how to plot a legend in python code example

Example 1: how to add legend to python plot

import numpy as np
import matplotlib.pyplot as plt

x = np.linspace(0, 20, 1000)
y1 = np.sin(x)
y2 = np.cos(x)

plt.plot(x, y1, "-b", label="sine")
plt.plot(x, y2, "-r", label="cosine")
plt.legend(loc="upper left")
plt.ylim(-1.5, 2.0)
plt.show()

Example 2: legend matplotlib

import matplotlib.pyplot as plt

#define x and ysin
plt.plot(x,ysin,label='sin(x)')
plt.legend()
plt.show()