Matplotlib for Python: Visually Represent Data with Plots/

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Adding a Legend to the Plot

Adding a Legend to the Plot

In this lesson, we will learn how to add a legend to the plot.

We'll cover the following...

What is a legend?

A legend provides a description for an element in the figure. A legend helps the user understand a figure when the figure contains many elements. For example, if there are two curves on a graph, then the legend can help the user distinguish between the curves.

There is more than one way to add a legend to a figure. In this lesson, we will learn two methods. Both use the plot() function. The difference, however, is in how the two methods set their labels.

Adding a legend without labels

In this method, we don’t pass the labels to the legend(), because the labels are passed in plot(). When legend() is called, the Axes would detect the labels automatically.

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import numpy as np
import matplotlib.pyplot as plt
points = np.linspace(-5, 5, 256)
y1 = np.tanh(points) + 0.5
y2 = np.sin(points) - 0.2
fig, axe = plt.subplots(dpi=800)
axe.plot(points, y1, label="tanh")
axe.plot(points, y2, label="sin")
axe.legend()
fig.savefig("output/output.png")
plt.close(fig)

As we can see in the example ...