The km3io Python package
This software provides a set of Python classes to read KM3NeT ROOT files without having ROOT, Jpp or aanet installed. It only depends on Python 3.5+ and the amazing uproot package and gives you access to the data via numpy arrays.
It's very easy to use and according to the uproot benchmarks, it is able to outperform the ROOT I/O performance.
Note: Beware that this package is in the development phase, so the API will change until version 1.0.0 is released!
Installation
Install km3io using pip:
pip install km3ioTo get the latest (stable) development release:
pip install git+https://git.km3net.de/km3py/km3io.gitReminder: km3io is not dependent on aanet, ROOT or Jpp!
Questions
If you have a question about km3io, please proceed as follows:
- Read the documentation below.
- Explore the examples in the documentation.
- Haven't you found an answer to your question in the documentation, post a git issue with your question showing us an example of what you have tried first, and what you would like to do.
- Have you noticed a bug, please post it in a git issue, we appreciate your contribution.
Tutorial
Table of contents:
Introduction
Most of km3net data is stored in root files. These root files are either created with Jpp or aanet software. A root file created with
Jpp is often referred to as "a Jpp root file". Similarly, a root file created with aanet is often referred to as "an aanet file". In km3io, an aanet root file will always be reffered to as an offline file, while a Jpp ROOT file will always be referred to as a online file.
km3io is a Python package that provides a set of classes (OnlineReader and OfflineReader) to read both online ROOT files and offline ROOT files without any dependency to aanet, Jpp or ROOT.
Data in km3io is often returned as a "lazyarray", a "jagged lazyarray" or a Numpy array. A lazyarray is an array-like object that reads data on demand! In a lazyarray, only the first and the last chunks of data are read in memory. A lazyarray can be used with all Numpy's universal functions. Here is how a lazyarray looks like:
# <ChunkedArray [5971 5971 5971 ... 5971 5971 5971] at 0x7fb2341ad810>A jagged array, is a 2+ dimentional array with different arrays lengths. In other words, a jagged array is an array of arrays of different sizes. So a jagged lazyarray is simply a jagged array of lazyarrays with different sizes. Here is how a jagged lazyarray looks like:
# <JaggedArray [[102 102 102 ... 11517 11518 11518] [] [101 101 102 ... 11518 11518 11518] ... [101 101 102 ... 11516 11516 11517] [] [101 101 101 ... 11517 11517 11518]] at 0x7f74b0ef8810>Overview of Online files
Online files are written by the DataWriter (part of Jpp) and contain events, timeslices and summary slices.
Overview of offline files
Offline files contain data about events, hits and tracks. Based on aanet version 2.0.0 documentation, the following tables show the definitions, the types and the units of the branches founds in the events, hits and tracks trees. A description of the file header are also displayed.
| type | name | definition |
|---|---|---|
| int | id | offline event identifier |
| int | det_id | detector identifier from DAQ |
| int | mc_id | identifier of the MC event (as found in ascii or antcc file) |
| int | run_id | DAQ run identifier |
| int | mc_run_id | MC run identifier |
| int | frame_index | from the raw data |
| ULong64_t | trigger_mask | trigger mask from raw data (i.e. the trigger bits) |
| ULong64_t | trigger_counter | trigger counter |
| unsigned int | overlays | number of overlaying triggered events |
| TTimeStamp | t | UTC time of the start of the timeslice the event came from |
| vec Hit | hits | list of hits |
| vec Trk | trks | list of reconstructed tracks (can be several because of prefits,showers, etc) |
| vec double | w | MC: Weights w[0]=w1 & w[1]=w2 & w[2]]=w3 |
| vec double | w2list | MC: factors that make up w[1]=w2 |
| vec double | w3list | MC: atmospheric flux information |
| double | mc_t | MC: time of the mc event |
| vec Hit | mc_hits | MC: list of MC truth hits |
| vec Trk | mc_trks | MC: list of MC truth tracks |
| string | comment | user can use this as he/she likes |
| int | index | user can use this as he/she likes |
| type | name | definition |
|---|---|---|
| int | id | hit id |
| int | dom_id | module identifier from the data (unique in the detector) |
| unsigned int | channel_id | PMT channel id {0,1, .., 31} local to module |
| unsigned int | tdc | hit tdc (=time in ns) |
| unsigned int | tot | tot value as stored in raw data (int for pyroot) |
| int | trig | non-zero if the hit is a trigger hit |
| int | pmt_id | global PMT identifier as found in evt files |
| double | t | hit time (from calibration or MC truth) |
| double | a | hit amplitude (in p.e.) |
| vec | pos | hit position |
| vec | dir | hit direction i.e. direction of the PMT |
| double | pure_t | photon time before pmt simultion (MC only) |
| double | pure_a | amptitude before pmt simution (MC only) |
| int | type | particle type or parametrisation used for hit (mc only) |
| int | origin | track id of the track that created this hit |
| unsigned | pattern_flags | some number that you can use to flag the hit |
| type | name | definition |
|---|---|---|
| int | id | track identifier |
| vec | pos | position of the track at time t |
| vec | dir | track direction |
| double | t | track time (when particle is at pos) |
| double | E | Energy (either MC truth or reconstructed) |
| double | len | length if applicable |
| double | lik | likelihood or lambda value (for aafit: lambda) |
| int | type | MC: particle type in PDG encoding |
| int | rec_type | identifyer for the overall fitting algorithm/chain/strategy |
| vec int | rec_stages | list of identifyers of succesfull fitting stages resulting in this track |
| int | status | MC status code |
| int | mother_id | MC id of the parent particle |
| vec double | fitinf | place to store additional fit info for jgandalf see FitParameters.csv |
| vec int | hit_ids | list of associated hit-ids (corresponds to Hit::id) |
| vec double | error_matrix | (5x5) error covariance matrix (stored as linear vector) |
| string | comment | user comment |
| name | definition |
|---|---|
| DAQ | livetime |
| cut_primary cut_seamuon cut_in cut_nu | Emin Emax cosTmin cosTmax |
| generator physics simul | program version date time |
| seed | program level iseed |
| PM1_type_area | type area TTS |
| i1 i2 | |
| model | interaction muon scattering numberOfEnergyBins |
| can | zmin zmax r |
| genvol | zmin zmax r volume numberOfEvents |
| merge | time gain |
| coord_origin | x y z |
| translate | x y z |
| genhencut | gDir Emin |
| k40 | rate time |
| norma | primaryFlux numberOfPrimaries |
| livetime | numberOfSeconds errorOfSeconds |
| flux | type key file_1 file_2 |
| spectrum | alpha |
| fixedcan | xcenter ycenter zmin zmax radius |
| start_run | run_id |
Online files reader
km3io is able to read events, summary slices and timeslices. Timeslices are
currently only supported with split level of 2 or more, which means that reading
L0 timeslices is currently not working (but in progress).
Let's have a look at some ORCA data (KM3NeT_00000044_00005404.root)
Reading Events
To get a lazy ragged array of the events:
import km3io
f = km3io.OnlineReader("KM3NeT_00000044_00005404.root")That's it, we created an object which gives access to all the events, but the relevant data is still not loaded into the memory (lazy access)! Now let's have a look at the hits data:
>>> f.events
Number of events: 17023
>>> f.events[23].snapshot_hits.tot
array([28, 22, 17, 29, 5, 27, 24, 26, 21, 28, 26, 21, 26, 24, 17, 28, 23,29, 27, 24, 23, 26, 29, 25, 18, 28, 24, 28, 26, 20, 25, 31, 28, 23, 26, 21, 30, 33, 27, 16, 23, 24, 19, 24, 27, 22, 23, 21, 25, 16, 28, 22, 22, 29, 24, 29, 24, 24, 25, 25, 21, 31, 26, 28, 30, 42, 28], dtype=uint8)The resulting arrays are numpy arrays.
Reading SummarySlices
The following example shows how to access summary slices, in particular the DOM
IDs of the slice with the index 23:
>>> f.summaryslices
<km3io.online.SummarySlices at 0x7effcc0e52b0>
>>> f.summaryslices.slices[23].dom_id
array([806451572, 806455814, 806465101, 806483369, 806487219, 806487226,
806487231, 808432835, 808435278, 808447180, 808447186, 808451904,
808451907, 808469129, 808472260, 808472265, 808488895, 808488990,
808489014, 808489117, 808493910, 808946818, 808949744, 808951460,
808956908, 808959411, 808961448, 808961480, 808961504, 808961655,
808964815, 808964852, 808964883, 808964908, 808969848, 808969857,
808972593, 808972598, 808972698, 808974758, 808974773, 808974811,
808974972, 808976377, 808979567, 808979721, 808979729, 808981510,
808981523, 808981672, 808981812, 808981864, 808982005, 808982018,
808982041, 808982066, 808982077, 808982547, 808984711, 808996773,
808997793, 809006037, 809007627, 809503416, 809521500, 809524432,
809526097, 809544058, 809544061], dtype=int32)The .dtype attribute (or in general, <TAB> completion) is useful to find out
more about the field structure:
>>> f.summaryslices.headers.dtype
dtype([(' cnt', '<u4'), (' vers', '<u2'), (' cnt2', '<u4'), (' vers2',
'<u2'), (' cnt3', '<u4'), (' vers3', '<u2'), ('detector_id', '<i4'), ('run',
'<i4'), ('frame_index', '<i4'), (' cnt4', '<u4'), (' vers4', '<u2'),
('UTC_seconds', '<u4'), ('UTC_16nanosecondcycles', '<u4')])
>>> f.summaryslices.headers.frame_index
<ChunkedArray [162 163 173 ... 36001 36002 36003] at 0x7effccd4af10>The resulting array is a ChunkedArray which is an extended version of a
numpy array and behaves like one.
Reading Timeslices
Timeslices are split into different streams since 2017 and km3io currently
supports everything except L0, i.e. L1, L2 and SN streams. The API is
work-in-progress and will be improved in future, however, all the data is
already accessible (although in ugly ways ;-)
To access the timeslice data:
>>> f.timeslices
Available timeslice streams: L1, SN
>>> f.timeslices.stream("L1", 24).frames
{806451572: <Table [<Row 1577843> <Row 1577844> ... <Row 1578147>],
806455814: <Table [<Row 1578148> <Row 1578149> ... <Row 1579446>],
806465101: <Table [<Row 1579447> <Row 1579448> ... <Row 1580885>],
...
}The frames are represented by a dictionary where the key is the DOM ID and
the value a numpy array of hits, with the usual fields to access the PMT
channel, time and ToT:
>>> f.timeslices.stream("L1", 24).frames[806451572].dtype
dtype([('pmt', 'u1'), ('tdc', '<u4'), ('tot', 'u1')])
>>> f.timeslices.stream("L1", 24).frames[806451572].tot
array([29, 21, 8, 29, 22, 20, 1, 37, 11, 22, 11, 22, 12, 20, 29, 94, 26,
26, 18, 16, 13, 22, 6, 29, 24, 30, 14, 26, 12, 23, 4, 25, 6, 27,
5, 13, 21, 28, 30, 4, 25, 10, 5, 6, 5, 17, 4, 27, 24, 25, 27,
28, 32, 6, 3, 15, 3, 20, 33, 30, 30, 20, 28, 6, 7, 3, 14, 12,
25, 27, 26, 25, 22, 21, 23, 6, 20, 21, 4, 4, 10, 24, 29, 12, 30,
5, 3, 24, 15, 14, 25, 5, 27, 23, 26, 4, 28, 15, 34, 22, 4, 29,
24, 26, 29, 23, 25, 28, 14, 31, 27, 26, 27, 28, 23, 54, 4, 25, 11,
28, 25, 24, 7, 27, 28, 28, 18, 3, 13, 14, 38, 28, 4, 21, 16, 16,
4, 21, 26, 21, 28, 64, 21, 1, 24, 21, 26, 26, 25, 4, 28, 11, 31,
10, 24, 24, 28, 10, 6, 4, 20, 26, 18, 5, 18, 24, 5, 27, 23, 20,
29, 20, 6, 18, 5, 24, 17, 28, 24, 15, 26, 27, 25, 9, 3, 18, 3,
34, 29, 10, 25, 30, 28, 19, 26, 34, 27, 14, 17, 15, 26, 8, 19, 5,
27, 13, 5, 27, 46, 3, 25, 13, 30, 9, 21, 12, 1, 32, 25, 8, 30,
4, 24, 11, 3, 11, 27, 5, 13, 5, 16, 18, 3, 22, 10, 7, 32, 29,
15, 20, 18, 16, 27, 5, 22, 4, 33, 5, 29, 24, 30, 7, 7, 25, 33,
7, 20, 8, 30, 4, 4, 6, 26, 8, 24, 22, 12, 6, 3, 21, 28, 11,
24, 27, 27, 6, 29, 5, 18, 11, 26, 5, 19, 32, 25, 4, 20, 35, 30,
5, 3, 26, 30, 23, 28, 6, 25, 25, 5, 45, 23, 18, 29, 28, 23],
dtype=uint8)Offline files reader
In general an offline file has two methods to fetch data: the header and the events. Let's start with the header.
Reading the file header
To read an offline file start with opening it with an OfflineReader:
import km3io
f = km3io.OfflineReader("mcv5.0.gsg_elec-CC_1-500GeV.sirene.jte.jchain.jsh.aanet.1.root")Calling the header can be done with:
>>> f.header
<km3io.offline.Header at 0x7fcd81025990>and provides lazy access. In offline files the header is unique and can be printed
>>> print(f.header)
MC Header:
DAQ(livetime=35.5)
XSecFile: /project/antares/public_student_software/genie/v3.00.02-hedis/Generator/genie_xsec/gSeaGen/G18_02a_00_000/gxspl-seawater.xml
coord_origin(x=457.8, y=574.3, z=0)
cut_nu(Emin=1, Emax=500, cosTmin=-1, cosTmax=1)
drawing: surface
fixedcan(xcenter=457.8, ycenter=574.3, zmin=0, zmax=475.6, radius=308.2)
genvol(zmin=0, zmax=475.6, r=308.2, volume=148000000.0, numberOfEvents=1000000.0)
simul(program='gSeaGen', version='dev', date=200616, time=223726)
simul_1: simul_1(field_0='GENIE', field_1='3.0.2', field_2=200616, field_3=223726)
simul_2: simul_2(field_0='GENIE_REWEIGHT', field_1='1.0.0', field_2=200616, field_3=223726)
simul_3: simul_3(field_0='JSirene', field_1='13.0.0-alpha.5-113-gaa686a6a-D', field_2='06/17/20', field_3=0)
spectrum(alpha=-3)
start_run(run_id=1)
tgen: 31556900.0An overview of the values in a the header are given in the Overview of offline files. To read the values in the header one can call them directly:
>>> f.header.DAQ.livetime
35.5
>>> f.header.cut_nu.Emin
1
>>> f.header.genvol.numberOfEvents
1000000.0Reading events
To start reading events call the events method on the file:
>>> f.events
<OfflineBranch[events]: 355 elements>Like the online reader lazy access is used. Using <TAB> completion gives an overview of available data. Alternatively the method keys can be used on events and it's data members containing a structure to see what is available for reading.
>>> f.events.keys()
dict_keys(['w2list', 'frame_index', 'overlays', 'comment', 'id', 'w', 'run_id', 'mc_t', 'mc_run_id', 'det_id', 'w3list', 'trigger_mask', 'mc_id', 'flags', 'trigger_counter', 'index', 't_sec', 't_ns', 'n_hits', 'n_mc_hits', 'n_tracks', 'n_mc_tracks'])
>>> f.events.tracks.keys()
dict_keys(['mother_id', 'status', 'lik', 'error_matrix', 'dir_z', 'len', 'rec_type', 'id', 't', 'dir_x', 'rec_stages', 'dir_y', 'fitinf', 'pos_z', 'hit_ids', 'comment', 'type', 'any', 'E', 'pos_y', 'usr_names', 'pos_x'])Reading the reconstructed values like energy and direction of an event can be done with:
>>> f.events.tracks.E
<ChunkedArray [[3.8892237665736844 0.0 0.0 ... 0.0 0.0 0.0] [2.2293441683824318 5.203533524801224 6.083598278897039 ... 0.0 0.0 0.0] [3.044857858677666 3.787165776302862 4.5667729757360656 ... 0.0 0.0 0.0] ... [2.205652079790387 2.120769181474425 1.813066579943641 ... 0.0 0.0 0.0] [2.1000775068170343 3.939512272391431 3.697537355163539 ... 0.0 0.0 0.0] [4.213600763523154 1.7412855636388889 1.6657605276356036 ... 0.0 0.0 0.0]] at 0x7fcd5acb0950>
>>> f.events.tracks.E[12]
array([ 4.19391543, 15.3079374 , 10.47125863, ..., 0. ,
0. , 0. ])
>>> f.events.tracks.dir_z
<ChunkedArray [[0.7855203887479368 0.7855203887479368 0.7855203887479368 ... -0.5680647731737454 1.0 1.0] [0.9759269228630431 0.2677622006758061 -0.06664626796127045 ... -2.3205103555187022e-08 1.0 1.0] [-0.12332041078454238 0.09537382569575953 0.09345521875272474 ... -0.6631226836266504 -0.6631226836266504 -0.6631226836266504] ... [-0.1396584943602339 -0.08400681020109765 -0.014562067998281832 ... 1.0 1.0 1.0] [0.011997491147399564 -0.08496327394947281 -0.12675279061755318 ... 0.12053665899140412 1.0 1.0] [0.6548114607791208 0.8115427935470209 0.9043563059276946 ... 1.0 1.0 1.0]] at 0x7fcd73746410>
>>> f.events.tracks.dir_z[12]
array([ 2.39745910e-01, 3.45008838e-01, 4.81870447e-01, 4.55139657e-01, ...,
-2.32051036e-08, 1.00000000e+00])Since reconstruction stages can be done multiple times and events can have multiple reconstructions, the vectors of reconstructed values can have variable length. Other data members like the header are always the same size. The definitions of data members can be found in the definitions folder. The definitions contain fit parameters, header information, reconstruction information, generator output and can be expaneded to include more.
To use the definitions imagine the following: the user wants to read out the MC value of the Bjorken-Y of event 12 that was generated with gSeaGen. This can be found in the gSeaGen definitions: "W2LIST_GSEAGEN_BY": 8,
This value is saved into w2list, so if an event is generated with gSeaGen the value can be fetched like:
>>> f.events.w2list[12][8]
0.393755Note that w2list can also contain other values if the event is generated with another generator.