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// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.searchlib.ranking.features;
import com.google.common.annotations.Beta;
import com.yahoo.searchlib.rankingexpression.evaluation.DoubleValue;
import com.yahoo.searchlib.rankingexpression.evaluation.Value;
import java.util.HashMap;
import java.util.Map;
/**
* Calculates the fieldTermMatch features
*
* @author bratseth
*/
@Beta
public class FieldTermMatch {
/**
* Computes the fieldTermMatch features:
* <ul>
* <li><code>firstPosition</code> - the position of the first occurrence of this query term in this index field</li>
* <li><code>occurrences</code> - the position of the first occurrence of this query term in this index field</li>
* </ul>
* @param queryTerm the term to return these features for
* @param field the field value to compute over, assumed to be a space-separated string of tokens
* @return a features object containing the two values described above
*/
public static Features compute(String queryTerm, String field) {
Map<String, Value> features = new HashMap<>();
String[] tokens = field.split(" ");
int occurrences = 0;
int firstPosition = 1000000;
for (int i = 0; i < tokens.length; i++) {
if (tokens[i].equals(queryTerm)) {
if (occurrences == 0)
firstPosition = i;
occurrences++;
}
}
features.put("firstPosition", new DoubleValue(firstPosition));
features.put("occurrences", new DoubleValue(occurrences));
return new Features(features);
}
}
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