Adding a New Gallery Example

This example demonstrates how to add a new PyVista Sphinx Gallery example as well as being a template that can be used in their creation.

Each example should have a reference tag/key in the form:

.. _<example-name>_example:

The .. _ is necessary. Everything that follows is your reference tag, which can potentially be used within a docstring. As convention, we keep all references all in snake_case.

This section should give a brief overview of what the example is about and/or demonstrates. The title should be changed to reflect the topic your example covers.

New examples should be added as python scripts to:

examples/<index>-<directory-name>/<some-example>.py

Note

Avoid creating new directories unless absolutely necessary.If you must create a new folder, make sure to add a README.txt containing a reference, a title and a single sentence description of the folder. Otherwise the new folder will be ignored by Sphinx.

Example file names should be hyphen separated snake case:

some-example.py

After this preamble is complete, the first code block begins. This is where you typically set up your imports.

import pyvista as pv
from pyvista import examples

Section Title

Code blocks can be broken up with text “sections” which are interpreted as restructured text.

This will also be translated into a markdown cell in the generated jupyter notebook or the HTML page.

Sections can contain any information you may have regarding the example such as step-by-step comments or notes regarding motivations etc.

As in Jupyter notebooks, if a statement is unassigned at the end of a code block, output will be generated and printed to the screen according to its __repr__ method. Otherwise, you can use print() to output text.

# Create a dataset and exercise it's repr method
dataset = pv.Sphere()
dataset

Header	Data Arrays
PolyData Information N Cells 1680 N Points 842 N Strips 0 X Bounds -4.993e-01, 4.993e-01 Y Bounds -4.965e-01, 4.965e-01 Z Bounds -5.000e-01, 5.000e-01 N Arrays 1	Name Field Type N Comp Min Max Normals Points float32 3 -1.000e+00 1.000e+00

Plots and images

If you use anything that outputs an image (for example, pyvista.Plotter.show()) the resulting image will be rendered within the output HTML.

Note

Unless sphinx_gallery_thumbnail_number = <int> is included at the top of the example script, first figure (this one) will be used for the gallery thumbnail image.

Also note that this image number uses one based indexing.

dataset.plot(text='Example Figure')

Caveat - Plotter must be within One Cell

It’s not possible for a single pyvista.Plotter object across multiple cells because these are closed out automatically at the end of a cell.

Here we just exercise the pyvista.Actor repr for demonstrating why you might want to instantiate a plotter without showing it in the same cell.

pl = pv.Plotter()
actor = pl.add_mesh(dataset)
actor

Actor (0x7f317d67c700)
  Center:                     (0.0, 0.0, 0.0)
  Pickable:                   True
  Position:                   (0.0, 0.0, 0.0)
  Scale:                      (1.0, 1.0, 1.0)
  Visible:                    True
  X Bounds                    -4.993E-01, 4.993E-01
  Y Bounds                    -4.965E-01, 4.965E-01
  Z Bounds                    -5.000E-01, 5.000E-01
  User matrix:                Unset
  Has mapper:                 True

Property (0x7f317d67c5e0)
  Ambient:                     0.0
  Ambient color:               Color(name='tan', hex='#d2b48cff', opacity=255)
  Anisotropy:                  0.0
  Color:                       Color(name='tan', hex='#d2b48cff', opacity=255)
  Culling:                     "none"
  Diffuse:                     1.0
  Diffuse color:               Color(name='tan', hex='#d2b48cff', opacity=255)
  Edge color:                  Color(name='black', hex='#000000ff', opacity=255)
  Interpolation:               0
  Lighting:                    True
  Line width:                  1.0
  Metallic:                    0.0
  Opacity:                     1.0
  Point size:                  5.0
  Render lines as tubes:       False
  Render points as spheres:    False
  Roughness:                   0.5
  Show edges:                  False
  Specular:                    0.0
  Specular color:              Color(name='tan', hex='#d2b48cff', opacity=255)
  Specular power:              100.0
  Style:                       "Surface"

DataSetMapper (0x7f317d67c5e0)
  Scalar visibility:           False
  Scalar range:                (0.0, 1.0)
  Interpolate before mapping:  True
  Scalar map mode:             default
  Color mode:                  direct

Attached dataset:
PolyData (0x7f3116c20c40)
  N Cells:    1680
  N Points:   842
  N Strips:   0
  X Bounds:   -4.993e-01, 4.993e-01
  Y Bounds:   -4.965e-01, 4.965e-01
  Z Bounds:   -5.000e-01, 5.000e-01
  N Arrays:   1

This Cell Cannot Run the Plotter

The plotter will already be closed by sphinx_gallery.

# This cannot be run here because the plotter is already closed and would raise
# an error:
# >>> pl.show()

# You can, however, close out the plotter or access other attributes.
pl.close()

Animations

You can even create animations, and while there is a full example in Create a MP4 Movie, this cell explains how you can create an animation within a single cell.

Here, we explode a simple sphere.

pl = pv.Plotter(off_screen=True)

# optimize for size
pl.open_gif('example_movie.gif', palettesize=16)

sphere = pv.Sphere(theta_resolution=10, phi_resolution=10)

# Add initial mesh to setup the camera
actor = pl.add_mesh(sphere)
pl.background_color = 'w'

# clear and overwrite the mesh on each frame
n_frames = 20
for i in range(n_frames):
    exploded = sphere.explode(factor=i / (n_frames * 2)).extract_surface()
    actor.mapper.dataset.copy_from(exploded)
    pl.camera.reset_clipping_range()
    pl.write_frame()  # Write this frame

# Be sure to close the plotter when finished
pl.close()

Adding Example Files

PyVista has a variety of example files all stored at pyvista/vtk_data, and you can add the file by following the directions there.

Under the hood, PyVista uses pooch, and you can easily access any files added with pyvista.examples.downloads.download_file().

filename = examples.download_file('bunny.ply')
filename

'/home/runner/.cache/pyvista_3/bunny.ply'

Adding a Wrapped Example

While it’s possible to simply download a file and then read it in, it’s better for you to write a wrapped download_<example-dataset>() within /pyvista/examples/downloads.py. For example download_bunny() downloads and reads with pyvista.read().

If you intend on adding an example file, you should add a new function in downloads.py to make it easy for users to add example files.

dataset = examples.download_bunny()
dataset


# Making a Pull Request
# ~~~~~~~~~~~~~~~~~~~~~
# Once your example is complete and you've verified it builds locally, you can
# make a pull request (PR).
#
# Branches containing examples should be prefixed with `docs/` as per the branch
# naming conventions found in out `Contributing Guidelines
# <https://github.com/pyvista/pyvista/blob/main/CONTRIBUTING.rst>`_.
#
# .. note::
#    You only need to create the Python source example (``*.py``).  The jupyter
#    notebook and the example HTML will be auto-generated via `sphinx-gallery
#    <https://sphinx-gallery.github.io/>`_.

PolyData	Information
N Cells	69451
N Points	35947
N Strips	0
X Bounds	-9.469e-02, 6.101e-02
Y Bounds	3.299e-02, 1.873e-01
Z Bounds	-6.187e-02, 5.880e-02
N Arrays	0