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"""
===============================
Snap 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.
"""
import matplotlib.pyplot as plt
import numpy as np
from matplotlib.widgets import Button, Slider
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()
fig.subplots_adjust(bottom=0.25)
l, = ax.plot(t, s, lw=2)
ax_freq = fig.add_axes([0.25, 0.1, 0.65, 0.03])
ax_amp = fig.add_axes([0.25, 0.15, 0.65, 0.03])
# 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 = fig.add_axes([0.8, 0.025, 0.1, 0.04])
button = Button(ax_reset, 'Reset', hovercolor='0.975')
def reset(event):
sfreq.reset()
samp.reset()
button.on_clicked(reset)
plt.show()
# %%
#
# .. admonition:: References
#
# The use of the following functions, methods, classes and modules is shown
# in this example:
#
# - `matplotlib.widgets.Slider`
# - `matplotlib.widgets.Button`
|
