How to make a discrete colorbar for a scatter plot in matplotlib?

MatplotlibServer Side ProgrammingProgramming

Using plt.colorbar(ticks=np.linspace(-2, 2, 5)), we can create a discrete color bar.

Steps

  • Return random floats in the half open interval, i.e., x, using np.random.random method.

  • Return random floats in the half open interval, i.e., y, using np.random.random method.

  • Return random integers from `low` (inclusive) to `high` (exclusive), i.e., z, using np.random.randint(-2, 3, 20) method.

  • Set the X-axis label using plt.xlabel().

  • Set the Y-axis label using plt.ylabel().

  • Use the built-in rainbow colormap.

  • Generate a colormap index based on discrete intervals.

  • A scatter plot of *y* vs. *x* with varying marker size and/or color, with x, y and z are created (Steps 1, 2, 3).

  • Create a colorbar for a ScalarMappable instance, *mappable*.

  • Use plt.show() to show the figure.

Example

from matplotlib import pyplot as plt
import numpy as np
from matplotlib import colors

x = np.random.random(20)
y = np.random.random(20)
z = np.random.randint(-2, 3, 20)

plt.xlabel('X-axis ')
plt.ylabel('Y-axis ')

cmap = plt.cm.rainbow
norm = colors.BoundaryNorm(np.arange(-2.5, 3, 1), cmap.N)

plt.scatter(x, y, c=z, cmap=cmap, norm=norm, s=100, edgecolor='none')
plt.colorbar(ticks=np.linspace(-2, 2, 5))

plt.show()

Output

raja
Published on 15-Mar-2021 12:39:00
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