Font size guidelines in Matplotlib - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the font size of the title in this plot?

Consider the following matplotlib code that sets font sizes for different parts of a plot. What will be the font size of the plot's title?

Matplotlib

import matplotlib.pyplot as plt
plt.figure()
plt.title('Sample Title', fontsize=16)
plt.xlabel('X-axis', fontsize=12)
plt.ylabel('Y-axis', fontsize=12)
plt.show()

A 12

B 10

C 16

D 14

💡 Hint

Look at the fontsize argument inside the plt.title() function.

The font size for the title is explicitly set to 16 using the fontsize=16 argument in plt.title(). Other font sizes do not affect the title.

❓ data_output

intermediate

What is the font size of x-axis tick labels after this code?

Given the code below, what will be the font size of the x-axis tick labels?

Matplotlib

import matplotlib.pyplot as plt
fig, ax = plt.subplots()
ax.plot([1, 2, 3], [4, 5, 6])
for tick in ax.get_xticklabels():
    tick.set_fontsize(14)
plt.show()

A 12

B 14

C 10

D 16

💡 Hint

Check the loop where set_fontsize is called on each tick label.

The code sets the font size of each x-axis tick label to 14 explicitly using set_fontsize(14).

❓ visualization

advanced

Identify the font size used for the legend text

Look at the code below that creates a plot with a legend. What font size will the legend text have?

Matplotlib

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], label='Line 1')
plt.plot([3, 2, 1], label='Line 2')
plt.legend(fontsize='small')
plt.show()

A 8 (x-small)

B 12 (medium)

C 14 (large)

D 10 (small)

💡 Hint

The fontsize argument in plt.legend() can take string values like 'small'.

The legend font size is set to 'small', which corresponds to a font size of 10 in matplotlib's default settings.

🧠 Conceptual

advanced

Why use relative font sizes in matplotlib?

Which of the following is the best reason to use relative font sizes (like 'small', 'medium', 'large') instead of fixed numeric sizes in matplotlib?

A Relative sizes automatically adjust when changing figure size or DPI, keeping proportions consistent.

B Relative sizes prevent any font size changes from user input.

C Relative sizes allow using any font family without errors.

D Relative sizes are faster to render than numeric sizes.

💡 Hint

Think about how plots scale on different screens or when saved at different resolutions.

Using relative font sizes helps keep text readable and proportional when the figure size or resolution changes.

🔧 Debug

expert

Why does this font size setting not apply to axis labels?

Examine the code below. The user wants to set the font size of axis labels to 14, but the labels remain small. What is the cause?

Matplotlib

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.xlabel('X-axis')
plt.ylabel('Y-axis')
plt.rcParams['font.size'] = 14
plt.show()

A The font size is set after the labels are created, so it does not affect existing labels.

B The font size must be set using plt.xlabel(fontsize=14) instead of rcParams.

C rcParams['font.size'] only affects tick labels, not axis labels.

D The plot command overrides all font size settings.

💡 Hint

Consider when rcParams changes take effect relative to plot commands.

Changing rcParams['font.size'] after creating labels does not update their font size. It must be set before or labels recreated.