How to Create a Line Plot in Matplotlib: Simple Guide

To create a line plot in matplotlib, use the plt.plot() function with your data points. Then call plt.show() to display the plot.

Syntax

The basic syntax to create a line plot is:

• plt.plot(x, y): Plots y versus x as lines and/or markers.
• x: List or array of x-axis values.
• y: List or array of y-axis values.
• plt.show(): Displays the plot window.

python

import matplotlib.pyplot as plt

x = [0, 1, 2, 3, 4, 5]
y = [0, 1, 2, 3, 4, 5]

plt.plot(x, y)
plt.show()

Example

This example shows how to plot a simple line graph of y = x squared for x values from 0 to 5.

python

import matplotlib.pyplot as plt

x = [0, 1, 2, 3, 4, 5]
y = [i**2 for i in x]

plt.plot(x, y)
plt.title('Line Plot of y = x^2')
plt.xlabel('x')
plt.ylabel('y')
plt.show()

Output

A line plot window showing a curve starting at (0,0) and rising steeply to (5,25).

Common Pitfalls

Common mistakes when creating line plots include:

• Not calling plt.show(), so the plot does not display.
• Passing x and y lists of different lengths, causing errors.
• Forgetting to import matplotlib.pyplot as plt.

python

import matplotlib.pyplot as plt

# Wrong: Different lengths
x = [1, 2, 3]
y = [4, 5]
# plt.plot(x, y)  # This will cause an error

# Right:
x = [1, 2, 3]
y = [4, 5, 6]
plt.plot(x, y)
plt.show()

Output

A line plot window showing a line connecting points (1,4), (2,5), and (3,6).

Quick Reference

Tips for creating line plots:

• Use plt.plot(x, y, 'color_marker_style') to customize lines (e.g., 'ro-' for red circles with lines).
• Add labels with plt.xlabel() and plt.ylabel().
• Use plt.title() to add a title.
• Call plt.grid(True) to add grid lines.

Key Takeaways

Use plt.plot(x, y) to create a line plot with your data points.

Always call plt.show() to display the plot window.

Ensure x and y have the same length to avoid errors.

Customize your plot with titles, labels, and colors for clarity.

Import matplotlib.pyplot as plt before plotting.