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Hi Bob,

thanks for you note and especially the example code. I have used the method
3. to get what I need for now (I had a clumsier version of this working
before). 

I am still confused by the use of the histogram(name) method -- the root of
my original question. It looks like it returns a Histogram object that is
trapped at compile time since (as per item 3.) one cannot use the statistics
methods on Histogram directly. This seems to contradict example 1. (which
would be very useful). 


"Johnson, Tony S." wrote: 

1) The histogram(name) method in EventAnalyzer returns a histogram. You can
do anything with that histogram that you would do with a histogram created
using new Histogram(name). E.g.        histogram("xyz").fill(10);
double mean = histogram("xyz").getMean();        Histogram xyz =
histogram("xyz");


 to be more precise, the Histogram(name) method does the following:

*	

	Looks to see if a histogram by that name already exists. If so
return it.
*	

	Otherwise create a new Histogram (using new Histogram(name)) and
return it.

Thus it is possible to use the histogram method with a Histogram1D, IF you
create the Histogram1D manually and then subsequently use histogram(name) to
find it. In this case you would be able to cast the returned histogram to a
Histogram1D, and use the getMean() method:
 
// Construtor
         new Histogram1D("Bobs1DHistogram");
// somewhere else
         ((Histogram1D) histogram()).getMean();
 
If you do not explicitly create the histogram using new Histogram1D() then
the histogram method will just create you a Histogram, and the cast will
fail (since a Histogram is not in general a Histogram1D).
 
The problem here is that it is not convenient to have to explicitly create
the histograms, especially in the case where you want to dynamically create
the names for the histograms, which is why I suggested a different way to do
it in my earlier e-mail. Maybe what we should add is a way to specify what
type of Histogram you want histogram() to create, perhaps on a folder by
folder basis.

Finally, for my continuing Java education .... 

4) You can rename histograms with the rename method, but you must catch the
RenameException, since some histograms may not support being renamed. In
this instance you probably don't really want to use renaming.I've attached
an example which illustrates all of this.Tony


I wasnt expecting people to directly call the rename method, so I made this
a bit obscure (as opposed to everything else which is crystal clear of
course). The RenameException is an internal class of NamedObject. So its
full name is:
 
hep.analysis.NamedObject.RenameException
 
so even if you have 
 
import hep.analysis.*;
 
you still need to refer to it as NamedObject.RenameException. I think you
can also do a:
 
import hep.analysis.NamedObject.*;
 
The reason for doing it this way was to avoid further polluting the
hep.analysis.* name space with what I thought would be an obscure and rarely
used exception.
 
Tony