| /* |
| * 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.Comparator; |
| import java.util.Objects; |
| import org.apache.wayang.core.util.Formats; |
| |
| /*** |
| * An estimate that is capable of expressing uncertainty. |
| * The estimate addresses uncertainty in the estimation process by |
| * expressing estimates as intervals |
| * and assigning a probability of correctness (in [0, 1]). |
| ***/ |
| public class ProbabilisticIntervalEstimate { |
| |
| /** |
| * 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 long lowerEstimate, upperEstimate; |
| |
| /** |
| * When merging instances somehow, overriding instance should be chosen over the others. |
| */ |
| private final boolean isOverride; |
| |
| public ProbabilisticIntervalEstimate(long lowerEstimate, long upperEstimate, double correctnessProb) { |
| this(lowerEstimate, upperEstimate, correctnessProb, false); |
| } |
| |
| public ProbabilisticIntervalEstimate(long lowerEstimate, long upperEstimate, double correctnessProb, boolean isOverride) { |
| assert lowerEstimate <= upperEstimate : String.format("%d > %d, 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 long getLowerEstimate() { |
| return this.lowerEstimate; |
| } |
| |
| public long getUpperEstimate() { |
| return this.upperEstimate; |
| } |
| |
| public long getAverageEstimate() { |
| return (this.getUpperEstimate() + this.getLowerEstimate()) / 2; |
| } |
| |
| public long getGeometricMeanEstimate() { |
| return Math.round(Math.pow((double) this.getLowerEstimate() * (double) 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.isExact() && this.upperEstimate == exactEstimate; |
| } |
| |
| /** |
| * Checks whether this instance is an exact value, i.e., it is a confident single-point estimate. |
| * |
| * @return whether this instance is exact |
| */ |
| public boolean isExact() { |
| return this.correctnessProb == 1d && this.lowerEstimate == this.upperEstimate; |
| } |
| |
| /** |
| * Creates a {@link Comparator} based on the mean of instances. |
| */ |
| public static <T extends ProbabilisticIntervalEstimate> Comparator<T> expectationValueComparator() { |
| return (t1, t2) -> { |
| if (t1.getCorrectnessProbability() == 0d) { |
| if (t2.getCorrectnessProbability() != 0d) { |
| return 1; |
| } |
| } else if (t2.getCorrectnessProbability() == 0d) { |
| return -1; |
| } |
| // NB: We do not assume a uniform distribution of the estimates within the instances. |
| return Long.compare(t1.getGeometricMeanEstimate(), t2.getGeometricMeanEstimate()); |
| }; |
| } |
| |
| @Override |
| public boolean equals(Object o) { |
| if (this == o) return true; |
| if (o == null || this.getClass() != o.getClass()) return false; |
| ProbabilisticIntervalEstimate estimate = (ProbabilisticIntervalEstimate) 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(ProbabilisticIntervalEstimate 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("%s[%s..%s, %s]", this.getClass().getSimpleName(), |
| Formats.formatLarge(this.lowerEstimate), Formats.formatLarge(this.upperEstimate), Formats.formatPercentage(this.correctnessProb) |
| ); |
| } |
| } |