Hi Alex,
T->Draw("fNvertex:fNtrack>>htemp") generates a scatter plot
with the original precision for the coordinates in x and y.
htemp->Draw takes the original points (from a TPolyMarker)
,fills a 2-d histogram and draw the cell content gnerating a number
of points proportional to the cell content.
If you want to get exactly the same result, do
T->Draw("fNvertex:fNtrack>>htemp","","hist");
Rene Brun
On Wed, 31 Jul 2002, Alexander Dietz wrote:
> Hi Rooters,
>
> I have the following code:
>
> TCanvas* c1=new TCanvas("c1","c1",10,10,800,600);
> TFile f("Event.root");
> T->SetMarkerStyle(7);
>
> // draw picture 1
> T->Draw("fNvertex:fNtrack>>htemp");
> c1->Print("test1.ps");
>
> TH1F* htemp=(TH1F*)gDirectory->Get("htemp");
> htemp->SetTitle("title");
> htemp->Draw();
> htemp->GetXaxis()->SetTitle("title1");
> htemp->GetYaxis()->SetTitle("title2");
>
> // draw picture 2
> c1->Print("test2.ps");
>
> I create a picture with a tree, give the output into a histogram and draw
> the histogram.
> While doing that, 'test1.ps' stores the output from the Tree:Draw and
> 'test2.ps' stores the output from TH1F:Draw.
> When you compare the two pictures you will find that they are completely
> different!
>
> My questions are:
>
> 1. How to give the output of a Tree:Draw into a histogram to draw exactly
> the same picture
>
> 2. Or how can I set titles to axis when drawing a tree? (There is no
> command TTree::GetXaxis() or similar..
>
> Cheers
>
> Alex
>
>
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