Manipulate string in column of a dataframe

Question

I have a data frame

a = data.frame("a" = c("aaa|abbb", "bbb|aaa", "bbb|aaa|ccc"), "b" = c(1,2,3))

     a       b
 aaa|abbb    1
 bbb|aaa     2
 bbb|aaa|ccc 3

I want to split the colum value by "|" and sort the output and merge them together to look like this

     a       b
 aaa|abbb    1
 aaa|bbb     2
|aaa|bbb|ccc 3

I tried to use following

paste(sort(ignore.case(unlist(strsplit(as.character(a$a), "\\|")))),collapse = ", ")

but that just combine everything together. How can I implement it on each value of column A and get the result as dataframe. I tried to use lapply but still got the same result, one combined list.

Answer 1

We could use separate_rows to split the values in 'a', then grouped by 'b', sort 'a' and paste the elements together

library(tidyverse)
a %>% 
 separate_rows(a) %>% 
 group_by(b) %>% 
 summarise(a = paste(sort(a), collapse="|")) %>%
 select(names(a))
# A tibble: 3 x 2
#  a               b
#  <chr>       <dbl>
#1 aaa|abbb        1
#2 aaa|bbb         2
#3 aaa|bbb|ccc     3