root cheat sheet

From: Pasha Murat (murat@cdfsga.fnal.gov)
Date: Fri Apr 10 1998 - 08:02:15 MEST


Steve Beach writes:
 > I'm a (very) new user of root, and as an aid to learning, I'm putting
 > together a 'root cheat sheet', a list of questions and answers about
 > using root.  Pretty basic questions, the things a new user would want to
 > know.  A preliminary copy is available at my home page (see below).
 > 
 > I have a lot of questions, but right now, I'd appreciate some help on
 > two basic ones:

	Steve, 

	let me encourage you (and also all new users) to read ROOT howto's
	(see http://root.cern.ch), you could find alot of answers there.
 > 
 > 1:  I've converted over a PAW hbook ntuple to a root tree.  Now, how do
 > I use that tree?  I'd like to do histograms on it, but
 > tree->Draw("event"); doesn't work, even though the variable "event"
 > exists.  Is there anything I'm missing?  

	See http://root.cern.ch/root/HowtoConvert.html 
 > 
 > 2:  Is there a way to find out what variables are in an ntuple?  (Could
 > be very handy for transferring files!)  PAW++ has such a feature.
 > 

	provided  `nt' is a pointer to your TTree (ntuple)

	nt->Print()

        does what you are asking for. You could also use ROOT browser 
	for this (see ROOT tutorials and .html above for more details)

					Regards, Pasha.



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