package org.djutils.stats.summarizers.quantileaccumulator;
   
   import org.djutils.exceptions.Throw;
   import org.djutils.stats.DistNormalTable;
   import org.djutils.stats.summarizers.Tally;
   
   /**
    * The no storage accumulator accumulates nothing and estimates all requested quantiles from mean, standard deviation, etc. (as
    * accumulated by the Tally class object). This is sensible if the input values are normally distributed. Do not use this
   * accumulator when the input values are not normally distributes.<br>
   * @author <a href="https://www.tudelft.nl/staff/p.knoppers/">Peter Knoppers</a>
   */
  public class NoStorageAccumulator implements QuantileAccumulator
  {
      @Override
      public double register(final double value)
      {
          Throw.when(Double.isNaN(value), IllegalArgumentException.class, "accumulator can not accumulate NaN value");
          return value;
      }
  
      @Override
      public double getQuantile(final Tally tally, final double probability)
      {
          Throw.whenNull(tally, "tally cannot be null");
          Throw.when(probability < 0 || probability > 1, IllegalArgumentException.class,
                  "probability should be between 0 and 1 (inclusive)");
          return DistNormalTable.getInverseCumulativeProbability(tally.getSampleMean(), Math.sqrt(tally.getSampleVariance()),
                  probability);
      }
  
      @Override
      public double getCumulativeProbability(final Tally tally, final double quantile) throws IllegalArgumentException
      {
          if (tally.getN() == 0)
          {
              return Double.NaN;
          }
          return DistNormalTable.getCumulativeProbability(tally.getPopulationMean(), tally.getPopulationStDev(), quantile);
      }
  
      @Override
      public String toString()
      {
          return "NoStorageAccumulator";
      }
  
      @Override
      public void initialize()
      {
          // Do nothing
      }
  
  }