cern.jet.stat.tfloat.quantile.FloatQuantileEstimator Maven / Gradle / Ivy

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Parallel Colt is a multithreaded version of Colt - a library for high performance scientific computing in Java. It contains efficient algorithms for data analysis, linear algebra, multi-dimensional arrays, Fourier transforms, statistics and histogramming.
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/*
Copyright (C) 1999 CERN - European Organization for Nuclear Research.
Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose 
is hereby granted without fee, provided that the above copyright notice appear in all copies and 
that both that copyright notice and this permission notice appear in supporting documentation. 
CERN makes no representations about the suitability of this software for any purpose. 
It is provided "as is" without expressed or implied warranty.
 */
package cern.jet.stat.tfloat.quantile;

import cern.colt.list.tfloat.FloatArrayList;
import cern.colt.list.tobject.ObjectArrayList;
import cern.jet.stat.Utils;

/**
 * The abstract base class for approximate quantile finders computing quantiles
 * over a sequence of float elements.
 */
// abstract class ApproximateFloatQuantileFinder extends Object implements
// FloatQuantileFinder {
abstract class FloatQuantileEstimator extends cern.colt.PersistentObject implements FloatQuantileFinder {
    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    protected FloatBufferSet bufferSet;

    protected FloatBuffer currentBufferToFill;

    protected int totalElementsFilled;

    /**
     * Makes this class non instantiable, but still let's others inherit from
     * it.
     */
    protected FloatQuantileEstimator() {
    }

    /**
     * Adds a value to the receiver.
     * 
     * @param value
     *            the value to add.
     */
    public void add(float value) {
        totalElementsFilled++;
        if (!sampleNextElement())
            return;

        // System.out.println("adding "+value);

        if (currentBufferToFill == null) {
            if (bufferSet._getFirstEmptyBuffer() == null)
                collapse();
            newBuffer();
        }

        currentBufferToFill.add(value);
        if (currentBufferToFill.isFull())
            currentBufferToFill = null;
    }

    /**
     * Adds all values of the specified list to the receiver.
     * 
     * @param values
     *            the list of which all values shall be added.
     */
    public void addAllOf(FloatArrayList values) {
        addAllOfFromTo(values, 0, values.size() - 1);
    }

    /**
     * Adds the part of the specified list between indexes from
     * (inclusive) and to (inclusive) to the receiver.
     * 
     * @param values
     *            the list of which elements shall be added.
     * @param from
     *            the index of the first element to be added (inclusive).
     * @param to
     *            the index of the last element to be added (inclusive).
     */
    public void addAllOfFromTo(FloatArrayList values, int from, int to) {
        /*
         * // the obvious version, but we can do quicker... float[] theValues =
         * values.elements(); int theSize=values.size(); for (int i=0; ifalse, otherwise continues.
     * @return false if the procedure stopped before all elements where
     *         iterated over, true otherwise.
     */
    public boolean forEach(cern.colt.function.tfloat.FloatProcedure procedure) {
        return this.bufferSet.forEach(procedure);
    }

    /**
     * Returns the number of elements currently needed to store all contained
     * elements. This number usually differs from the results of method
     * size(), according to the underlying datastructure.
     */
    public long memory() {
        return bufferSet.memory();
    }

    /**
     * Not yet commented.
     */
    protected abstract void newBuffer();

    /**
     * Returns how many percent of the elements contained in the receiver are
     * <= element. Does linear interpolation if the element is not
     * contained but lies in between two contained elements.
     * 
     * @param the
     *            element to search for.
     * @return the percentage p of elements <= element (
     *         0.0 <= p <=1.0).
     */
    public float phi(float element) {
        return bufferSet.phi(element);
    }

    /**
     * Not yet commented.
     */
    protected abstract void postCollapse(FloatBuffer[] toCollapse);

    /**
     * Default implementation does nothing.
     */
    protected FloatArrayList preProcessPhis(FloatArrayList phis) {
        return phis;
    }

    /**
     * Computes the specified quantile elements over the values previously
     * added.
     * 
     * @param phis
     *            the quantiles for which elements are to be computed. Each phi
     *            must be in the interval [0.0,1.0]. phis must be
     *            sorted ascending.
     * @return the approximate quantile elements.
     */
    public FloatArrayList quantileElements(FloatArrayList phis) {
        /*
         * //check parameter FloatArrayList sortedPhiList = phis.copy();
         * sortedPhiList.sort(); if (! phis.equals(sortedPhiList)) { throw new
         * IllegalArgumentException("Phis must be sorted ascending."); }
         */

        // System.out.println("starting to augment missing values, if
        // necessary...");
        phis = preProcessPhis(phis);

        long[] triggerPositions = new long[phis.size()];
        long totalSize = this.bufferSet.totalSize();
        for (int i = phis.size(); --i >= 0;) {
            triggerPositions[i] = Utils.epsilonCeiling(phis.get(i) * totalSize) - 1;
        }

        // System.out.println("triggerPositions="+cern.colt.Arrays.toString(triggerPositions));
        // System.out.println("starting to determine quantiles...");
        // System.out.println(bufferSet);

        FloatBuffer[] fullBuffers = bufferSet._getFullOrPartialBuffers();
        float[] quantileElements = new float[phis.size()];

        // do the main work: determine values at given positions in sorted
        // sequence
        return new FloatArrayList(bufferSet.getValuesAtPositions(fullBuffers, triggerPositions));
    }

    /**
     * Not yet commented.
     */
    protected abstract boolean sampleNextElement();

    /**
     * Initializes the receiver
     */
    protected void setUp(int b, int k) {
        if (!(b >= 2 && k >= 1)) {
            throw new IllegalArgumentException("Assertion: b>=2 && k>=1");
        }
        this.bufferSet = new FloatBufferSet(b, k);
        this.clear();
    }

    /**
     * Returns the number of elements currently contained in the receiver
     * (identical to the number of values added so far).
     */
    public long size() {
        return totalElementsFilled;
    }

    /**
     * Returns a String representation of the receiver.
     */

    public String toString() {
        String s = this.getClass().getName();
        s = s.substring(s.lastIndexOf('.') + 1);
        int b = bufferSet.b();
        int k = bufferSet.k();
        return s + "(mem=" + memory() + ", b=" + b + ", k=" + k + ", size=" + size() + ", totalSize="
                + this.bufferSet.totalSize() + ")";
    }

    /**
     * Returns the number of elements currently needed to store all contained
     * elements. This number usually differs from the results of method
     * size(), according to the underlying datastructure.
     */
    public long totalMemory() {
        return bufferSet.b() * bufferSet.k();
    }
}