In This Package:

Example_GenEvent.py

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#!/usr/bin/env python

# Load GaudiPython
from GaudiPython.GaudiAlgs import GaudiAlgo
from GaudiPython import SUCCESS, FAILURE
from GaudiPython import gbl
from GaudiPython import loaddict
from DybPython.Util import irange

# Load HepMC classes
loaddict('libHepMCRflx')

# Make shortcuts to ROOT classes
TH1F = gbl.TH1F

# Make your algorithm
class ExampleAlg(GaudiAlgo):
    "Example Python Algorithm"
    def __init__(self,name):
        GaudiAlgo.__init__(self,name)
        return

    def initialize(self):
        status = GaudiAlgo.initialize(self)
        print "Init ExampleAlg",self.name()
        if status.isFailure(): return status
        return SUCCESS

    def execute(self):
        print "Executing ExampleAlg",self.name()
        evt = self.evtSvc()
        hdr = evt["/Event/Gen/GenHeader"]
        event = hdr.event()
        for vertex in irange(event.vertices_begin(),
                             event.vertices_end()):
            pos = vertex.position()
            print "vertex position = ", pos.x(), pos.y(), pos.z() 
            for particle in irange(vertex.particles_out_const_begin(),
                                   vertex.particles_out_const_end()):
                mom = particle.momentum()
                print "4 momentum = ", mom.px(), mom.py(), mom.pz(), mom.e()
        return SUCCESS
        
    def finalize(self):        
        print "Finalizing ExampleAlg",self.name()
        status = GaudiAlgo.finalize(self)
        return status

def configure():
    return

def run(app):
    '''
    Configure and add an algorithm to job
    '''
    example = ExampleAlg("MyExample")
    app.addAlgorithm(example)
    pass

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