Java ListIterator Usage incrementalComponentWiseAverageArbitraryDepth(Object average, int n, Object newItems)

Description

A more general version of incrementalComputationOfComponentWiseAverage(List, int, List) that operates on lists of lists of arbitrary depth, including depth 0, that is, on Number s.

License

Open Source License

Parameter

Parameter	Description
average	previously calculated averages.
n	averages out of 'n' numbers.
newItems	new numbers.

Return

an incrementally calculated component-wise average.

Declaration

@SuppressWarnings("unchecked")
public static Object incrementalComponentWiseAverageArbitraryDepth(Object average, int n, Object newItems)

Method Source Code

//package com.java2s;
/*//from   ww w.  ja  v  a 2  s  . c om
 * Copyright (c) 2013, SRI International
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 * Licensed under the The BSD 3-Clause License;
 * you may not use this file except in compliance with the License.
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import java.util.Arrays;

import java.util.LinkedHashSet;

import java.util.List;
import java.util.ListIterator;

import java.util.Set;

public class Main {
    /**
     * A more general version of incrementalComputationOfComponentWiseAverage(List, int,
     * List) that operates on lists of lists of arbitrary depth,
     * including depth 0, that is, on {@link Number}s. It is in-place and
     * returns <code>average</code> if given objects are lists, or returns a new
     * Number otherwise.
     * 
     * @param average
     *            previously calculated averages.
     * @param n
     *            averages out of 'n' numbers.
     * @param newItems
     *            new numbers.
     * @return an incrementally calculated component-wise average.
     */
    @SuppressWarnings("unchecked")
    public static Object incrementalComponentWiseAverageArbitraryDepth(Object average, int n, Object newItems) {
        if (average instanceof Number) {
            return (((Number) average).doubleValue() * n + ((Number) newItems).doubleValue()) / (n + 1);
        }
        ListIterator averageIterator = ((List<Number>) average).listIterator();
        ListIterator newItemsIt = ((List) newItems).listIterator();
        while (averageIterator.hasNext()) {
            Object averageElement = averageIterator.next();
            Object newItemsElement = newItemsIt.next();
            Object newAverageElement = incrementalComponentWiseAverageArbitraryDepth(averageElement, n,
                    newItemsElement);
            if (newAverageElement != averageElement) {
                averageIterator.set(newAverageElement);
            }
        }
        return average;
    }

    public static <T> Set<T> set(T... elements) {
        return new LinkedHashSet<T>(Arrays.asList(elements));
    }
}