Font size guidelines in Matplotlib - Mini Project: Build & Apply

Font size guidelines

📖 Scenario: You are creating a simple bar chart to show sales data for a small store. You want to make sure the text on the chart is easy to read by setting appropriate font sizes for the title, axis labels, and tick labels.

🎯 Goal: Build a bar chart using matplotlib with custom font sizes for the title, x-axis label, y-axis label, and tick labels.

📋 What You'll Learn

Create a list of sales data for 4 products

Set font sizes for the chart title, x-axis label, y-axis label, and tick labels

Use matplotlib.pyplot to plot the bar chart

Display the chart with the specified font sizes

💡 Why This Matters

🌍 Real World

In real life, clear and readable charts help people understand data quickly, such as sales reports or survey results.

💼 Career

Data scientists and analysts often customize chart fonts to make reports and presentations more professional and accessible.

1

Create sales data

Create a list called sales with these exact values: 150, 200, 300, 250.

Matplotlib

# Create a list called sales with the values 150, 200, 300, 250
# Your code here

Hint

Use square brackets [] to create a list and separate values with commas.

2

Set font size variables

Create four variables to set font sizes: title_font_size to 16, x_label_font_size to 12, y_label_font_size to 12, and tick_font_size to 10.

Matplotlib

sales = [150, 200, 300, 250]
# Create font size variables for title, x-axis label, y-axis label, and tick labels
# Your code here

Hint

Assign the numbers directly to the variable names using =.

3

Plot bar chart with font sizes

Import matplotlib.pyplot as plt. Create a list products with 'A', 'B', 'C', 'D'. Use plt.bar() to plot products on x-axis and sales on y-axis. Set the chart title to 'Sales by Product' with font size title_font_size. Set x-axis label to 'Product' with font size x_label_font_size. Set y-axis label to 'Sales' with font size y_label_font_size. Set tick label font size to tick_font_size using plt.xticks() and plt.yticks().

Matplotlib

sales = [150, 200, 300, 250]
title_font_size = 16
x_label_font_size = 12
y_label_font_size = 12
tick_font_size = 10

# Import matplotlib.pyplot as plt
# Create products list
# Plot bar chart with font sizes
# Your code here

Hint

Use fontsize parameter to set font sizes in plt.title(), plt.xlabel(), plt.ylabel(), and plt.xticks(), plt.yticks().

4

Display the chart

Use plt.show() to display the bar chart with the font sizes applied.

Matplotlib

import matplotlib.pyplot as plt

sales = [150, 200, 300, 250]
title_font_size = 16
x_label_font_size = 12
y_label_font_size = 12
tick_font_size = 10

products = ['A', 'B', 'C', 'D']
plt.bar(products, sales)
plt.title('Sales by Product', fontsize=title_font_size)
plt.xlabel('Product', fontsize=x_label_font_size)
plt.ylabel('Sales', fontsize=y_label_font_size)
plt.xticks(fontsize=tick_font_size)
plt.yticks(fontsize=tick_font_size)

# Display the chart
# Your code here

Hint

Call plt.show() to display the plot window.

Practice

1. Why is it important to set font sizes in a matplotlib chart?

easy

A. To increase the chart size

B. To change the chart colors

C. To add more data points

D. To make the chart text clear and easy to read

Solution

1. Step 1: Understand the role of font size in charts

   Font size controls how big or small the text appears on the chart, affecting readability.

2. Step 2: Connect font size to clarity

   Clear and readable text helps viewers understand the chart easily without straining their eyes.

3. Final Answer:

   To make the chart text clear and easy to read -> Option D

4. Quick Check:

   Font size improves readability = D [OK]

Hint: Font size controls text clarity on charts [OK]

Common Mistakes:

• Confusing font size with chart colors
• Thinking font size changes data points
• Assuming font size changes chart dimensions

2. Which of the following is the correct way to set the font size of the title in matplotlib?

easy

A. plt.title('My Chart', fontsize=14)

B. plt.title('My Chart', size=14px)

C. plt.title('My Chart', font=14)

D. plt.title('My Chart', font_size='large')

Solution

1. Step 1: Recall matplotlib title font size syntax

   The correct parameter to set font size is fontsize with an integer value.

2. Step 2: Check each option for correct syntax

   plt.title('My Chart', fontsize=14) uses fontsize=14, which is correct. Others use invalid parameters or units.

3. Final Answer:

   plt.title('My Chart', fontsize=14) -> Option A

4. Quick Check:

   Use fontsize=number for title font size = C [OK]

Hint: Use fontsize=number to set font size in matplotlib [OK]

Common Mistakes:

• Using size=14px instead of fontsize=14
• Using font_size or font parameters incorrectly
• Adding units like 'px' which matplotlib does not accept

3. What will be the font size of the x-axis label in this code?

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.xlabel('X Axis', fontsize=16)
plt.show()

medium

A. 16 points

B. Default font size (usually 10)

C. 12 points

D. No label will appear

Solution

1. Step 1: Identify the font size parameter in xlabel

   The code uses fontsize=16 in plt.xlabel, which sets the label font size to 16 points.

2. Step 2: Understand matplotlib default behavior

   Since fontsize is explicitly set, it overrides the default size (usually 10).

3. Final Answer:

   16 points -> Option A

4. Quick Check:

   Explicit fontsize=16 sets label size = A [OK]

Hint: Check fontsize parameter value to find label size [OK]

Common Mistakes:

• Assuming default size when fontsize is set
• Confusing label font size with tick font size
• Thinking label won't show without extra commands

4. Identify the error in this code that tries to set font sizes for ticks:

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.tick_params(axis='x', labelsize=14)
plt.yticks(fontsize='large')
plt.show()

medium

A. plt.tick_params syntax is wrong

B. fontsize='large' is invalid for plt.yticks

C. plt.plot syntax is wrong

D. plt.show() is missing

Solution

1. Step 1: Check syntax for tick font sizes

   Matplotlib expects labelsize=int in tick_params, not fontsize='large' in plt.yticks.

2. Step 2: Identify which line has the error

   plt.yticks(fontsize='large') is invalid and will cause an error.

3. Final Answer:

   fontsize='large' is invalid for plt.yticks -> Option B

4. Quick Check:

   Use tick_params(labelsize=int) for ticks [OK]

Hint: Use plt.tick_params(labelsize=number) for tick font sizes [OK]

Common Mistakes:

• Using string values like 'large' for tick fontsize
• Thinking plt.tick_params syntax is wrong
• Ignoring error messages about parameter types

5. You want to create a plot with a large title, medium axis labels, and small tick labels for clarity. Which font size settings follow good font size guidelines?

hard

A. Title fontsize=14, labels fontsize=14, ticks fontsize=14

B. Title fontsize=8, labels fontsize=20, ticks fontsize=14

C. Title fontsize=20, labels fontsize=14, ticks fontsize=8

D. Title fontsize=8, labels fontsize=8, ticks fontsize=8

Solution

1. Step 1: Understand font size roles for clarity

   Title should be largest to stand out, axis labels medium for readability, ticks smallest to avoid clutter.

2. Step 2: Match options to guideline

   Title fontsize=20, labels fontsize=14, ticks fontsize=8 matches this pattern: 20 (large), 14 (medium), 8 (small). Others do not follow this order.

3. Final Answer:

   Title fontsize=20, labels fontsize=14, ticks fontsize=8 -> Option C

4. Quick Check:

   Large title, medium labels, small ticks = A [OK]

Hint: Title > labels > ticks in font size for clarity [OK]

Common Mistakes:

• Making tick labels larger than title
• Using same font size for all text elements
• Choosing too small font sizes causing unreadable text