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From chiwanpark <...@git.apache.org>
Subject [GitHub] flink pull request: [FLINK-2030][FLINK-2274][core][utils]Histogram...
Date Fri, 04 Sep 2015 09:33:10 GMT
Github user chiwanpark commented on a diff in the pull request:

    https://github.com/apache/flink/pull/861#discussion_r38735587
  
    --- Diff: flink-core/src/main/java/org/apache/flink/api/common/accumulators/ContinuousHistogram.java
---
    @@ -0,0 +1,534 @@
    +/*
    + * Licensed to the Apache Software Foundation (ASF) under one
    + * or more contributor license agreements.  See the NOTICE file
    + * distributed with this work for additional information
    + * regarding copyright ownership.  The ASF licenses this file
    + * to you under the Apache License, Version 2.0 (the
    + * "License"); you may not use this file except in compliance
    + * with the License.  You may obtain a copy of the License at
    + *
    + *     http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +
    +package org.apache.flink.api.common.accumulators;
    +
    +import java.util.AbstractMap;
    +import java.util.HashMap;
    +import java.util.Iterator;
    +import java.util.Map;
    +import java.util.PriorityQueue;
    +import java.util.Set;
    +import java.util.TreeMap;
    +
    +import static java.lang.Double.MAX_VALUE;
    +
    +/**
    + * A Histogram accumulator designed for Continuous valued data.
    + * It supports:
    + * -- {@link #quantile(double)}
    + * 		Computes a quantile of the data
    + * -- {@link #count(double)}
    + *		Computes number of items less than the given value in the data
    + * <p>
    + * A continuous histogram stores values in bins in sorted order and keeps their associated
    + * number of items. It is assumed that the items associated with every bin are scattered
around
    + * it, half to the right and half to the left.
    + * <p>
    + * bin counters:  m_1    m_2    m_3    m_4    m_5    m_6
    + *                10     12     5      10     4      6
    + *                |  5   |  6   |  2.5 |  5   |  2   |
    + *             5  |  +   |  +   |   +  |  +   |  +   |  3
    + *                |  6   |  2.5 |   5  |  2   |  3   |
    + * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    + * bin index:     1      2      3      4      5      6
    + * bin values:    v_1 <  v_2 <  v_3 <  v_4 <  v_5 <  v_6
    + * <p>
    + * The number of items between v_i and v_(i+1) is directly proportional to the area of
    + * trapezoid (v_i, v_(i+1), m_(i+1), m_i)
    + * <p>
    + * Adapted from Ben-Haim and Yom-Tov's
    + * <a href = "http://www.jmlr.org/papers/volume11/ben-haim10a/ben-haim10a.pdf">Streaming
Decision Tree Algorithm's histogram</a>
    + */
    +public class ContinuousHistogram implements Accumulator<Double, TreeMap<Double,
Integer>> {
    +
    +	protected TreeMap<Double, Integer> treeMap = new TreeMap<Double, Integer>();
    +
    +	protected long counter = 0;
    +
    +	private int bin;
    +
    +	private double lower;
    +
    +	private double upper;
    +
    +	private PriorityQueue<KeyDiff> diffQueue;
    +
    +	private HashMap<Double, KeyProps> keyUpdateTimes;
    +
    +	private long timestamp;
    +
    +	/**
    +	 * Creates a new Continuous histogram with the given number of bins
    +	 * Bins represents the number of values the histogram stores to approximate the continuous
    +	 * data set. The higher this value, the more we move towards an exact representation
of data.
    +	 *
    +	 * @param numBins Number of bins in the histogram
    +	 */
    +	public ContinuousHistogram(int numBins) {
    +		if (numBins <= 0) {
    +			throw new IllegalArgumentException("Number of bins must be greater than zero");
    +		}
    +		bin = numBins;
    +		lower = MAX_VALUE;
    +		upper = -MAX_VALUE;
    +		diffQueue = new PriorityQueue<>();
    +		keyUpdateTimes = new HashMap<>();
    +		timestamp = 0;
    +	}
    +
    +	/**
    +	 * Consider using {@link #add(double)} for primitive double values to get better performance.
    +	 */
    +	@Override
    +	public void add(Double value) {
    +		add(value, 1);
    +	}
    +
    +	public void add(double value) {
    +		add(value, 1);
    +	}
    +
    +	@Override
    +	public TreeMap<Double, Integer> getLocalValue() {
    +		return this.treeMap;
    +	}
    +
    +	/**
    +	 * Get the total number of items added to this histogram.
    +	 * This is preserved across merge operations.
    +	 *
    +	 * @return Total number of items added to the histogram
    +	 */
    +	public long getTotal() {
    +		return counter;
    +	}
    +
    +	/**
    +	 * Get the current size of the {@link #treeMap}
    +	 *
    +	 * @return Size of the {@link #treeMap}
    +	 */
    +	public int getSize() {
    +		return treeMap.size();
    +	}
    +
    +	@Override
    +	public void resetLocal() {
    +		treeMap.clear();
    +		counter = 0;
    +		lower = MAX_VALUE;
    +		upper = -MAX_VALUE;
    +		diffQueue.clear();
    +		keyUpdateTimes.clear();
    +	}
    +
    +	@Override
    +	public void merge(Accumulator<Double, TreeMap<Double, Integer>> other) {
    +		fill(other.getLocalValue().entrySet());
    +	}
    +
    +	/**
    +	 * Merges the given other histogram into this histogram, with the number of bins in
the
    +	 * merged histogram being {@code numBins}.
    +	 *
    +	 * @param other   Histogram to be merged
    +	 * @param numBins Bins in the merged histogram
    +	 */
    +	public void merge(Accumulator<Double, TreeMap<Double, Integer>> other, int
numBins) {
    +		bin = numBins;
    +		merge(other);
    +	}
    +
    +	@Override
    +	public Accumulator<Double, TreeMap<Double, Integer>> clone() {
    +		ContinuousHistogram result = new ContinuousHistogram(bin);
    +		result.treeMap = new TreeMap<>(treeMap);
    +		result.counter = counter;
    +		result.lower = lower;
    +		result.upper = upper;
    +		// initialize all differences and key update times for the new histogram
    +		result.computeDiffs();
    +		return result;
    +	}
    +
    +	void add(double value, int count) {
    --- End diff --
    
    Why this method is protected?


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