.. 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_specialty_plots_anscombe.py:
==================
Anscombe's quartet
==================
`Anscombe's quartet`_ is a group of datasets (x, y) that have the same mean,
standard deviation, and regression line, but which are qualitatively different.
It is often used to illustrate the importance of looking at a set of data
graphically and not only relying on basic statistic properties.
.. _Anscombe's quartet: https://en.wikipedia.org/wiki/Anscombe%27s_quartet
.. image:: /gallery/specialty_plots/images/sphx_glr_anscombe_001.png
:alt: anscombe
:class: sphx-glr-single-img
.. code-block:: default
import matplotlib.pyplot as plt
import numpy as np
x = [10, 8, 13, 9, 11, 14, 6, 4, 12, 7, 5]
y1 = [8.04, 6.95, 7.58, 8.81, 8.33, 9.96, 7.24, 4.26, 10.84, 4.82, 5.68]
y2 = [9.14, 8.14, 8.74, 8.77, 9.26, 8.10, 6.13, 3.10, 9.13, 7.26, 4.74]
y3 = [7.46, 6.77, 12.74, 7.11, 7.81, 8.84, 6.08, 5.39, 8.15, 6.42, 5.73]
x4 = [8, 8, 8, 8, 8, 8, 8, 19, 8, 8, 8]
y4 = [6.58, 5.76, 7.71, 8.84, 8.47, 7.04, 5.25, 12.50, 5.56, 7.91, 6.89]
datasets = {
'I': (x, y1),
'II': (x, y2),
'III': (x, y3),
'IV': (x4, y4)
}
fig, axs = plt.subplots(2, 2, sharex=True, sharey=True, figsize=(6, 6),
gridspec_kw={'wspace': 0.08, 'hspace': 0.08})
axs[0, 0].set(xlim=(0, 20), ylim=(2, 14))
axs[0, 0].set(xticks=(0, 10, 20), yticks=(4, 8, 12))
for ax, (label, (x, y)) in zip(axs.flat, datasets.items()):
ax.text(0.1, 0.9, label, fontsize=20, transform=ax.transAxes, va='top')
ax.tick_params(direction='in', top=True, right=True)
ax.plot(x, y, 'o')
# linear regression
p1, p0 = np.polyfit(x, y, deg=1)
x_lin = np.array([np.min(x), np.max(x)])
y_lin = p1 * x_lin + p0
ax.plot(x_lin, y_lin, 'r-', lw=2)
# add text box for the statistics
stats = (f'$\\mu$ = {np.mean(y):.2f}\n'
f'$\\sigma$ = {np.std(y):.2f}\n'
f'$r$ = {np.corrcoef(x, y)[0][1]:.2f}')
bbox = dict(boxstyle='round', fc='blanchedalmond', ec='orange', alpha=0.5)
ax.text(0.95, 0.07, stats, fontsize=9, bbox=bbox,
transform=ax.transAxes, horizontalalignment='right')
plt.show()
.. _sphx_glr_download_gallery_specialty_plots_anscombe.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: anscombe.py `
.. container:: sphx-glr-download sphx-glr-download-jupyter
:download:`Download Jupyter notebook: anscombe.ipynb `
.. only:: html
.. rst-class:: sphx-glr-signature
Keywords: matplotlib code example, codex, python plot, pyplot
`Gallery generated by Sphinx-Gallery
`_