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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