Customize Check Buttons in Matplotlib

Question

I am trying to customize the CheckButtons:

rax = plt.axes(
        [0.55, 0.8, 0.08, 0.08],
        facecolor=secondary_color
    )

    check = CheckButtons(rax, ('Mn vs. Pn', 'ØMn vs. ØPn'), (True, True))

but can't find a way to set the opacity (alpha parameter) of the button box, the marker and the font color.

Any help would be apreciated

Answer 1

As seen in the documentation of matplotlib.widgets.CheckButtons, the labels, the button rectangles and the lines (of the marker) can be accessed from the class instance.
With check = CheckButtons(..)

• check.rectangles returns a list of the buttons' backgrounds as matplotlib.patches.Rectangle
• check.labels returns a list of the labels as matplotlib.text.Text
• check.lines returns a list of tuples of two matplotlib.lines.Line2D which serve as the markers.

All of them have set_alpha methods.

To set the background the easiest way is to provide a color with an alpha value already being set, like col = (0,0,1,0.2) where the last value is the alpha of the blue color. This can be set to the checkbutton axes using the facecolorargument.

Here is a complete example.

import matplotlib.pyplot as plt
from matplotlib.widgets import CheckButtons

fig= plt.figure(figsize=(4,1.5))
ax = plt.axes([0.4, 0.2, 0.4, 0.6] )
ax.plot([2,3,1])
col = (0,0.3,0.75,0.2)
rax = plt.axes([0.1, 0.2, 0.2, 0.6], facecolor=col )
check = CheckButtons(rax, ('red', 'blue', 'green'), (1,0,1))
for r in check.rectangles:
    r.set_facecolor("blue") 
    r.set_edgecolor("k")
    r.set_alpha(0.2) 

[ll.set_color("white") for l in check.lines for ll in l]
[ll.set_linewidth(3) for l in check.lines for ll in l]
for i, c in enumerate(["r", "b", "g"]):
    check.labels[i].set_color(c)
    check.labels[i].set_alpha(0.7)

plt.show()