Histograms lost

ROOT
1

Hi!

I have a problem running a simple script in python:
I try to make a

uncerts = ["AllUncert","BaselineJES","CloseBy","FlavourComp","FlavourResponse","FwdJES","Mu","NPV"]

uncertFullUp = [[],[],[],[],[],[],[],[]] 
uncertFullDown = [[],[],[],[],[],[],[],[]] 

for un in uncerts:
    s_uncert = "JIXSMC12Kt6"+un
    f = TFile("../JIXSMC"+suffix+"/JIXSMC12Kt6NoUncert.root")
    fUncertUp = TFile("../JIXSMC"+suffix+"/"+s_uncert+suffix+".root")
    fUncertDown = TFile("../JIXSMC"+suffix+"/"+s_uncert+suffix+".root")
    
    h_data = f.Get("mjjyATLAS")
    h_datauncertUp = fUncertUp.Get("mjjyATLAS")
    h_datauncertDown = fUncertDown.Get("mjjyATLAS")  
    
    for i in range(h_data.GetNbinsY()):
        hdata = h_data.ProjectionX("mjjtruth"+str(i)+un, i, i).Rebin(nMassBins, "mjjtruth", massBins)
        SetOwnership(hdata,False)
      
        huncertUp = hdata.Clone("huncertUp"+un+str(i))
        SetOwnership(huncertUp,False)
        
        huncertDown = hdata.Clone("huncertDown"+un+str(i))
        SetOwnership(huncertDown,False)

        uncertFullUp[uncerts.index(un, )].append(huncertUp)
        uncertFullDown[uncerts.index(un, )].append(huncertDown)
        print uncertFullDown[uncerts.index(un, )][i].GetName()
        print "NEntries in %i - %i: %d"%(uncerts.index(un, ),i,uncertFullDown[uncerts.index(un, )][i].GetEntries())
        print "NEntries in %i - %i: %d"%(0,0,uncertFullDown[0][0].GetEntries())

and the output is

huncertDownAllUncert0
NEntries in 0 - 0: 0
NEntries in 0 - 0: 0
huncertDownAllUncert1
NEntries in 0 - 1: 337
NEntries in 0 - 0: 0
huncertDownAllUncert2
NEntries in 0 - 2: 87
NEntries in 0 - 0: 0
huncertDownAllUncert3
NEntries in 0 - 3: 22
NEntries in 0 - 0: 0
huncertDownAllUncert4
NEntries in 0 - 4: 30
NEntries in 0 - 0: 0
huncertDownAllUncert5
NEntries in 0 - 5: 139
NEntries in 0 - 0: 0
huncertDownAllUncert6
NEntries in 0 - 6: 0
NEntries in 0 - 0: 0
huncertDownAllUncert7
NEntries in 0 - 7: 0
NEntries in 0 - 0: 0
huncertDownAllUncert8
NEntries in 0 - 8: 0
NEntries in 0 - 0: 0
huncertDownBaselineJES0
NEntries in 1 - 0: 0
Traceback (most recent call last):
  File "PlotMakros/CalcJESUncert.py", line 165, in <module>
    print "NEntries in %i - %i: %d"%(0,0,uncertFullDown[0][0].GetEntries())
AttributeError: 'PyROOT_NoneType' object has no attribute 'GetEntries'

where the last line should be “NEntries in 0 - 0: 0” again.
I guessed that the garbage collection somehow deletes the histogram, but SetOwnership didn’t solve the problem…
I would be happy about any idea why this code fails.

Thanks,

Tobias

2

Hi,

the histograms are part of the file, so when that closes (when the file goes out of scope), the get taken with it by the C++ side (the SetOwnership only changes things on the python side). I think calling SetDirectory(0) on the histogram should do the trick.

Cheers,
Wim

3

Thanks a lot!
Using SetDirectory(0) solved the problem.

Cheers,

Tobias