.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "python_module/02_eddy_identification/pet_radius_vs_area.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

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

        :ref:`Go to the end <sphx_glr_download_python_module_02_eddy_identification_pet_radius_vs_area.py>`
        to download the full example code. or to run this example in your browser via Binder

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

.. _sphx_glr_python_module_02_eddy_identification_pet_radius_vs_area.py:


Radius vs area
==============

.. GENERATED FROM PYTHON SOURCE LINES 6-14

.. code-block:: Python

    from matplotlib import pyplot as plt
    from numpy import array, pi

    from py_eddy_tracker import data
    from py_eddy_tracker.generic import coordinates_to_local
    from py_eddy_tracker.observations.observation import EddiesObservations
    from py_eddy_tracker.poly import poly_area








.. GENERATED FROM PYTHON SOURCE LINES 15-16

Load detection files

.. GENERATED FROM PYTHON SOURCE LINES 16-26

.. code-block:: Python

    a = EddiesObservations.load_file(data.get_demo_path("Anticyclonic_20190223.nc"))
    areas = list()
    # For each contour area will be compute in local reference
    for i in a:
        x, y = coordinates_to_local(
            i["contour_lon_s"], i["contour_lat_s"], i["lon"], i["lat"]
        )
        areas.append(poly_area(x, y))
    areas = array(areas)








.. GENERATED FROM PYTHON SOURCE LINES 27-29

Radius provided by eddy detection is computed with :func:`~py_eddy_tracker.poly.fit_circle` method.
This radius will be compared with an equivalent radius deduced from polygon area.

.. GENERATED FROM PYTHON SOURCE LINES 29-38

.. code-block:: Python

    ax = plt.subplot(111)
    ax.set_aspect("equal")
    ax.grid()
    ax.set_xlabel("Speed radius computed with fit_circle")
    ax.set_ylabel("Radius deduced from area\nof contour_lon_s/contour_lat_s")
    ax.set_title("Area vs radius")
    ax.plot(a["radius_s"] / 1000.0, (areas / pi) ** 0.5 / 1000.0, ".")
    ax.plot((0, 250), (0, 250), "r")




.. image-sg:: /python_module/02_eddy_identification/images/sphx_glr_pet_radius_vs_area_001.png
   :alt: Area vs radius
   :srcset: /python_module/02_eddy_identification/images/sphx_glr_pet_radius_vs_area_001.png
   :class: sphx-glr-single-img


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

 .. code-block:: none


    [<matplotlib.lines.Line2D object at 0x74903cb99730>]



.. GENERATED FROM PYTHON SOURCE LINES 39-40

Fit circle give a radius bigger than polygon area

.. GENERATED FROM PYTHON SOURCE LINES 42-43

When error is tiny, radius are very close.

.. GENERATED FROM PYTHON SOURCE LINES 43-49

.. code-block:: Python

    ax = plt.subplot(111)
    ax.grid()
    ax.set_xlabel("Radius ratio")
    ax.set_ylabel("Shape error")
    ax.set_title("err = f(radius_ratio)")
    ax.plot(a["radius_s"] / (areas / pi) ** 0.5, a["shape_error_s"], ".")



.. image-sg:: /python_module/02_eddy_identification/images/sphx_glr_pet_radius_vs_area_002.png
   :alt: err = f(radius_ratio)
   :srcset: /python_module/02_eddy_identification/images/sphx_glr_pet_radius_vs_area_002.png
   :class: sphx-glr-single-img


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

 .. code-block:: none


    [<matplotlib.lines.Line2D object at 0x74904187e0c0>]




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

   **Total running time of the script:** (0 minutes 0.435 seconds)


.. _sphx_glr_download_python_module_02_eddy_identification_pet_radius_vs_area.py:

.. only:: html

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

    .. container:: binder-badge

      .. image:: images/binder_badge_logo.svg
        :target: https://mybinder.org/v2/gh/AntSimi/py-eddy-tracker/master?urlpath=lab/tree/notebooks/python_module/02_eddy_identification/pet_radius_vs_area.ipynb
        :alt: Launch binder
        :width: 150 px

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

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

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

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

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

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


.. only:: html

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

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