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;
21
22import androidx.annotation.FloatRange;
23import androidx.annotation.NonNull;
24import androidx.annotation.RestrictTo;
25import androidx.collection.ArrayMap;
26import androidx.collection.SimpleArrayMap;
27import androidx.core.util.Preconditions;
28
29import java.util.ArrayList;
30import java.util.Collections;
31import java.util.Comparator;
32import java.util.List;
33import java.util.Map;
34
35/**
36 * Helper object for setting and getting entity scores for classified text.
37 *
38 * @hide
39 */
40@RestrictTo(RestrictTo.Scope.LIBRARY)
41final class EntityConfidence implements Parcelable {
42
43    private final ArrayMap<String, Float> mEntityConfidence = new ArrayMap<>();
44    private final ArrayList<String> mSortedEntities = new ArrayList<>();
45
46    EntityConfidence() {}
47
48    EntityConfidence(@NonNull EntityConfidence source) {
49        Preconditions.checkNotNull(source);
50        mEntityConfidence.putAll((SimpleArrayMap<String, Float>) source.mEntityConfidence);
51        mSortedEntities.addAll(source.mSortedEntities);
52    }
53
54    /**
55     * Constructs an EntityConfidence from a map of entity to confidence.
56     *
57     * Map entries that have 0 confidence are removed, and values greater than 1 are clamped to 1.
58     *
59     * @param source a map from entity to a confidence value in the range 0 (low confidence) to
60     *               1 (high confidence).
61     */
62    EntityConfidence(@NonNull Map<String, Float> source) {
63        Preconditions.checkNotNull(source);
64
65        // Prune non-existent entities and clamp to 1.
66        mEntityConfidence.ensureCapacity(source.size());
67        for (Map.Entry<String, Float> it : source.entrySet()) {
68            if (it.getValue() <= 0) continue;
69            mEntityConfidence.put(it.getKey(), Math.min(1, it.getValue()));
70        }
71        resetSortedEntitiesFromMap();
72    }
73
74    /**
75     * Returns an immutable list of entities found in the classified text ordered from
76     * high confidence to low confidence.
77     */
78    @NonNull
79    public List<String> getEntities() {
80        return Collections.unmodifiableList(mSortedEntities);
81    }
82
83    /**
84     * Returns the confidence score for the specified entity. The value ranges from
85     * 0 (low confidence) to 1 (high confidence). 0 indicates that the entity was not found for the
86     * classified text.
87     */
88    @FloatRange(from = 0.0, to = 1.0)
89    public float getConfidenceScore(String entity) {
90        if (mEntityConfidence.containsKey(entity)) {
91            return mEntityConfidence.get(entity);
92        }
93        return 0;
94    }
95
96    @Override
97    public String toString() {
98        return mEntityConfidence.toString();
99    }
100
101    @Override
102    public int describeContents() {
103        return 0;
104    }
105
106    @Override
107    public void writeToParcel(Parcel dest, int flags) {
108        dest.writeInt(mEntityConfidence.size());
109        for (Map.Entry<String, Float> entry : mEntityConfidence.entrySet()) {
110            dest.writeString(entry.getKey());
111            dest.writeFloat(entry.getValue());
112        }
113    }
114
115    public static final Parcelable.Creator<EntityConfidence> CREATOR =
116            new Parcelable.Creator<EntityConfidence>() {
117                @Override
118                public EntityConfidence createFromParcel(Parcel in) {
119                    return new EntityConfidence(in);
120                }
121
122                @Override
123                public EntityConfidence[] newArray(int size) {
124                    return new EntityConfidence[size];
125                }
126            };
127
128    private EntityConfidence(Parcel in) {
129        final int numEntities = in.readInt();
130        mEntityConfidence.ensureCapacity(numEntities);
131        for (int i = 0; i < numEntities; ++i) {
132            mEntityConfidence.put(in.readString(), in.readFloat());
133        }
134        resetSortedEntitiesFromMap();
135    }
136
137    private void resetSortedEntitiesFromMap() {
138        mSortedEntities.clear();
139        mSortedEntities.ensureCapacity(mEntityConfidence.size());
140        mSortedEntities.addAll(mEntityConfidence.keySet());
141        Collections.sort(mSortedEntities, new EntityConfidenceComparator());
142    }
143
144    /** Helper to sort entities according to their confidence. */
145    private class EntityConfidenceComparator implements Comparator<String> {
146        @Override
147        public int compare(String e1, String e2) {
148            float score1 = mEntityConfidence.get(e1);
149            float score2 = mEntityConfidence.get(e2);
150            return Float.compare(score2, score1);
151        }
152    }
153}
154