How to use axline with log scale axis?

Question

I'm trying to plot a linear line through zero:

fig, ax = plt.subplots()

l2 = ax.axline(xy1=(0, 0), slope=0.3)

ax.set_xlim(0.1, 10)
ax.set_ylim(0.1, 10)

It works well:

However, if I change the scale to log, it would be empty:

fig, ax = plt.subplots()

l2 = ax.axline(xy1=(0, 0), slope=0.3)

ax.set_xlim(0.1, 10)
ax.set_ylim(0.1, 10)

ax.set_xscale('log')
ax.set_yscale('log')

Answer 1

Unfortunately the order of operations has hidden the actual error message from appearing for you. If you were to modify your code to the following:

fig, ax = plt.subplots()
ax.set_xscale('log')
ax.set_yscale('log')
ax.axline(xy1=(0, 0), slope=0.3)

You would have seen the following error

TypeError: 'slope' cannot be used with non-linear scales

However, you can still generate the line if you wish with something like the following:

import matplotlib.pyplot as plt
import numpy as np
fig, ax = plt.subplots()
ax.set_xscale('log')
ax.set_yscale('log')

x = np.linspace(0.1, 10, 1000)
plt.plot(x, 0.3 * x)
ax.set_xlim(0.1, 10)
ax.set_ylim(0.1, 10)

Which would give you the following figure