Font properties customization in Matplotlib - Mini Project: Build & Apply

Font properties customization

📖 Scenario: Imagine you are creating a simple chart to show sales data for a small shop. You want to make the chart easy to read by changing the font style and size of the title and labels.

🎯 Goal: You will create a bar chart and customize the font properties of the title and axis labels using matplotlib.

📋 What You'll Learn

Create a bar chart with sales data

Customize the font size and font family of the chart title

Customize the font size and font style of the x-axis and y-axis labels

Display the chart with the customized fonts

💡 Why This Matters

🌍 Real World

Customizing font properties helps make charts clearer and more attractive for reports and presentations.

💼 Career

Data scientists and analysts often need to create visualizations that communicate data effectively, including styling text for readability.

1

Create sales data dictionary

Create a dictionary called sales with these exact entries: 'Apples': 30, 'Bananas': 45, 'Cherries': 15, 'Dates': 10.

Matplotlib

# Create the sales dictionary with fruit names and their sales numbers
# Your code here

Hint

Use curly braces {} to create a dictionary with keys as fruit names and values as sales numbers.

2

Set font properties for title and labels

Create two variables: title_font as a dictionary with 'fontsize' set to 16 and 'fontfamily' set to 'serif', and label_font as a dictionary with 'fontsize' set to 12 and 'fontstyle' set to 'italic'.

Matplotlib

sales = {'Apples': 30, 'Bananas': 45, 'Cherries': 15, 'Dates': 10}
# Create title_font and label_font dictionaries with font properties
# Your code here

Hint

Use dictionaries to store font properties like fontsize, fontfamily, and fontstyle.

3

Create bar chart with customized fonts

Import matplotlib.pyplot as plt. Use plt.bar() to create a bar chart from sales.keys() and sales.values(). Use plt.title() with text 'Fruit Sales' and font properties from title_font. Use plt.xlabel() with text 'Fruit' and font properties from label_font. Use plt.ylabel() with text 'Quantity' and font properties from label_font.

Matplotlib

sales = {'Apples': 30, 'Bananas': 45, 'Cherries': 15, 'Dates': 10}
title_font = {'fontsize': 16, 'fontfamily': 'serif'}
label_font = {'fontsize': 12, 'fontstyle': 'italic'}
# Import matplotlib.pyplot as plt
# Create bar chart and set title and labels with font properties
# Your code here

Hint

Use fontdict parameter in plt.title(), plt.xlabel(), and plt.ylabel() to apply font properties.

4

Display the chart

Use plt.show() to display the bar chart with the customized font properties.

Matplotlib

import matplotlib.pyplot as plt

sales = {'Apples': 30, 'Bananas': 45, 'Cherries': 15, 'Dates': 10}
title_font = {'fontsize': 16, 'fontfamily': 'serif'}
label_font = {'fontsize': 12, 'fontstyle': 'italic'}

plt.bar(sales.keys(), sales.values())
plt.title('Fruit Sales', fontdict=title_font)
plt.xlabel('Fruit', fontdict=label_font)
plt.ylabel('Quantity', fontdict=label_font)
# Display the plot
# Your code here

Hint

Call plt.show() to open a window showing the chart.

Practice

1. Which font property controls the thickness of the text in a matplotlib plot?

easy

A. family

B. size

C. weight

D. color

Solution

1. Step 1: Understand font properties

   Font properties include size, weight, family, style, and color.

2. Step 2: Identify the property for thickness

   The thickness or boldness of text is controlled by the 'weight' property.

3. Final Answer:

   weight -> Option C

4. Quick Check:

   Font thickness = weight [OK]

Hint: Thickness means weight in font properties [OK]

Common Mistakes:

• Confusing size with weight
• Thinking color controls thickness
• Mixing family with weight

2. Which of the following is the correct way to set the font size of a plot title to 16 using fontdict in matplotlib?

easy

A. plt.title('My Title', font={'fontsize':16})

B. plt.title('My Title', fontdict={'size':16})

C. plt.title('My Title', font={'size':16})

D. plt.title('My Title', fontdict={'fontsize':16})

Solution

1. Step 1: Recall fontdict usage

   In matplotlib, fontdict keys include 'size' for font size, not 'fontsize'.

2. Step 2: Check correct syntax

   Using fontdict={'size':16} correctly sets font size to 16.

3. Final Answer:

   plt.title('My Title', fontdict={'size':16}) -> Option B

4. Quick Check:

   fontdict uses 'size' key [OK]

Hint: Use 'size' key inside fontdict for font size [OK]

Common Mistakes:

• Using 'fontsize' instead of 'size'
• Using 'font' instead of 'fontdict'
• Wrong dictionary key names

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

import matplotlib.pyplot as plt
plt.xlabel('X Axis', fontdict={'size':20, 'weight':'bold'})
plt.show()

medium

A. 20

B. Bold but default size

C. Default size (usually 10)

D. Error due to wrong fontdict

Solution

1. Step 1: Analyze fontdict in xlabel

   The fontdict sets 'size' to 20 and 'weight' to 'bold'.

2. Step 2: Understand effect on label

   The label will use size 20 and bold weight as specified.

3. Final Answer:

   20 -> Option A

4. Quick Check:

   fontdict size = 20 [OK]

Hint: fontdict size sets label font size directly [OK]

Common Mistakes:

• Assuming default size
• Ignoring weight property
• Thinking code causes error

4. Identify the error in this code snippet that tries to set the legend font to italic:

import matplotlib.pyplot as plt
plt.plot([1,2,3], label='Line')
plt.legend(prop={'style':'italic'})
plt.show()

medium

A. Missing plt.legend() call

B. No error, code runs fine

C. Incorrect label argument in plot

D. 'style' is not a valid font property key for legend prop

Solution

1. Step 1: Check font property keys for legend

   Valid keys include 'size', 'weight', 'family', 'style', and 'color'. 'style' is valid but must be a recognized value.

2. Step 2: Verify 'italic' usage

   'italic' is a valid style, so the key is correct. However, in matplotlib, 'style' should be set inside a FontProperties object or as a string, not directly in prop dict.

3. Step 3: Identify actual error

   The error is that 'prop' expects a FontProperties object or a dictionary with correct keys, but 'style' key is not always recognized directly in prop dict in some matplotlib versions.

4. Final Answer:

   'style' is not a valid font property key for legend prop -> Option D

5. Quick Check:

   Legend prop keys must be valid font properties [OK]

Hint: Use FontProperties for complex font styles in legend [OK]

Common Mistakes:

• Using wrong keys in prop dict
• Forgetting to import FontProperties
• Assuming all keys work directly

5. You want to create a plot with a title that uses a custom font family 'Comic Sans MS', size 18, bold weight, and blue color. Which code snippet correctly applies all these font properties?

hard

A. plt.title('My Plot', fontdict={'family':'Comic Sans MS', 'size':18, 'weight':'bold', 'color':'blue'})

B. plt.title('My Plot', fontdict={'fontfamily':'Comic Sans MS', 'fontsize':18, 'fontweight':'bold', 'fontcolor':'blue'})

C. plt.title('My Plot', font={'family':'Comic Sans MS', 'size':18, 'weight':'bold', 'color':'blue'})

D. plt.title('My Plot', fontdict={'family':'Comic Sans MS', 'fontsize':18, 'weight':'bold', 'color':'blue'})

Solution

1. Step 1: Check correct fontdict keys

   Valid keys are 'family', 'size', 'weight', and 'color'. 'fontsize' and 'fontweight' are incorrect keys here.

2. Step 2: Verify values and syntax

   plt.title('My Plot', fontdict={'family':'Comic Sans MS', 'size':18, 'weight':'bold', 'color':'blue'}) uses correct keys and values for family, size, weight, and color.

3. Final Answer:

   plt.title('My Plot', fontdict={'family':'Comic Sans MS', 'size':18, 'weight':'bold', 'color':'blue'}) -> Option A

4. Quick Check:

   Use 'family', 'size', 'weight', 'color' keys in fontdict [OK]

Hint: Use standard keys: family, size, weight, color in fontdict [OK]

Common Mistakes:

• Using 'fontsize' instead of 'size'
• Using 'fontcolor' instead of 'color'
• Passing fontdict as 'font'