code: private List<Integer> extractRgroups(String data){
  	  Pattern pattern = Pattern.compile("R[1-9]\\d*");
  	  Matcher matcher = pattern.matcher(data);
  	  List<Integer> listValues = new ArrayList<Integer>();
  	  
  	  while(matcher.find()){
  		listValues.add(Integer.parseInt(matcher.group().split("R")[1]));  
  	  }
  	  return listValues;
    }
docs: extract Rgroups from extended smiles
  
  @param data extended smiles
  @return List of Rgroups