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

Question

Data I have:

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

What I want:

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

EDIT: I get the error — “Can’t supply ‘.by’ when ‘.data’ is a grouped data frame.” for all of the comments below. The original data I am manipulating has been left-joined and then grouped. How do I approach this?

Answer 1

You can try below

library(dplyr)
df %>%
    left_join(
        (.) %>%
            summarise(group = as.factor(toString(sort(B))), .by = A) %>%
            mutate(group = as.integer(group))
    )

or you can use membership from igraph package in addition

library(dplyr)
library(igraph)
df %>%
    mutate(group = {
        (.) %>%
            graph_from_data_frame() %>%
            components() %>%
            membership()
    }[B])

which gives

  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

bonus (for the igraph interest)

df %>%
    graph_from_data_frame() %>%
    plot()

shows the groups

Answer 2

library(dplyr)

data1 |>
  mutate(group = paste(sort(B), collapse = ""), .by = A) |>
  mutate(group = cur_group_id(), .by = group)

Output

  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