Hi Rene,
A couple of months ago I discovered that a TGraph's SetMinimum/Maximum got
overwritten when you set the title of the axis after plotting it. Thank you
for fixing this.
I have discovered another similar feature (which has been bugging me (excuse
pun) for a long time and took hours to track down!).
If you do the following:
1.) Create the graph
2.) Set it's min/max
3.) Fill it with points
4.) Plot it
5.) Set the axis title
Then the min/max you set gets overwritten.
If you do the following (swap 2 and 3 around):
1.) Create the graph
2.) Fill it with points
3.) Set it's min/max
4.) Plot it
5.) Set the axis title
Then you are ok, so this indicates that it is something to do with the order
in which you fill with points and set min/max.
However, if you do my first example but don't include step 5 then you are
also ok, as in:
1.) Create the graph
2.) Set it's min/max
3.) Fill it with points
4.) Plot it
Setting min/max first is ok as long as you don't want to set the title on
the axis!!!!!!
I have included a little code snippet below illustrating the problem.
Many thanks,
Jeff.
P.S. Using latest root.
Int_t height=2000;
Int_t numPoints=10;
TGraph* g=new TGraph(numPoints);
TGraph* g2=new TGraph(numPoints);
TGraph* g3=new TGraph(numPoints);
//set g2 and g3 min/max before SetPoint
g2->SetMinimum(0);
g2->SetMaximum(5000);
g3->SetMinimum(0);
g3->SetMaximum(5000);
for (Int_t i=0;i<numPoints;i++){
height+=100;
g->SetPoint(i,i,height);
g2->SetPoint(i,i,height);
g3->SetPoint(i,i,height);
}
//set g min/max after SetPoint
g->SetMinimum(0);
g->SetMaximum(5000);
TCanvas *c=new TCanvas("c","c",0,0,1200,800);
c->SetFillColor(0);
c->Divide(3,1);
//first plot
c->cd(1);
g->Draw("AP");
g->SetTitle("Plot Ok - Min/max set after SetPoint()");
g->SetMarkerStyle(3);
g->SetMarkerColor(2);
g->SetMarkerSize(0.4);
g->GetXaxis()->SetTitle("x Value");
g->GetYaxis()->SetTitle("Height");
g->GetXaxis()->CenterTitle();
g->GetYaxis()->CenterTitle();
//second plot
c->cd(2);
g2->Draw("AP");
g2->SetTitle("Plot Ok - Min/max set before SetPoint() (no axis
modification)");
g2->SetMarkerStyle(3);
g2->SetMarkerColor(2);
g2->SetMarkerSize(0.4);
//third plot
c->cd(3);
g3->Draw("AP");
g3->SetTitle("Plot NOT Ok - Min/max set before SetPoint() and axis
modification");
g3->SetMarkerStyle(3);
g3->SetMarkerColor(2);
g3->SetMarkerSize(0.4);
g3->GetXaxis()->SetTitle("x Value");
g3->GetYaxis()->SetTitle("Height");
g3->GetXaxis()->CenterTitle();
g3->GetYaxis()->CenterTitle();
----- Original Message -----
From: "Rene Brun" <brun@pcbrun.cern.ch>
To: "Jeff Hartnell" <jeffrey.hartnell@physics.ox.ac.uk>
Cc: <roottalk@cern.ch>
Sent: Friday, December 06, 2002 10:09 PM
Subject: Re: [ROOT] TGraph & SetMinimum
> Hi Jeff,
>
> Add the statement
> c->Update();
> after your Draw calls, eg:
>
> //second plot
> c->cd(2);
> g2->Draw("AP");
> c->Update();
> g2->SetMinimum(0);
>
>
> //third plot
> c->cd(3);
> g3->Draw("AP");
> c->Update();
> g3->SetMinimum(0);
>
> This is not necessary anymore if you use the development version in CVS.
>
> Rene Brun
>
> On Fri, 6 Dec 2002, Jeff Hartnell wrote:
>
> > Hi Rene,
> > I've tracked down the problem. Doing what you suggest works BUT if you
> > then set the title on the axis it somehow resets the scale!!!
> >
> > g->Draw("AP");
> > g->SetMinimum(0);
> >
> > Works just fine but
> >
> > g->Draw("AP");
> > g->SetMinimum(0);
> >
> > g2->GetXaxis()->SetTitle("x value");
> >
> > doesn't work and the scale gets reset.
> >
> > See my macro below demonstrating the problem.
> >
> > Cheers,
> > Jeff.
> >
> > Int_t height=2000;
> > Int_t numPoints=10;
> >
> > TGraph* g=new TGraph(numPoints);
> > TGraph* g2=new TGraph(numPoints);
> > TGraph* g3=new TGraph(numPoints);
> > TGraph* g4=new TGraph(numPoints);
> >
> > for (Int_t i=0;i<numPoints;i++){
> > height+=100;
> > g->SetPoint(i,i,height);
> > g2->SetPoint(i,i,height);
> > g3->SetPoint(i,i,height);
> > g4->SetPoint(i,i,height);
> > }
> >
> > TCanvas *c=new TCanvas("c","c",0,0,1200,800);
> > c->SetFillColor(0);
> > c->Divide(2,2);
> >
> > //first plot
> > c->cd(1);
> > g->Draw("AP");
> > g->SetMinimum(0);
> > g->SetTitle("Test plot - I work");
> > g->SetMarkerStyle(3);
> > g->SetMarkerColor(2);
> > g->SetMarkerSize(0.2);
> >
> > //second plot
> > c->cd(2);
> > g2->Draw("AP");
> > g2->SetMinimum(0);
> > g2->SetTitle("Test plot - I don't work (x-axis matters)");
> > g2->SetMarkerStyle(3);
> > g2->SetMarkerColor(2);
> > g2->SetMarkerSize(0.2);
> >
> > g2->GetXaxis()->SetTitle("x value");
> > //g2->GetXaxis()->CenterTitle();
> >
> > //third plot
> > c->cd(3);
> > g3->Draw("AP");
> > g3->SetMinimum(0);
> > g3->SetTitle("Test plot - I don't work (y-axis matters)");
> > g3->SetMarkerStyle(3);
> > g3->SetMarkerColor(2);
> > g3->SetMarkerSize(0.2);
> >
> > g3->GetXaxis()->SetTitle("x value");
> > g3->GetXaxis()->CenterTitle();
> > g3->GetYaxis()->SetTitle("height");
> > g3->GetYaxis()->CenterTitle();
> >
> > //fourth plot
> > c->cd(4);
> > g4->Draw("AP");
> > g4->SetMinimum(0);
> > g4->SetTitle("Test plot - I work (SetMin last)");
> > g4->SetMarkerStyle(3);
> > g4->SetMarkerColor(2);
> > g4->SetMarkerSize(0.2);
> >
> > g4->GetXaxis()->SetTitle("x value");
> > g4->GetXaxis()->CenterTitle();
> > g4->GetYaxis()->SetTitle("height");
> > g4->GetYaxis()->CenterTitle();
> > //call again right at the end to sort it out!!!!
> > g4->SetMinimum(0);
> >
> >
> >
> > ********************************************
> > Jeffrey Hartnell, Oxford/RAL DPhil student.
> >
> > Email: jeffrey.hartnell@physics.ox.ac.uk
> > Phone numbers, addresses etc on website:
> > http://www-pnp.physics.ox.ac.uk/~hartnell/
> > ********************************************
> >
> > ----- Original Message -----
> > From: "Rene Brun" <brun@pcbrun.cern.ch>
> > To: "Jeff Hartnell" <jeffrey.hartnell@physics.ox.ac.uk>
> > Cc: <roottalk@cern.ch>
> > Sent: Friday, December 06, 2002 2:44 PM
> > Subject: Re: [ROOT] TGraph & SetMinimum
> >
> >
> > > Hi Jeff,
> > >
> > > What you do should work
> > > g->Draw("ap");
> > > g->SetMinimum(0);
> > >
> > > if not, please send me a short but running script showing the problem.
> > >
> > > Rene Brun
> > >
> > > On Fri, 6 Dec 2002, Jeff Hartnell wrote:
> > >
> > > > Hi,
> > > > It seems to be impossible to override the automatic axis scaling in
> > > > TGraph when you draw it with the "a" option.
> > > >
> > > > I found this in the digest:
> > > >
> > > > From: Rene Brun (Rene.Brun@cern.ch)
> > > > Date: Wed Mar 20 2002 - 10:33:17 MET
> > > >
> > > > a.. Next message: Rene Brun: "Re: [ROOT] TGaxis"
> > > > b.. Previous message: Rene Brun: "Re: [ROOT] TGeant3, TGeant4 from
> > > > AliSoft"
> > > > c.. In reply to: Steffen Grohmann: "[ROOT] SetRangeUser Problem on
> > > > Y-axis"
> > > > d.. Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
> > > >
> > >
> > > ----------------------------------------------------------------------
> > --
> > > > --------
> > > >
> > > >
> > > > Hi Steffen,
> > > >
> > > > When you use the option "a" in TAxis::Draw, the axis limits are
> > > > automatically recomputed from the range of the actual Y values.
> > > > You can force a max/min of the y axis via
> > TAxis::SetMaximum/SetMinimum.
> > > > An alternative solution is to use TPad::DrawFrame.
> > > >
> > > > Rene Brun
> > > >
> > > > but TAxis doesn't have SetMaximum or minimum does it?
> > > >
> > > > I do this:
> > > >
> > > > gAdcPhNear[l]->Draw("AP");
> > > > gAdcPhNear[l]->SetMinimum(0);
> > > >
> > > > but it still gets drawn with the minimum above zero. Why doesn't
> > this
> > > > work? Can it be made to work?
> > > >
> > > > Has anyone found a solution to this problem? I could always draw a
> > > > histogram first with the appropriate scale, but that's ugly!
> > > > Thanks,
> > > > Jeff.
> > > >
> > > > p.s. using latest root on redhat 7.3.1
> > > >
> > > >
> > >
> >
>
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