Legend placement options in Matplotlib - Mini Project: Build & Apply

Legend placement options

📖 Scenario: You are creating a simple line chart to compare sales of two products over 5 months. You want to add a legend to explain which line is which. The legend can be placed in different positions on the chart.

🎯 Goal: Learn how to add a legend to a matplotlib plot and place it in different positions using the loc parameter.

📋 What You'll Learn

Create a line plot with two lines representing sales data for Product A and Product B.

Add a legend with labels for each product.

Set the legend position using the loc parameter with a string value.

💡 Why This Matters

🌍 Real World

Legends help explain different data series in charts, making them easier to understand in reports and presentations.

💼 Career

Data scientists and analysts often create visualizations with legends to clearly communicate insights to stakeholders.

1

Create sales data and plot lines

Create two lists called months and sales_a with values [1, 2, 3, 4, 5] and [10, 15, 13, 17, 20] respectively. Also create a list called sales_b with values [12, 14, 16, 18, 22]. Then import matplotlib.pyplot as plt and plot sales_a and sales_b against months using plt.plot(). Use labels 'Product A' and 'Product B' for the lines.

Matplotlib

# Create months, sales_a, sales_b lists
# Import matplotlib.pyplot as plt
# Plot sales_a and sales_b against months with labels

Need a hint?

Use plt.plot(x_values, y_values, label='name') to plot lines with labels.

2

Add a legend with default placement

Add a legend to the plot by calling plt.legend() without any arguments.

Matplotlib

months = [1, 2, 3, 4, 5]
sales_a = [10, 15, 13, 17, 20]
sales_b = [12, 14, 16, 18, 22]
import matplotlib.pyplot as plt
plt.plot(months, sales_a, label='Product A')
plt.plot(months, sales_b, label='Product B')
# Add a legend with default placement

Need a hint?

Call plt.legend() to add the legend with default position.

3

Change legend position to upper left

Modify the legend call to place the legend in the upper left corner by passing loc='upper left' to plt.legend().

Matplotlib

months = [1, 2, 3, 4, 5]
sales_a = [10, 15, 13, 17, 20]
sales_b = [12, 14, 16, 18, 22]
import matplotlib.pyplot as plt
plt.plot(months, sales_a, label='Product A')
plt.plot(months, sales_b, label='Product B')
# Change legend position to upper left

Need a hint?

Use plt.legend(loc='upper left') to move the legend.

4

Display the plot

Add a line to display the plot by calling plt.show().

Matplotlib

months = [1, 2, 3, 4, 5]
sales_a = [10, 15, 13, 17, 20]
sales_b = [12, 14, 16, 18, 22]
import matplotlib.pyplot as plt
plt.plot(months, sales_a, label='Product A')
plt.plot(months, sales_b, label='Product B')
plt.legend(loc='upper left')
# Display the plot

Need a hint?

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