1.hist and show
import numpy as np
import matplotlib.pyplot as plt
greyhounds = 500
labs = 500
grey_height = 28 + 4 * np.random.randn(greyhounds)
lab_height = 24 + 4 * np.random.randn(labs)
plt.hist([grey_height, lab_height], stacked=True, color=['r','b'])
plt.show()