matplotlib柱状图

 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()