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

.. only:: html

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

        Click :ref:`here <sphx_glr_download_gallery_distance_mask.py>`
        to download the full example code

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

.. _sphx_glr_gallery_distance_mask.py:


Mask grid points by distance
============================

Sometimes, data points are unevenly distributed. In such cases, we might not
want to have interpolated grid points that are too far from any data point.
Function :func:`verde.distance_mask` allows us to set such points to NaN or
some other value.

.. GENERATED FROM PYTHON SOURCE LINES 16-60



.. image-sg:: /gallery/images/sphx_glr_distance_mask_001.png
   :alt: Only keep grid points that are close to data
   :srcset: /gallery/images/sphx_glr_distance_mask_001.png
   :class: sphx-glr-single-img


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

 Out:

 .. code-block:: none

    [[ True  True  True ...  True  True  True]
     [ True  True  True ...  True  True  True]
     [ True  True  True ...  True  True  True]
     ...
     [False False False ... False False False]
     [False False False ... False False False]
     [False False False ... False False False]]
    /home/runner/work/verde/verde/doc/gallery_src/distance_mask.py:58: UserWarning: All kwargs are being ignored. They are accepted to guarantee backward compatibility.
      vd.datasets.setup_baja_bathymetry_map(ax, land=None)






|

.. code-block:: default

    import cartopy.crs as ccrs
    import matplotlib.pyplot as plt
    import numpy as np
    import pyproj

    import verde as vd

    # The Baja California bathymetry dataset has big gaps on land. We want to mask
    # these gaps on a dummy grid that we'll generate over the region.
    data = vd.datasets.fetch_baja_bathymetry()
    region = vd.get_region((data.longitude, data.latitude))

    # Generate the coordinates for a regular grid mask
    spacing = 10 / 60
    coordinates = vd.grid_coordinates(region, spacing=spacing)

    # Generate a mask for points that are more than 2 grid spacings away from any
    # data point. The mask is True for points that are within the maximum distance.
    # Distance calculations in the mask are Cartesian only. We can provide a
    # projection function to convert the coordinates before distances are
    # calculated (Mercator in this case). In this case, the maximum distance is
    # also Cartesian and must be converted from degrees to meters.
    mask = vd.distance_mask(
        (data.longitude, data.latitude),
        maxdist=spacing * 2 * 111e3,
        coordinates=coordinates,
        projection=pyproj.Proj(proj="merc", lat_ts=data.latitude.mean()),
    )
    print(mask)

    # Create a dummy grid with ones that we can mask to show the results.
    # Turn points that are too far into NaNs so they won't show up in our plot.
    dummy_data = np.ones_like(coordinates[0])
    dummy_data[~mask] = np.nan

    # Make a plot of the masked data and the data locations.
    crs = ccrs.PlateCarree()
    plt.figure(figsize=(7, 6))
    ax = plt.axes(projection=ccrs.Mercator())
    ax.set_title("Only keep grid points that are close to data")
    ax.plot(data.longitude, data.latitude, ".y", markersize=0.5, transform=crs)
    ax.pcolormesh(*coordinates, dummy_data, transform=crs)
    vd.datasets.setup_baja_bathymetry_map(ax, land=None)
    plt.show()


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

   **Total running time of the script:** ( 0 minutes  3.358 seconds)


.. _sphx_glr_download_gallery_distance_mask.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: distance_mask.py <distance_mask.py>`



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

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


.. only:: html

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

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