Multiple Plots and subplots

You can plot multiple lines on the same plot by simply calling the plot() function multiple times before displaying the figure. Each call can have different datasets and customizations, allowing for comparative analysis within a single visualization.

Example:

import matplotlib.pyplot as plt

# Sample data
x = [1, 2, 3, 4, 5]
y1 = [1, 4, 9, 16, 25]  # Quadratic
y2 = [2, 3, 5, 7, 11]   # Prime numbers

# Create a line plot
plt.plot(x, y1, label='Quadratic', color='blue', linestyle='-')
plt.plot(x, y2, label='Prime', color='red', linestyle='--')

# Add title and labels
plt.title('Multiple Lines on Same Plot')
plt.xlabel('X-axis')
plt.ylabel('Y-axis')

# Add legend
plt.legend()

# Show the plot
plt.show()

In this example:

- Two lines are plotted on the same axes: one for quadratic values (y1) and another for prime numbers (y2).
- A legend is added to differentiate between the two lines.

Using subplot() to create multiple plots in one figure

The subplot() function allows you to create a grid of subplots within a single figure. You can specify the number of rows and columns in the grid, as well as the index of the current subplot.

Syntax:

plt.subplot(nrows, ncols, index)

Example:

import matplotlib.pyplot as plt

# Sample data for two plots
x = [1, 2, 3, 4, 5]
y1 = [1, 4, 9, 16, 25]  # Quadratic
y2 = [2, 3, 5, 7, 11]   # Prime numbers

# Create a figure
plt.figure(figsize=(10, 6))

# First subplot
plt.subplot(2, 1, 1)  # 2 rows, 1 column, 1st subplot
plt.plot(x, y1, label='Quadratic', color='blue')
plt.title('Quadratic Function')
plt.xlabel('X-axis')
plt.ylabel('Y-axis')
plt.legend()

# Second subplot
plt.subplot(2, 1, 2)  # 2 rows, 1 column, 2nd subplot
plt.plot(x, y2, label='Prime Numbers', color='red')
plt.title('Prime Numbers')
plt.xlabel('X-axis')
plt.ylabel('Y-axis')
plt.legend()

# Adjust layout
plt.tight_layout()

# Show the plots
plt.show()

In this example:

- Two subplots are created: one for the quadratic function and another for prime numbers.
- The tight_layout() function is used to adjust the spacing between the plots for better visual clarity.


3. Exercises:

Exercise: 1
1. Create multiple lines on one plot. Use the following data:
x = [1, 2, 3, 4, 5]
y1 = [2, 4, 6, 8, 10] (Linear)
y2 = [1, 3, 5, 7, 9] (Odd numbers)
2. Plot both lines on the same graph with appropriate labels, a title, and a legend.

Exercise: 2
1. Create a 2x2 grid of subplots using the following data:
a. First subplot: Linear function (y1)
b. Second subplot: Quadratic function (y2)
c. Third subplot: Cubic function (y3 = [1, 8, 27, 64, 125])
d. Fourth subplot: Prime numbers (y2)
2. Add titles and labels for each subplot.

Exercise: 3
1. Create a single figure with one main plot showing both y1 and y2 from Exercise 1.
2. Below that, create two subplots: one for the quadratic function and one for the cubic function from Exercise 2.
3. Ensure that all plots have appropriate titles and labels.


Conclusion
In this lesson, we learned how to plot multiple lines on the same graph for comparative analysis and how to create multiple subplots within a single figure using the subplot() function. These techniques are essential for presenting complex data in a clear and organized manner. In the next lesson, we will explore additional customization options for improving the appearance and functionality of our plots.