Only displaying some legend contents

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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

ggplot2 legend r
1 Answers

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)

EDIT In case of scale_fill_manual one option would be to name your list of colors. This has the additional benefit that you could assign colors to names or Categories without bothering about the order in which you pass the colors to the values argument of the scale:

# Example color palette
colourslist <- scales::hue_pal()(length(unique(df$group)))
# Name your list of colors
names(colourslist) <- unique(df$group)

ggplot(df, aes("1", sample.size, fill = group)) +
  geom_col(width = 1, color="darkgrey") +
  scale_fill_manual(values = colourslist, breaks = top_group) +
  coord_polar("y", start = 0)

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