[R] How to use RColorBrewer in ggplot2?

[Rui Barradas]

Hello,

You can create as many colors as you like with

brewer.pal(n, name)

where name is the palette name.
Then, combine with the other color.

library(ggplot2)
library(RColorBrewer)

brew_colrs <- brewer.pal(4, "Paired")
black <- "#000000"

# set the names to the possible value of 'z'
colrs <- c(brew_cols, black) |> setNames(1:5)

set.seed(50)
x <- runif(15, 0, 1)
df <- data.frame(x = x,
                 y = x^2 + runif(15, 0, 1),
                 z = rep(1:5, 3))

ggplot(df, aes(x=x, y=y, colour=factor(z))) +
   geom_point(size=4) +
   scale_colour_manual(values = colrs)


Hope this helps,

Rui Barradas




On 8/15/2025 5:42 AM, Luigi Marongiu wrote:
> Thank you, that worked fine.
> May I also ask how to create a vector of colors with RColorBrewer?
> Let's say I wanted to color z with 4 shade colors from the "Paired"
> palette, but then assign the fifth with a color of my choice, say
> "black", to distinguish clearly the fifth class.
> If I run
> ```
>> scale_fill_brewer(palette="BrBG")
> <ggproto object: Class ScaleDiscrete, Scale, gg>
>      aesthetics: fill
>      axis_order: function
>      break_info: function
>      break_positions: function
>      breaks: waiver
>      call: call
>      clone: function
>      dimension: function
>      drop: TRUE
>      expand: waiver
>      get_breaks: function
>      get_breaks_minor: function
>      get_labels: function
>      get_limits: function
>      get_transformation: function
>      guide: legend
>      is_discrete: function
>      is_empty: function
>      labels: waiver
>      limits: NULL
>      make_sec_title: function
>      make_title: function
>      map: function
>      map_df: function
>      n.breaks.cache: NULL
>      na.translate: TRUE
>      na.value: NA
>      name: waiver
>      palette: function
>      palette.cache: NULL
>      position: left
>      range: environment
>      rescale: function
>      reset: function
>      train: function
>      train_df: function
>      transform: function
>      transform_df: function
>      super:  <ggproto object: Class ScaleDiscrete, Scale, gg>
> ```
> while the help says "The brewer scales provide sequential, diverging
> and qualitative colour schemes".
> How can I generate 4 shades with RColorBrewer?
> Thanks.
> 
> On Thu, Aug 14, 2025 at 10:00 AM Marttila Mikko
> <mikko.marttila using orionpharma.com> wrote:
>>
>> 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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