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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.ranking;
// scale and adjust the score according to the range
// of the original and final score values to avoid that
// a score from the backend is larger than finalScores_low
class RangeAdjuster {
private double initialScores_high = -Double.MAX_VALUE;
private double initialScores_low = Double.MAX_VALUE;
private double finalScores_high = -Double.MAX_VALUE;
private double finalScores_low = Double.MAX_VALUE;
boolean rescaleNeeded() {
return (initialScores_low > finalScores_low
&&
initialScores_high >= initialScores_low
&&
finalScores_high >= finalScores_low);
}
void withInitialScore(double score) {
if (score < initialScores_low) initialScores_low = score;
if (score > initialScores_high) initialScores_high = score;
}
void withFinalScore(double score) {
if (score < finalScores_low) finalScores_low = score;
if (score > finalScores_high) finalScores_high = score;
}
private double initialRange() {
double r = initialScores_high - initialScores_low;
if (r < 1.0) r = 1.0;
return r;
}
private double finalRange() {
double r = finalScores_high - finalScores_low;
if (r < 1.0) r = 1.0;
return r;
}
double scale() { return finalRange() / initialRange(); }
double bias() { return finalScores_low - initialScores_low * scale(); }
}
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