在点周围放置边框 [英] Place a border around points

问题描述

我想使用 ggplot2 在基于数据填充的散点图上的点周围放置黑色边框.另外，我想避免黑色边框的图例条目，因为它将在每个点上.基本上我正在寻找这个情节，但每个点周围都有黑色边框.

df <- data.frame(id=runif(12), x=1:12, y=runif(12))ggplot(df，aes(x=x，y=y))+geom_point(aes(颜色=id)，大小=12)

作为奖励，我不想有黑色边框的图例条目.我最好的尝试是:

df <- data.frame(id=runif(12), x=1:12, y=runif(12))ggplot(df, aes(x=x, y=y))+geom_point(aes(fill=id, colour="black"), size=12)

给出:

我不明白为什么这没有给我想要的东西，更糟糕的是(对于我在 ggplot2 中的教育)我不明白为什么它似乎没有将填充颜色映射到任何东西！有什么帮助吗?

也许如果我能正确地获得轮廓和填充映射，我可以使用像最后一组数字中的那个黑客.该问题的公认答案使用@joran 的答案中显示的分层技术，但(IMO)@jbaums 使用 pch=21 技术的答案更胜一筹.(我认为 shape=21 是 pch=21 的替代方案，甚至可能更受欢迎.)

PS 如果要绝对设置而不是根据一些变量...

I'd like to place a black border around points on a scatterplot that are filled based on data, using ggplot2. Also, I would like to avoid having a legend entry for the black border since it will be on each point. Basically I'm looking for this plot, but with a black border around each point.

df <- data.frame(id=runif(12), x=1:12, y=runif(12))
ggplot(df, aes(x=x, y=y))+geom_point(aes(colour=id), size=12)

As a bonus, I'd like to not have a legend entry for the black border. My best try is:

df <- data.frame(id=runif(12), x=1:12, y=runif(12))
ggplot(df, aes(x=x, y=y))+geom_point(aes(fill=id, colour="black"), size=12)

Which gives:

I don't understand why that doesn't give me what I want, and worse (for my education in ggplot2) I don't understand why it doesn't seem to map fill color to anything! Any help?

Perhaps if I can get the outline and fill mapping right I can use a hack like the one in hte last set of figures here to turn off the legend.

解决方案

It's a bit obscure, but you have to use pch>20 (I think 21:25 are the relevant shapes): fill controls the interior colo(u)ring and colour controls the line around the edge.

(g0 <- ggplot(df, aes(x=x, y=y))+geom_point(aes(fill=id), 
       colour="black",pch=21, size=5))

update: with recent ggplot2 versions (e.g. 2.0.0, don't know how far back it goes) the default guide is a colourbar. Need g0 + guides(fill="legend") to get a legend with points as in the plot shown here. The default breaks have changed, too: to exactly replicate this plot you need g0 + scale_fill_continuous(guide="legend",breaks=seq(0.2,0.8,by=0.1)) ...

Related but not identical: how to create a plot with customized points in R? . The accepted answer to that question uses the layering technique shown in @joran's answer, but (IMO) the answer by @jbaums, which uses the pch=21 technique, is superior. (I think shape=21 is an alternative, and perhaps even preferred, to pch=21.)

PS you should put colour outside the mapping (aes bit) if you want to set it absolutely and not according to the value of some variable ...

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