Definition of scatter plots in ROOT?

ROOT
1

Hi,

I have just a general (maybe naive) question:
what happens in detail when I plot from a tuple two variables with something like
myNTuple->Draw(Var1:Var2);
is the resulting plot a “real” scatter plot – i.e. each data point is represented
or does ROOT plot a histogramm with some standard binning and produces some pseudo scatter plot?

Cheers & Thanks,
Thomas

2

In this case this is a scatter plot (aka TGraph)

3

Are you using TGraph metaphorically, or can one actually get access to a TGraph after using TTree->Draw()?

4

I mean it literally:

TFile *_file0 = TFile::Open("hsimple.root"); ntuple->Draw("px:py"); TGraph *result = (TGraph*)gPad->FindObject("Graph")

Cheers,
Philippe.

5

When you do :

ntuple->Draw(“px:py”);

One single marker is drawn at each (px:py) poisition. So it is a real scatter plot not a pseudo one (plotting random points in each bin) like the SCAT option for 2D histograms.

6

[quote=“pcanal”]I mean it literally:

TFile *_file0 = TFile::Open("hsimple.root"); ntuple->Draw("px:py"); TGraph *result = (TGraph*)gPad->FindObject("Graph")

Cheers,
Philippe.[/quote]

Sweet! :smiley: I did not know that!