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Python read-only implementation of the EventIO file format

Project description

pyeventio |Build Status|
========================

A Python (read-only) implementation of the EventIO data format invented
by Konrad Bernloehr as used for example by the IACT extension for
CORSIKA: https://www.ikp.kit.edu/corsika

Reading the data of the following Objects is currently supported:

+--------+-------------------------------+
| Code | Description |
+========+===============================+
| 1200 | CORSIKA Run Header |
+--------+-------------------------------+
| 1201 | CORSIKA Telescope Positions |
+--------+-------------------------------+
| 1202 | CORSIKA Event Header |
+--------+-------------------------------+
| 1203 | CORSIKA Array Offsets |
+--------+-------------------------------+
| 1204 | CORSIKA Telescope Data |
+--------+-------------------------------+
| 1205 | IACT Photons |
+--------+-------------------------------+
| 1209 | CORSIKA Event End Block |
+--------+-------------------------------+
| 1210 | CORSIKA Run End Block |
+--------+-------------------------------+
| 1211 | CORSIKA Longitudinal Block |
+--------+-------------------------------+
| 1212 | CORSIKA Input Card |
+--------+-------------------------------+

The following blocks are known, but reading their data is not (yet)
implemented:

+--------+-----------------------+
| Code | Description |
+========+=======================+
| 1206 | IACT Layout |
+--------+-----------------------+
| 1207 | IACT Trigger Time |
+--------+-----------------------+
| 1208 | IACT PhotoElectrons |
+--------+-----------------------+

install with
------------

::

pip install eventio

Open a file produced by the IACT CORSIKA extension
--------------------------------------------------

First Example
~~~~~~~~~~~~~

One may iterate over an instance of ``IACTFile`` class in order to
retrieve events. Events have a small number of fields. The most
important one is the ``photon_bunches`` field, which is dictionary
mapping telescope ids to a simple structured ``np.array``, containing
the typical parameters Cherekov photons bunches in Corsika have, like:

- ``x``, ``y`` coordinate in the observation plane (in cm)
- direction cosine ``cx``, ``cy`` in x and y direction of the incident
angle of the photon
- wavelength ``lambda`` of the photon (in nm)
- number of ``photons`` associated with this bunch
- the ``time`` since the first interaction (in ns, I believe)
- the production height of the photon bunch (called ``zem``)
- a bool flag, whether the photon was scattered in the atmosphere

An event has the following attributes: \* ``header``: a dictionary
containing the Corsika Event Header data \* ``end_block``: a numpy array
containing the Corsika Event End data \* ``time_offset``, ``x_offset``,
``y_offsett``, the offset of the array

This prints the number of photons for the first telescope in every
event:

.. code:: {python}

import eventio

with eventio.IACTFile('data/telescope.dat') as f:
for event in f:
print(event.photon_buches[0]['photons'].sum())

Second Example
~~~~~~~~~~~~~~

If you like to plot the origin of the Cherenkov photons of the first
event in file ``data/telescope.dat`` for the first telescope, have a
look into `this
example <https://github.com/fact-project/pyeventio/blob/new_api/examples/plot_production_3d.py>`__

It might look similar to this picture:

.. figure:: https://raw.githubusercontent.com/fact-project/pyeventio/master/a_shower.png
:alt: an example shower

an example shower

Low level access
----------------

For more low level access to the items of an ``EventIO`` file (or to
implement a higher level abstraction like ``IACTFile``) one can use the
``EventIOFile`` class which gives access to the ``Objects`` and
``subitems`` in ``EventIO`` files.

This is how our test file looks like in the low level view:

::

In [1]: import eventio

In [2]: eventio.EventIOFile('eventio/resources/one_shower.dat')
Out[2]:
EventIOFile(path=eventio/resources/one_shower.dat, objects=[
CorsikaRunHeader(first=0, length=1096)
CorsikaInputCard(first=1112, length=448)
CorsikaTelescopeDefinition(first=1576, length=20)
CorsikaEventHeader(first=1612, length=1096)
CorsikaArrayOffsets(first=2724, length=16)
CorsikaTelescopeData(first=2756, length=6136, subitems=1)
CorsikaEventEndBlock(first=8908, length=1096)
CorsikaRunEndBlock(first=10020, length=16)
])

And this is how a ``sim_telarray`` file looks like (sim\_telarray
objects are not implemted yet):

::

In [3]: eventio.EventIOFile('gamma_test.simtel')
Out[3]:
EventIOFile(path=../../CTA/ctapipe/ctapipe-extra/datasets/gamma_test.simtel, objects=[
UnknownObject[70](first=0, length=11960, subitems=131)
UnknownObject[70](first=11976, length=1744732, subitems=21526)
UnknownObject[70](first=1756724, length=838000, subitems=11186)
UnknownObject[2000](first=2594740, length=1876)
...
UnknownObject[2010](first=50007852, length=1782080, subitems=19)
UnknownObject[2021](first=51789948, length=12)
UnknownObject[2026](first=51789976, length=3536)
UnknownObject[2010](first=51793528, length=1560656, subitems=9)
])

.. |Build Status| image:: https://travis-ci.org/fact-project/pyeventio.svg?branch=master
:target: https://travis-ci.org/fact-project/pyeventio

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