Labelling subplotsΒΆ

Labelling subplots is relatively straightforward, and varies, so Matplotlib does not have a general method for doing this.

Simplest is putting the label inside the axes. Note, here we use pyplot.subplot_mosaic, and use the subplot labels as keys for the subplots, which is a nice convenience. However, the same method works with pyplot.subplots or keys that are different than what you want to label the subplot with.

import matplotlib.pyplot as plt
import matplotlib.transforms as mtransforms

fig, axs = plt.subplot_mosaic([['a)', 'c)'], ['b)', 'c)'], ['d)', 'd)']],
                              constrained_layout=True)

for label, ax in axs.items():
    # label physical distance in and down:
    trans = mtransforms.ScaledTranslation(10/72, -5/72, fig.dpi_scale_trans)
    ax.text(0.0, 1.0, label, transform=ax.transAxes + trans,
            fontsize='medium', verticalalignment='top', fontfamily='serif',
            bbox=dict(facecolor='0.7', edgecolor='none', pad=3.0))

plt.show()
label subplots

We may prefer the labels outside the axes, but still aligned with each other, in which case we use a slightly different transform:

fig, axs = plt.subplot_mosaic([['a)', 'c)'], ['b)', 'c)'], ['d)', 'd)']],
                              constrained_layout=True)

for label, ax in axs.items():
    # label physical distance to the left and up:
    trans = mtransforms.ScaledTranslation(-20/72, 7/72, fig.dpi_scale_trans)
    ax.text(0.0, 1.0, label, transform=ax.transAxes + trans,
            fontsize='medium', va='bottom', fontfamily='serif')

plt.show()
label subplots

If we want it aligned with the title, either incorporate in the title or use the loc keyword argument:

fig, axs = plt.subplot_mosaic([['a)', 'c)'], ['b)', 'c)'], ['d)', 'd)']],
                              constrained_layout=True)

for label, ax in axs.items():
    ax.set_title('Normal Title', fontstyle='italic')
    ax.set_title(label, fontfamily='serif', loc='left', fontsize='medium')

plt.show()
a), Normal Title, c), Normal Title, b), Normal Title, d), Normal Title

References

The use of the following functions, methods, classes and modules is shown in this example:

Total running time of the script: ( 0 minutes 1.501 seconds)

Keywords: matplotlib code example, codex, python plot, pyplot Gallery generated by Sphinx-Gallery