| /* |
| * 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.wayang.core.optimizer; |
| |
| import java.util.Objects; |
| |
| /*** |
| * An value representation that is capable of expressing uncertainty. |
| * It addresses uncertainty by expressing estimates as intervals and assigning a probability of correctness (in [0, 1]). |
| */ |
| public class ProbabilisticDoubleInterval { |
| |
| /** |
| * Instance that basically represents the value {@code 0d}. |
| */ |
| public static final ProbabilisticDoubleInterval zero = ProbabilisticDoubleInterval.ofExactly(0d); |
| |
| /** |
| * Probability of correctness between in the interval [0, 1]. This helps |
| * Wayang in situations with many estimates to pick the best one. |
| */ |
| private final double correctnessProb; |
| |
| /** |
| * Lower and upper estimate. Not that this is not a bounding box, i.e., there is no guarantee that the finally |
| * observed value will be within the estimated interval. |
| */ |
| private final double lowerEstimate, upperEstimate; |
| |
| /** |
| * When merging instances somehow, overriding instance should be chosen over the others. |
| */ |
| private final boolean isOverride; |
| |
| /** |
| * Creates a new instance with a zero-width interval and a confidence of {@code 1}. |
| * |
| * @param value lower and upper value |
| * @return the new instance |
| */ |
| public static ProbabilisticDoubleInterval ofExactly(double value) { |
| return new ProbabilisticDoubleInterval(value, value, 1d); |
| } |
| |
| public ProbabilisticDoubleInterval(double lowerEstimate, double upperEstimate, double correctnessProb) { |
| this(lowerEstimate, upperEstimate, correctnessProb, false); |
| } |
| |
| public ProbabilisticDoubleInterval(double lowerEstimate, double upperEstimate, double correctnessProb, boolean isOverride) { |
| assert lowerEstimate <= upperEstimate : String.format("%f > %f, which is illegal.", lowerEstimate, upperEstimate); |
| assert correctnessProb >= 0 && correctnessProb <= 1 : String.format("Illegal probability %f.", correctnessProb); |
| |
| this.correctnessProb = correctnessProb; |
| this.lowerEstimate = lowerEstimate; |
| this.upperEstimate = upperEstimate; |
| this.isOverride = isOverride; |
| } |
| |
| public double getLowerEstimate() { |
| return this.lowerEstimate; |
| } |
| |
| public double getUpperEstimate() { |
| return this.upperEstimate; |
| } |
| |
| public double getAverageEstimate() { |
| return (this.getUpperEstimate() + this.getLowerEstimate()) / 2; |
| } |
| |
| public long getGeometricMeanEstimate() { |
| return Math.round(Math.pow(this.getLowerEstimate() * this.getUpperEstimate(), 0.5)); |
| } |
| |
| public double getCorrectnessProbability() { |
| return this.correctnessProb; |
| } |
| |
| /** |
| * Checks whether this instance is an exact estimate of the given value. |
| * |
| * @param exactEstimate the hypothesized exact estimation value |
| * @return whether this instance is exactly {@code exactEstimate} |
| */ |
| public boolean isExactly(long exactEstimate) { |
| return this.correctnessProb == 1d && this.lowerEstimate == this.upperEstimate && this.upperEstimate == exactEstimate; |
| } |
| |
| /** |
| * Creates a new instance that represents the sum of the {@code this} and {@code that} instance. |
| * |
| * @param that the other summand |
| * @return the sum |
| */ |
| public ProbabilisticDoubleInterval plus(ProbabilisticDoubleInterval that) { |
| return new ProbabilisticDoubleInterval( |
| this.getLowerEstimate() + that.getLowerEstimate(), |
| this.getUpperEstimate() + that.getUpperEstimate(), |
| Math.min(this.getCorrectnessProbability(), that.getCorrectnessProbability()) |
| ); |
| } |
| |
| @Override |
| public boolean equals(Object o) { |
| if (this == o) return true; |
| if (o == null || this.getClass() != o.getClass()) return false; |
| ProbabilisticDoubleInterval estimate = (ProbabilisticDoubleInterval) o; |
| return Double.compare(estimate.correctnessProb, this.correctnessProb) == 0 && |
| this.lowerEstimate == estimate.lowerEstimate && |
| this.upperEstimate == estimate.upperEstimate; |
| } |
| |
| /** |
| * Compares with this instance equals with {@code that} instance within given delta bounds. |
| */ |
| public boolean equalsWithinDelta(ProbabilisticDoubleInterval that, |
| double probDelta, |
| long lowerEstimateDelta, |
| long upperEstimateDelta) { |
| return Math.abs(that.correctnessProb - this.correctnessProb) <= probDelta && |
| Math.abs(this.lowerEstimate - that.lowerEstimate) <= lowerEstimateDelta && |
| Math.abs(this.upperEstimate - that.upperEstimate) <= upperEstimateDelta; |
| } |
| |
| public boolean isOverride() { |
| return this.isOverride; |
| } |
| |
| @Override |
| public int hashCode() { |
| return Objects.hash(this.correctnessProb, this.lowerEstimate, this.upperEstimate); |
| } |
| |
| @Override |
| public String toString() { |
| return String.format("(%,.2f..%,.2f ~ %.1f%%)", |
| this.lowerEstimate, this.upperEstimate, this.correctnessProb * 100d); |
| } |
| |
| } |