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This page holds a few example code-snippets for use in pyana analysis. The analysis is written in python and uses MatPlotLib.PyPlot for plotting of data. Compare with myana user examples to see how (some of) the same things can be done using the myana analysis framework. The most reliable place for up-to-date information about all the event getters in pyana, see: https://confluence.slac.stanford.edu/display/PCDS/Pyana+Reference+Manual#PyanaReferenceManual-Classpyana.event.Event
For all the examples, you may assume that the pyana module contains a class with at least 'beginjob', 'event' and 'endjob' functions that starts something like this:
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import numpy as np
import matplotlib.pyplot as plt
from pypdsdata import xtc
class mypyana(object):
def __init__(self,source=""):
self.source = source
self.counter = None
def beginjob(self,evt,env):
self.counter = 0
def event(self,evt,env):
self.counter += 1
# snippet code goes here
thedata = evt.get(xtc.TypeId.Type.Id_SomeType, self.source )
def endjob(self,evt,env):
print "Job done! Processed %d events. " % self.counter
# place for plotting etc
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To read out energy, charge and position of the beam from the beamline data, use getEBeam(). It returns a class/structure that has the following members/fields:
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def event(self,evt,env):
ebeam = evt.getEBeam()
try :
beamChrg = ebeam.fEbeamCharge
beamEnrg = ebeam.fEbeamL3Energy
beamPosX = ebeam.fEbeamLTUPosX
beamPosY = ebeam.fEbeamLTUPosY
beamAngX = ebeam.fEbeamLTUAngX
beamAngY = ebeam.fEbeamLTUAngY
beamPkCr = ebeam.fEbeamPkCurrBC2
print "ebeam: ", beamChrg, beamEnrg, beamPosX, beamPosY, beamAngX, beamAngY, beamPkCr
except:
print "No EBeam object found"
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To read out the energy from the front end enclosure (FEE) gas detector, use getFeeGasDet(). This returns and array of 4 numbers:
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fee_energy_array = evt.getFeeGasDet()
gdENRC11 = fee_energy_array[0]
gdENRC12 = fee_energy_array[1]
gdENRC21 = fee_energy_array[2]
gdENRC22 = fee_energy_array[3]
energy = (gdENRC21 - gdENRC22) / 2
# or use the first two that has a different gain:
energy = (gdENRC11 - gdENRC12) / 2
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To read out fit time and charge of the phase cavity, use getPhaseCavity() which returns a structure with the following fields:
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pc = evt.getPhaseCavity()
try:
pcFitTime1 = pc.fFitTime1
pcFitTime2 = pc.fFitTime2
pcCharge1 = pc.fCharge1
pcCharge2 = pc.fCharge2
print "PhaseCavity: ", pcFitTime1, pcFitTime2, pcCharge1, pcCharge2
except :
print "No Phase Cavity object found"
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Encoder data (delay scanner)
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def event(self,evt,env):
try:
encoder = evt.get(xtc.TypeId.Type.Id_EncoderData, self.enc_source )
encoder_value = encoder.value()
except:
print "No encoder found in this event"
return
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The time of the event can be obtained within the event function:
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def event ( self, evt, env ) :
event_time = evt.getTime().seconds() + 1.0e-9*evt.getTime().nanoseconds() )
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