.. only:: html

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

        Click :ref:`here <sphx_glr_download_auto_examples_plot_longitude_slices.py>`     to download the full example code
    .. rst-class:: sphx-glr-example-title

    .. _sphx_glr_auto_examples_plot_longitude_slices.py:


Plotting constant longitude slices
==================================

This example shows how to plot slices of constant longitude from a MAS model
output.

First, load the required modules.


.. code-block:: default

    from psipy.model import MASOutput
    import matplotlib.pyplot as plt








Next, load a set of MAS output files. You will need to change this line to
point to a folder with MAS files in them.


.. code-block:: default

    mas_path = '/Users/dstansby/github/psipy/data/helio'
    model = MASOutput(mas_path)








Each MAS model contains a number of variables. The variable names can be
accessed using the ``.variables`` attribute.


.. code-block:: default

    print(model.variables)





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

 Out:

 .. code-block:: none

    ['p', 't', 'va', 'br', 'vp', 'jp', 'jr', 'bp', 'vr', 'bt', 'vt', 'rho', 'jt']




Set parameters for plotting. The first line will give us a horizontal
errorbar underneath the plots. The second line is the index to select for the
longitude slice.


.. code-block:: default

    cbar_kwargs = {'orientation': 'horizontal'}
    phi_idx = 40








Plot the slices

Note that for density (rho) and pressure (p) we first normalise the data
relative to a power law decrease, to make it easer to see spatial variations.


.. code-block:: default

    fig = plt.figure()
    axs = [plt.subplot(1, 3, i + 1, projection='polar') for i in range(3)]

    ax = axs[0]
    model['vr'].plot_phi_cut(phi_idx, ax=ax, cbar_kwargs=cbar_kwargs)

    ax = axs[1]
    rho = model['rho']
    rho_r2 = rho.radial_normalized(2)
    rho_r2.plot_phi_cut(phi_idx, ax=ax, cbar_kwargs=cbar_kwargs)

    ax = axs[2]
    p = model['p']
    p_r3 = p.radial_normalized(3)
    p_r3.plot_phi_cut(phi_idx, ax=ax, cbar_kwargs=cbar_kwargs)


    # Add a contour of br = 0 (the heliopsheric current sheet) to all the axes
    for ax in axs:
        model['br'].contour_phi_cut(phi_idx, levels=[0], ax=ax,
                                    colors='white', linestyles='--', linewidths=1)

    plt.show()



.. image:: /auto_examples/images/sphx_glr_plot_longitude_slices_001.png
    :alt: vr, $\phi$= 112.50$^{\circ}$, rho $r^2$, $\phi$= 112.50$^{\circ}$, p $r^3$, $\phi$= 112.50$^{\circ}$
    :class: sphx-glr-single-img






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

   **Total running time of the script:** ( 0 minutes  1.434 seconds)


.. _sphx_glr_download_auto_examples_plot_longitude_slices.py:


.. only :: html

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



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

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



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

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


.. only:: html

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

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