Bar 柱状图

详解：4.2Python数据处理篇之Matplotlib系列(二)---plt.scatter()散点图 - 梦并不遥远 - 博客园 (cnblogs.com)

 1 import matplotlib.pyplot as plt
 2 import numpy as np
 3 
 4 n = 12
 5 X = np.arange(n)
 6 Y1 = (1-X/float(n))*np.random.uniform(0.5,1.0,n) #从一个均匀分布[0.5,1.0)中随机采样
 7 Y2 = (1-X/float(n))*np.random.uniform(0.5,1.0,n)
 8 
 9 #柱状图
10 plt.bar(X,+Y1,facecolor='#9999ff',edgecolor='white')
11 plt.bar(X,-Y2,facecolor='#ff9999',edgecolor='white')
12 
13 for x,y in zip(X,Y1):
14     #ha: horizontal alignment
15     plt.text(x+0.1,y+0.08,'%.2f'%y,ha='center',va='bottom')
16 
17 for x,y in zip(X,Y2):
18     #ha: horizontal alignment
19     plt.text(x+0.1,-y-0.12,'-%.2f'%y,ha='center',va='bottom')
20 
21 
22 plt.xlim(-1,n)
23 plt.xticks(())
24 plt.ylim(-1.25,1.25)
25 plt.yticks(())
26 
27 plt.show()

运行结果如下：