org.onebusaway.nyc.vehicle_tracking.impl.inference.likelihood.NullStateLikelihood.java Source code

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/**
 * Copyright (c) 2011 Metropolitan Transportation Authority
 * 
 * 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 org.onebusaway.nyc.vehicle_tracking.impl.inference.likelihood;

import org.onebusaway.nyc.vehicle_tracking.impl.inference.BlockStateService;
import org.onebusaway.nyc.vehicle_tracking.impl.inference.state.BlockStateObservation;
import org.onebusaway.nyc.vehicle_tracking.impl.inference.state.VehicleState;
import org.onebusaway.nyc.vehicle_tracking.impl.particlefilter.BadProbabilityParticleFilterException;
import org.onebusaway.nyc.vehicle_tracking.impl.particlefilter.SensorModelResult;
import org.onebusaway.realtime.api.EVehiclePhase;

import org.apache.commons.math.util.FastMath;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
public class NullStateLikelihood implements SensorModelRule {

    @Autowired
    public void setBlockStateService(BlockStateService blockStateService) {
    }

    private static final double nonNullLik = 0.9999d;

    static public enum NullStates {
        NULL_STATE, NON_NULL_STATE
    }

    @Override
    public SensorModelResult likelihood(Context context) throws BadProbabilityParticleFilterException {
        final SensorModelResult result = new SensorModelResult("pNullState", 1.0);

        final NullStates state = getNullState(context);
        switch (state) {
        case NULL_STATE:
            result.addResultAsAnd("null-state", 1d - nonNullLik);
            break;
        case NON_NULL_STATE:
            result.addResultAsAnd("non-null-state", nonNullLik);
            break;
        }
        return result;
    }

    public static NullStates getNullState(Context context) {
        final VehicleState state = context.getState();
        // final Observation obs = context.getObservation();
        final BlockStateObservation blockStateObs = state.getBlockStateObservation();
        EVehiclePhase phase = state.getJourneyState().getPhase();

        if (blockStateObs == null) {
            return NullStates.NULL_STATE;
        } else {

            final boolean hasScheduledTime = FastMath
                    .abs(state.getBlockStateObservation().getScheduleDeviation()) > 0d;

            if (!hasScheduledTime) {
                return NullStates.NULL_STATE;
            }

            if (!state.getBlockStateObservation().isSnapped() && ((EVehiclePhase.DEADHEAD_AFTER == phase
                    && state.getBlockStateObservation().getScheduleDeviation() == 0d)
                    || EVehiclePhase.AT_BASE == phase
                    || (EVehiclePhase.DEADHEAD_BEFORE == phase
                            && state.getBlockStateObservation().getScheduleDeviation() == 0d)
                    || (EVehiclePhase.LAYOVER_BEFORE == phase)
                            && state.getBlockStateObservation().getScheduleDeviation() == 0d)) {
                return NullStates.NULL_STATE;
            }

            return NullStates.NON_NULL_STATE;
        }
    }

}