How to Create Dashed Line in Matplotlib: Simple Guide

To create a dashed line in matplotlib, use the linestyle='--' parameter in the plotting function like plt.plot(). This tells Matplotlib to draw the line with dashes instead of solid lines.

Syntax

Use the linestyle parameter in plotting functions to set the line style. Common values are:

• '-': solid line
• '--': dashed line
• '-.': dash-dot line
• ':': dotted line

Example syntax:

plt.plot(x, y, linestyle='--')

python

plt.plot(x, y, linestyle='--')

Example

This example shows how to plot a simple dashed line using matplotlib. It plots a line with x values from 0 to 4 and y values as their squares, using a dashed line style.

python

import matplotlib.pyplot as plt

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

plt.plot(x, y, linestyle='--', color='blue', marker='o')
plt.title('Dashed Line Example')
plt.xlabel('x')
plt.ylabel('y')
plt.grid(True)
plt.show()

Output

A plot window showing a blue dashed line connecting points (0,0), (1,1), (2,4), (3,9), (4,16) with circle markers and grid lines.

Common Pitfalls

Common mistakes when creating dashed lines include:

• Using linestyle='dash' instead of '--'. The correct value for dashed lines is '--'.
• Not importing matplotlib.pyplot as plt.
• Overriding linestyle by specifying style or other conflicting parameters.

Example of wrong and right usage:

python

import matplotlib.pyplot as plt

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

# Wrong: linestyle value incorrect
# plt.plot(x, y, linestyle='dash')  # This will cause an error or default to solid

# Right:
plt.plot(x, y, linestyle='--')
plt.show()

Output

A plot window showing a dashed line connecting points (0,0), (1,1), (2,4).

Quick Reference

Here is a quick reference for common linestyle values in Matplotlib:

Linestyle	Description	Example
'-'	Solid line	plt.plot(x, y, linestyle='-')
'--'	Dashed line	plt.plot(x, y, linestyle='--')
'-.'	Dash-dot line	plt.plot(x, y, linestyle='-.')
':'	Dotted line	plt.plot(x, y, linestyle=':')

Key Takeaways

Use linestyle='--' in plt.plot() to create dashed lines in Matplotlib.

Common linestyle options include '-', '--', '-.', and ':'.

Avoid incorrect linestyle values like 'dash' which cause errors or default styles.

Combine linestyle with color and marker for clearer plots.

Always import matplotlib.pyplot as plt before plotting.