001/*
002 * Copyright (c) 2015-2020, Oracle and/or its affiliates. All rights reserved.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.tribuo.math.la;
018
019/**
020 * A mutable tuple used to avoid allocation when iterating a vector.
021 * <p>
022 * While it does implement hashcode, don't use it as a key as the hashcode is data dependent.
023 */
024public class VectorTuple {
025
026    public static final double DELTA = 1e-12;
027
028    public int index;
029
030    public double value;
031
032    public VectorTuple() {
033        this.index = -1;
034        this.value = Double.NaN;
035    }
036
037    public VectorTuple(int index, int value) {
038        this.index = index;
039        this.value = value;
040    }
041
042    @Override
043    public boolean equals(Object o) {
044        if (o instanceof VectorTuple) {
045            VectorTuple otherM = (VectorTuple) o;
046            if (index == otherM.index) {
047                return (Math.abs(value - otherM.value) < DELTA);
048            } else {
049                return false;
050            }
051        } else {
052            return false;
053        }
054    }
055
056    @Override
057    public int hashCode() {
058        int result = index;
059        result = 31 * result + (int) Double.doubleToLongBits(value);
060        return result;
061    }
062
063    @Override
064    public String toString() {
065        return "VectorTuple(index="+index+",value="+value+")";
066    }
067}