text: Q:
  
  Regex expression in R to detect single digit and two digits keeping the delimiters
  
  I am trying to split row into multiple rows using the tidy R package.
  This is a single cell in my dataset
  column 1
   1. a
   2. b
  33. c
  
  df = separate_rows(df,`column 1`, sep = "(?=\\d[\\.]\\s)"
  
  When I use the above code:
  I get 
  Actual Output  |  Desired Output
  1. a           |      1. a
  2. b           |      2. b  
  3              |     33. c
  3. c           |
  
  A:
  
  You may use
  separate_rows(df,`column 1`, sep = "(?m)(?!\\A)(?=^\\d+\\.\\s)")
  
  Regex details
  
  (?m) - ^ now matches start of a line position
  (?!\A) - a negative lookahead that fails the match when at the start of  a string
  (?=^\d+\.\s) - a positive lookahead that, immediately to the right of the current location, requires
  
  ^ - start of a line
  \d+ - 1+ digits
  \. - a dot  
  \s - a whitespace.
  
  