Unequal subplot sizes in Matplotlib - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of unequal subplot sizes with gridspec

What is the output of this code snippet that creates two subplots with different widths using matplotlib's gridspec?

Matplotlib

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

fig = plt.figure()
gs = GridSpec(1, 2, width_ratios=[3, 1])
ax1 = fig.add_subplot(gs[0])
ax2 = fig.add_subplot(gs[1])
ax1.plot([1, 2, 3], [1, 4, 9])
ax2.plot([1, 2, 3], [1, 2, 3])
plt.show()
print((ax1.get_position().width > ax2.get_position().width))

A Raises ValueError

B True

C Raises AttributeError

D False

💡 Hint

Check the width_ratios parameter and how it affects subplot widths.

The width_ratios=[3,1] means the first subplot is three times wider than the second. So ax1's width is greater than ax2's, making the print output True.

❓ data_output

intermediate

Number of axes created with unequal subplot sizes

How many axes objects are created by this code that uses GridSpec with unequal height ratios?

Matplotlib

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])
ax2 = fig.add_subplot(gs[1])
plt.close(fig)
print(len(fig.axes))

A 0

B 1

C 2

D Raises IndexError

💡 Hint

Count how many subplots are added to the figure.

Two subplots are created and added to the figure, so fig.axes contains two axes objects.

🔧 Debug

advanced

Identify the error in subplot size code

What error does this code raise when trying to create subplots with unequal sizes using gridspec?

Matplotlib

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

fig = plt.figure()
gs = GridSpec(1, 2, width_ratios=[2])
ax1 = fig.add_subplot(gs[0])
ax2 = fig.add_subplot(gs[1])
plt.show()

A ValueError: width_ratios must have length 2

B IndexError: index out of range

C TypeError: unsupported operand type(s)

D No error, plots successfully

💡 Hint

Check the length of width_ratios compared to number of columns.

width_ratios must match the number of columns (2), but only one value is given, causing a ValueError.

❓ visualization

advanced

Visual difference in subplot heights

Which option produces a figure with two vertically stacked subplots where the top subplot is twice as tall as the bottom one?

A

gs = GridSpec(2, 1, height_ratios=[1, 2])
fig.add_subplot(gs[0])
fig.add_subplot(gs[1])

B

gs = GridSpec(1, 2, width_ratios=[2, 1])
fig.add_subplot(gs[0])
fig.add_subplot(gs[1])

C

gs = GridSpec(1, 2, width_ratios=[1, 2])
fig.add_subplot(gs[0])
fig.add_subplot(gs[1])

D

gs = GridSpec(2, 1, height_ratios=[2, 1])
fig.add_subplot(gs[0])
fig.add_subplot(gs[1])

💡 Hint

Height ratios control vertical size; width ratios control horizontal size.

Option D sets height_ratios=[2,1] for two rows, making the top subplot twice as tall as the bottom.

🚀 Application

expert

Create a complex layout with unequal subplot sizes

You want to create a figure with 3 subplots arranged in 2 rows and 2 columns. The top row has one subplot spanning both columns, and the bottom row has two subplots with widths ratio 3:1. Which code snippet achieves this layout?

A

gs = GridSpec(2, 2, width_ratios=[3, 1])
ax1 = fig.add_subplot(gs[0, :])
ax2 = fig.add_subplot(gs[1, 0])
ax3 = fig.add_subplot(gs[1, 1])

B

gs = GridSpec(2, 2, width_ratios=[1, 3])
ax1 = fig.add_subplot(gs[0, :])
ax2 = fig.add_subplot(gs[1, 0])
ax3 = fig.add_subplot(gs[1, 1])

C

gs = GridSpec(2, 2, height_ratios=[1, 2])
ax1 = fig.add_subplot(gs[0, :])
ax2 = fig.add_subplot(gs[1, 0])
ax3 = fig.add_subplot(gs[1, 1])

D

gs = GridSpec(2, 2)
ax1 = fig.add_subplot(gs[0, :])
ax2 = fig.add_subplot(gs[1, 0])
ax3 = fig.add_subplot(gs[1, 1])

💡 Hint

Use width_ratios to control bottom row widths and slice for top row spanning both columns.

Option A uses width_ratios=[3,1] to set bottom row widths and gs[0, :] to span top subplot across both columns.