[SOLVED] Labeling a particular cluster in K-means in R

Labeling a particular cluster in K-means in R

What are the modifications in code required if I want to label only datapoints in cluster 3?

> library(datasets)
head(iris)
library(ggplot2)
ggplot(iris, aes(Petal.Length, Petal.Width, color = Species)) + geom_point()
set.seed(20)
irisCluster <- kmeans(iris[, 3:4], 3, nstart = 20)
irisCluster

table(irisCluster$cluster, iris$Species)
    setosa versicolor virginica

irisCluster$cluster <- as.factor(irisCluster$cluster)
ggplot(iris, aes(Petal.Length, Petal.Width, color = irisCluster$cluster)) + geom_point()`

Solution

You can turn the labels as blank for cluster which is not 3. You may need to adjust the position of labels based on your actual data.

library(dplyr)
library(ggplot2)

iris %>%
  mutate(cluster = irisCluster$cluster, 
         label = replace(Petal.Length, cluster != 3, '')) %>%
  ggplot() + aes(Petal.Length, Petal.Width, color = cluster, label = label) + 
  geom_point() + geom_text(vjust = -0.5, hjust = -0.4)