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NOTE: The call below to smd.sum() (or min()/max()) only accepts numpy arrays or None.  This requirement allows cores that don't see any events to not cause errors when summing across cores.  All cores must call .sum() or the process will hang (a property of the underlying mpi "Reduce" call).

Code Block
languagepy
from psana import DataSource
import numpy as np
import os

# OPTIONAL callback with "gathered" small data from all cores.
# usually used for creating realtime plots when analyzing from
# DAQ shared memory. Called back on each SRV node.
def my_smalldata(data_dict):
    print(data_dict)

# sets the number of h5 files to write. 1 is sufficient for 120Hz operation
# optional: only needed if you are saving h5.
os.environ['PS_SRV_NODES']='1'

ds = DataSource(exp='tmoc00118', run=222, dir='/cds/data/psdm/prj/public01/xtc', max_events=10)
# batch_size is optional. specifies how often the dictionary of small
# user data is gathered. if you write out large data (NOT RECOMMENDED) it needs to be set small.
smd = ds.smalldata(filename='mysmallh5.h5', batch_size=5, callbacks=[my_smalldata])

for run in ds.runs():
    opal = run.Detector('tmo_opal1')
    ebeam = run.Detector('ebeam')

    runsum  = np.zeros((3),dtype=float) # beware of datatypes when summing: can overflow
    for evt in run.events():
        img = opal.raw.image(evt)
        photonEnergy = ebeam.raw.ebeamPhotonEnergy(evt)
        # important: always check for missing data
        if img is None or photonEnergy is None: continue
        evtsum = np.sum(img)
        # pass either dictionary or kwargs
        smd.event(evt, evtsum=evtsum, photonEnergy=photonEnergy)
        runsum += img[0,:3] # local sum on one mpi core
 
    # optional summary data for whole run
    if smd.summary:
        tot_runsum = smd.sum(runsum) # sum (or max/min) across all mpi cores. Must be numpy array or None.
        # pass either dictionary or kwargs
        smd.save_summary({'sum_over_run' : tot_runsum}, summary_int=1)
    smd.done()

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