# python 3.0
import numpy as np
import matplotlib.pyplot as mpl

x = np.array([1, 2, 3, 4, 5])
y = np.array([2, 5, 3, 8, 7])

A = np.vstack([x, np.ones(len(x))]).T

m, c = np.linalg.lstsq(A, y)[0]

import matplotlib.pyplot as plt
plt.plot(x, y, 'o', label='Original data', markersize=10)
plt.plot(x, m*x + c, 'r', label='Fitted line')
plt.legend()
plt.show()