How to plot a matplotlib line plot using colormap?

Question

How can I create a lineplot using python matplotlib in such a way that the color of the line varies in respect of another series?

For a simple example:

import numpy as np
import matplotlib.pyplot as plt

t = np.arange(0.0, 2.0, 0.01)
y = np.sin(2 * np.pi * t)
z = (t-1) ** 2

fig = plt.figure()
ax = plt.axes()
ax.plot(t, y)
ax.plot(t, z)
plt.show()

Instead of:

I would like to graph only (t, y) in a way that the line color represents the value of z following a certain colormap (cmap), for instance 'plasma'.

Edit:

This question was tagged as possibly duplicate, but references to a question where the desired result is a line changing color to help follow the path it was draw (sequence information), instead of adding information on another value (in this case z).

It is closer to this example , as pointed out in the comments, but I was looking for something simpler than having to create a set of line segments and color them individually.

Answer 1

I don't think there's an easy way to do it with line plots, but with scatter, it's pretty easy. If you still want a connecting line, you can fake it a bit with a gray line behind it:

ax.scatter(t, y, c=z, marker='.')
ax.plot(t, y, c='gray')

Answer 2

Using the colorline function referenced in an answer to the question you said is not a duplicate of this , this can be done:

from colorline import colorline

colorline(t, y, z)
plt.xlim(t.min(), t.max())
plt.ylim(y.min(), y.max())
plt.show()

This creates multiple line segments, each with a color determined by z .