import Matplotlib.pyplot as pltpt.rcParams['font.sans-serif']='SimHei'fig,ax1=plt.subplot(figsize=(8,6))x=['3月','4月','5月','6月','7月']y1=[100,90,80,110,84]y2=[10,9,14,7,11]#第一条折线ax1.plot(x,y1,color='blue',label='营业额')ax1.set_xlabel('月份')ax1.set_ylabel('营业额')#关键代码:ax2=ax1.twinx()#第二条折线ax2.plot(x,y2,color='red',label='销量')ax2.set_ylabel('销量')ax1.set_title('每个月的营业额和销量变化情况')lines1,labels1=ax1.get_legend_handles_labels()lines2,labels2=ax2.get_legend_handles_labels()ax1.legend(lines1+lines2,labels1+labels2,loc='best')plt.show()