ggplot2圖例中的希臘符號（密度圖）

Question

我在ggplot中創建了一個密度圖並試圖在圖例中使用希臘符號。這就是我想：

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）

我怎樣才能得到傳說，顯示希臘的符號，顏色和線型的一個傳奇！？

Thx提前！

編輯：這是數據幀

> 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：

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

而且做了相當多的：

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

堆疊數據框，以簡化繪圖後沒有成果的實驗，我終於找到了：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))) 

生產這一點，並注意到，該線型不匹配後，我花了considerale徒勞的時間，試圖錘ggplot就範沒有成功。我現在發現htat這是一個已被確認爲問題但尚未解決的問題： https://github.com/hadley/ggplot2/issues/802