Ejemplo n.º 1
0
  private void rescale(long newLandmarkInSeconds) {
    // rescale the weights based on a new landmark to avoid numerical overflow issues

    final double factor = Math.exp(-alpha * (newLandmarkInSeconds - landmarkInSeconds));

    weightedCount *= factor;

    postOrderTraversal(
        root,
        new Callback() {
          @Override
          public boolean process(Node node) {
            double oldWeight = node.weightedCount;

            node.weightedCount *= factor;

            if (oldWeight >= ZERO_WEIGHT_THRESHOLD && node.weightedCount < ZERO_WEIGHT_THRESHOLD) {
              --nonZeroNodeCount;
            }

            return true;
          }
        });

    landmarkInSeconds = newLandmarkInSeconds;
  }
Ejemplo n.º 2
0
 private double weight(long timestamp) {
   return Math.exp(alpha * (timestamp - landmarkInSeconds));
 }