Interactive matplotlib plot with two sliders

In addition to what @triplepoint mentioned, have a look at the slider widget.

There’s an example on the matplotlib examples page. It’s a graphical slider bar rather than keyboard bindings, but it works quite well for what you want to do.

Also note that to guarantee the sliders and buttons remain responsive and not garbage-collected, references to the objects (amp_slider, freq_slider, etc.) should be maintained by yourself.

(I’m making this community wiki, as I’m just copy-pasting from the example. This particular example teaches bad habits (e.g. from pylab import *), but it gets the point across. The example has been fixed to avoid the use of pylab.)

from numpy import pi, sin
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.widgets import Slider, Button, RadioButtons

def signal(amp, freq):
    return amp * sin(2 * pi * freq * t)

axis_color="lightgoldenrodyellow"

fig = plt.figure()
ax = fig.add_subplot(111)

# Adjust the subplots region to leave some space for the sliders and buttons
fig.subplots_adjust(left=0.25, bottom=0.25)

t = np.arange(0.0, 1.0, 0.001)
amp_0 = 5
freq_0 = 3

# Draw the initial plot
# The 'line' variable is used for modifying the line later
[line] = ax.plot(t, signal(amp_0, freq_0), linewidth=2, color="red")
ax.set_xlim([0, 1])
ax.set_ylim([-10, 10])

# Add two sliders for tweaking the parameters

# Define an axes area and draw a slider in it
amp_slider_ax  = fig.add_axes([0.25, 0.15, 0.65, 0.03], facecolor=axis_color)
amp_slider = Slider(amp_slider_ax, 'Amp', 0.1, 10.0, valinit=amp_0)

# Draw another slider
freq_slider_ax = fig.add_axes([0.25, 0.1, 0.65, 0.03], facecolor=axis_color)
freq_slider = Slider(freq_slider_ax, 'Freq', 0.1, 30.0, valinit=freq_0)

# Define an action for modifying the line when any slider's value changes
def sliders_on_changed(val):
    line.set_ydata(signal(amp_slider.val, freq_slider.val))
    fig.canvas.draw_idle()
amp_slider.on_changed(sliders_on_changed)
freq_slider.on_changed(sliders_on_changed)

# Add a button for resetting the parameters
reset_button_ax = fig.add_axes([0.8, 0.025, 0.1, 0.04])
reset_button = Button(reset_button_ax, 'Reset', color=axis_color, hovercolor="0.975")
def reset_button_on_clicked(mouse_event):
    freq_slider.reset()
    amp_slider.reset()
reset_button.on_clicked(reset_button_on_clicked)

# Add a set of radio buttons for changing color
color_radios_ax = fig.add_axes([0.025, 0.5, 0.15, 0.15], facecolor=axis_color)
color_radios = RadioButtons(color_radios_ax, ('red', 'blue', 'green'), active=0)
def color_radios_on_clicked(label):
    line.set_color(label)
    fig.canvas.draw_idle()
color_radios.on_clicked(color_radios_on_clicked)

plt.show()