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Adding vertical/horizontal lines with different line styles in a Python plot

In this article, we are going to learn how to add vertical/horizontal lines with different line styles in matplotlib figures (Python plot)?
Submitted by Anuj Singh, on July 30, 2020

Adding a vertical and horizontal line together could be required for marking the extreme regions or something related to boundary limit in a plot. We can use different line styles in a plot to draw multiple lines in a plot stating multiple meanings. Matplotlib provides different types of line styles for such operations and in this article, we are going to explore some of them.

Supported line styles: '-', '--', '-.', ':', 'None', ' ', '', 'solid', 'dashed', 'dashdot', 'dotted'

Python code for adding vertical/horizontal lines with different line styles in a plot

import numpy as np
import matplotlib.pyplot as plt

x = np.arange(0.1, 5, 0.1)
y = np.exp(-x)

plt.figure()
plt.plot(x,y, 'o', color='purple')
plt.axvline(x=3)
plt.axhline(y=0.6)
plt.title('Region Saperation using Lines')
plt.show()

plt.figure()
plt.plot(x,y, 'o', color='purple')
plt.axvline(x=3, ls='--', linewidth=3.0, color='grey')
plt.axhline(y=0.6, ls='--', linewidth=3.0, color='grey')
plt.title('Region Saperation using Lines')
plt.show()

plt.figure()
plt.plot(x,y, 'o', color='purple')
plt.axvline(x=3, ls=':', linewidth=3.0, color='grey')
plt.axhline(y=0.6, ls=':', linewidth=3.0, color='grey')
plt.title('Region Saperation using Lines')
plt.show()

plt.figure()
plt.plot(x,y, 'o', color='purple')
plt.axvline(x=3, ls=':', linewidth=3.0, color='grey')
plt.axhline(y=0.6, ls='--', linewidth=3.0, color='grey')
plt.title('Region Saperation using Lines')
plt.show()

plt.figure()
plt.plot(x,y, 'o', color='purple')
plt.axvline(x=3, ls='-.', linewidth=3.0, color='grey')
plt.axhline(y=0.6, ls='-.', linewidth=3.0, color='grey')
plt.title('Region Saperation using Lines')
plt.show()

Output:

Output is as figure