How to remove rows that have only 1 combination for a given ID

Question

I have a dataframe like this

ID <- c(\"A\",\"A\",\"A\",\"B\",\"B\",\"C\",\"C\")
Measurement <- c (\"Length\",\"Breadth\",\"Breadth\",\"Breadth\",\"Leng         


        

Answer 1

In dplyr, it would be

library(dplyr)

df %>% group_by(ID) %>% filter(n_distinct(Measurement) > 1)
##       ID Measurement Value
##          
## 1      A      Length   4.5
## 2      A     Breadth   6.6
## 3      A     Breadth   7.5
## 4      B     Breadth   3.3
## 5      B      Length   5.6