setting some colors of ggplot with the same colour and get rid of labels

November 24, 2021

I have a much larger dataframe but I post here a tow example for reproducibility.

df = data.frame(fc_col = c(rep('apple',3),rep('orange',3),rep('banana',3)),var1 = c(rep(1:3,3)),var2 = c(20,10,5,30,15,2,40,27,8))

If I plot:

> ggplot(data=df, aes(x=var1, y=var2,colour = fc_col))+
+     geom_line()

I get this:

I would like to get something like apple to black and banana orange to a single color say blue. Imagine there are not 3 levels of factor fc_col like in this case but 300. I would also like to get rid of the label banana orange and write a single one say fruits and have it there with the blue color as mentioned.

>Solution :

This may helps.

The trick is, keep fc_col that keeps fruits themselves, will be used as group in aes(). And make another variable new_fac for color argument .

library(dplyr)
library(ggplot2)

df %>%
  mutate(new_fac = ifelse(fc_col == "apple", fc_col, "fruits") %>% as.factor()) %>%
  ggplot(aes(var1, var2, colour = new_fac, gruop = fc_col)) +
  geom_line() +
  scale_color_manual(values = c("black", "blue"))

`data.table`

library(data.table)
df2 <- setDT(df)[,new_fac := ifelse(fc_col == "apple", "apple", "fruits")][]
ggplot(df2, aes(var1, var2, colour = new_fac, gruop = fc_col)) +
  geom_line() +
  scale_color_manual(values = c("black", "blue"))