PyRoot Tree Help

ROOT
1

_ROOT Version:6.08
Platform:Ubuntu 16.04

I am trying to fill a TH1F histogram with a lead within a tree

from ROOT import *
#-------------------------------------------------------------------------------
rootfile = 'AOD_1.root'

def main():

    # read all entries and fill the histograms
    c1 = TCanvas('c1', 'Histogram', 200, 10, 700, 900)
    hpx = TH1F("hpx","DY MC Ntuple AOD_ele pt hist", 0, 100, 4200)

    myfile = TFile.Open(rootfile)
    #lldjNtuple.cd()
    #treeshow = EventTree.Print()
    mytree = myfile.Get("lldjNtuple/EventTree")
    entries = mytree.GetEntries()
    mytree.Print()
    print(entries)

    for i in range(entries):
        #pt = mytree.
        mytree.GetEntry(i)
        #mytree.GetEntry(i)
        #ept = getattr(mytree, 'AOD_elePt')        

        #    print(mytree.AOD_elePt)
        #mytree.GetLeaf("AOD_elePt")

        #pt = event.AOD_elePt
        hpx.Fill(AOD_elePt,1)
        hpx.Fill(AOD_eleEta,1)
    #        hpx.Fill(ePt,1)
    myfile.Close()
    #hfile.Close()

Root file’s structure is

root->lldjNtuple directory - >EventTree (tree) -> Leaf of AOD_elePt and AOD_eleEta

I want to plot AOD_elePt in histogram, which should be simple, but all documents and postings are for C++.

I have to go through each entry since I have more codings to add-on, but at this moment, I wanted to confirm how I would fill in TH1F histogram using GetEntry method for my root file

How can I fill TH1F histogram with AOD_elePt for my root file’s structure?

Thanks

2

@etejedor perhaps you can help here please?

3

Hi @trenta_coollime

Can you try this?

from ROOT import *
rootfile = 'AOD_1.root'

def main():

    # read all entries and fill the histograms
    c1 = TCanvas('c1', 'Histogram', 200, 10, 700, 900)
    hpx = TH1F("hpx","DY MC Ntuple AOD_ele pt hist", 0, 100, 4200)

    myfile = TFile.Open(rootfile)
    mytree = myfile.Get("lldjNtuple/EventTree")
    mytree.Print()

    for entry in mytree:
        pt = entry.AOD_elePt
        eta = entry.AOD_eleEta
        hpx.Fill(pt,1)
        hpx.Fill(eta,1)

    myfile.Close()
4

To. etejedor

  1. I get an error message
Traceback (most recent call last):
  File "2tree.py", line 36, in <module>
    main()
  File "2tree.py", line 27, in main
    hpx.Fill(pt,1)
TypeError: none of the 3 overloaded methods succeeded. Full details:
  int TH1::Fill(double x) =>
    takes at most 1 arguments (2 given)
  int TH1::Fill(const char* name, double w) =>
    could not convert argument 1 (expected string or Unicode object, vector<float> found)
  int TH1::Fill(double x, double w) =>
    could not convert argument 1 (a float is required)

which is what I had been getting before.

  1. I did EventTree.Print() for just more information
******************************************************************************
*Tree    :EventTree : Event data                                             *
*Entries :    15153 : Total =        46235915 bytes  File  Size =   14941157 *
*        :          : Tree compression factor =   3.09                       *
******************************************************************************
*Br    0 :run       : run/I                                                  *
*Entries :    15153 : Total  Size=      61228 bytes  File Size  =        516 *
*Baskets :        2 : Basket Size=      32000 bytes  Compression= 117.76     *
*............................................................................*
*Br    1 :event     : event/L                                                *
*Entries :    15153 : Total  Size=     122014 bytes  File Size  =      32996 *
*Baskets :        4 : Basket Size=      32000 bytes  Compression=   3.68     *
*............................................................................*
*Br    2 :lumis     : lumis/I                                                *
*Entries :    15153 : Total  Size=      61240 bytes  File Size  =       1011 *
*Baskets :        2 : Basket Size=      32000 bytes  Compression=  60.10     *
.
.
.
*............................................................................*
*Br  190 :nAODEle   : nAODEle/I                                              *
*Entries :    15153 : Total  Size=      61252 bytes  File Size  =       8291 *
*Baskets :        2 : Basket Size=      32000 bytes  Compression=   7.33     *
*............................................................................*
*Br  191 :AOD_elePt : vector<float>                                          *
*Entries :    15153 : Total  Size=     251386 bytes  File Size  =      91160 *
*Baskets :       10 : Basket Size=      32000 bytes  Compression=   2.75     *
*............................................................................*
*Br  192 :AOD_eleEn : vector<float>                                          *
*Entries :    15153 : Total  Size=     251386 bytes  File Size  =      91490 *
*Baskets :       10 : Basket Size=      32000 bytes  Compression=   2.74     *
*............................................................................*
*Br  193 :AOD_eleEta : vector<float>                                         *
*Entries :    15153 : Total  Size=     251400 bytes  File Size  =      92955 *
*Baskets :       10 : Basket Size=      32000 bytes  Compression=   2.70     *
*............................................................................*
.
.
.

Thank you.

5

Hi @trenta_coollime

I see, it seems that AOD_elePt and AOD_eleEta are not floats, but vectors of floats. And you can’t fill the histogram with a vector.

Would this be closer to what you want?

for entry in mytree:
    vec_pts = entry.AOD_elePt  # vec_pts is a vector of floats
    vec_etas = entry.AOD_eleEta  # vec_etas is a vector of floats
    for pt in vec_pts:
        hpx.Fill(pt,1)
    for eta in vec_etas:
        hpx.Fill(eta,1)