ggplot(data = mergedata)+
geom_line(aes(x=date,y=ret),colour="black",size=0.5)+
geom_line(aes(x=date,y=alw,colour="red"),size=1)+
geom_line(aes(x=date,y=StpPro,colour="blue"),size=1)+
geom_line(aes(x=date,y=StpPro1Yea,colour="green"),size=1)+
geom_line(aes(x=date,y=StpProLos,colour="yellow"),size=1)+
theme(legend.position = "right")+xlab("时间")+ylab("收益率")+ggtitle("收益率曲线")+
scale_colour_hue("曲线说明:",breaks=c("black","red","blue","green","yellow"),labels= c(1:5))
为什么标注里没有黑色的