In This Package:

ExampleTree.py

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#!/usr/bin/env python
#
# Simple Example of filling and writing a ROOT TTree 
#
#  Usage:
#   nuwa.py -n -1 ExampleTree simulationData.root

# Load DybPython
from DybPython.DybPythonAlg import DybPythonAlg
from GaudiPython import SUCCESS, FAILURE
from GaudiPython import gbl
from DybPython.Util import irange

# Make shortcuts to any ROOT classes you want to use
TTree = gbl.TTree
from array import array


# Define the algorithm
class ExampleTreeAlg(DybPythonAlg):
    "Example Tree-writing Python Algorithm"
    def __init__(self,name):
        DybPythonAlg.__init__(self,name)
        return

    def initialize(self):
        status = DybPythonAlg.initialize(self)
        if status.isFailure(): return status
        self.info("initializing")

        # Initialize services
        #  Statistics Service: Use for histograms, graphs, trees
        self.statsSvc = self.svc('IStatisticsSvc','StatisticsSvc')
        if self.statsSvc == None:
            self.error("Failed to initialize statistics service.")
            return FAILURE        

        # Make a tree
        self.simTree= TTree("simTree","Tree of Simulated Hits")

        # Make branch addresses for single-numbers. 'i'=int, 'd'=double
        self.simTime = array('d',[0])
        self.nSimHits = array('i',[0])
        # Make branch addresses for array branches
        self.maxSimHits = 4096
        self.simHitPmtId = array('i',self.maxSimHits*[0])
        self.simHitTime = array('d',self.maxSimHits*[0])

        # Make Branches
        self.simTree.Branch('simTime',self.simTime,'simTimeSec/D')
        self.simTree.Branch('nSimHits',self.nSimHits,'nSimHits/I')
        self.simTree.Branch('simHitPmtId',self.simHitPmtId,
                            'simHitPmtId[nSimHits]/I')
        self.simTree.Branch('simHitTime',self.simHitTime,
                            'simHitTime[nSimHits]/D')

        status = self.statsSvc.put('/file0/sim/simTree', self.simTree)
        if status.isFailure(): return status

        return SUCCESS

    def execute(self):
        self.info("executing")

        # Access current data
        evt = self.evtSvc()
        simHdr = evt["/Event/Sim/SimHeader"]
        if simHdr == None:
            self.error("Failed to get current sim header")
            return FAILURE

        # Set Branch values
        self.simTime[0] = simHdr.timeStamp().GetSeconds()
        # Loop over hits in each detector
        shh = simHdr.hits()
        hitCollectionMap = shh.hitCollection()
        nHits = 0
        for shcPair in irange(hitCollectionMap.begin(),
                              hitCollectionMap.end()):
            detectorId = shcPair.first
            hitCollection = shcPair.second
            self.info( "Found %d hits for detector %d"
                       % ( hitCollection.collection().size(),
                           detectorId )
                       )
            for hit in hitCollection.collection():
                self.simHitPmtId[nHits] = hit.sensDetId()
                self.simHitTime[nHits] = hit.hitTime()
                nHits += 1
        self.nSimHits[0] = nHits

        # Fill the tree with current branch values
        self.simTree.Fill()

        return SUCCESS
        
    def finalize(self):
        self.info("finalizing")
        status = DybPythonAlg.finalize(self)
        return status


#####  Job Configuration for nuwa.py ########################################

def configure():
    from StatisticsSvc.StatisticsSvcConf import StatisticsSvc
    statsSvc = StatisticsSvc()
    statsSvc.Output ={"file0":"simHitStats.root"}
    return

def run(app):
    '''
    Configure and add an algorithm to job
    '''
    app.ExtSvc += ["StatisticsSvc"]
    example = ExampleTreeAlg("MyTreeExample")
    app.addAlgorithm(example)
    pass

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