CODEWITHSUNDEEP
rdata.table
chay
chay

Reputation: 45

Generate unique pairwise combinations of a column values based on 2 others columns in a data.table

I have tried a lot of things and I even searched for similar questions but couldn't find solutions.

Suppose that we have a data.table in R:

ID = c("1","1","1","2","2")
Code = c("A","B","C","B","C")
N = c("3","3","3","2","2")

so basically, I want to have unique pairwise combinations for column "Code" based on "ID" and "N" columns.

Is there an R function to return the following?

ID = c("1","1","1","2")
Combinations = c("A.B","B.C","C.A","B.C")
N = c("3","3","3","2")

as I said before I have tried many things but if gives me a data.table which contains only the combinations however in my final result I need to have a column for ID and 2 others for combinations and N

Do you have an idea how to do it ?

Upvotes: 0

Views: 652

Answers (1)

Ronak Shah
Ronak Shah

Reputation: 388817

You may use combn in group_by -

library(dplyr)

result <- df %>%
  group_by(ID, N) %>%
  summarise(Code = combn(Code, 2, paste0, collapse = '.'), .groups = 'drop')

result

#  ID    N     Code 
#  <chr> <chr> <chr>
#1 1     3     A.B  
#2 1     3     A.C  
#3 1     3     B.C  
#4 2     2     B.C

data

df <- data.frame(ID, Code, N)

Upvotes: 1

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