在一个 ggplot 上使用两个比例颜色渐变 [英] using two scale colour gradients on one ggplot

问题描述

我想将散点图上点的色阶渐变与散点图上某些文本的色阶渐变组合在一起.我可以如下面的示例所示分别执行它们，但我似乎无法将它们放在一起......有没有办法做到这一点?

I would like to combine a colour scale gradient for the points on a scatter plot together with a colour scale gradient for some text that goes on the plot. I can do them separately as shown in my example below, but i can't seem to put them together...is there a way of doing this?

这是我想要组合的两种类型的图(p 和 p1)的示例代码

Here is my example code of the two types of plots (p and p1) that I want to combine

l <- data.frame(prev=rnorm(1266), 
            aft=rnorm(1266), 
            day=as.factor(wday(sample(c(2:6),1266,replace=TRUE),abbr=TRUE, label=TRUE)), 
            month=as.factor(month(Sys.Date()+months(sample(0:11,1266,replace=TRUE)),abbr=TRUE, label=TRUE)), 
            ind=c(1:1266))
cors <- ddply(l, c("month", "day"), summarise, cor = round(cor(prev, aft), 3))


# below the text gains the colour gradient
p <- ggplot(l, aes(x=prev, y=aft)) + 
    geom_point() + 
    scale_colour_gradient(low = "red", high="blue")+ 
    facet_grid(day~month, scales="free_x")+
    geom_text(data=cors,aes(label=paste("r= ",cor,sep=""), size=abs(cor), colour=cor), x=Inf, y=Inf, vjust=1, hjust=1, show_guide=FALSE)+
    geom_hline(aes(yintercept=0))+
    geom_smooth(method="loess")
p

# below the points gain the colour gradient
p1 <- ggplot(l, aes(x=prev, y=aft)) + 
    geom_point(aes(colour=ind)) + 
    scale_colour_gradient("gray")+ 
    facet_grid(day~month, scales="free_x")+
    geom_text(data=cors,aes(label=paste("r= ",cor,sep=""), size=abs(cor), colour=cor), x=Inf, y=Inf, vjust=1, hjust=1, show_guide=FALSE)+
    geom_hline(aes(yintercept=0))+
    opts(legend.position="none") +
    geom_smooth(method="loess")

p1

推荐答案

我不希望这能做到.一个情节每个美学只有一个尺度.我相信，如果您添加多个 scale_color，第二个将覆盖第一个.我认为哈德利是故意创造这种行为的，在一个图中从数据到图中比例的映射，例如颜色，是独一无二的.这确保可以轻松比较图中的所有颜色，因为它们共享相同的 scale_color.

I do not expect that this can be done. A plot only has one scale per aesthetic. I believe that if you add multiple scale_color's, the second will overwrite the first. I think Hadley created this behavior on purpose, within a plot the mapping from data to a scale in the plot, e.g. color, is unique. This ensures that all color in the plot can be compared easily, because they share the same scale_color.

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