How set color of points in R ggplot by function?

Question

I tried to set color of points in ggplot and something not works.

Here is a simplified version of code.

library(tidyverse)

get_point_color <- function(x) {
  if(x <= 10) s <- "red"
  if((x > 10) & (x <= 20)) s <- "orange"
  if((x > 20) & (x <= 50)) s <- "blue"
  s
}

mtcars %>% 
  ggplot(aes(mpg, disp)) +
  geom_point(colour = get_point_color(mpg)) +
  geom_smooth() +
  theme_bw()

Any help is appreciated!

Ronak Shah · Accepted Answer · 2021-10-02 13:12:51Z

1

Using case_when since it is vectorised and scale_color_identity to color the points according to the name of the color.

library(ggplot2)

get_point_color <- function(x) {
  dplyr::case_when(x <= 10 ~ "red",
                   x > 10 & x <= 20 ~ "orange",
                   x > 20 & x <= 500 ~ "blue")
}

ggplot(mtcars, aes(mpg, disp, colour = get_point_color(mpg))) +
  geom_point() +
  geom_smooth() +
  scale_color_identity() + 
  theme_bw()

answered Oct 2, 2021 at 13:12

Ronak Shah

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1 Comment

Andrii Over a year ago

Wow! Super!!! Thanks, Ronak. I will accept it as a final solution. Very cool

akrun · Accepted Answer · 2021-10-02 19:00:52Z

0

We could use ifelse

get_point_color <- function(x) {
  ifelse(x <= 10, "red",
     ifelse(
                   x > 10 & x <= 20,"orange",
               ifelse(    x > 20 & x <= 500, "blue")))
}

and then use the function

ggplot(mtcars, aes(mpg, disp, colour = get_point_color(mpg))) +
  geom_point() +
  geom_smooth() +
  scale_color_identity() + 
  theme_bw()

answered Oct 2, 2021 at 19:00

akrun

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