Gathering values to a list from each df in grouped

I have a dataframe df:

spell_num	id
1	15
2	16
2	17
3	14
4	18
4	19
4	20

and I want to get the new_df, with unique values in spell_num column and values from the id column collected in a list:

spell_num	id
1	list(15)
2	list(16,17)
3	list(14)
4	list(18,19,20)

I tried this code:

  new_df <- df %>%
    dplyr::group_by(spell_num) %>%
    dplyr::group_map(~gather_ids) %>%
    dplyr::slice(1)

where gather_ids is a function:

gather_ids <- function(x) {
  result <- x %>%
    dplyr::mutate(ids_lst = as.list(x$id))
  result
}

but it didn't work. Can you help me get the desired output either by helping to improve this code or suggesting a better approach? Thanks

CodePudding user response：

library(dplyr)

df %>% 
  group_by(spell_num) %>% 
  summarise(id = list(list(ID)))

Output

spell_num   ID
1           list(15) 
2           list(16:17) 
3           list(14) 
4           list(18:20)

Data

df <- structure(list(spell_num = c(1L, 2L, 2L, 3L, 4L, 4L, 4L), ID = c(15L, 
16L, 17L, 14L, 18L, 19L, 20L)), class = "data.frame", row.names = c(NA, 
-7L))