Plotting Lines with Varying Colors

In matplotlib, plotting a line with distinct color segments can be achieved through several approaches. The choice depends on the number of line segments to be plotted.

Small Number of Line Segments

If only a few line segments are required, as in plotting a trajectory, consider the following:

import numpy as np
import matplotlib.pyplot as plt

# Generate random data
xy = (np.random.random((10, 2)) - 0.5).cumsum(axis=0)

fig, ax = plt.subplots()

# Plot each line segment with a unique color
for start, stop in zip(xy[:-1], xy[1:]):
    x, y = zip(start, stop)
    ax.plot(x, y, color=plt.cm.gist_ncar(np.random.random()))

plt.show()

Large Number of Line Segments

When handling a vast number of line segments, a more efficient method is utilizing a LineCollection.

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.collections import LineCollection

# Generate random data
xy = (np.random.random((1000, 2)) - 0.5).cumsum(axis=0)

# Reshape data for compatibility with LineCollection
xy = xy.reshape(-1, 1, 2)
segments = np.hstack([xy[:-1], xy[1:]])

fig, ax = plt.subplots()

# Create a LineCollection with randomly assigned colors
coll = LineCollection(segments, cmap=plt.cm.gist_ncar)
coll.set_array(np.random.random(xy.shape[0]))

# Add the LineCollection to the plot
ax.add_collection(coll)
ax.autoscale_view()

plt.show()

In both methods, the selected colormap can be changed by referring to the Matplotlib documentation.