Matplotlib axis break with different size subplots

Question

I'm making a plot with an x-axis break // using different size subplots as described in this post. However, when I set the subplots to be different sizes, the diagonal axes break symbols '/' no longer have the same angle, creating an odd visual effect. Does anyone know how to create axis breaks with subplots of different sizes?

fig, (ax1, ax2) = plt.subplots(1, 2, sharey=True, figsize=(10,8), gridspec_kw={'width_ratios': [3, 1]})
fig.subplots_adjust(wspace=0.05)  # adjust space between axes

# zoom-in / limit the view to different portions of the data
ax1.set_xlim(0, 60)  # outliers only
ax2.set_xlim(380, 550)  # most of the data

# hide the spines between ax and ax2
ax1.spines.right.set_visible(False)
ax2.spines.left.set_visible(False)
ax2.axes.yaxis.set_visible(False)

d = .015 # how big to make the diagonal lines in axes coordinates
# arguments to pass plot, just so we don't keep repeating them
kwargs = dict(transform=ax1.transAxes, color='k', clip_on=False)
ax1.plot((1-d,1+d), (-d,+d), **kwargs)
ax1.plot((1-d,1+d),(1-d,1+d), **kwargs)

kwargs.update(transform=ax2.transAxes)  # switch to the bottom axes
ax2.plot((-d,+d), (1-d,1+d), **kwargs)
ax2.plot((-d,+d), (-d,+d), **kwargs)

plt.show()

Stef · Accepted Answer · 2022-09-02T09:18:59.053

You need to introduce a factor f taking into account the different axis scales:

d = .015 # how big to make the diagonal lines in axes coordinates
f = (np.diff(ax1.get_xlim()) / np.diff(ax2.get_xlim())).item()
# arguments to pass plot, just so we don't keep repeating them
kwargs = dict(transform=ax1.transAxes, color='k', clip_on=False)
ax1.plot((1-d*f,1+d*f), (-d,+d), **kwargs)
ax1.plot((1-d*f,1+d*f),(1-d,1+d), **kwargs)

kwargs.update(transform=ax2.transAxes)  # switch to the bottom axes
ax2.plot((-d,+d), (1-d,1+d), **kwargs)
ax2.plot((-d,+d), (-d,+d), **kwargs)

Update:
An easier way is to use the approach shown in the official Broken Axis Example:

import matplotlib.pyplot as plt
import numpy as np
fig, (ax1, ax2) = plt.subplots(1, 2, sharey=True, figsize=(10,8), gridspec_kw={'width_ratios': [3, 1]})
fig.subplots_adjust(wspace=0.05)  # adjust space between axes

# zoom-in / limit the view to different portions of the data
ax1.set_xlim(0, 60)  # outliers only
ax2.set_xlim(380, 550)  # most of the data

# hide the spines between ax and ax2
ax1.spines.right.set_visible(False)
ax2.spines.left.set_visible(False)
ax2.axes.yaxis.set_visible(False)

d = 2
kwargs = dict(marker=[(-1, -d), (1, d)], markersize=12,
              linestyle="none", color='k', mec='k', mew=1, clip_on=False)
ax1.plot([1, 1], [0, 1], transform=ax1.transAxes, **kwargs)
ax2.plot([0, 0], [0, 1], transform=ax2.transAxes, **kwargs)

Matplotlib axis break with different size subplots

1 Answers1