How to Share Axis Between Subplots in Matplotlib

In matplotlib, you can share axes between subplots by using the sharex and sharey parameters in plt.subplots(). Setting these to True or to an existing axis shares the respective axis, aligning ticks and labels across subplots.

Syntax

The plt.subplots() function accepts sharex and sharey parameters to share axes between subplots.

• sharex=True: Share the x-axis among subplots.
• sharey=True: Share the y-axis among subplots.
• You can also pass an existing axis object to share axes selectively.

python

import matplotlib.pyplot as plt
fig, axs = plt.subplots(nrows=2, ncols=1, sharex=True, sharey=False)

Example

This example creates two vertical subplots sharing the x-axis. The x-axis labels and ticks are aligned and shown only on the bottom subplot for clarity.

python

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(0, 10, 100)
y1 = np.sin(x)
y2 = np.cos(x)

fig, axs = plt.subplots(2, 1, sharex=True)

axs[0].plot(x, y1)
axs[0].set_title('Sine Wave')

axs[1].plot(x, y2)
axs[1].set_title('Cosine Wave')

plt.show()

Output

A figure window with two stacked plots: the top plot shows a sine wave, the bottom plot shows a cosine wave, and both share the same x-axis scale and ticks.

Common Pitfalls

Common mistakes when sharing axes include:

• Not setting sharex or sharey when creating subplots, leading to independent axes.
• Trying to share axes after subplot creation, which is more complex.
• Forgetting that shared axes hide tick labels on all but the bottom or left subplot by default.

Always set sharing parameters during plt.subplots() call for best results.

python

import matplotlib.pyplot as plt

# Wrong way: creating subplots separately
fig = plt.figure()
ax1 = fig.add_subplot(211)
ax2 = fig.add_subplot(212)

# Axes are not shared, x-axis ticks appear on both

# Right way: share x-axis during creation
fig, (ax1, ax2) = plt.subplots(2, 1, sharex=True)

Quick Reference

Parameter	Description	Values
sharex	Share x-axis among subplots	True, False, or axis object
sharey	Share y-axis among subplots	True, False, or axis object

Key Takeaways

Use sharex and sharey in plt.subplots() to share axes easily.

Shared axes align ticks and labels, improving plot readability.

Set sharing parameters when creating subplots, not after.

Shared axes hide redundant tick labels on inner subplots by default.

You can share axes selectively by passing existing axis objects.