如何在R的ggplot中添加图例？

如何解决如何在R的ggplot中添加图例？

我正在用 2 y 轴绘制一个情节，一切都好，只是我的情节中不能有我的图例，

我试过命令：

• scale_color_hue
• scale_color_manuel

还是什么都没有，

这是我的代码：

ggplot() + 
  geom_bar(mapping = aes(x = meteo$Date,y = meteo$Moyenne.de.Tre.sol.à....10.cm),stat = "identity",fill = "gray") +
  geom_line(mapping = aes(x = flux$Date,y = flux$Moyenne.de.CO2GPP_flux),lty=2,size = 0.2,color = "green") +
  geom_line(mapping = aes(x = flux$Date,y = flux$Moyenne.de.CO2Reco_flux),color = "yellow") +
  geom_line(mapping = aes(x = flux$Date,y = flux$Moyenne.de.CO2NEE_flux),size = 0.5,color = "blue") +
  #geom_errorbar(width=.1,aes(ymin=flux$Moyenne.de.CO2NEE_flux- var(flux$Moyenne.de.CO2NEE_flux),ymax=flux$Moyenne.de.CO2NEE_flux+ var(flux$Moyenne.de.CO2NEE_flux)),colour="red")
  geom_point(mapping = aes(x = flux$Date,pch =16,size = 1,color = "blue") +
  scale_x_date(name = "") +
  scale_y_continuous(name = "Température du sol",sec.axis = sec_axis(~./(abs(max(meteo$Moyenne.de.Tre.sol.à....10.cm))/abs(max(flux$Moyenne.de.CO2GPP_flux))),name = "CO2 Flux")) +
  scale_color_hue(breaks=c("OJ","VC"),labels=c("Orange juice","Ascorbic acid"),l=40) +
  theme(axis.title.y = element_text(color = "black"),axis.title.y.right = element_text(color = "black"),legend.text = element_text(size = 8,colour = "red"),legend.title=element_blank(),legend.position = c(1,0))

感谢您的帮助，祝您有美好的一天：D