R: Coloring Individual Bars in Barplots - r

Question

I am working with the R programming language.
I simulated the following data:
set.seed(123)
myFun <- function(n = 5000) {
a <- do.call(paste0, replicate(5, sample(LETTERS, n, TRUE), FALSE))
paste0(a, sprintf("%04d", sample(9999, n, TRUE)), sample(LETTERS, n, TRUE))
}
name = myFun(400)
variable = rnorm(400, 50,10)
part1 = data.frame(name,variable)
name = myFun(10)
variable = rnorm(10, 130,10)
part2 = data.frame(name,variable)
final = rbind(part1, part2)
final$name = substr(final$name,1,3)
Then, I made a barplot of this data:
library(ggplot2)
p<-ggplot(data=final, aes(x=name, y=variable)) +
geom_bar(stat="identity") + ggtitle(" Title of Barplot")
Is there a way I can take the "names" with the ten largest values of "variable" and place them as labels on top of the corresponding bars?
I saw this link over here that shows how to do this for all bars (https://www.geeksforgeeks.org/how-to-add-labels-over-each-bar-in-barplot-in-r/) - but is there a way to do this only for the 10 largest bars?
Thanks!
Note: Is there some way to better "center" the labels and prevent them from overlapping?

Answer 1

Another option using geom_text_repel which has a lot of options for positioning your labels. Here is a reproducible example:
set.seed(123)
myFun <- function(n = 5000) {
a <- do.call(paste0, replicate(5, sample(LETTERS, n, TRUE), FALSE))
paste0(a, sprintf("%04d", sample(9999, n, TRUE)), sample(LETTERS, n, TRUE))
}
name = myFun(400)
variable = rnorm(400, 50,10)
part1 = data.frame(name,variable)
name = myFun(10)
variable = rnorm(10, 130,10)
part2 = data.frame(name,variable)
final = rbind(part1, part2)
library(dplyr)
# Create subset dataframe
final_10 <- final %>%
arrange(desc(variable)) %>%
slice(1:10)
library(ggplot2)
library(ggrepel)
ggplot(data=final, aes(x=name, y=variable)) +
geom_bar(stat="identity") +
geom_text_repel(data = final_10, aes(x = name, y = variable, label = variable), size = 2, segment.color = "grey50") +
ggtitle(" Title of Barplot")
Created on 2022-08-24 with reprex v2.0.2

Answer 2

Here you go, just create a new variable with the name for the top 10 and NA otherwise
# Setup
library(tidyverse)
# Create a label column
final <-
final %>%
arrange(desc(variable)) %>%
mutate(label = ifelse(row_number() <= 10, name, NA))
# Add geom_text() for label
p <-
ggplot(
data = final,
aes(
x = name,
y = variable,
label = label)) +
geom_bar(stat="identity") +
geom_text() +
ggtitle(" Title of Barplot")