python绘图在图中添加标记

• 1.代码讲解
• 2.过程数据

import pandas as pd
import matplotlib.pyplot as plt

df = pd.DataFrame({'A': [0, 2, 4, 6], 'B': [2, 2.5, 5, 8], 'C': [1, 2, 3, 4]},
                  index=['2020-1-1', '2020-1-2', '2020-1-3', '2020-1-4'])

for col in df:
    plt.plot(df[col], label=col)

for name, value in df.max().items():  # df按列求最大值
    plt.text(3.05, value, name, size=10, ha='left', va='center')  # 标记A、B、C

df
Out[13]: 
          A    B  C
2020-1-1  0  2.0  1
2020-1-2  2  2.5  2
2020-1-3  4  5.0  3
2020-1-4  6  8.0  4

df.max()
Out[14]: 
A    6.0
B    8.0
C    4.0
dtype: float64