有没有办法为ggplot的alpha添加图例？ [英] Is there a way to add a legend for ggplot's alpha?

问题描述

我有一个有很多重叠点的图（从2-10开始）。将抖动添加到点使其非常嘈杂和不吸引人。我喜欢在美学中添加一个阿尔法。不过，我希望有一个图例，读者可以看到每个透明胶片有多少点重叠。有没有这样的方法？

  ggplot（data = mydata，aes（x = x，y = y））+ geom_point（ size = 3，shape = 2，aes（alpha = 1/3））
  

上面的代码。如何为alpha添加图例？

解决方案

下面是一个如何伪造这个的例子。尝试它几次，同时改变 alpha 。

  require（ggplot2） 
 
n = 10000 
 alpha = 0.01 
 
 set.seed（12345）
 data = data.frame（replicate（2，rnorm（n）） ）
 
 dev.new（width = 4，height = 3）
p = qplot（X1，X2，data = data，alpha = alpha）
 
 fake_scale = scale_alpha（'重叠pts'的数目，breaks = pretty（c（alpha，1）），labels = as.character（pretty（c（alpha，1））/ alpha））
 
p + fake_scale 
  

alpha = 0.1

alpha = 0.01

I have a plot with many overlapping points (goes from 2-10). Adding jitter to the points makes it very noisy and unappealing. I like adding a alpha in the aesthetics. However, I'd like to have a legend where a reader can see how many points are overlapping for each of those transparencies. Is there such a way?

ggplot(data=mydata,aes(x=x,y=y)) + geom_point(size=3,shape=2,aes(alpha=1/3))

Let's say I use the above code. How would I incorporate a legend for the alpha?

解决方案

Here is an example of how to fake this. Try it a couple times while varying alpha.

require(ggplot2)

n = 10000
alpha = 0.01

set.seed(12345)
data = data.frame(replicate(2, rnorm(n)))

dev.new(width=4, height=3)
p = qplot(X1, X2, data=data, alpha=alpha)

fake_scale = scale_alpha('# of overlapping pts', breaks=pretty(c(alpha, 1)), labels=as.character(pretty(c(alpha, 1))/alpha))

p + fake_scale

alpha = 0.1

alpha = 0.01

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