RE: [ROOT] marker when a tree is drawn

From: Philippe Canal (pcanal@fnal.gov)
Date: Wed Jul 30 2003 - 18:17:37 MEST 

Hi Michael,

Your solution has actually a side effect that may or may not be desired.
    myTree->Draw("var1:var2",cut);
will draw on the screen every single real data point in its exact location.
    myTree->Draw("var1:var2>>histo",cut);
will first bunch the data point in the appropriate bin, losing some
precision
(i.e. instead of knowing a value is exactly 3.2, it will only know it is
between 3 and 4).  The histogram will then be drawn using only the binned
information (and point will be put in more or random position within each
bin
limits)

Cheers,
Philippe.

-----Original Message-----
From: Michael Wiesmann [mailto:wiesmann@e18.physik.tu-muenchen.de]
Sent: Wednesday, July 30, 2003 3:17 AM
To: Philippe Canal
Cc: Stilianos Kesisoglou; roottalk@pcroot.cern.ch
Subject: RE: [ROOT] marker when a tree is drawn


Hi!


I think the easiest solution is to define the histo with the draw
command. Two options:

1. myTree->Draw("var1:var2>>histo",cut);

  makes a new histogramm with the name "histo". afaik then one can
  modify histo

2. myTree->Draw("var1:var2>>histo2(100,0,1,100,0,1)",cut);
   makes a 2d histogram with 100 bins x, 100 bins y

Greets
Michael



Philippe Canal writes:
 > Hi,
 >
 > When doing: myTree->Draw("var1:var2",cut);
 > rather than drawing an histogram, ALL the data is drawn using a
TPolyMarker.
 >
 > The simpliest solution is to set a default marker for the tree:
 > 	myTree->SetMarkerStyle(3);
 >        myTree->Draw("var1:var2",cut);
 > Or after the fact you can do
 >  	myTree->Draw("var1:var2",cut);
 >        p = dynamic_cast<TPolyMaker*>(
 > gPad->GetListOfPrimitives()->FindObject("TPolyMaker") );
 >        if (p) p->SetMarketStyle(3);
 >
 > Cheers,
 > Philippe.
 >
 > -----Original Message-----
 > From: owner-roottalk@pcroot.cern.ch
[mailto:owner-roottalk@pcroot.cern.ch]On
 > Behalf Of Stilianos Kesisoglou
 > Sent: Tuesday, July 29, 2003 3:13 PM
 > To: roottalk@pcroot.cern.ch
 > Subject: [ROOT] marker when a tree is drawn
 >
 >
 > Hi,
 >
 >     I am having a problem to set the marker size and style when I draw
 > directly from a tree:
 >
 >         myTree->Draw("var1:var2",cut);
 >
 >     If I try to set the marker attributes for the histogram "htemp" there
is
 > no effect. The same happens
 > if I try to do it interactively with the mouse.
 >
 >     When I first book a TH2F histogram (named "histo") and then I do:
 >
 >         myTree->Draw("var1:var2>>histo",cut);
 >
 > then I can set the marker attributes for the histogram "histo".
 >
 >     Any way to do it directly on the first case without booking a
histogram?
 >
 >     Thanks!
 >
 > Stelios.
 >
 >
 > #################################################################
 > #################################################################
 > #################################################################
 > #####
 > #####
 > #####
 > #################################################################
 > #################################################################
 > #################################################################

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