/*******************************************************************************
* Copyright 2012-2014 Analog Devices, Inc.
*
* 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 com.analog.lyric.dimple.solvers.sumproduct.customFactors;
import java.util.List;
import com.analog.lyric.dimple.model.factors.Factor;
import com.analog.lyric.dimple.model.values.Value;
import com.analog.lyric.dimple.model.variables.VariablePredicates;
import com.analog.lyric.dimple.solvers.core.parameterizedMessages.NormalParameters;
import com.analog.lyric.dimple.solvers.sumproduct.SumProductSolverGraph;
import com.google.common.collect.Iterables;
public class CustomGaussianSum extends GaussianFactorBase
{
protected int _sumIndex;
private int _sumPort;
private double _constantSum;
public CustomGaussianSum(Factor factor, SumProductSolverGraph parent)
{
super(factor, parent);
_sumIndex = 0; // Index that is the sum of all the others
assertUnboundedReal(factor);
}
@Override
public void doUpdateEdge(int outPortNum)
{
// uout = ua + ub + uc
// ub = uout-ua-uc
// sigma^2 = othersigma^2 + theothersigma^2 ...
if (outPortNum == _sumPort)
updateSumEdge();
else
updateSummandEdge(outPortNum);
}
private void updateSumEdge()
{
double mean = _constantSum;
double variance = 0;
for (int i = 0, n = getSiblingCount(); i < n; i++)
{
if (i != _sumPort)
{
NormalParameters msg = getSiblingEdgeState(i).varToFactorMsg;
mean += msg.getMean();
variance += msg.getVariance();
}
}
NormalParameters outMsg = getSiblingEdgeState(_sumPort).factorToVarMsg;
outMsg.setMean(mean);
outMsg.setVariance(variance);
}
private void updateSummandEdge(int outPortNum)
{
double mean = -_constantSum; // For summands, use negative of constant sum
double variance = 0;
for (int i = 0, n = getSiblingCount(); i < n; i++)
{
if (i != outPortNum)
{
NormalParameters msg = getSiblingEdgeState(i).varToFactorMsg;
if (i == _sumPort)
mean += msg.getMean();
else
mean -= msg.getMean();
variance += msg.getVariance();
}
}
NormalParameters outMsg = getSiblingEdgeState(outPortNum).factorToVarMsg;
outMsg.setMean(mean);
outMsg.setVariance(variance);
}
@Override
public void initialize()
{
super.initialize();
// Pre-compute sum associated with any constant edges
final Factor factor = _model;
_sumPort = factor.hasConstantAtIndex(_sumIndex) ? -1 : _sumIndex; // If sum isn't a variable, then set port to invalid value
_constantSum = 0;
if (_model.hasConstants())
{
List<Value> constantValues = factor.getConstantValues();
int[] constantIndices = factor.getConstantIndices();
for (int i = 0, n = constantValues.size(); i < n; i++)
{
double constant = constantValues.get(i).getDouble();
if (constantIndices[i] == _sumIndex)
_constantSum -= constant; // Constant sum value counts as negative
else
_constantSum += constant; // Constant summand value counts as positive
}
}
}
/**
* Utility to indicate whether or not a factor is compatible with the requirements of this custom factor
* @deprecated as of release 0.08
*/
@Deprecated
public static boolean isFactorCompatible(Factor factor)
{
return Iterables.all(factor.getSiblings(), VariablePredicates.isUnboundedReal());
}
}