Home/ Questions/Q 7923613
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-06-03T17:22:53+00:00

I’d like to place a black border around points on a scatterplot that are

  • 0

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)

the plot I want, except it doesn't have borders around the points

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:

not at all the plot I want

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.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    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)) …

    enter image description here

    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 …

    • 0