Figure and Axes mental model in Matplotlib - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this code?

Consider the following code using matplotlib. What will be the type of the variable ax?

Matplotlib

import matplotlib.pyplot as plt
fig, ax = plt.subplots()
print(type(ax))

A <class 'matplotlib.axes._subplots.AxesSubplot'>

B <class 'matplotlib.figure.Figure'>

C <class 'list'>

D <class 'tuple'>

💡 Hint

Remember that plt.subplots() returns a Figure and Axes object.

The plt.subplots() function returns a Figure and an Axes object. The Axes object represents the plot area where data is drawn.

❓ data_output

intermediate

How many Axes are created?

What is the number of Axes objects created by this code?

Matplotlib

import matplotlib.pyplot as plt
fig, axs = plt.subplots(2, 2)
print(len(axs.flatten()))

A 4

B 2

C 1

D 0

💡 Hint

The argument (2, 2) creates a grid of subplots.

plt.subplots(2, 2) creates a 2x2 grid of Axes, so there are 4 Axes objects.

🔧 Debug

advanced

Identify the error in this code

What error will this code raise when run?

Matplotlib

import matplotlib.pyplot as plt
fig = plt.figure()
ax1, ax2 = fig.add_subplot(121)
ax3 = fig.add_subplot(122)
print(type(ax1))

A TypeError: 'int' object is not iterable

B AttributeError: 'Figure' object has no attribute 'add_subplot'

C ValueError: not enough values to unpack (expected 2, got 1)

D No error, prints <class 'matplotlib.axes._subplots.AxesSubplot'>

💡 Hint

Check the return value of add_subplot when called with a single argument.

fig.add_subplot(121) returns a single Axes object, so trying to unpack it into two variables causes a ValueError.

❓ visualization

advanced

What does this plot look like?

Given this code, what is the layout of the subplots?

Matplotlib

import matplotlib.pyplot as plt
fig, axs = plt.subplots(1, 3)
for i, ax in enumerate(axs):
    ax.plot([0, 1], [i, i+1])
plt.show()

A A single empty plot

B Three plots stacked vertically

C One plot with three lines

D Three plots side by side horizontally

💡 Hint

The arguments (1, 3) create a grid with 1 row and 3 columns.

plt.subplots(1, 3) creates 3 Axes arranged horizontally in one row.

🧠 Conceptual

expert

Understanding Figure and Axes relationship

Which statement correctly describes the relationship between Figure and Axes in matplotlib?

A A Figure can only contain one Axes object at a time.

B A Figure can contain multiple Axes, but each Axes belongs to exactly one Figure.

C Each Axes can belong to multiple Figures simultaneously.

D Axes and Figure are independent and unrelated objects.

💡 Hint

Think about how plots are organized inside a figure.

A Figure is the overall window or page, and it can hold many Axes (plots). Each Axes is part of one Figure only.