[ROOT] on plotting a variable of an TTree with a constraint in a specified range

From: Isard_Dunietz (dunietz@fnal.gov)
Date: Wed Jun 27 2001 - 17:41:48 MEST 

I have a TTree * with several variables inside it.  Instead of using the
MakeClass machinery I wonder whether there is a simple and straightforward
way to plot out a variable subject to a constraint, this can be done as
in:

root [1] TTree * hitdata = ...;
root [2] hitdata->Draw("_1.mresid","_1.senstype == 3");


However I would want to have the histogram have the limit xmin < x < xmax
and so I used:

root [10] TH1D mresidHist1 = TH1D( "mresidHist1", "bla", 100, -.05, 0.05);
root [11] hitdata->Draw("_1.resid >> mresidHist1");


However, I wish to draw _1.resid under the constraint "_1.senstype == 3"
and within the limit -.05< x < + 0.05,
 and I do not know how to combine both
(a) the constraint, and

(b) the histogram limit:

in a simple fashion.  I am using at present root v2_26_00g.

          Thank you, Isi

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