B2A104-SimulateAndReconstruct-withBeamBkg.py

#!/usr/bin/env python3
 
 
 
# ########################################################################
#                                                                        #
# Stuck? Ask for help at questions.belle2.org                            #
#                                                                        #
# This tutorial demonstrates how to perform detector simulation and      #
# reconstruction (track finding+track fitting+ecl reconstruction+...)    #
# on a previously generated events with beam background mixing.          #
#                                                                        #
# In this example Beam Background is added. See                          #
# B2A103-SimulateAndReconstruct-withoutBeamBkg.py to check               #
# how to simulate+reconstruct without beam background.                   #
#                                                                        #
# The processed events are saved to the output ROOT file that            #
# now contain in addition to the generated particles                     #
# (MCParticle objects stored in the StoreArray<MCParticle>) also         #
# reconstructed MDST objects (Track/ECLCluster/KLMCluster/...).          #
#                                                                        #
# ########################################################################
 
import basf2 as b2
import modularAnalysis as ma
import simulation as si
import reconstruction as re
import glob
import os.path
 
 
# check if the required input file exists (from B2A101 example)
if not os.path.isfile('B2A101-Y4SEventGeneration-evtgen.root'):
    b2.B2FATAL(
        'Required input file (B2A101-Y4SEventGeneration-evtgen.root) does not exist. \n'
        'Please run B2A101-Y4SEventGeneration.py tutorial script first.')
 
# create a path
my_path = b2.create_path()
 
# load input ROOT file
ma.inputMdst('default', 'B2A101-Y4SEventGeneration-evtgen.root', path=my_path)
 
# background files
# location of the files is obtained from a shell variable - check first if it is set
if 'BELLE2_BACKGROUND_DIR' not in os.environ:
    b2.B2FATAL(
        'BELLE2_BACKGROUND_DIR variable is not set. \n'
        'Please export (setenv) the variable to the location of BG overlay sample. \n'
        'Check https://confluence.desy.de/display/BI/Beam+background+samples to find them')
# get list of files and check the list length
bg = glob.glob(os.environ['BELLE2_BACKGROUND_DIR'] + '/*.root')
if len(bg) == 0:
    b2.B2FATAL('No files found in ', os.environ['BELLE2_BACKGROUND_DIR'])
 
# simulation
si.add_simulation(path=my_path, bkgfiles=bg)
 
# reconstruction
re.add_reconstruction(path=my_path)
 
# dump in MDST format
re.add_mdst_output(path=my_path,
                   mc=True,
                   filename='B2A101-Y4SEventGeneration-gsim-BKGx1.root')
 
# Show progress of processing
my_path.add_module('ProgressBar')
 
# Process the events
b2.process(my_path)
 
# print out the summary
print(b2.statistics)