BES3 Data Reading
Read ROOT file (rtraw, dst, rec)
To make uproot know about BES3 ROOT files, import pybes3 before opening any file:
>>> import pybes3
>>> import uproot
Then, open file using uproot:
>>> f = uproot.open("test.rtraw")
>>> evt = f["Event"]
Print information about this "event" tree:
>>> evt.show(name_width=30)
name | typename | interpretation
-------------------------------+--------------------------+-------------------------------
TEvtHeader | TEvtHeader | AsGroup(<TBranchElement 'TE...
TEvtHeader/TObject | unknown | <UnknownInterpretation 'non...
TEvtHeader/m_eventId | int32_t | AsDtype('>i4')
TEvtHeader/m_runId | int32_t | AsDtype('>i4')
...
TMcEvent | TMcEvent | AsGroup(<TBranchElement 'TM...
TMcEvent/TObject | unknown | <UnknownInterpretation 'non...
TMcEvent/m_mdcMcHitCol | TMdcMc | AsBes3(TObjArray[TMdcMc])
TMcEvent/m_emcMcHitCol | TEmcMc | AsBes3(TObjArray[TEmcMc])
TMcEvent/m_tofMcHitCol | TTofMc | AsBes3(TObjArray[TTofMc])
TMcEvent/m_mucMcHitCol | TMucMc | AsBes3(TObjArray[TMucMc])
TMcEvent/m_mcParticleCol | TMcParticle | AsBes3(TObjArray[TMcParticle])
TDigiEvent | TDigiEvent | AsGroup(<TBranchElement 'TD...
TDigiEvent/TObject | unknown | <UnknownInterpretation 'non...
TDigiEvent/m_fromMc | bool | AsDtype('bool')
TDigiEvent/m_mdcDigiCol | TMdcDigi | AsBes3(TObjArray[TMdcDigi])
...
To read TMcEvent (Note: use arrays() instead of array() here):
>>> mc_evt = evt["TMcEvent"].arrays()
>>> mc_evt.fields
['m_mdcMcHitCol', 'm_emcMcHitCol', 'm_tofMcHitCol', 'm_mucMcHitCol', 'm_mcParticleCol']
Now go to event 0:
>>> evt0 = mc_evt[0]
>>> evt0.m_mcParticleCol.m_particleID
<Array [23, 4, -4, 91, 443, 11, ..., 111, 211, -211, 22, 22] type='12 * int32'>
>>> mc_evt[0].m_mcParticleCol.m_eInitialMomentum
<Array [3.1, 1.55, 1.55, 3.1, ..., 1.23, 0.178, 1.28] type='12 * float64'>
This indicates that in event 0, there are 12 MC particles. Their PDGIDs are 23, 4, -3, ... and initial energies are 3.1, 1.55, 1.55, ... (GeV).
It is recommended that only read the branches you need.
To read a specific branch (Note: use array() instead of arrays() here):
>>> pdgid_arr = evt["TMcEvent/m_mcParticleCol/m_particleID"].array()
>>> e_init_arr = evt["TMcEvent/m_mcParticleCol/m_eInitialMomentum"].array()
or you can retrieve branches from mc_evt:
>>> pdgid_arr = mc_evt["m_mcParticleCol/m_particleID"].array()
>>> e_init_arr = mc_evt["m_mcParticleCol/m_eInitialMomentum"].array()
Read raw data file
BES3 raw data files contain only digits information. To read a raw data file, use pybes3.open_raw:
>>> import pybes3 as p3
>>> reader = p3.open_raw("/bes3fs/offline/data/raw/round17/231117/run_0079017_All_file001_SFO-1.raw")
>>> reader
BesRawReader
- File: /bes3fs/offline/data/raw/round17/231117/run_0079017_All_file001_SFO-1.raw
- Run Number: 79017
- Entries: 100112
- File Size: 2010 MB
To read all data out:
>>> all_digi = reader.arrays()
>>> all_digi
<Array [{evt_header: {...}, ...}, ..., {...}] type='100112 * {evt_header: {...'>
>>> all_digi.fields
['evt_header', 'mdc', 'tof', 'emc', 'muc']
>>> all_digi.mdc.fields
['id', 'adc', 'tdc', 'overflow']
To only read some sub-detectors:
>>> mdc_tof_digi = reader.arrays(sub_detectors=['mdc', 'tof']) # 'emc', 'muc' are also available
>>> mdc_tof_digi.fields
['evt_header', 'mdc', 'tof']
To read part of file:
>>> some_digi = reader.arrays(n_blocks=1000)
>>> some_digi
<Array [{evt_header: {...}, ...}, ..., {...}] type='1000 * {evt_header: {ev...'>
Info
n_blocks instead of n_entries is used here because only data blocks are continuous in memory. Most of the time, there is one event in a data block.
Warning
By so far, besio can only read original raw digi data without any T-Q matching or post-processing.