Precise control over subplot locations in matplotlib

Question

I am currently producing a figure for a paper, which looks like this:

The above is pretty close to how I want it to look, but I have a strong feeling that I\'m

Answer 1

Here is a possible solution. You'd start with the figure width (which makes sense when preparing a paper) and calculate your way through, using the aspects of the figures, some arbitrary spacings between the subplots and the margins. The formulas are similar to the ones I used in this answer. And the unequal aspects are taken care of by GridSpec's width_ratios argument. You then end up with a figure height such that the subplots' are equal in height.

So you cannot avoid typing in some numbers, but they are not "magic". All are related to acessible quatities like fraction of figure size or fraction of mean subplots size. Since the system is closed, changing any number will simply produce a different figure height, but will not destroy the layout.

import matplotlib.pyplot as plt
import matplotlib.gridspec as gridspec
import numpy as np; np.random.seed(42)

imgs = []
shapes = [(550,200), ( 550,205), (1100,274) ]
for shape in shapes:
    imgs.append(np.random.random(shape))

# calculate inverse aspect(width/height) for all images
inva = np.array([ img.shape[1]/float(img.shape[0]) for img in imgs])
# set width of empty column used to stretch layout
emptycol = 0.02
r = np.array([inva[0],inva[1], emptycol, inva[2], 3*emptycol, emptycol])
# set a figure width in inch
figw = 8
# border, can be set independently of all other quantities
left = 0.1; right=1-left
bottom=0.1; top=1-bottom
# wspace (=average relative space between subplots)
wspace = 0.1
#calculate scale
s = figw*(right-left)/(len(r)+(len(r)-1)*wspace) 
# mean aspect
masp = len(r)/np.sum(r)
#calculate figheight
figh = s*masp/float(top-bottom)


gs = gridspec.GridSpec(3,len(r), width_ratios=r)

fig = plt.figure(figsize=(figw,figh))
plt.subplots_adjust(left, bottom, right, top, wspace)

ax1 = plt.subplot(gs[:,0])
ax2 = plt.subplot(gs[:,1])
ax2.set_yticks([])

ax3 = plt.subplot(gs[:,3])
ax3.yaxis.tick_right()
ax3.yaxis.set_label_position("right")

cax1 = plt.subplot(gs[0,5])
cax2 = plt.subplot(gs[1,5])
cax3 = plt.subplot(gs[2,5])


im1 = ax1.imshow(imgs[0], cmap="viridis")
im2 = ax2.imshow(imgs[1], cmap="plasma")
im3 = ax3.imshow(imgs[2], cmap="RdBu")

fig.colorbar(im1, ax=ax1, cax=cax1)
fig.colorbar(im2, ax=ax2, cax=cax2)
fig.colorbar(im3, ax=ax3, cax=cax3)

ax1.set_title("image title")
ax1.set_xlabel("xlabel")
ax1.set_ylabel("ylabel")

plt.show()