Using ROOT and opening TCanvas

[jj15g]

I'm creating a program to make some histograms from a datafile. I'm not sure how to use ROOT for this. This is my code

#! /usr/bin/env python3
"""
ntp.py: Example PyROOT program which stores data
in a ROOT TNtuple which is then plotted using
the ROOT plotting routines.
---
John Jacke
PHZ4151C
Florida State University
April 1, 2019
Updated: Sean Dobbs, March 30, 2020
"""
from ROOT import TH1F,TLorentzVector,TCanvas
import numpy as np
import ROOT


def func( aX ):
        """ calculates exp(-x) * sin^2(3x) """
        return np.exp( -aX ) * np.sin( 3.0 * aX )**2


# Open a ROOT TFile
rootFile = ROOT.TFile("n3pi.root", "RECREATE")
#Creating histograms below
Hnppm = TH1F("nppm","Neutron,PiPlus,PiPlus,PiMinus",150,0.8,2.3)
Hppm = TH1F("ppm","PiPlus,PiPlus,PiMinus",150,0.8,2.3)
Hp1m = TH1F("p1m","PiPlus1,PiMinus",150,0.8,2.3)
Hp2m = TH1F("p2m","PiPlus2,PiMinus",150,0.8,2.3)
Hpp = TH1F("pp","PiPlus1,PiPlus2",150,0.8,2.3)
Hnp1 = TH1F("np1","Neutron,PiPlus1",150,0.8,2.3)
Hnp2 = TH1F("np2","Neutron,PiPlus2",150,0.8,2.3)
Hnm = TH1F("nm","Neutron,PiMinus",150,0.8,2.3)

Photon,PiPlus = TLorentzVector(),2*[TLorentzVector()]
Proton = TLorentzVector(0.0,0.0,0.0,0.938)
PiMinus = TLorentzVector(0.0,0.0,0.0,0.0)
nEvents=0

with open("n3pi.dat", "r") as dataFile:
        for line in dataFile:
                word = line.split() # split line into a list of words
                value = int(word[0])
                if value == 4:
                        #print("New event Information")
                        nPiPlus = 0
                        nEvents+=1
                if value == 1:
                        #print("\tPhoton Beam with Energy: %f"%(float(word[5])))
                        Photon.SetPxPyPzE(float(word[2]),float(word[3]),float(word[4]),float(word[5]))
                if value == 8:
                        # piPlus meson
                        #print("\tPiPlus[%d] meson with Energy: %f"%(nPiPlus, float(word[5])))
                        PiPlus[nPiPlus].SetPxPyPzE(float(word[2]),float(word[3]),float(word[4]),float(word[5]))
                        nPiPlus += 1
                if value == 9:
                        #print("\tPiMinus meson with Energy: %f"%(float(word[5])))
                        PiMinus.SetPxPyPzE(float(word[2]),float(word[3]),float(word[4]),float(word[5]))
                Neutron = (Photon + Proton - (PiMinus+PiPlus[0]+PiPlus[1]))
#Filling the histograms with values obtained above
                Hnppm.Fill((Neutron + PiPlus[0] + PiPlus[1] + PiMinus).Mag())                                                                                                           
                Hppm.Fill((PiPlus[0] + PiPlus[1] + PiMinus).Mag())
                Hp1m.Fill((PiPlus[0] + PiMinus).Mag())
                Hp2m.Fill((PiPlus[1] + PiMinus).Mag())
                Hpp.Fill((PiPlus[0] + PiPlus[1]).Mag())
                Hnp1.Fill((Neutron + PiPlus[0]).Mag())
                Hnp2.Fill((Neutron+PiPlus[1]).Mag())
                Hnm.Fill((Neutron + PiMinus).Mag())
#Creating a TCanvas
Canvas = TCanvas("cc","invariant masses",10,10,800,600)
Canvas.Divide(2,4)
Canvas.cd(3)
Hnppm.Draw()
# Save the ROOT TFile containing ROOT objects
rootFile.Write()

....

Should I save this as a .root file? When trying to run it with root I type the following commands into the command prompt:
root -l
root "filename.py"

I am getting the error

Error:
"ROOT_prompt_0:1:5: error: expected ';' after expression
root Problem1c.root"

[deanhystad]

This is a python program that uses ROOT through pyroot. You run it by typing "python" (maybe "python3") followed by the program's filename.