edu.byu.nlp.crowdsourcing.EmpiricalMeasurementProvider.java Source code

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Here is the source code for edu.byu.nlp.crowdsourcing.EmpiricalMeasurementProvider.java

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/**
 * Copyright 2012 Brigham Young University
 *
 * Licensed 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 edu.byu.nlp.crowdsourcing;

import java.util.List;
import java.util.Set;

import com.google.common.collect.Lists;
import com.google.common.collect.Multimap;
import com.google.common.collect.Sets;

import edu.byu.nlp.data.FlatInstance;
import edu.byu.nlp.data.types.Measurement;
import edu.byu.nlp.data.util.EmpiricalAnnotations;
import edu.byu.nlp.dataset.Datasets;

/**
 * Provides annotation as found in recorded data
 * 
 * @author pfelt
 *
 */
public class EmpiricalMeasurementProvider<D> implements LabelProvider<D, Measurement> {

    private EmpiricalAnnotations<D, Integer> annotations;
    private Set<FlatInstance<D, Integer>> usedAnnotations = Sets.newIdentityHashSet();
    private int annotatorId;

    public EmpiricalMeasurementProvider(int annotatorId, EmpiricalAnnotations<D, Integer> annotations) {
        this.annotatorId = annotatorId;
        this.annotations = annotations;
    }

    /** {@inheritDoc} */
    @Override
    public Measurement labelFor(String source, D datum) {
        return nextAnnotation(annotations.getAnnotationsFor(source, datum));
    }

    /**
     * Annotates based on historical data for the annotator set in the 
     * constructor. Returns the first annotation for this instance 
     * that has not been returned before.  
     */
    private Measurement nextAnnotation(Multimap<Integer, FlatInstance<D, Integer>> instanceAnnotations) {
        // return next unused annotation for this annotator
        List<FlatInstance<D, Integer>> annotationList = Lists.newArrayList(instanceAnnotations.get(annotatorId));
        Datasets.sortAnnotationsInPlace(annotationList);

        for (FlatInstance<D, Integer> ann : annotationList) {
            if (!usedAnnotations.contains(ann)) {
                // return earliest annotation that hasn't already been used
                usedAnnotations.add(ann);
                return ann.getMeasurement();
            }
        }
        return null;

    }

}