c4bab39245
Also, the executable component uses a dependency that keeps having security vulnerabilities.
66 lines
2.1 KiB
Java
66 lines
2.1 KiB
Java
/*
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* Copyright (c) 2019 Joel Therrien.
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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package ca.joeltherrien.randomforest.tree;
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import ca.joeltherrien.randomforest.Row;
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import java.util.Iterator;
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import java.util.List;
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import java.util.stream.Collectors;
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public abstract class SimpleSplitFinder<Y> implements SplitFinder<Y> {
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@Override
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public SplitAndScore<Y, ?> findBestSplit(Iterator<Split<Y, ?>> splitIterator) {
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Double bestScore = null;
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Split<Y, ?> bestSplit = null;
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while(splitIterator.hasNext()){
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final Split<Y, ?> candidateSplit = splitIterator.next();
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final List<Y> leftHand = candidateSplit.getLeftHand().stream().map(Row::getResponse).collect(Collectors.toList());
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final List<Y> rightHand = candidateSplit.getRightHand().stream().map(Row::getResponse).collect(Collectors.toList());
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if(leftHand.isEmpty() || rightHand.isEmpty()){
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continue;
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}
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final Double score = getScore(leftHand, rightHand);
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if(score != null && (bestScore == null || score > bestScore)){
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bestScore = score;
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bestSplit = candidateSplit;
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}
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}
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if(bestSplit == null){
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return null;
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}
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return new SplitAndScore<>(bestSplit, bestScore);
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}
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/**
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* Return a score; higher is better.
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*
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* @param leftHand
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* @param rightHand
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* @return
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*/
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public abstract Double getScore(List<Y> leftHand, List<Y> rightHand);
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}
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