.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "examples/plot_01_random_surface_sampling.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

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

        :ref:`Go to the end <sphx_glr_download_examples_plot_01_random_surface_sampling.py>`
        to download the full example code.

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

.. _sphx_glr_examples_plot_01_random_surface_sampling.py:


.. _random_surface_sampling_example:

Random Surface Sampling
~~~~~~~~~~~~~~~~~~~~~~~

Random points on a dataset of antarctica are sampled uniformly within the area
of the mesh.

.. GENERATED FROM PYTHON SOURCE LINES 10-19

.. code-block:: Python


    import numpy as np
    import pyvista as pv
    from pyvista import examples

    import pyransame

    antarctica = examples.download_antarctica_velocity()








.. GENERATED FROM PYTHON SOURCE LINES 20-22

The units of this mesh are in meters, which causes plotting issues
over an entire continent.  So the units are first converted to kilometers.

.. GENERATED FROM PYTHON SOURCE LINES 22-25

.. code-block:: Python


    antarctica.points /= 1000.0  # convert to kilometers








.. GENERATED FROM PYTHON SOURCE LINES 26-27

sample 500 points uniformly randomly.

.. GENERATED FROM PYTHON SOURCE LINES 27-31

.. code-block:: Python


    points = pyransame.random_surface_dataset(antarctica, 500)
    points






.. raw:: html

    <div class="output_subarea output_html rendered_html output_result">
    <table style='width: 100%;'><tr><th>Header</th><th>Data Arrays</th></tr><tr><td>
    <table style='width: 100%;'>
    <tr><th>PolyData</th><th>Information</th></tr>
    <tr><td>N Cells</td><td>500</td></tr>
    <tr><td>N Points</td><td>500</td></tr>
    <tr><td>N Strips</td><td>0</td></tr>
    <tr><td>X Bounds</td><td>-2.453e+03, 2.463e+03</td></tr>
    <tr><td>Y Bounds</td><td>-2.126e+03, 2.157e+03</td></tr>
    <tr><td>Z Bounds</td><td>0.000e+00, 0.000e+00</td></tr>
    <tr><td>N Arrays</td><td>5</td></tr>
    </table>

    </td><td>
    <table style='width: 100%;'>
    <tr><th>Name</th><th>Field</th><th>Type</th><th>N Comp</th><th>Min</th><th>Max</th></tr>
    <tr><td>node_value</td><td>Points</td><td>int64</td><td>1</td><td>0.000e+00</td><td>2.300e+01</td></tr>
    <tr><td><b>ssavelocity</b></td><td>Points</td><td>float64</td><td>3</td><td>-8.487e+02</td><td>1.208e+03</td></tr>
    <tr><td>vtkValidPointMask</td><td>Points</td><td>int8</td><td>1</td><td>1.000e+00</td><td>1.000e+00</td></tr>
    <tr><td>vtkGhostType</td><td>Points</td><td>uint8</td><td>1</td><td>0.000e+00</td><td>0.000e+00</td></tr>
    <tr><td>vtkGhostType</td><td>Cells</td><td>uint8</td><td>1</td><td>0.000e+00</td><td>0.000e+00</td></tr>
    </table>

    </td></tr> </table>
    </div>
    <br />
    <br />

.. GENERATED FROM PYTHON SOURCE LINES 32-36

:func:`pyransame.random_surface_dataset` returns a `pyvista.PolyData` object
containing 500 points (and 500 corresponding vertex cells).  The cell and
point data is also sampled onto ``points``. Each randomly sampled point is
plotted as a sphere with radius 50 km and colored by ``ssavelocity``.

.. GENERATED FROM PYTHON SOURCE LINES 36-44

.. code-block:: Python


    pl = pv.Plotter()
    pl.add_mesh(antarctica, color="tan")
    spheres = points.glyph(geom=pv.Sphere(radius=50), scale=False, orient=False)
    pl.add_mesh(spheres, scalars="ssavelocity", clim=[0, 750])
    pl.view_xy()
    pl.show()








.. tab-set::



   .. tab-item:: Static Scene



            
     .. image-sg:: /examples/images/sphx_glr_plot_01_random_surface_sampling_001.png
        :alt: plot 01 random surface sampling
        :srcset: /examples/images/sphx_glr_plot_01_random_surface_sampling_001.png
        :class: sphx-glr-single-img
     


   .. tab-item:: Interactive Scene



       .. offlineviewer:: /home/runner/work/pyransame/pyransame/doc/examples/images/sphx_glr_plot_01_random_surface_sampling_001.vtksz






.. GENERATED FROM PYTHON SOURCE LINES 45-52

Comparison to sampling mesh points
----------------------------------
A different approach to sampling is to select random mesh points that define
the topology of the mesh.  This approach does not lead to effective uniform
sampling of mesh area (or length/volume as applicable), which will be
demonstrated in this example. The area of each cell is stored first, which will
be useful for explaining the later results.

.. GENERATED FROM PYTHON SOURCE LINES 52-55

.. code-block:: Python


    antarctica = antarctica.compute_cell_sizes()








.. GENERATED FROM PYTHON SOURCE LINES 56-57

Sample 500 random vertices that define the cells.

.. GENERATED FROM PYTHON SOURCE LINES 57-60

.. code-block:: Python


    vertices = np.random.default_rng().choice(antarctica.points, 500)








.. GENERATED FROM PYTHON SOURCE LINES 61-64

Plot the mesh colored by area of each cell.  Plot the location of each point.
Note that these points do not have sampled data in this case, so color them
red.

.. GENERATED FROM PYTHON SOURCE LINES 64-72

.. code-block:: Python


    pl = pv.Plotter()
    pl.add_mesh(antarctica, scalars="Area")
    spheres = pv.wrap(vertices).glyph(geom=pv.Sphere(radius=50), scale=False, orient=False)
    pl.add_mesh(spheres, color="red")
    pl.view_xy()
    pl.show()








.. tab-set::



   .. tab-item:: Static Scene



            
     .. image-sg:: /examples/images/sphx_glr_plot_01_random_surface_sampling_002.png
        :alt: plot 01 random surface sampling
        :srcset: /examples/images/sphx_glr_plot_01_random_surface_sampling_002.png
        :class: sphx-glr-single-img
     


   .. tab-item:: Interactive Scene



       .. offlineviewer:: /home/runner/work/pyransame/pyransame/doc/examples/images/sphx_glr_plot_01_random_surface_sampling_002.vtksz






.. GENERATED FROM PYTHON SOURCE LINES 73-78

The sampled points are not uniformly sampled on the area of the mesh.  The
points are clustered in regions that have small cell sizes, i.e. there is
a higher density of mesh points that define the cells.  ``pyransame``
does not use this approach and instead samples the space uniformly randomly
with respect to the area of the mesh.


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

   **Total running time of the script:** (0 minutes 19.782 seconds)


.. _sphx_glr_download_examples_plot_01_random_surface_sampling.py:

.. only:: html

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

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

      :download:`Download Jupyter notebook: plot_01_random_surface_sampling.ipynb <plot_01_random_surface_sampling.ipynb>`

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

      :download:`Download Python source code: plot_01_random_surface_sampling.py <plot_01_random_surface_sampling.py>`


.. only:: html

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

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