# How do I find the intersection of two line segments in Matplotlib?

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To find the intersection of two lines segments in Matplotlib and pass the horizontal and vertical lines through that point, we can take the following steps −

• Set the figure size and adjust the padding between and around the subplots.
• Create two lines using slopes (m1, m2) and intercepts (c1 and c2). Initialize the slopes and intercept values.
• Create x data points using numpy.
• Plot x, m1, m2, c2 and c1 data points using plot() method.
• Using intercepts and slope values, find the point of intersection.
• Plot the horizontal and vertical lines with dotted linestyle.
• Plot xi and yi points on the plot.
• To display the figure, use show() method.

## Example

import matplotlib.pyplot as plt
import numpy as np

plt.rcParams["figure.figsize"] = [7.50, 3.50]
plt.rcParams["figure.autolayout"] = True

m1, c1 = 0.1, 2.0
m2, c2 = 2.0, -3.0

x = np.linspace(-10, 10, 500)

plt.plot(x, x * m1 + c1, 'red')
plt.plot(x, x * m2 + c2, 'green')

plt.xlim(-2, 8)
plt.ylim(-2, 8)

xi = (c1 - c2) / (m2 - m1)
yi = m1 * xi + c1

plt.axvline(x=xi, color='gray', linestyle='--')
plt.axhline(y=yi, color='gray', linestyle='--')

plt.scatter(xi, yi, color='black')

plt.show()

## Output

Updated on 18-Jun-2021 10:48:02

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