Pie chart color customization in Matplotlib - Mini Project: Build & Apply

Pie chart color customization

📖 Scenario: You are working with sales data for different fruits in a small grocery store. You want to show the sales distribution using a pie chart. To make the chart clearer and more attractive, you want to customize the colors of each slice.

🎯 Goal: Create a pie chart that shows the sales of fruits with custom colors for each fruit slice.

📋 What You'll Learn

Create a dictionary called fruit_sales with exact fruit names and sales numbers.

Create a list called colors with exact color names matching the fruits order.

Use matplotlib's plt.pie() function with the colors parameter to customize slice colors.

Print the pie chart with a title 'Fruit Sales Distribution'.

💡 Why This Matters

🌍 Real World

Pie charts are often used in business to show parts of a whole, like sales distribution among products.

💼 Career

Data analysts and scientists use pie charts to communicate data insights clearly to stakeholders.

1

Create the fruit sales data

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

Matplotlib

# Create the fruit_sales dictionary with exact values
# Your code here

Hint

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

2

Create the colors list

Create a list called colors with these exact color names in order: 'red', 'yellow', 'pink', 'brown'.

Matplotlib

fruit_sales = {'Apples': 30, 'Bananas': 15, 'Cherries': 45, 'Dates': 10}
# Create the colors list with exact color names
# Your code here

Hint

Use square brackets [] to create a list of color names as strings.

3

Create the pie chart with custom colors

Import matplotlib.pyplot as plt. Use plt.pie() with fruit_sales.values() as data and colors=colors to set slice colors. Add labels using fruit_sales.keys(). Add a title 'Fruit Sales Distribution' using plt.title().

Matplotlib

fruit_sales = {'Apples': 30, 'Bananas': 15, 'Cherries': 45, 'Dates': 10}
colors = ['red', 'yellow', 'pink', 'brown']
# Import matplotlib.pyplot as plt
# Create pie chart with fruit_sales values and colors list
# Add labels from fruit_sales keys
# Add title 'Fruit Sales Distribution'
# Your code here

Hint

Remember to import matplotlib.pyplot as plt first. Use the colors parameter inside plt.pie() to customize colors.

4

Display the pie chart

Use plt.show() to display the pie chart.

Matplotlib

import matplotlib.pyplot as plt

fruit_sales = {'Apples': 30, 'Bananas': 15, 'Cherries': 45, 'Dates': 10}
colors = ['red', 'yellow', 'pink', 'brown']

plt.pie(fruit_sales.values(), labels=fruit_sales.keys(), colors=colors)
plt.title('Fruit Sales Distribution')
# Display the pie chart
# Your code here

Hint

Use plt.show() to make the pie chart appear on the screen.

Practice

1. What does the colors parameter do in a matplotlib pie chart?

easy

A. It changes the size of the pie chart.

B. It changes the chart title.

C. It adds labels to the pie slices.

D. It sets the colors of each slice in the pie chart.

Solution

1. Step 1: Understand the role of colors in pie charts

   The colors parameter is used to specify the colors for each slice of the pie chart.

2. Step 2: Compare with other options

   Options A, C, and D relate to size, labels, and title, which are controlled by other parameters.

3. Final Answer:

   It sets the colors of each slice in the pie chart. -> Option D

4. Quick Check:

   colors parameter = slice colors [OK]

Hint: Remember: colors parameter controls slice colors [OK]

Common Mistakes:

• Confusing colors with labels
• Thinking colors change chart size
• Mixing colors with title settings

2. Which of the following is the correct way to set colors in a matplotlib pie chart?

easy

A. plt.pie(data, colors=['red', 'blue', 'green'])

B. plt.pie(data, color=['red', 'blue', 'green'])

C. plt.pie(data, col=['red', 'blue', 'green'])

D. plt.pie(data, set_colors=['red', 'blue', 'green'])

Solution

1. Step 1: Recall the correct parameter name

   The correct parameter to set slice colors is colors, not color, col, or set_colors.

2. Step 2: Check syntax correctness

   plt.pie(data, colors=['red', 'blue', 'green']) uses colors with a list of color names, which is the correct syntax.

3. Final Answer:

   plt.pie(data, colors=['red', 'blue', 'green']) -> Option A

4. Quick Check:

   Use colors= list for slice colors [OK]

Hint: Use exact parameter name 'colors' for slice colors [OK]

Common Mistakes:

• Using 'color' instead of 'colors'
• Using undefined parameters like 'col' or 'set_colors'
• Passing colors as a string instead of a list

3. What will be the color of the second slice in this code?

import matplotlib.pyplot as plt
sizes = [30, 40, 30]
colors = ['#FF0000', '#00FF00', '#0000FF']
plt.pie(sizes, colors=colors)
plt.show()

medium

A. Blue

B. Red

C. Green

D. Black

Solution

1. Step 1: Identify the colors list order

   The colors list is ['#FF0000', '#00FF00', '#0000FF'], which correspond to red, green, and blue in order.

2. Step 2: Match the second slice color

   The second slice uses the second color '#00FF00', which is green.

3. Final Answer:

   Green -> Option C

4. Quick Check:

   Second color in list = green [OK]

Hint: Colors list order matches slice order [OK]

Common Mistakes:

• Mixing hex codes with color names
• Assuming default colors override given list
• Confusing slice index starting at 0 or 1

4. Find the error in this pie chart color code:

import matplotlib.pyplot as plt
sizes = [25, 25, 50]
colors = 'red, blue, green'
plt.pie(sizes, colors=colors)
plt.show()

medium

A. colors should be a list, not a string

B. sizes list has wrong values

C. plt.pie does not accept colors parameter

D. Missing plt.show() call

Solution

1. Step 1: Check the type of colors parameter

   The colors parameter must be a list of color names or hex codes, but here it is a single string.

2. Step 2: Understand the impact of wrong type

   Passing a string will cause matplotlib to treat it as one color or raise an error.

3. Final Answer:

   colors should be a list, not a string -> Option A

4. Quick Check:

   colors must be list, not string [OK]

Hint: Always pass colors as a list, not a single string [OK]

Common Mistakes:

• Passing colors as comma-separated string
• Ignoring type requirements for colors
• Assuming plt.show() is optional

5. You want to create a pie chart with 4 slices and use custom colors: red, green, blue, and yellow. Which code correctly applies these colors and also adds labels for each slice?

hard

A. plt.pie([10, 20, 30, 40], colors=['red', 'green', 'blue', 'yellow'], label=['A', 'B', 'C', 'D'])

B. plt.pie([10, 20, 30, 40], colors=['red', 'green', 'blue', 'yellow'], labels=['A', 'B', 'C', 'D'])

C. plt.pie([10, 20, 30, 40], colors=['red', 'green', 'blue'], labels=['A', 'B', 'C', 'D'])

D. plt.pie([10, 20, 30, 40], color=['red', 'green', 'blue', 'yellow'], labels=['A', 'B', 'C', 'D'])

Solution

1. Step 1: Verify the colors parameter and list length

   The colors parameter must be named exactly 'colors' and have 4 colors for 4 slices.

2. Step 2: Check the labels parameter name and length

   The labels parameter must be named 'labels' and have 4 labels matching the slices.

3. Step 3: Identify errors in other options

   plt.pie([10, 20, 30, 40], color=['red', 'green', 'blue', 'yellow'], labels=['A', 'B', 'C', 'D']) uses 'color' instead of 'colors'. plt.pie([10, 20, 30, 40], colors=['red', 'green', 'blue'], labels=['A', 'B', 'C', 'D']) has only 3 colors for 4 slices. plt.pie([10, 20, 30, 40], colors=['red', 'green', 'blue', 'yellow'], label=['A', 'B', 'C', 'D']) uses 'label' instead of 'labels'.

4. Final Answer:

   plt.pie([10, 20, 30, 40], colors=['red', 'green', 'blue', 'yellow'], labels=['A', 'B', 'C', 'D']) -> Option B

5. Quick Check:

   Use colors= and labels= with matching list lengths [OK]

Hint: Match colors and labels list lengths with data slices [OK]

Common Mistakes:

• Using wrong parameter names like 'color' or 'label'
• Mismatched list lengths for colors or labels
• Forgetting to pass labels parameter