import matplotlib.pyplot as plt
#plt.figure(figsize=(20,10))
plt.axhline(y=2,ls=":",c="black")#添加水平直线
plt.axvline(x=4,ls="-.",c="green")#添加垂直直线
import matplotlib.pyplot as plt
#plt.figure(figsize=(20,10))
plt.axhline(y=2,ls=":",c="black")#添加水平直线
plt.axvline(x=4,ls="-.",c="green")#添加垂直直线