How to Use Pyplot in Matplotlib: Simple Guide with Examples

Use matplotlib.pyplot by importing it as plt. Call plotting functions like plt.plot() to create graphs, then use plt.show() to display the plot.

Syntax

The basic syntax to use pyplot involves importing it, creating plots with functions like plot(), and displaying them with show(). You can also add titles, labels, and legends.

• import matplotlib.pyplot as plt: Imports pyplot with alias plt.
• plt.plot(x, y): Plots y versus x as lines or markers.
• plt.title(), plt.xlabel(), plt.ylabel(): Add title and axis labels.
• plt.show(): Displays the plot window.

python

import matplotlib.pyplot as plt

x = [1, 2, 3]
y = [4, 5, 6]
plt.plot(x, y)
plt.title('Sample Plot')
plt.xlabel('X axis')
plt.ylabel('Y axis')
plt.show()

Output

A line plot window showing points (1,4), (2,5), (3,6) connected with a line, titled 'Sample Plot' with labeled axes.

Example

This example shows how to create a simple line plot with labels and display it using pyplot.

python

import matplotlib.pyplot as plt

# Data
x = [0, 1, 2, 3, 4]
y = [0, 1, 4, 9, 16]

# Create plot
plt.plot(x, y, marker='o', linestyle='-', color='blue')
plt.title('Square Numbers')
plt.xlabel('Number')
plt.ylabel('Square')

# Show plot
plt.show()

Output

A blue line plot with circular markers showing points (0,0), (1,1), (2,4), (3,9), (4,16) connected, titled 'Square Numbers' with labeled axes.

Common Pitfalls

Common mistakes when using pyplot include forgetting to call plt.show(), which means the plot won't display, or calling plt.plot() without data. Another pitfall is not clearing plots between multiple plots, causing overlap.

Always use plt.clf() or plt.close() to clear plots if making multiple figures in one script.

python

import matplotlib.pyplot as plt

# Wrong: Missing plt.show()
plt.plot([1, 2, 3], [4, 5, 6])

# Right: Add plt.show() to display
plt.plot([1, 2, 3], [4, 5, 6])
plt.show()

Output

The first plot does not display; the second plot window appears showing the line plot.

Quick Reference

Function	Purpose	Example
plt.plot()	Create line or scatter plot	plt.plot(x, y)
plt.title()	Set plot title	plt.title('My Plot')
plt.xlabel()	Set x-axis label	plt.xlabel('X axis')
plt.ylabel()	Set y-axis label	plt.ylabel('Y axis')
plt.show()	Display the plot	plt.show()
plt.clf()	Clear current figure	plt.clf()
plt.close()	Close plot window	plt.close()

Key Takeaways

Import pyplot as plt to access plotting functions easily.

Use plt.plot() to create plots and plt.show() to display them.

Add titles and labels for clarity using plt.title(), plt.xlabel(), and plt.ylabel().

Remember to call plt.show() or your plot will not appear.

Clear plots with plt.clf() or plt.close() when making multiple figures.