EntityConfidence.java revision ac5fe7c617c66850fff75a9fce9979c6e5674b0f 
1/*
2 * Copyright (C) 2018 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package androidx.textclassifier;
18
19import android.os.Parcel;
20import android.os.Parcelable;
21import androidx.annotation.FloatRange;
22import androidx.annotation.NonNull;
23import androidx.annotation.RestrictTo;
24import androidx.collection.ArrayMap;
25import androidx.core.util.Preconditions;
26import androidx.collection.SimpleArrayMap;
27
28import java.util.ArrayList;
29import java.util.Collections;
30import java.util.Comparator;
31import java.util.List;
32import java.util.Map;
33
34/**
35 * Helper object for setting and getting entity scores for classified text.
36 *
37 * @hide
38 */
39@RestrictTo(RestrictTo.Scope.LIBRARY)
40final class EntityConfidence implements Parcelable {
41
42    private final ArrayMap<String, Float> mEntityConfidence = new ArrayMap<>();
43    private final ArrayList<String> mSortedEntities = new ArrayList<>();
44
45    EntityConfidence() {}
46
47    EntityConfidence(@NonNull EntityConfidence source) {
48        Preconditions.checkNotNull(source);
49        mEntityConfidence.putAll((SimpleArrayMap<String, Float>) source.mEntityConfidence);
50        mSortedEntities.addAll(source.mSortedEntities);
51    }
52
53    /**
54     * Constructs an EntityConfidence from a map of entity to confidence.
55     *
56     * Map entries that have 0 confidence are removed, and values greater than 1 are clamped to 1.
57     *
58     * @param source a map from entity to a confidence value in the range 0 (low confidence) to
59     *               1 (high confidence).
60     */
61    EntityConfidence(@NonNull Map<String, Float> source) {
62        Preconditions.checkNotNull(source);
63
64        // Prune non-existent entities and clamp to 1.
65        mEntityConfidence.ensureCapacity(source.size());
66        for (Map.Entry<String, Float> it : source.entrySet()) {
67            if (it.getValue() <= 0) continue;
68            mEntityConfidence.put(it.getKey(), Math.min(1, it.getValue()));
69        }
70        resetSortedEntitiesFromMap();
71    }
72
73    /**
74     * Returns an immutable list of entities found in the classified text ordered from
75     * high confidence to low confidence.
76     */
77    @NonNull
78    public List<String> getEntities() {
79        return Collections.unmodifiableList(mSortedEntities);
80    }
81
82    /**
83     * Returns the confidence score for the specified entity. The value ranges from
84     * 0 (low confidence) to 1 (high confidence). 0 indicates that the entity was not found for the
85     * classified text.
86     */
87    @FloatRange(from = 0.0, to = 1.0)
88    public float getConfidenceScore(String entity) {
89        if (mEntityConfidence.containsKey(entity)) {
90            return mEntityConfidence.get(entity);
91        }
92        return 0;
93    }
94
95    @Override
96    public String toString() {
97        return mEntityConfidence.toString();
98    }
99
100    @Override
101    public int describeContents() {
102        return 0;
103    }
104
105    @Override
106    public void writeToParcel(Parcel dest, int flags) {
107        dest.writeInt(mEntityConfidence.size());
108        for (Map.Entry<String, Float> entry : mEntityConfidence.entrySet()) {
109            dest.writeString(entry.getKey());
110            dest.writeFloat(entry.getValue());
111        }
112    }
113
114    public static final Parcelable.Creator<EntityConfidence> CREATOR =
115            new Parcelable.Creator<EntityConfidence>() {
116                @Override
117                public EntityConfidence createFromParcel(Parcel in) {
118                    return new EntityConfidence(in);
119                }
120
121                @Override
122                public EntityConfidence[] newArray(int size) {
123                    return new EntityConfidence[size];
124                }
125            };
126
127    private EntityConfidence(Parcel in) {
128        final int numEntities = in.readInt();
129        mEntityConfidence.ensureCapacity(numEntities);
130        for (int i = 0; i < numEntities; ++i) {
131            mEntityConfidence.put(in.readString(), in.readFloat());
132        }
133        resetSortedEntitiesFromMap();
134    }
135
136    private void resetSortedEntitiesFromMap() {
137        mSortedEntities.clear();
138        mSortedEntities.ensureCapacity(mEntityConfidence.size());
139        mSortedEntities.addAll(mEntityConfidence.keySet());
140        Collections.sort(mSortedEntities, new EntityConfidenceComparator());
141    }
142
143    /** Helper to sort entities according to their confidence. */
144    private class EntityConfidenceComparator implements Comparator<String> {
145        @Override
146        public int compare(String e1, String e2) {
147            float score1 = mEntityConfidence.get(e1);
148            float score2 = mEntityConfidence.get(e2);
149            return Float.compare(score2, score1);
150        }
151    }
152}
153