根据文档，您可以使用event.ind：

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

def onpick1(event):
    print('event')
    if isinstance(event.artist, LineCollection):
        print('LineCollection')
        thoselines = event.artist
        print('Which line did I clicked on ? ')
        print(event.ind)  # <- HERE

def linecoll(N):
    x = np.random.rand(N, 3)
    y = np.random.rand(N, 3)
    C = np.random.rand(N, 3)
    L = [str(i) for i in range(N)]
    data = np.stack((x, y), axis=2)
    fig, ax = plt.subplots()
    fig.canvas.mpl_connect('pick_event', onpick1)
    lines = ax.add_collection(LineCollection(data,colors=C ))
    lines.set_picker(2)
    lines.labels = L
    plt.show()

linecoll(10)

输出：

event
LineCollection
Which line did I clicked on ? 
[6]
event
LineCollection
Which line did I clicked on ? 
[5]
event
LineCollection
Which line did I clicked on ? 
[3 6]  # <- intersection

请注意，如果您单击两条线的交叉点，event.ind将包含两个LineCollection的索引。