Can I give a border (outline) to a line in matplotlib plot function?

Question

I try:

points = [...]
axe.plot([i[0] for i in points], [i[1] for i in points], linestyle=\'-\', linewidth=10, 
color=\'black\', markeredgewidth=2, markeredge         


        

Answer 1

Just plot the line twice with different thicknesses:

axe.plot([i[0] for i in points], [i[1] for i in points], linestyle='-', linewidth=10, 
color='green')
axe.plot([i[0] for i in points], [i[1] for i in points], linestyle='-', linewidth=5, 
color='black')

Answer 2

The more general answer is to use patheffects. Easy outlines and shadows (and other things) for any artist rendered with a path.
The matplotlib docs (and examples) are quite accessible.

http://matplotlib.org/users/patheffects_guide.html

http://matplotlib.org/examples/pylab_examples/patheffect_demo.html

Answer 3

If you plot a line twice it won't show up in the legend. It's indeed better to use patheffects. Here are two simple examples:

import matplotlib.pyplot as plt
import numpy as np
import matplotlib.patheffects as pe

# setup data
x = np.arange(0.0, 1.0, 0.01)
y = np.sin(2*2*np.pi*t)

# create line plot including an outline (stroke) using path_effects
plt.plot(x, y, color='k', lw=2, path_effects=[pe.Stroke(linewidth=5, foreground='g'), pe.Normal()])
# custom plot settings
plt.grid(True)
plt.ylim((-2, 2))
plt.legend(['sine'])
plt.show()

Or if you want to add a line shadow

# create line plot including an simple line shadow using path_effects
plt.plot(x, y, color='k', lw=2, path_effects=[pe.SimpleLineShadow(shadow_color='g'), pe.Normal()])
# custom plot settings
plt.grid(True)
plt.ylim((-2, 2))
plt.legend(['sine'])
plt.show()