[R] How to use RColorBrewer in ggplot2?

[Marttila Mikko]

Hi Luigi,

As you map z to colour, you need scale_colour_brewer, not the fill version.
And to get discrete colours, you need to make z discrete. A separate group
mapping isn't needed in this case. Try this:

    ggplot(df, aes(x=x, y=y, colour=factor(z))) +
      geom_point(size=4) +
      scale_colour_brewer(palette = "Paired")

Best,

Mikko

-----Original Message-----
From: R-help <r-help-bounces using r-project.org> On Behalf Of Luigi Marongiu
Sent: Thursday, 14 August 2025 06:25
To: r-help <r-help using r-project.org>
Subject: [R] How to use RColorBrewer in ggplot2?

Hello,
I would like to define a color range to custom color some plot, specifically made in ggplot2 (but also for normal plots).
I have been trying to use RColorBrewer but I don't get any value out of this function. I expected it would create a vector of color values, but I must be missing something.
What is the correct you of this function?
Thank you.

EXAMPLE
```
set.seed(50)
df = data.frame(x = runif(15, 0, 1),
                y = x^2 + runif(15, 0, 1),
                z = rep(1:5, 3))
library(ggplot2)
library(RColorBrewer)
ggplot(df, aes(x=x, y=y, colour=z, group=z)) +
  geom_point(size=4) +
  scale_fill_brewer(palette = "Paired")
```


--
Best regards,
Luigi

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