1/*
2 * Copyright (C) 2012 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 android.bordeaux.services;
18
19import android.bordeaux.services.ILearning_MulticlassPA;
20import android.bordeaux.services.IntFloat;
21import android.content.Context;
22import android.os.RemoteException;
23import android.util.Log;
24
25import java.util.ArrayList;
26import java.util.List;
27import java.util.HashMap;
28import java.util.Map;
29
30/** Classifier for the Learning framework.
31 *  For training: call trainOneSample
32 *  For classifying: call classify
33 *  Data is represented as sparse key, value pair. And key is an integer, value
34 *  is a float. Class label(target) for the training data is an integer.
35 *  Note: since the actual classifier is running in a remote the service.
36 *  Sometimes the connection may be lost or not established.
37 *
38 */
39public class BordeauxClassifier {
40    static final String TAG = "BordeauxClassifier";
41    private Context mContext;
42    private String mName;
43    private ILearning_MulticlassPA mClassifier;
44    private ArrayList<IntFloat> getArrayList(final HashMap<Integer, Float> sample) {
45        ArrayList<IntFloat> intfloat_sample = new ArrayList<IntFloat>();
46        for (Map.Entry<Integer, Float> x : sample.entrySet()) {
47           IntFloat v = new IntFloat();
48           v.index = x.getKey();
49           v.value = x.getValue();
50           intfloat_sample.add(v);
51        }
52        return intfloat_sample;
53    }
54
55    private boolean retrieveClassifier() {
56        if (mClassifier == null)
57            mClassifier = BordeauxManagerService.getClassifier(mContext, mName);
58        // if classifier is not available, return false
59        if (mClassifier == null) {
60            Log.i(TAG,"Classifier not available.");
61            return false;
62        }
63        return true;
64    }
65
66    public BordeauxClassifier(Context context) {
67        mContext = context;
68        mName = "defaultClassifier";
69        mClassifier = BordeauxManagerService.getClassifier(context, mName);
70    }
71
72    public BordeauxClassifier(Context context, String name) {
73        mContext = context;
74        mName = name;
75        mClassifier = BordeauxManagerService.getClassifier(context, mName);
76    }
77
78    public boolean update(final HashMap<Integer, Float> sample, int target) {
79        if (!retrieveClassifier())
80            return false;
81        try {
82            mClassifier.TrainOneSample(getArrayList(sample), target);
83        } catch (RemoteException e) {
84            Log.e(TAG,"Exception: training one sample.");
85            return false;
86        }
87        return true;
88    }
89
90    public int classify(final HashMap<Integer, Float> sample) {
91        // if classifier is not available return -1 as an indication of fail.
92        if (!retrieveClassifier())
93            return -1;
94        try {
95            return mClassifier.Classify(getArrayList(sample));
96        } catch (RemoteException e) {
97            Log.e(TAG,"Exception: classify the sample.");
98            // return an invalid number.
99            // TODO: throw exception.
100            return -1;
101        }
102    }
103}
104