rdpRecursive function

Implementation

List<MapEntry<DateTime, double>> rdpRecursive(
  List<MapEntry<DateTime, double>> points,
  double epsilon,
) {
  if (points.length < 3) return points;

  // Find the point with maximum distance from line segment.
  var maxDistance = 0.0;
  var maxIndex = 0;

  final firstPoint = points.first;
  final lastPoint = points.last;

  for (var i = 1; i < points.length - 1; i++) {
    final distance = perpendicularDistance(
      points[i],
      firstPoint,
      lastPoint,
      points.length,
    );
    if (distance > maxDistance) {
      maxDistance = distance;
      maxIndex = i;
    }
  }

  // If max distance is greater than epsilon, recursively simplify.

  if (maxDistance > epsilon) {
    final left = rdpRecursive(points.sublist(0, maxIndex + 1), epsilon);
    final right = rdpRecursive(points.sublist(maxIndex), epsilon);

    // Combine results (remove duplicate middle point)
    return [...left.sublist(0, left.length - 1), ...right];
  } else {
    // If max distance is less than epsilon, keep only endpoints.
    return [firstPoint, lastPoint];
  }
}