ggplot图例中缺少标签

debugcn 发表于 Dev

隐士

我想绘制一些数据，然后为平均值和平均值+/-标准偏差添加回归线和水平线，每种颜色均不同。我已经做到了，但我无法正确理解图例。它显示了前两个的标签，但对三个水平线什么也没说。我怎样才能使图例也为这三行都贴上标签？

另一篇文章提到show_guide = TRUE，但这对我不起作用。我也一直在寻找scale_colour_manual的文档，但这对我没有帮助。

我的代码是这样的：

p <- qplot(mpg, wt, data = mtcars, colour="1")
p <- p + geom_smooth(method='lm',aes(x=mpg,y=wt,colour="2"),formula=y~x)
p <- p + geom_hline(yintercept = mean(mtcars$wt), colour = "3")
p <- p + geom_hline(yintercept = mean(mtcars$wt) + sd(mtcars$wt), colour = "3",    linetype="dashed")
p <- p + geom_hline(yintercept = mean(mtcars$wt) - sd(mtcars$wt), colour = "3", linetype="dashed")      
p <- p + labs(colour="")    
p <- p + scale_colour_manual(values = c("red","blue", "green","green","green"),labels=c("Data","Regression","Mean","Mean + SD","Mean - SD"))
p <- p + guides(colour = guide_legend())
print(p)

任何帮助将不胜感激，加油！

乔兰

我认为这可能更接近您想要的：

d <- data.frame(yint = c(mean(mtcars$wt) - sd(mtcars$wt),
                mean(mtcars$wt),
                mean(mtcars$wt) + sd(mtcars$wt)),
                grp = c('dashed','solid','dashed'))

p <- ggplot(data = mtcars,aes(mpg, wt)) + 
    geom_point(aes(color = "Data")) +
    geom_smooth(method='lm',aes(x=mpg,y=wt,color = "Regression"),formula=y~x) + 
    geom_hline(data = d,aes(yintercept = yint,linetype = grp,color = "Mean +/- SD")) + 
    scale_linetype_manual(values = c('dashed' = 'dashed','solid' = 'solid')) + 
    labs(color = "")
print(p)

关于分别标记每条水平线的问题，我的回答是，这根本不属于图例。这些标签应标有geom_text()：

d <- data.frame(yint = c(mean(mtcars$wt) - sd(mtcars$wt),
                         mean(mtcars$wt),
                         mean(mtcars$wt) + sd(mtcars$wt)),
                         grp = c('dashed','solid','dashed'),
                         lab = c('-SD','Mean','+SD'))

p <- ggplot(data = mtcars,aes(mpg, wt)) + 
    geom_point(aes(color = "Data")) +
    geom_smooth(method='lm',aes(x=mpg,y=wt,color = "Regression"),formula=y~x) + 
    geom_hline(data = d,aes(yintercept = yint,linetype = grp),color = "green") + 
    geom_text(data = d,aes(y = yint,label = lab),
              vjust = -0.5,hjust = 1,x = Inf,size = 3) +
    scale_linetype_manual(values = c('dashed' = 'dashed','solid' = 'solid')) + 
    labs(color = "")
print(p)

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