Beispiel #1
0
 /**
  * Computes an alpha trimmed mean upon the current region of the current function. Note that this
  * method uses memory to make a copy of the input values. Larger input regions might require a lot
  * of memory.
  *
  * @param alpha A number between 0 and 0.5 specifying the proportion of samples to ignore on each
  *     end.
  * @return The measured value
  */
 public double alphaTrimmedMean(double alpha) {
   if ((alpha < 0) || (alpha >= 0.5))
     throw new IllegalArgumentException("alpha value must be >= 0 and < 0.5");
   T tmp = func.createOutput();
   values.clear();
   iter.reset();
   while (iter.hasNext()) {
     long[] pos = iter.next();
     func.compute(pos, tmp);
     values.add(tmp.getRealDouble());
   }
   values.sortValues();
   double tailSize = alpha * values.size();
   // can we avoid interpolation?
   if (tailSize == Math.floor(tailSize)) {
     // yes, trim count is exactly an integer
     return calcTrimmedMean(values, (int) tailSize);
   }
   // no, trim count is a float value
   // calc two trimmed means and interpolate to find the value between them
   double mean1 = calcTrimmedMean(values, (int) Math.floor(tailSize));
   double mean2 = calcTrimmedMean(values, (int) Math.ceil(tailSize));
   double fraction = tailSize - Math.floor(tailSize);
   double interpolation = ((1 - fraction) * mean1) + (fraction * mean2);
   return interpolation;
 }
Beispiel #2
0
 /**
  * Resets the StatCalculator to work with a new function and/or region. The calculator does the
  * minimum amount of reinitialization.
  *
  * @param newFunc The new {@link Function} to use for obtaining sample values
  * @param newRegion The new {@link PointSet} region over which to gather samples
  */
 public void reset(Function<long[], T> newFunc, PointSet newRegion) {
   func = newFunc;
   if (newRegion == region) {
     iter.reset();
   } else {
     region = newRegion;
     iter = region.iterator();
   }
   values.clear();
 }
Beispiel #3
0
 /**
  * Computes a trimmed mean upon the current region of the current function. Note that this method
  * uses memory to make a copy of the input values. Larger input regions might require a lot of
  * memory.
  *
  * @param halfTrimSize The number of samples to ignore from each end of the data
  * @return The measured value
  */
 public double trimmedMean(int halfTrimSize) {
   T tmp = func.createOutput();
   values.clear();
   iter.reset();
   while (iter.hasNext()) {
     long[] pos = iter.next();
     func.compute(pos, tmp);
     values.add(tmp.getRealDouble());
   }
   values.sortValues();
   return calcTrimmedMean(values, halfTrimSize);
 }
Beispiel #4
0
  /**
   * Computes the median upon the current region of the current function. Note that this method uses
   * memory to make a copy of the input values. Larger input regions might require a lot of memory.
   *
   * @return The measured value
   */
  public double median() {
    T tmp = func.createOutput();
    values.clear();
    iter.reset();
    while (iter.hasNext()) {
      long[] pos = iter.next();
      func.compute(pos, tmp);
      values.add(tmp.getRealDouble());
    }
    final int numElements = values.size();
    if (numElements <= 0)
      throw new IllegalArgumentException("number of samples must be greater than 0");

    values.sortValues();

    // odd number of elements
    if ((numElements % 2) == 1) return values.get(numElements / 2);

    // else an even number of elements
    double value1 = values.get((numElements / 2) - 1);
    double value2 = values.get((numElements / 2));
    return (value1 + value2) / 2;
  }