Auto Subplots Adjust

Automatically adjust subplot parameters. This example shows a way to determine a subplot parameter from the extent of the ticklabels using a callback on the draw_event.

Note that a similar result would be achieved using tight_layout or constrained_layout; this example shows how one could customize the subplot parameter adjustment.

import matplotlib.pyplot as plt
import matplotlib.transforms as mtransforms
fig, ax = plt.subplots()
ax.plot(range(10))
ax.set_yticks((2,5,7))
labels = ax.set_yticklabels(('really, really, really', 'long', 'labels'))

def on_draw(event):
   bboxes = []
   for label in labels:
       bbox = label.get_window_extent()
       # the figure transform goes from relative coords->pixels and we
       # want the inverse of that
       bboxi = bbox.inverse_transformed(fig.transFigure)
       bboxes.append(bboxi)

   # this is the bbox that bounds all the bboxes, again in relative
   # figure coords
   bbox = mtransforms.Bbox.union(bboxes)
   if fig.subplotpars.left < bbox.width:
       # we need to move it over
       fig.subplots_adjust(left=1.1*bbox.width) # pad a little
       fig.canvas.draw()
   return False

fig.canvas.mpl_connect('draw_event', on_draw)

plt.show()

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References

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

import matplotlib
matplotlib.artist.Artist.get_window_extent
matplotlib.transforms.Bbox
matplotlib.transforms.Bbox.inverse_transformed
matplotlib.transforms.Bbox.union
matplotlib.figure.Figure.subplots_adjust
matplotlib.figure.SubplotParams
matplotlib.backend_bases.FigureCanvasBase.mpl_connect