在一个ggplot上使用两个标度颜色梯度 [英] using two scale colour gradients on one ggplot

问题描述

我想将散点图上的点的颜色标度梯度与绘图上某些文本的颜色标度梯度组合在一起。我可以单独做他们，如我下面的例子所示，但我不能把它们放在一起...是否有一种方法这样做？

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?

这里是我想要合并的两种类型的图（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

我不期望这可以做到。一个情节只有一个美学的尺度。我相信如果你添加多个 scale_color 的，第二个将覆盖第一个。我认为Hadley有意地创建了这个行为，在一个情节从数据到图中的比例的映射，例如。颜色，是独一无二的。这确保了绘图中的所有颜色都可以容易地比较，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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