import numpy as np

 import matplotlib.pyplot as plt

 size = 5

 a = np.random.random(size)

 b = np.random.random(size)

 c = np.random.random(size)

 d = np.random.random(size)

 x = np.arange(size)

 total_width, n = 0.8, 3     # 有多少个类型，只需更改n即可

 width = total_width / n

 x = x - (total_width - width) / 2

 plt.bar(x, a,  width=width, label='a')

 plt.bar(x + width, b, width=width, label='b')

 plt.bar(x + 2 * width, c, width=width, label='c')

 plt.legend()

 plt.show()