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

.. only:: html

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

        Click :ref:`here <sphx_glr_download_gallery_southern-africa-gravity.py>`
        to download the full example code

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

.. _sphx_glr_gallery_southern-africa-gravity.py:


Gravity ground-based surveys of Southern Africa
-----------------------------------------------

This dataset is a compilation of several public domain ground measurements
of gravity from Southern Africa. The observations are the absolute gravity
values in mGal. The horizontal datum is not specified and heights are
referenced to "sea level", which we will interpret as the geoid (which
realization is likely not relevant since the uncertainty in the height is
probably larger than geoid model differences).

**Original source:** `NOAA NCEI
<https://ngdc.noaa.gov/mgg/geodas/trackline.html>`__

**Pre-processing:** `Source code for preparation of the original dataset for
redistribution in Ensaio
<https://github.com/fatiando-data/southern-africa-gravity>`__

.. GENERATED FROM PYTHON SOURCE LINES 25-30

.. code-block:: default

    import pandas as pd
    import pygmt

    import ensaio








.. GENERATED FROM PYTHON SOURCE LINES 31-32

Download and cache the data and return the path to it on disk

.. GENERATED FROM PYTHON SOURCE LINES 32-35

.. code-block:: default

    fname = ensaio.fetch_southern_africa_gravity(version=1)
    print(fname)





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

 Out:

 .. code-block:: none

    /home/runner/work/_temp/cache/ensaio/v1/southern-africa-gravity.csv.xz




.. GENERATED FROM PYTHON SOURCE LINES 36-37

Load the CSV formatted data with pandas

.. GENERATED FROM PYTHON SOURCE LINES 37-40

.. code-block:: default

    data = pd.read_csv(fname)
    data






.. raw:: html

    <div class="output_subarea output_html rendered_html output_result">
    <div>
    <style scoped>
        .dataframe tbody tr th:only-of-type {
            vertical-align: middle;
        }

        .dataframe tbody tr th {
            vertical-align: top;
        }

        .dataframe thead th {
            text-align: right;
        }
    </style>
    <table border="1" class="dataframe">
      <thead>
        <tr style="text-align: right;">
          <th></th>
          <th>longitude</th>
          <th>latitude</th>
          <th>height_sea_level_m</th>
          <th>gravity_mgal</th>
        </tr>
      </thead>
      <tbody>
        <tr>
          <th>0</th>
          <td>18.34444</td>
          <td>-34.12971</td>
          <td>32.2</td>
          <td>979656.12</td>
        </tr>
        <tr>
          <th>1</th>
          <td>18.36028</td>
          <td>-34.08833</td>
          <td>592.5</td>
          <td>979508.21</td>
        </tr>
        <tr>
          <th>2</th>
          <td>18.37418</td>
          <td>-34.19583</td>
          <td>18.4</td>
          <td>979666.46</td>
        </tr>
        <tr>
          <th>3</th>
          <td>18.40388</td>
          <td>-34.23972</td>
          <td>25.0</td>
          <td>979671.03</td>
        </tr>
        <tr>
          <th>4</th>
          <td>18.41112</td>
          <td>-34.16444</td>
          <td>228.7</td>
          <td>979616.11</td>
        </tr>
        <tr>
          <th>...</th>
          <td>...</td>
          <td>...</td>
          <td>...</td>
          <td>...</td>
        </tr>
        <tr>
          <th>14354</th>
          <td>21.22500</td>
          <td>-17.95833</td>
          <td>1053.1</td>
          <td>978182.09</td>
        </tr>
        <tr>
          <th>14355</th>
          <td>21.27500</td>
          <td>-17.98333</td>
          <td>1033.3</td>
          <td>978183.09</td>
        </tr>
        <tr>
          <th>14356</th>
          <td>21.70833</td>
          <td>-17.99166</td>
          <td>1041.8</td>
          <td>978182.69</td>
        </tr>
        <tr>
          <th>14357</th>
          <td>21.85000</td>
          <td>-17.95833</td>
          <td>1033.3</td>
          <td>978193.18</td>
        </tr>
        <tr>
          <th>14358</th>
          <td>21.98333</td>
          <td>-17.94166</td>
          <td>1022.6</td>
          <td>978211.38</td>
        </tr>
      </tbody>
    </table>
    <p>14359 rows × 4 columns</p>
    </div>
    </div>
    <br />
    <br />

.. GENERATED FROM PYTHON SOURCE LINES 41-42

Make a PyGMT map with the data points colored by the gravity data.

.. GENERATED FROM PYTHON SOURCE LINES 42-64

.. code-block:: default

    fig = pygmt.Figure()
    fig.basemap(
        region=[
            data.longitude.min() - 1,
            data.longitude.max() + 1,
            data.latitude.min() - 1,
            data.latitude.max() + 1,
        ],
        projection="M15c",
        frame=True,
    )
    pygmt.makecpt(cmap="viridis", series=[data.gravity_mgal.min(), data.gravity_mgal.max()])
    fig.plot(
        x=data.longitude,
        y=data.latitude,
        color=data.gravity_mgal,
        cmap=True,
        style="c0.05c",
    )
    fig.colorbar(frame='af+l"gravity [mGal]"')
    fig.coast(shorelines=True, water="royalblue4", area_thresh=1e4)
    fig.show()



.. image-sg:: /gallery/images/sphx_glr_southern-africa-gravity_001.png
   :alt: southern africa gravity
   :srcset: /gallery/images/sphx_glr_southern-africa-gravity_001.png
   :class: sphx-glr-single-img


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

 Out:

 .. code-block:: none

    <IPython.core.display.Image object>





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

   **Total running time of the script:** ( 0 minutes  6.476 seconds)


.. _sphx_glr_download_gallery_southern-africa-gravity.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: southern-africa-gravity.py <southern-africa-gravity.py>`



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

     :download:`Download Jupyter notebook: southern-africa-gravity.ipynb <southern-africa-gravity.ipynb>`


.. only:: html

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

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