I want to cumulate a list of string values by date

Question

I have column A, which is a date and B which is a string value.

	A	B
1	01/02/23	apple
2	01/02/23	pear
3	01/02/23	apple
4	02/02/23	apple
3	02/02/23	apple
3	02/02/23	banana
3	02/02/23	banana
3	02/02/23	apple

I would like the output to be a list on unique dates, with cumulation day on day of the string values in B.

Like so

	A	B
1	01/02/23	apple
		pear
1	02/02/23	apple
		pear
		banana

Thank you in advance!!!!

I've tried basic cumulations but cant seem to get to the desired result when i use string value not numbers.

Answer 1

Update removed first answer: We can do it using accumulate together with union and some data tweaking:

library(dplyr)
library(tidyr) 

df %>% 
  arrange(A) %>% 
  mutate(cumulative = accumulate(B, ~union(.x, .y))) %>% 
  reframe(B = last(cumulative), .by=A) %>% 
  unnest(B) %>% 
  mutate(A = ifelse(row_number() != 1, "", A), .by=A)

  A      B
1 1  apple
2     pear
3 2  apple
4     pear
5   banana