/*
* Copyright (c) 2009-2010 Chris Smith
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package uk.co.md87.android.common.aggregator;
import java.util.HashMap;
import java.util.Map;
/**
* Aggregates a stream of classifications and performs averaging in order to
* smooth out results. Each classification supplied to the aggregator is used
* to alter the 'probabilities' of that classification holding. These
* probabilities are calculated hierarchically, and the aggregator can in some
* cases produce a result that is not in itself a normal activity because of
* this (for example, it may classify unclear data as
* CLASSIFIED/VEHICLE
, rather than as a sub-type as expected).
*
* @author chris
*/
public class Aggregator {
static final double DELTA = 0.25;
static final double THRESHOLD = 0.5;
private final HashMap> scores
= new HashMap>() {{
put("", new HashMap() {{
put("null", 0.5d);
put("CLASSIFIED", 0.5d);
}});
put("CLASSIFIED", new HashMap() {{
put("null", 0.2d);
put("DANCING", 0.2d);
put("WALKING", 0.2d);
put("VEHICLE", 0.2d);
put("IDLE", 0.2d);
}});
put("CLASSIFIED/WALKING", new HashMap() {{
put("null", 0.5d);
put("STAIRS", 0.5d);
}});
put("CLASSIFIED/VEHICLE", new HashMap() {{
put("null", 0.333d);
put("CAR", 0.333d);
put("BUS", 0.333d);
}});
put("CLASSIFIED/IDLE", new HashMap() {{
put("null", 0.333d);
put("STANDING", 0.333d);
put("SITTING", 0.333d);
}});
put("CLASSIFIED/WALKING/STAIRS", new HashMap() {{
put("null", 0.333d);
put("UP", 0.333d);
put("DOWN", 0.333d);
}});
}};
public void addClassification(final String classification) {
String path = "";
for (String part : classification.split("/")) {
if (!scores.containsKey(path)) {
throw new RuntimeException("Path not found: " + path
+ " (classification: " + classification + ")");
}
updateScores(scores.get(path), part);
path = path + (path.length() == 0 ? "" : "/") + part;
}
if (scores.containsKey(path)) {
// This classification has children which we're not using
// e.g. we've received CLASSIFIED/WALKING, but we're not walking
// up or down stairs
updateScores(scores.get(path), "null");
}
}
void updateScores(final Map map, final String target) {
for (Map.Entry entry : map.entrySet()) {
//Log.d(getClass().getName(), "Score for " + entry.getKey() + " was: " + entry.getValue());
entry.setValue(entry.getValue() * (1 - DELTA));
if (entry.getKey().equals(target)) {
entry.setValue(entry.getValue() + DELTA);
}
//Log.d(getClass().getName(), "Score for " + entry.getKey() + " is now: " + entry.getValue());
}
}
public String getClassification() {
String path = "";
do {
final Map map = scores.get(path);
double best = THRESHOLD;
String bestPath = "null";
for (Map.Entry entry : map.entrySet()) {
if (entry.getValue() >= best) {
best = entry.getValue();
bestPath = entry.getKey();
}
}
path = path + (path.length() == 0 ? "" : "/") + bestPath;
} while (scores.containsKey(path));
return path.replaceAll("(^CLASSIFIED)?/?null$", "");
}
}