleClientMessage(Event_t*) + 0x22 from 
/opt/root/root/lib/libGui.so
 0x41206331 in TGFrame::HandleEvent(Event_t*) + 0x1fd from 
/opt/root/root/lib/libGui.so
 0x411eddd3 in TGClient::HandleEvent(Event_t*) + 0xd1 from 
/opt/root/root/lib/libGui.so
 0x411edac7 in TGClient::ProcessOneEvent() + 0x71 from 
/opt/root/root/lib/libGui.so
 0x411edb59 in TGClient::HandleInput() + 0x2d from 
/opt/root/root/lib/libGui.so
 0x411ec65a in TGInputHandler::Notify() + 0x1e from 
/opt/root/root/lib/libGui.so 0x401c6909 in 
TUnixSystem::DispatchOneEvent(bool) + 0x3b from 
/opt/root/root/lib/libCore.so
 0x4013553c in TSystem::InnerLoop() + 0x18 from 
/opt/root/root/lib/libCore.so
 0x401354e1 in TSystem::Run() + 0x6f from /opt/root/root/lib/libCore.so
 0x400e630d in TApplication::Run(bool) + 0x2d from 
/opt/root/root/lib/libCore.so 0x40dd9697 in TRint::Run(bool) + 0x31d from 
/opt/root/root/lib/libRint.so
 0x08048861 in main + 0x71 from /opt/root/root/bin/root.exe
 0x42015574 in __libc_start_main + 0xe4 from /lib/tls/libc.so.6
 0x08048761 in _Unwind_Resume + 0x31 from /opt/root/root/bin/root.exe
Root >



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