.. 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_widgets_slider_snap_demo.py:
===================================
Snapping Sliders to Discrete Values
===================================
You can snap slider values to discrete values using the ``valstep`` argument.
In this example the Freq slider is constrained to be multiples of pi, and the
Amp slider uses an array as the ``valstep`` argument to more densely sample
the first part of its range.
See :doc:`/gallery/widgets/slider_demo` for an example of using
a ``Slider`` to control a single float.
See :doc:`/gallery/widgets/range_slider` for an example of using
a ``RangeSlider`` to define a range of values.
.. code-block:: default
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.widgets import Slider, Button
t = np.arange(0.0, 1.0, 0.001)
a0 = 5
f0 = 3
s = a0 * np.sin(2 * np.pi * f0 * t)
fig, ax = plt.subplots()
plt.subplots_adjust(bottom=0.25)
l, = plt.plot(t, s, lw=2)
slider_bkd_color = 'lightgoldenrodyellow'
ax_freq = plt.axes([0.25, 0.1, 0.65, 0.03], facecolor=slider_bkd_color)
ax_amp = plt.axes([0.25, 0.15, 0.65, 0.03], facecolor=slider_bkd_color)
# define the values to use for snapping
allowed_amplitudes = np.concatenate([np.linspace(.1, 5, 100), [6, 7, 8, 9]])
# create the sliders
samp = Slider(
ax_amp, "Amp", 0.1, 9.0,
valinit=a0, valstep=allowed_amplitudes,
color="green"
)
sfreq = Slider(
ax_freq, "Freq", 0, 10*np.pi,
valinit=2*np.pi, valstep=np.pi,
initcolor='none' # Remove the line marking the valinit position.
)
def update(val):
amp = samp.val
freq = sfreq.val
l.set_ydata(amp*np.sin(2*np.pi*freq*t))
fig.canvas.draw_idle()
sfreq.on_changed(update)
samp.on_changed(update)
ax_reset = plt.axes([0.8, 0.025, 0.1, 0.04])
button = Button(ax_reset, 'Reset', color=slider_bkd_color, hovercolor='0.975')
def reset(event):
sfreq.reset()
samp.reset()
button.on_clicked(reset)
plt.show()
.. image:: /gallery/widgets/images/sphx_glr_slider_snap_demo_001.png
:alt: slider snap demo
: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.widgets.Slider
matplotlib.widgets.Button
.. _sphx_glr_download_gallery_widgets_slider_snap_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: slider_snap_demo.py `
.. container:: sphx-glr-download sphx-glr-download-jupyter
:download:`Download Jupyter notebook: slider_snap_demo.ipynb `
.. only:: html
.. rst-class:: sphx-glr-signature
Keywords: matplotlib code example, codex, python plot, pyplot
`Gallery generated by Sphinx-Gallery
`_