Only displaying some legend contents

Question

I am interested in displaying only the top 3 most abundant groups in my ggplot2 legend.

for example, in this table, i have 7 groups and i would only like to display groups D, E, F in my ggplot2 legend

group	sample size
A	2
B	3
C	1
D	25
E	23
F	20
G	3

I tried searching online but the closest answers i got was to reorder the legend.

Thanks in advance!

Cheers, Mel

Answer 1

You could achieve this by setting the breaks for the fill scale:

df <- data.frame(
             group = c("A", "B", "C", "D", "E", "F", "G"),
       sample.size = c(2L, 3L, 1L, 25L, 23L, 20L, 3L)
)

library(ggplot2)
library(dplyr)

top_group <- df %>% top_n(3, sample.size) %>% pull(group)

ggplot(df, aes(group, sample.size, fill = group)) +
  geom_col() +
  scale_fill_discrete(breaks = top_group)