ggplot2图例中的希腊符号（密度图）

Question

我在 ggplot 中创建了一个密度图，并尝试在图例中使用希腊符号。这就是我尝试过的：

value1 = 0.8
value2 = 0.8
value3 = 0
greeks <- list(bquote(rho==.(value1)), bquote(rho==.(value2)), bquote(rho==.(value3)))

ggplot(data=df)+
  stat_density(aes(x=R1, colour="rho = -0,6",linetype="rho = -0,6"), 
               adjust=4, lwd=0.5, geom="line", position="identity")+
  stat_density(aes(x=R2, colour="rho = 0,6",linetype="rho = 0,6"), 
               adjust=4, lwd=0.5, geom="line", position="identity")+
  stat_density(aes(x=R3, colour="rho = 0", linetype="rho = 0"), 
               adjust=4, lwd=0.5, geom="line", position="identity")+
  xlim(-1, 1)+
  xlab("Renditen")+
  ylab("Dichte")+
  ggtitle("Renditeverteilung im Heston-Modell")+
  theme(plot.title=element_text(face="bold", size=16, vjust=2, family="Times New Roman"),  
        axis.title.x=element_text(vjust=-1, size=14, family="Times New Roman"),
        axis.title.y=element_text(vjust=-0.25, size=14, family="Times New Roman"), 
        legend.text=element_text(size=14, family="Times New Roman"), legend.title=element_blank(),
        legend.margin=unit(1, "cm"),
        legend.key.height=unit(1, "line"), 
        legend.key.size=unit(0.4, "cm"), 
        legend.key=element_rect(fill=NA), 
        legend.background=element_blank(),
        plot.margin=unit(c(1,1,1,1), "cm"))+
  scale_colour_manual(values=c("rho = -0,6"="red", "rho = 0,6"="blue", 
                               "rho = 0"="black"), labels=greeks)+
  scale_linetype_manual(values=c("rho = -0,6"=1, "rho = 0,6"=1, 
                                 "rho = 0"=3))

!(http://i.imgur.com/LOWfs63.jpg)

如何让图例在一个图例中显示希腊符号、颜色和线型？

提前谢谢！

编辑：这是数据框

> head(df)
          R1          R2            R3
1 0.22338963  0.15997630  0.2014689661
2 0.04803470 -0.12353615 -0.0802556036
3 0.15555398  0.19013430  0.1984939928
4 0.07646570 -0.05518703 -0.0004357738
5 0.03526795 -0.05357581 -0.0103695887
6 0.14946339  0.06930905  0.1079376659

我的回答：

value1 = "0,6"
value2 = "0"
value3 = "-0,6"
greeks <- list(bquote(rho==.(value1)), bquote(rho==.(value2)), bquote(rho==.(value3)))


ggplot(data=df)+
  stat_density(aes(x=R1, colour="rho = -0,6"), 
               adjust=4, lwd=0.5, geom="line", position="identity")+
  stat_density(aes(x=R2, colour="rho = 0,6"), 
               adjust=4, lwd=0.5, geom="line", position="identity")+
  stat_density(aes(x=R3, colour="rho = 0"), 
               adjust=4, lwd=0.5, linetype=2, geom="line", position="identity")+
  xlim(-1, 1)+
  xlab("Renditen")+
  ylab("Dichte")+
  ggtitle("Renditeverteilung im Heston-Modell")+
  theme(plot.title=element_text(face="bold", size=16, vjust=2, family="Times New Roman"),  
        axis.title.x=element_text(vjust=-1, size=14, family="Times New Roman"),
        axis.title.y=element_text(vjust=-0.25, size=14, family="Times New Roman"), 
        legend.text=element_text(size=14, family="Times New Roman"), legend.title=element_blank(),
        legend.margin=unit(1, "cm"),
        legend.key.height=unit(1, "line"), 
        legend.key.size=unit(0.4, "cm"), 
        legend.key=element_rect(fill=NA), 
        legend.background=element_blank(),
        plot.margin=unit(c(1,1,1,1), "cm"))+
  scale_colour_manual(values=c("red","blue", "black"), labels=greeks)+
  guides(colour=guide_legend(override.aes=list(linetype=c(1,2,1))))

Answer 1

堆叠数据框以简化绘图后：

df2 <- stack(df)
df2$ind <- as.character(df2$ind)

又做了很多无果的实验，终于找到了：problems with ggplot scale, color and linetype parameters

value1 = 0.8
value2 = 0.8
value3 = 0
greeks <- list(bquote(rho==.(value1)), bquote(rho==.(value2)), bquote(rho==.(value3)))

ggplot(data=df2)+
  stat_density(aes(x=values, group=ind, color=ind), 
               adjust=4, lwd=0.5, geom="line", position="identity")+
  xlim(-3, 3)+
  xlab("Renditen")+
  ylab("Dichte")+
  ggtitle("Renditeverteilung im Heston-Modell")+
  theme(plot.title=element_text(face="bold", size=16, vjust=2, family="Times New Roman"),  
        axis.title.x=element_text(vjust=-1, size=14, family="Times New Roman"),
        axis.title.y=element_text(vjust=-0.25, size=14, family="Times New Roman"), 
        legend.text=element_text(size=14, family="Times New Roman"), 
            legend.title=element_blank(),
        legend.margin=unit(1, "cm"),
        legend.key.height=unit(1, "line"), 
        legend.key.size=unit(0.4, "cm"), 
        legend.key=element_rect(fill=NA), 
        legend.background=element_blank(),
        plot.margin=unit(c(1,1,1,1), "cm"))+
  scale_colour_manual(values=1:3, labels=greeks) 
 +guides(colour=guide_legend(override.aes=list(linetype=1:3)))

在制作完这个并注意到线型不匹配之后，我花了很多无用的时间尝试将 ggplot 提交但没有成功。我现在发现 htat 这已被认为是一个问题但尚未解决： https://github.com/hadley/ggplot2/issues/802