common x label for subplots

Question

I would like to create a plot with 3 subplots. This plot should have a common y and common x label I followed: Common xlabel/ylabel for matplotlib subplots.

I am however changing the aspect ratio aspect=0.5 and this results in the x-label being too far from the plot. Do you know how to fix this?

> Minimal Reproducible Example here:

import numpy as np
import matplotlib.pyplot as plt

# Get Data 
data1 = np.random.rand(100,100)
data2 = np.random.rand(100,100)
data3 = np.random.rand(100,100)
data = [data1,data2,data3]
# Create Figure
fig, axes = plt.subplots(nrows=1, ncols=3, sharex=True, sharey=True)
for i,ax in enumerate(axes.flat):
    im = ax.imshow(data[i], origin="lower", interpolation='quadric', cmap='jet', extent=[50,250,0,400], aspect=0.5, vmin=0, vmax = 1)


cbar_ax = fig.add_axes([1, 0.35, 0.01, 0.3])
fig.colorbar(im, cax=cbar_ax) # orientation='horizontal'
fig.tight_layout(pad=0.7)

## add a big axis, hide frame
fig.add_subplot(111, frameon=False)
## hide tick and tick label of the big axis
plt.tick_params(labelcolor='none', top=False, bottom=False, left=False, right=False)
plt.xlabel("common X")
plt.ylabel("common Y")


plt.show()

There is of course plt.xlabel("common X", labelpad=n), which takes negative n-values - but it is an absolute value. — Mr. T

Léonard Léonard · Accepted Answer · 2020-10-24T11:28:39

Here is a solution. The idea is to create a big axis with actual extremal positions of the set of subplots. This should be flexible with different subplot settings.

import numpy as np
import matplotlib.pyplot as plt

# Get Data
data1 = np.random.rand(100,100)
data2 = np.random.rand(100,100)
data3 = np.random.rand(100,100)
data = [data1,data2,data3]
# Create Figure
fig, axes = plt.subplots(nrows=1, ncols=3, sharex=True, sharey=True)
for i,ax in enumerate(axes.flat):
    im = ax.imshow(data[i], origin="lower", interpolation='quadric', cmap='jet', extent=[50,250,0,400], aspect=0.5, vmin=0, vmax = 1)


cbar_ax = fig.add_axes([1, 0.35, 0.01, 0.3])
fig.colorbar(im, cax=cbar_ax) # orientation='horizontal'
fig.tight_layout(pad=1.5)

# Get extents of subplot
x0 = min([ax.get_position().x0 for ax in axes])
y0 = min([ax.get_position().y0 for ax in axes])
x1 = max([ax.get_position().x1 for ax in axes])
y1 = max([ax.get_position().y1 for ax in axes])

# Hidden axes for common x and y labels
plt.axes([x0, y0, x1 - x0, y1 - y0], frameon=False)
plt.tick_params(labelcolor='none', top=False, bottom=False, left=False, right=False)

# Labelize
plt.xlabel("common X")
plt.ylabel("common Y")
plt.title('Common Title')

plt.show()
# plt.savefig("example.png", bbox_inches="tight")  # save figure

common x label for subplots

2 Answers