plt.eventplot refuses lineoffsets

Question

This should be quite easy to reproduce:

plt.eventplot(positions=[1, 2, 3], lineoffsets=[1, 2, 3])

raises

ValueError: lineoffsets and positions are unequal sized sequences

For reasons I can't figure out, because they clearly aren't.

Answer 1

If I understand correctly you want to plot 3 lines, at different starting heights (offsets). The way this works with plt.eventplot is as follows:

import numpy as np
import matplotlib.pyplot as plt

positions = np.array([1, 2, 3])[:,np.newaxis]   # or np.array([[1], [2], [3]])
offsets = [1,2,3]

plt.eventplot(positions, lineoffsets=offsets)
plt.show()

You have to set the offset for each group of data you want to plot. In your case, you have to divide the list into a 3D array (shape (m,n) with m the number of datasets, and n number of data points per set). This way plt.eventplot knows it has to use the different offsets for each group of data. Also see this example.