[FIXED] How to plot axline within each subplot

Issue

I'm trying to add an axline with slope=1 to each of a series of subplots.

• I'm following the axline example but it does not seem to work with my modifications.
• This appears to be the closest question on SO, but doesn't answer my question

Code attempts and errors

01. As in axline example:

import matplotlib.pyplot as plt
import pandas as pd

fig, axes = plt.subplots(4, 2, sharex=True, sharey=True, figsize=(12, 10))
plt.xlim([-5, 10])
plt.ylim([-5, 10])
for ax in axes.flat:
    ax.axline((0,0), slope=1, color='r', linewidth=2, linestyle='--')

'AxesSubplot' object has no attribute 'axline'

02. Within each subplot:

fig, axes = plt.subplots(4, 2, sharex=True, sharey=True, figsize=(12, 10))
row, col = 0, 0
for q in questions: # questions defined by my data
    question_scatter(df, q, row, col) # UDF to create a scatter plot in axes[row, col]
    axes[row, col].axline((0,0), slope=1, color='r', linewidth=2, linestyle='--')
    if row < 3:
        row += 1
    else:
        row = 0
        col += 1

'AxesSubplot' object has no attribute 'axline'

03. Apply globally:

fig, axes = plt.subplots(4, 2, sharex=True, sharey=True, figsize=(12, 10))
axes.axline((0,0), slope=1, color='r', linewidth=2, linestyle='--')

numpy.ndarray' object has no attribute 'axline'

Solution

As @suraj shourie points out, my first solution works if I upgrade matplotlib to v3.3.0.

For completeness:

$ pip install  -U matplotlib==3.3.0

import matplotlib.pyplot as plt
import pandas as pd

fig, axes = plt.subplots(4, 2, sharex=True, sharey=True, figsize=(12, 10))
for ax in axes.flat:
    ax.axline((0,0), slope=1, color='r', linewidth=2, linestyle='--')

Answered By - alexwhitworth