Sorry if this is an obvious question, but I’m new to PyROOT. Our experiment has it’s data in a relatively large number of identically structured files. From what I’ve read, this is exactly what the TChain is for. I created a TChain with a subset of the data.
filelist = ['Workspace/data/all/cf/calib_Prodv5-3_lite_011208a_cf.root', 'Workspace/data/all/cf/calib_Prodv5-3_011307a_cf.root', 'Workspace/data/all/cf/calib_Prodv5-3_011301a_cf.root', 'Workspace/data/all/cf/calib_Prodv5-3_011204a_cf.root'] dataChain = TChain('rrqDir/calibzip1') for fName in filelist: dataChain.Add(fName)
I would like to read out a single branch for all files in the TChain, but whenever I grab a branch from the chain it just grabs from the first file. For example below: I can get the total number of entries in the chain, but I only get the entries from a single file when I run GetBranch(). How do I access the same branch from each of the rest of the files in the TChain?
In : dataChain.GetEntries() Out: 1733321L In : dataChain.GetBranch('ytNF').GetEntries() Out: 166631L