Axis change in TH3::Project3D("xy");

ROOT
1

I found the following. Even though I can live with it it seems a bit odd and I don’t know the extent to which it is a problem. In any case it bothers me a bit.

running the following script you can see that when you make a proyection to the x-y plane in a TH3, the x and y axis are switched:

{
TH3D* hist3 = new TH3D("hist3","hist3",100,0,100,10,0,100,3,0,9);

cout << " X " << hist3->GetXaxis()->GetNbins() << " Y " << hist3->GetYaxis()->GetNbins() << endl;

TH2D* hist2 = (TH2D*) hist3->Project3D("xy");

cout << " X " << hist2->GetXaxis()->GetNbins() << " Y " << hist2->GetYaxis()->GetNbins() << endl;
}

The output is:

root [0]
Processing proyection.C...
 X 100 Y 10
 X 10 Y 100
2

Hi,

Use

See root.cern.ch/root/html/src/TH3.c … :Project3D

Cheers,
Philippe.