calculate frequency of unique values per group in R

Question

How can I count the number of unique values such that I go from:

organisation <- c("A","A","A","A","B","B","B","B","C","C","C","C","D","D","D","D")
variable <- c("0","0","1","2","0","0","1","1","0","0","1","1","0","0","2","2")
df <- data.frame(organisation,variable)

organisation | variable
A            | 0
A            | 1
A            | 2
A            | 2
B            | 0
B            | 0
B            | 1
B            | 1
C            | 0
C            | 0
C            | 1
C            | 1
D            | 0
D            | 2
D            | 2
D            | 2

To:

unique_values | frequency
0,1,2         | 1
0,1           | 2
0,2           | 1

There are only 3 possible sequences:

• 0,1,2
• 0,1
• 0,2

Answer 1

Try this

s <- aggregate(. ~ organisation , data = df , \(x) names(table(x)))
s$variable <- sapply(s$variable , \(x) paste0(x , collapse = ","))
setNames(aggregate(. ~ variable , data = s , length) , c("unique_values" , "frequency"))

• output

  unique_values frequency
1           0,1         2
2         0,1,2         1
3           0,2         1