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.martt...@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-boun...@r-project.org> On Behalf Of Luigi Marongiu
Sent: Thursday, 14 August 2025 06:25
To: r-help <r-help@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
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide https://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
This e-mail transmission may contain confidential or legally privileged
information that is intended only for the individual or entity named in the
e-mail address. If you are not the intended recipient, you are hereby notified
that any disclosure, copying, distribution, or reliance upon the contents of
this e-mail is strictly prohibited. If you have received this e-mail
transmission in error, please reply to the sender, so that they can arrange for
proper delivery, and then please delete the message from your computer systems.
Thank you.
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide https://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
