Changing the GridSpec properties after generating the subplots

Question

Suppose something comes up in my plot that mandates that I change the height ratio between two subplots that I've generated within my plot. I've tried changing GridSpec's height ratio to no avail.

import matplotlib.pyplot as plt
from matplotlib.gridspec import GridSpec

fig = plt.figure()
gs = GridSpec(2, 1, height_ratios=[2, 1])

ax1 = fig.add_subplot(gs[0])
ax1 = fig.axes[0]
ax2 = fig.add_subplot(gs[1])
ax2 = fig.axes[1]

ax1.plot([0, 1], [0, 1])
ax2.plot([0, 1], [1, 0])

gs.height_ratios = [2, 5]

The last line has no effect on the plot ratio.

In my actual code, it is not feasible without major reworking to set the height_ratios to 2:5 ahead of time.

How do I get this to update like I want?

Answer 1

The axes of relevant subplots can be manipulated and adjusted to get new height ratios.

import matplotlib.pyplot as plt
from matplotlib.gridspec import GridSpec

fig = plt.figure()
gs = GridSpec(2, 1, height_ratios=[2, 1]) #nrows, ncols

ax1 = fig.add_subplot(gs[0])
ax1 = fig.axes[0]
ax2 = fig.add_subplot(gs[1])
ax2 = fig.axes[1]

ax1.plot([0, 1], [0, 1])
ax2.plot([0, 1], [1, 0])

# new height ratio: 2:5 is required for the 2 subplots
rw, rh = 2, 5

# get dimensions of the 2 axes
box1 = ax1.get_position()
box2 = ax2.get_position()
# current dimensions
w1,h1 = box1.x1-box1.x0, box1.y1-box1.y0
w2,h2 = box2.x1-box2.x0, box2.y1-box2.y0
top1 = box1.y0+h1
#top2 = box2.y0+h2
full_h = h1+h2   #total height

# compute new heights for each axes
new_h1 = full_h*rw/(rw + rh)
new_h2 = full_h*rh/(rw + rh)

#btm1,btm2 = box1.y0, box2.y0
new_bottom1 = top1-new_h1

# finally, set new location/dimensions of the axes
ax1.set_position([box1.x0, new_bottom1, w1, new_h1])
ax2.set_position([box2.x0, box2.y0, w2, new_h2])

plt.show()

The output for ratio: (2, 5):

The output for (2, 10):