.. 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_images_contours_and_fields_contour_demo.py:
============
Contour Demo
============
Illustrate simple contour plotting, contours on an image with
a colorbar for the contours, and labelled contours.
See also the :doc:`contour image example
`.
.. code-block:: default
import matplotlib
import numpy as np
import matplotlib.cm as cm
import matplotlib.pyplot as plt
delta = 0.025
x = np.arange(-3.0, 3.0, delta)
y = np.arange(-2.0, 2.0, delta)
X, Y = np.meshgrid(x, y)
Z1 = np.exp(-X**2 - Y**2)
Z2 = np.exp(-(X - 1)**2 - (Y - 1)**2)
Z = (Z1 - Z2) * 2
Create a simple contour plot with labels using default colors. The inline
argument to clabel will control whether the labels are draw over the line
segments of the contour, removing the lines beneath the label.
.. code-block:: default
fig, ax = plt.subplots()
CS = ax.contour(X, Y, Z)
ax.clabel(CS, inline=True, fontsize=10)
ax.set_title('Simplest default with labels')
.. image:: /gallery/images_contours_and_fields/images/sphx_glr_contour_demo_001.png
:alt: Simplest default with labels
:class: sphx-glr-single-img
.. rst-class:: sphx-glr-script-out
Out:
.. code-block:: none
Text(0.5, 1.0, 'Simplest default with labels')
Contour labels can be placed manually by providing list of positions (in data
coordinate). See :doc:`/gallery/event_handling/ginput_manual_clabel_sgskip`
for interactive placement.
.. code-block:: default
fig, ax = plt.subplots()
CS = ax.contour(X, Y, Z)
manual_locations = [
(-1, -1.4), (-0.62, -0.7), (-2, 0.5), (1.7, 1.2), (2.0, 1.4), (2.4, 1.7)]
ax.clabel(CS, inline=True, fontsize=10, manual=manual_locations)
ax.set_title('labels at selected locations')
.. image:: /gallery/images_contours_and_fields/images/sphx_glr_contour_demo_002.png
:alt: labels at selected locations
:class: sphx-glr-single-img
.. rst-class:: sphx-glr-script-out
Out:
.. code-block:: none
Text(0.5, 1.0, 'labels at selected locations')
You can force all the contours to be the same color.
.. code-block:: default
fig, ax = plt.subplots()
CS = ax.contour(X, Y, Z, 6, colors='k') # Negative contours default to dashed.
ax.clabel(CS, fontsize=9, inline=True)
ax.set_title('Single color - negative contours dashed')
.. image:: /gallery/images_contours_and_fields/images/sphx_glr_contour_demo_003.png
:alt: Single color - negative contours dashed
:class: sphx-glr-single-img
.. rst-class:: sphx-glr-script-out
Out:
.. code-block:: none
Text(0.5, 1.0, 'Single color - negative contours dashed')
You can set negative contours to be solid instead of dashed:
.. code-block:: default
matplotlib.rcParams['contour.negative_linestyle'] = 'solid'
fig, ax = plt.subplots()
CS = ax.contour(X, Y, Z, 6, colors='k') # Negative contours default to dashed.
ax.clabel(CS, fontsize=9, inline=True)
ax.set_title('Single color - negative contours solid')
.. image:: /gallery/images_contours_and_fields/images/sphx_glr_contour_demo_004.png
:alt: Single color - negative contours solid
:class: sphx-glr-single-img
.. rst-class:: sphx-glr-script-out
Out:
.. code-block:: none
Text(0.5, 1.0, 'Single color - negative contours solid')
And you can manually specify the colors of the contour
.. code-block:: default
fig, ax = plt.subplots()
CS = ax.contour(X, Y, Z, 6,
linewidths=np.arange(.5, 4, .5),
colors=('r', 'green', 'blue', (1, 1, 0), '#afeeee', '0.5'),
)
ax.clabel(CS, fontsize=9, inline=True)
ax.set_title('Crazy lines')
.. image:: /gallery/images_contours_and_fields/images/sphx_glr_contour_demo_005.png
:alt: Crazy lines
:class: sphx-glr-single-img
.. rst-class:: sphx-glr-script-out
Out:
.. code-block:: none
Text(0.5, 1.0, 'Crazy lines')
Or you can use a colormap to specify the colors; the default
colormap will be used for the contour lines
.. code-block:: default
fig, ax = plt.subplots()
im = ax.imshow(Z, interpolation='bilinear', origin='lower',
cmap=cm.gray, extent=(-3, 3, -2, 2))
levels = np.arange(-1.2, 1.6, 0.2)
CS = ax.contour(Z, levels, origin='lower', cmap='flag', extend='both',
linewidths=2, extent=(-3, 3, -2, 2))
# Thicken the zero contour.
zc = CS.collections[6]
plt.setp(zc, linewidth=4)
ax.clabel(CS, levels[1::2], # label every second level
inline=True, fmt='%1.1f', fontsize=14)
# make a colorbar for the contour lines
CB = fig.colorbar(CS, shrink=0.8)
ax.set_title('Lines with colorbar')
# We can still add a colorbar for the image, too.
CBI = fig.colorbar(im, orientation='horizontal', shrink=0.8)
# This makes the original colorbar look a bit out of place,
# so let's improve its position.
l, b, w, h = ax.get_position().bounds
ll, bb, ww, hh = CB.ax.get_position().bounds
CB.ax.set_position([ll, b + 0.1*h, ww, h*0.8])
plt.show()
.. image:: /gallery/images_contours_and_fields/images/sphx_glr_contour_demo_006.png
:alt: Lines with colorbar
:class: sphx-glr-single-img
------------
References
""""""""""
The use of the following functions and methods is shown
in this example:
.. code-block:: default
import matplotlib
matplotlib.axes.Axes.contour
matplotlib.pyplot.contour
matplotlib.figure.Figure.colorbar
matplotlib.pyplot.colorbar
matplotlib.axes.Axes.clabel
matplotlib.pyplot.clabel
matplotlib.axes.Axes.set_position
matplotlib.axes.Axes.get_position
.. rst-class:: sphx-glr-script-out
Out:
.. code-block:: none
.. rst-class:: sphx-glr-timing
**Total running time of the script:** ( 0 minutes 2.209 seconds)
.. _sphx_glr_download_gallery_images_contours_and_fields_contour_demo.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: contour_demo.py `
.. container:: sphx-glr-download sphx-glr-download-jupyter
:download:`Download Jupyter notebook: contour_demo.ipynb `
.. only:: html
.. rst-class:: sphx-glr-signature
Keywords: matplotlib code example, codex, python plot, pyplot
`Gallery generated by Sphinx-Gallery
`_