.. only:: html
.. note::
:class: sphx-glr-download-link-note
Click :ref:`here ` to download the full example code
.. rst-class:: sphx-glr-example-title
.. _sphx_glr_gallery_pie_and_polar_charts_nested_pie.py:
=================
Nested pie charts
=================
The following examples show two ways to build a nested pie chart
in Matplotlib. Such charts are often referred to as donut charts.
.. code-block:: default
import matplotlib.pyplot as plt
import numpy as np
The most straightforward way to build a pie chart is to use the
`~matplotlib.axes.Axes.pie` method.
In this case, pie takes values corresponding to counts in a group.
We'll first generate some fake data, corresponding to three groups.
In the inner circle, we'll treat each number as belonging to its
own group. In the outer circle, we'll plot them as members of their
original 3 groups.
The effect of the donut shape is achieved by setting a ``width`` to
the pie's wedges through the *wedgeprops* argument.
.. code-block:: default
fig, ax = plt.subplots()
size = 0.3
vals = np.array([[60., 32.], [37., 40.], [29., 10.]])
cmap = plt.get_cmap("tab20c")
outer_colors = cmap(np.arange(3)*4)
inner_colors = cmap([1, 2, 5, 6, 9, 10])
ax.pie(vals.sum(axis=1), radius=1, colors=outer_colors,
wedgeprops=dict(width=size, edgecolor='w'))
ax.pie(vals.flatten(), radius=1-size, colors=inner_colors,
wedgeprops=dict(width=size, edgecolor='w'))
ax.set(aspect="equal", title='Pie plot with `ax.pie`')
plt.show()
.. image:: /gallery/pie_and_polar_charts/images/sphx_glr_nested_pie_001.png
:alt: Pie plot with `ax.pie`
:class: sphx-glr-single-img
However, you can accomplish the same output by using a bar plot on
axes with a polar coordinate system. This may give more flexibility on
the exact design of the plot.
In this case, we need to map x-values of the bar chart onto radians of
a circle. The cumulative sum of the values are used as the edges
of the bars.
.. code-block:: default
fig, ax = plt.subplots(subplot_kw=dict(polar=True))
size = 0.3
vals = np.array([[60., 32.], [37., 40.], [29., 10.]])
#normalize vals to 2 pi
valsnorm = vals/np.sum(vals)*2*np.pi
#obtain the ordinates of the bar edges
valsleft = np.cumsum(np.append(0, valsnorm.flatten()[:-1])).reshape(vals.shape)
cmap = plt.get_cmap("tab20c")
outer_colors = cmap(np.arange(3)*4)
inner_colors = cmap([1, 2, 5, 6, 9, 10])
ax.bar(x=valsleft[:, 0],
width=valsnorm.sum(axis=1), bottom=1-size, height=size,
color=outer_colors, edgecolor='w', linewidth=1, align="edge")
ax.bar(x=valsleft.flatten(),
width=valsnorm.flatten(), bottom=1-2*size, height=size,
color=inner_colors, edgecolor='w', linewidth=1, align="edge")
ax.set(title="Pie plot with `ax.bar` and polar coordinates")
ax.set_axis_off()
plt.show()
.. image:: /gallery/pie_and_polar_charts/images/sphx_glr_nested_pie_002.png
:alt: Pie plot with `ax.bar` and polar coordinates
:class: sphx-glr-single-img
------------
References
""""""""""
The use of the following functions, methods, classes and modules is shown
in this example:
.. code-block:: default
import matplotlib
matplotlib.axes.Axes.pie
matplotlib.pyplot.pie
matplotlib.axes.Axes.bar
matplotlib.pyplot.bar
matplotlib.projections.polar
matplotlib.axes.Axes.set
matplotlib.axes.Axes.set_axis_off
.. rst-class:: sphx-glr-script-out
Out:
.. code-block:: none
.. _sphx_glr_download_gallery_pie_and_polar_charts_nested_pie.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: nested_pie.py `
.. container:: sphx-glr-download sphx-glr-download-jupyter
:download:`Download Jupyter notebook: nested_pie.ipynb `
.. only:: html
.. rst-class:: sphx-glr-signature
Keywords: matplotlib code example, codex, python plot, pyplot
`Gallery generated by Sphinx-Gallery
`_