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TOVAL comprises a set of java classes for common programming issues. It includes utils for arrays, lists, sets and collections for convenient handling and modification, but also support for mathematic definitions concerning logic (clauses + resolution) together with some algorithms for permutations, powersets and resolution. Additionally it contains a number of types for multisets, matrices with object keys and much more.

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package de.invation.code.toval.statistic;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;

/**
 * Extension of the class {@link Observation}, that adds additional information.

 * By using Observations for the expectation value and the moments,

 * it is possible to analyze their progress along the insertion steps.
 * 
 * @author Thomas Stocker
 */
public class ExtendedObservation extends Observation {
	
	/**
	 * Observation for expectations.
	 * @see Observation#expectation
	 * @see Observation#getExpectation()
	 */
	private Observation expectations = new Observation("expectation", true);
	
	/**
	 * Observations for moments.
	 * @see Observation#moments
	 * @see Observation#getMoments()
	 */
	private HashMap momentObservation = new HashMap(DEFAULT_MOMENTS.size());
	
	
	public ExtendedObservation() {
		this(DEFAULT_NAME);
	}
	
	public ExtendedObservation(String name) {
		super(name, true);
		resetMomentObservation();
	}
	
	/**
	 * Returns the expectations for every insertion step in form of an observation.
	 * @return The expectation observation
	 */
	public Observation getExpectationObservation(){
		return expectations;
	}

	/**
	 * Returns the expectations for every insertion step in form of a list.
	 * @return The expectation progress
	 */
	public List getExpectations(){
		return Collections.unmodifiableList(expectations.getValues());
	}
	
	/**
	 * Returns the expectation for a certain insertion step specified by the given index.
	 * @param index Index of the desired insertion step
	 * @return The expectation for the specified insertion step
	 */
	public double getExpectationAt(int index){
		if(index <0 || index>=expectations.getObservationCount())
			throw new IndexOutOfBoundsException();
		return expectations.getValueAt(index);
	}
	
	/**
	 * Returns the values of all moments for a certain insertion step specified by the given index.
	 * @param index Index of the desired insertion step
	 * @return moment values for the specified insertion step
	 */
	public HashMap getMomentsAt(int index){
		if(index <0 || index>=getObservationCount())
			throw new IndexOutOfBoundsException();
		HashMap ret = new HashMap();
		for(Integer m: momentObservation.keySet()) {
			Double value = momentObservation.get(m).getValueAt(index);
			if(value != null)
				ret.put(m, value);
		}
		return ret;
	}
	
	/**
	 * Determines the expectation which is a probabilistic measure,

	 * estimating the next inserted value based on all values inserted so far.
	 * Overrides a superclass method to additionally consider the expectation observation {@link #expectations}.
	 * @see Observation#setExpectation()
	 */
	@Override
	protected void setExpectation() {
		super.setExpectation();
		expectations.addValue(expectation);
	}

	/**
	 * Determines moments (probabilistic measure) of all degrees specified by {@link #momentDegrees}.
	 * Moments are characteristics of random variables (in this case relating to the inserted values)
	 * 
	 * 2nd moment: variance
	 * 3rd moment: skewness (Schiefe)
	 * 4th moment: kurtosis (Woelbung)
	 * ...
	 * 
	 * 

	 * Overrides a superclass method to additionally co0nsider the moment observations {@link #momentObservation}.
	 * @see Observation#setMoments()
	 */
	@Override
	protected void setMoments() {
		super.setMoments();
		for(Integer degree: momentDegrees) {
			momentObservation.get(degree).addValue(moments.get(degree));
		}
	}
	
	/**
	 * Resets the extended observation to the initial state after creation.

	 * Potential changed values for update behavior or moment degrees are kept.

	 * Overrides a superclass method to additionally reset observations for moments and expectation.
	 */
	@Override
	public void reset() {
		super.reset();
		resetMomentObservation();
		expectations.reset();
	}
	
	/**
	 * Resets the moment observations.

	 * If there are no observations yet, new observations are created and added to the map.

	 * Otherwise existing observations are reset.
	 */
	private void resetMomentObservation() {
		if (momentObservation.isEmpty()) {
			Observation o;
			for (int i : momentDegrees) {
				o = new Observation("moment "+i, true);
				o.setStandardPrecision(momentPrecision);
				momentObservation.put(i, o);
			}
		} else {
			for (Observation o : momentObservation.values())
				o.reset();
		}
	}
	
	/**
	 * Returns a String representation of the extended observation containing all values and characteristics

	 * using identation which is specified by identation as the number of spaces.
	 * @param identation The number of spaces used for identation
	 * @return A String representation of the extended observation with identation
	 */
	@Override
	public String toString(int identation) {
		if(identation <0)
			throw new IllegalArgumentException("identation cannot be <0");
		String header;
		if(identation ==0) header="";
		  else header = String.format(String.format("%%%ss", identation), "");
		StringBuilder builder = new StringBuilder();
		builder.append(super.toString(identation));
		builder.append(header);
		builder.append("   Observations:\n\n");
		builder.append(header);
		builder.append(expectations.toString(6));
		builder.append("\n");
		for(Integer i: momentObservation.keySet()) {
			builder.append(header);
			builder.append(momentObservation.get(i).toString(6));
		}
		builder.append("\n");
		return builder.toString();
	}

}