Is there an R code that checks whether all values in a group are the same as all values in another group?

Data I have:

A	B
1	a
2	c
2	e
3	f
4	h
5	c
5	e

What I want:

If all values of B in different groups of A match, then they’re in the same group. In this case, all B values (c and e) match for 2 and 5.

A	B	Group
1	a	1
2	c	2
2	e	2
3	f	3
4	h	4
5	c	2
5	e	2

Code I attempted:

library(readxl)
library(dplyr)
library(stringr)
data1 <- read_excel("testing.xlsx")
data2 <- data1 %>% 
  group_by(A) %>% 
  group_by(B) %>% 
  mutate(Group = cur_group_id()) %>% 
  ungroup()

What I’m getting from this code:

A	B	Group
1	a	1
2	c	2
2	e	3
3	f	4
4	h	5
5	c	2
5	e	3

NOTE: The original data I am manipulating has been left-joined and then grouped.

Solution

One trick is to group by the list of elements that share the same "A". You can then use cur_group_id properly. I add an arrange call first to make sure that identical groups are recognized as such even if the order is different in the original data.

library(dplyr)
library(tidyr)
dat |> 
  arrange(A, B) |> 
  summarise(B = list(B), .by = A) |> 
  mutate(Group = cur_group_id(), .by = B) |> 
  unnest_longer(B)

#   A B Group
# 1 1 a     1
# 2 2 c     2
# 3 2 e     2
# 4 3 f     3
# 5 4 h     4
# 6 5 c     2
# 7 5 e     2