Display an artist’s label instead of x, y coordinates

Use an event handler to change the annotation text.

import numpy as np
import matplotlib.pyplot as plt
import mplcursors

x = np.linspace(0, 10, 100)

fig, ax = plt.subplots()
ax.set_title("Click on a line to display its label")

# Plot a series of lines with increasing slopes.
for i in range(1, 20):
    ax.plot(x, i * x, label=f"$y = {i}x$")

# Use a Cursor to interactively display the label for a selected line.
mplcursors.cursor().connect(
    "add", lambda sel: sel.annotation.set_text(sel.artist.get_label()))

plt.show()