.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "auto_examples/tutorials/theta_square.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_auto_examples_tutorials_theta_square.py>`
        to download the full example code.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_auto_examples_tutorials_theta_square.py:


Make a theta-square plot
========================

This is a basic example to analyze some events and make a
:math:`\Theta^2` plot

.. GENERATED FROM PYTHON SOURCE LINES 9-23

.. code-block:: Python
   :lineno-start: 10


    # %matplotlib inline

    import matplotlib.pyplot as plt
    import numpy as np
    from astropy import units as u
    from astropy.coordinates import angular_separation
    from tqdm.auto import tqdm

    from ctapipe.calib import CameraCalibrator
    from ctapipe.image import ImageProcessor
    from ctapipe.io import EventSource
    from ctapipe.reco import ShowerProcessor








.. GENERATED FROM PYTHON SOURCE LINES 24-26

Get source events in MC dataset.


.. GENERATED FROM PYTHON SOURCE LINES 26-59

.. code-block:: Python
   :lineno-start: 27


    source = EventSource(
        "dataset://gamma_prod5.simtel.zst",
        #     allowed_tels={1, 2, 3, 4},
    )

    subarray = source.subarray

    calib = CameraCalibrator(subarray=subarray)
    image_processor = ImageProcessor(subarray=subarray)
    shower_processor = ShowerProcessor(subarray=subarray)

    off_angles = []

    for event in tqdm(source):
        # calibrating the event
        calib(event)
        image_processor(event)
        shower_processor(event)

        reco_result = event.dl2.stereo.geometry["HillasReconstructor"]

        # get angular offset between reconstructed shower direction and MC
        # generated shower direction
        true_shower = event.simulation.shower
        off_angle = angular_separation(
            true_shower.az, true_shower.alt, reco_result.az, reco_result.alt
        )

        # Appending all estimated off angles
        off_angles.append(off_angle.to(u.deg).value)






.. rst-class:: sphx-glr-script-out

 .. code-block:: none


    0it [00:00, ?it/s]
    2it [00:00,  8.49it/s]
    4it [00:00,  9.62it/s]
    5it [00:00,  6.05it/s]
    7it [00:00,  8.43it/s]
    7it [00:00,  8.07it/s]




.. GENERATED FROM PYTHON SOURCE LINES 60-62

calculate theta square for angles which are not nan


.. GENERATED FROM PYTHON SOURCE LINES 62-67

.. code-block:: Python
   :lineno-start: 63


    off_angles = np.array(off_angles)
    thetasquare = off_angles[np.isfinite(off_angles)] ** 2









.. GENERATED FROM PYTHON SOURCE LINES 68-71

Plot the results
----------------


.. GENERATED FROM PYTHON SOURCE LINES 71-76

.. code-block:: Python
   :lineno-start: 72


    plt.hist(thetasquare, bins=10, range=[0, 0.4])
    plt.xlabel(r"$\theta^2$ (deg)")
    plt.ylabel("# of events")
    plt.show()



.. image-sg:: /auto_examples/tutorials/images/sphx_glr_theta_square_001.png
   :alt: theta square
   :srcset: /auto_examples/tutorials/images/sphx_glr_theta_square_001.png
   :class: sphx-glr-single-img






.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 2.641 seconds)


.. _sphx_glr_download_auto_examples_tutorials_theta_square.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: theta_square.ipynb <theta_square.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: theta_square.py <theta_square.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: theta_square.zip <theta_square.zip>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_