rExtractVars function

Implementation

List<String> rExtractVars(String txt) {
  // Command/string to identify start point of the extracttion.

  String cmd = '> names(ds)';

  // Split the string based on lines.

  List<String> lines = txt.split('\n');

  // The result is a list of variable names (Strings).

  List<String> result = [];

  // Find the start of the latest string of interest, searching from the last
  // line backwards. Begin by initializing a value that indicates no start index
  // found.

  int startIndex = -1;

  for (int i = lines.length - 1; i >= 0; i--) {
    if (lines[i].contains(cmd)) {
      startIndex = i;
      break;
    }
  }

  // If the pattern of interest was found then begin collecting lines of output
  // from the R Console.

  if (startIndex != -1) {
    for (int i = startIndex + 1; i < lines.length; i++) {
      if (lines[i].startsWith('>')) {
        // Found the next line starting with the R prompt '>'. Stop adding lines
        // to the result. Assumes no lines, after the pattern of interest, that
        // contain the output we want to capture start with the R prompt '>'.

        break;
      }

      result.add(lines[i]);
    }
  }

  // Join all lines into one string to work on it now to extract the variable
  // names.

  String vars = result.join(' ');

  // debugPrint('R EXTRACT VARS JOIN: $vars');

  // Remove the [1] etc line numbering in the output.

  vars = vars.replaceAll(RegExp(r' *\[\d+\] *'), ' ');

  // Remove the quotes around the var names.

  vars = vars.replaceAll('"', '');

  // Remove extra spaces.

  vars = vars.replaceAll(RegExp(r' +'), ' ');
  vars = vars.replaceAll(RegExp(r'^ +'), '');
  vars = vars.replaceAll(RegExp(r' +$'), '');

  // Split into the list of variable names.

  result = vars.split(' ');

  // Return the list of variable names.

  // debugPrint('R EXTRACT VARS FINAL: $result');

  return result;
}