Change column value from character to number or duplicate row in R

Question

I'm having an issue with a variable in some data that I have in R. I have a table that looks something like this,

Variable X	Variable Y
11	[1]
15	[400]
17	[1,2]
21	[13,14]

What I want to do, is that for every entry in 'Variable Y', if there is only one number in the square brackets, I want to get rid of the square brackets. If there are more than one number, I want to get rid of the brackets and then duplicate the entire row, just changing the value in 'Variable Y' in each duplicate. I basically want this table to look like this,

Variable X	Variable Y
11	1
15	400
17	1
17	2
21	13
21	14

I've been able to convert the single bracket entries to numbers using the parse number function in the readr package, but it's very slow so I'd like to improve it. I also have no idea how I can get the duplicates based on more than one entry in the square brackets. Any help would be greatly appreciated, thank you.

Answer 1

You can first remove the square brackets and then separate_rows:

library(dplyr)
library(tidyr)
df %>%
  mutate(Y = gsub("\\[|\\]", "", Y)) %>%
  separate_rows(Y, sep = ",")
# A tibble: 6 × 2
      X Y    
  <dbl> <chr>
1    11 1    
2    15 400  
3    17 1    
4    17 2    
5    21 13   
6    21 14