Draw branch of an array variable from command line

ROOT
1

Hi all,

I have a branch which is an array
i.e. energy[multiplicity] for each event, to fill a histogram with it in a script
one has to loop over the multiplicities for each event and fill the histogram,
so my question is what does root do when this branch is drawn from the
command line? Does it dump all the elements of the array? Does it fill the
histogram only with the first or the last elements? Or is it completely wrong to try to draw these branches using the command line?

Thanks,
step0ut

2

see the many examples given in teh users Guide page216-220
ftp://root.cern.ch/root/doc/12Trees.pdf

By default tree.Draw(“array”) will histogram all elements of array (fix or variable length)

Rene

3

thanks your the promt reply.
It does indeed have all these in the manual.
however, I have one more specific question again for drawing from the command line.
When channels were less in our experiments data from e.g. one detector
with 10 channels were stored as

det_1_e
det_2_e
…
det_10_e

with a lot of zeros of course since only one-two would fire,
moving to a more efficient zero suppressed storage, the data are now
stored in the following way

energy[multiplicity]
det[multiplicity] // detector (paddle) number

I am sure many use similar ways to store data from multi-channel detectors. In the old way it was easy from the command line to draw
some correlations like det_1_e:det_2_e, however having the data stored
in the new way it seems as this correlation is not possible without a script.
Is this a true limitation or I am missing something?

Thanks again

4

See the answer to your indentical post: root.cern.ch/phpBB2/viewtopic.php?t=6895