TTree in PyROOT?

ROOT
1

Dear all,

I’m using the following code to create a TTree in a *.root file.

[code]import ROOT
from ROOT import *
import numpy

f = ROOT.TFile(“datatree.root”,“RECREATE”)

m = numpy.array([0.,0.,0.,0.,0.])
for part in [‘detector_A’,‘detector_B’,‘detector_C’,‘detector_D’]:
tree = ROOT.TTree(part,"%s PARTITION"%part)
for mod in range(1,65):
branch = tree.Branch(part+"_m%02i"%mod,m,“channel/D:time/D:constant/D:constant_db/D:deviation/D”)
tree.Write()
del tree
f.Close()
[/code]

Now, I should be able to fill the tree by doing the following.

f = ROOT.TFile("datatree.root","UPDATE") tree = f.Get("detector_A") m = numpy.array([2.,0.,2.,0.,2.]) branch = tree.Branch("detector_A_m10",m,"channel/D:time/D:constant/D:constant_db/D:deviation/D") branch.Fill() tree.Write() f.Write() f.Close()

However, it seems my “data” [2,0,2,0,2] is not stored in the tree, when I inspect it with the TBrowser. Why does it not work?

Any help is most welcomed,
Marco

2

Still not sure why the other code “fails”, but this piece of code seems to work (for future reference):

[code]import ROOT
import numpy as n
import numpy as m

f = ROOT.TFile(“treetest.root”, “recreate”)
t = ROOT.TTree(“detector_A”, “detector_A”)
n = n.zeros(5, dtype=float)
u = m.zeros(5, dtype=float)
t.Branch(‘detector_A_m30’, n, “channel/D:time/D:constant/D:constant_db/D:deviation/D”)
t.Branch(‘detector_A_m31’, u, “channel/D:time/D:constant/D:constant_db/D:deviation/D”)
channel = 1
time = 213232.
constant = 2.
constant_db = 3.
deviation = constant/constant_db - 1.
t.Fill()
f.Write()
f.Close()

f = ROOT.TFile(“treetest.root”, “update”)
t = ROOT.TTree(“detector_A”, “detector_A”)
t.Branch(‘TILECAL_LBA_m30’, n, “channel/D:time/D:constant/D:constant_db/D:deviation/D”)
t.Branch(‘TILECAL_LBA_m31’, u, “channel/D:time/D:constant/D:constant_db/D:deviation/D”)
channel = 1
time = 213232.
constant = 2.
constant_db = 3.
deviation = constant/constant_db - 1.
for i in xrange(100000):
n[0] = channelROOT.gRandom.Uniform()
n[1] = timeROOT.gRandom.Uniform()
n[2] = constantROOT.gRandom.Uniform()
n[3] = constant_dbROOT.gRandom.Uniform()
n[4] = deviationROOT.gRandom.Uniform()
u[0] = channelROOT.gRandom.Uniform()
u[1] = timeROOT.gRandom.Uniform()
u[2] = constantROOT.gRandom.Uniform()
u[3] = constant_dbROOT.gRandom.Uniform()
u[4] = deviationROOT.gRandom.Uniform()
t.Fill()
f.Write()
f.Close()[/code]

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