How to Set Line Style in Matplotlib: Simple Guide

In Matplotlib, you set the line style using the linestyle parameter in plotting functions like plot(). You can use styles like '-' for solid, '--' for dashed, ':' for dotted, or '-.' for dash-dot lines.

Syntax

The linestyle parameter controls the style of the line in Matplotlib plots. It accepts strings that define the pattern of the line.

• '-': solid line (default)
• '--': dashed line
• ':': dotted line
• '-.': dash-dot line

You use it inside plotting functions like plt.plot(x, y, linestyle='--').

python

import matplotlib.pyplot as plt

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

plt.plot(x, y, linestyle='--')  # Dashed line
plt.show()

Output

A plot with a dashed line connecting points (1,2), (2,3), and (3,5).

Example

This example shows how to plot multiple lines with different line styles using the linestyle parameter.

python

import matplotlib.pyplot as plt

x = [0, 1, 2, 3, 4]
y1 = [0, 1, 4, 9, 16]
y2 = [0, 1, 2, 3, 4]
y3 = [0, 1, 0, 1, 0]

plt.plot(x, y1, linestyle='-')   # Solid line
plt.plot(x, y2, linestyle='--')  # Dashed line
plt.plot(x, y3, linestyle=':')   # Dotted line
plt.title('Different Line Styles in Matplotlib')
plt.show()

Output

A plot with three lines: solid, dashed, and dotted, each showing different data.

Common Pitfalls

Common mistakes when setting line styles include:

• Using incorrect strings like 'dash' instead of '--'.
• Forgetting to use the linestyle keyword argument.
• Confusing linestyle with style or ls (though ls is a valid shortcut).

Always use one of the accepted strings or the shortcut aliases.

python

import matplotlib.pyplot as plt

x = [1, 2, 3]
y = [3, 2, 1]

# Wrong way (won't change line style):
plt.plot(x, y, linestyle='dash')  # Incorrect string
plt.title('Wrong linestyle example')
plt.show()

# Right way:
plt.plot(x, y, linestyle='--')  # Correct dashed line
plt.title('Correct linestyle example')
plt.show()

Output

First plot shows a solid line because 'dash' is invalid; second plot shows a dashed line as expected.

Quick Reference

Line Style	String Code	Description
Solid	'-'	Continuous solid line
Dashed	'--'	Line with dashes
Dotted	':'	Line with dots
Dash-dot	'-.'	Line with dash-dot pattern
None	'' or 'None'	No line drawn

Key Takeaways

Use the linestyle parameter in plotting functions to set line styles in Matplotlib.

Common line styles include '-', '--', ':', and '-.'.

Use correct string codes; invalid strings default to solid lines.

You can also use the shortcut 'ls' instead of 'linestyle'.

Line style helps make plots clearer and visually distinct.