/*******************************************************************************
* Copyright 2012 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.factorfunctions;
import java.util.Map;
import org.eclipse.jdt.annotation.Nullable;
import com.analog.lyric.dimple.factorfunctions.core.FactorFunctionUtilities;
import com.analog.lyric.dimple.factorfunctions.core.IParametricFactorFunction;
import com.analog.lyric.dimple.factorfunctions.core.UnaryFactorFunction;
import com.analog.lyric.dimple.model.values.Value;
import com.analog.lyric.dimple.solvers.core.parameterizedMessages.DirichletParameters;
/**
* Factor for an exchangeable set of Dirichlet distributed variables
* associated with a variable or fixed parameter vector. The variables are
* ordered as follows in the argument list:
* <p>
* <ul>
* <li> Parameters (non-negative RealJoint variable).
* <li> ...) An arbitrary number of RealJoint variables, each one a Dirichlet distributed random variable.
* </ul>
* The parameters may optionally be specified as constants in the constructor.
* In this case, the parameters are not included in the list of arguments.
*/
public class Dirichlet extends UnaryFactorFunction implements IParametricFactorFunction
{
private static final long serialVersionUID = 1L;
protected DirichletParameters _parameters;
private boolean _parametersConstant;
private int _firstDirectedToIndex;
/*--------------
* Construction
*/
protected Dirichlet(DirichletParameters parameters, int index)
{
super((String)null);
_parameters = parameters;
_parametersConstant = index == 0;
_firstDirectedToIndex = index;
}
public Dirichlet() // Variable parameters
{
this(new DirichletParameters(), 1);
}
public Dirichlet(DirichletParameters parameters)
{
this(parameters, 0);
}
public Dirichlet(double[] alpha) // Constant parameters
{
this(new DirichletParameters(alpha.length));
_parameters.setAlpha(alpha);
}
/**
* Construct from specified parameters
* @param parameters the following values are supported:
* <ul>
* <li>alpha (default 1.0)
* <li>beta (default 1.0)
* </ul>
* @since 0.07
*/
public Dirichlet(Map<String,Object> parameters)
{
this((double[])require(parameters, "alpha", "alphas"));
}
protected Dirichlet(Dirichlet other)
{
super(other);
_parameters = other._parameters.clone();
_firstDirectedToIndex = other._firstDirectedToIndex;
_parametersConstant = other._parametersConstant;
}
@Override
public Dirichlet clone()
{
return new Dirichlet(this);
}
/*----------------
* IDatum methods
*/
@Override
public boolean objectEquals(@Nullable Object other)
{
if (this == other)
{
return true;
}
if (other instanceof Dirichlet)
{
Dirichlet that = (Dirichlet)other;
return _parametersConstant == that._parametersConstant &&
_parameters.objectEquals(((Dirichlet) other)._parameters) &&
_firstDirectedToIndex == that._firstDirectedToIndex;
}
return false;
}
/*------------------------
* FactorFunction methods
*/
@Override
public final double evalEnergy(Value[] arguments)
{
int index = 0;
if (!_parametersConstant)
{
final double[] alpha = arguments[index++].getDoubleArray(); // First variable is array of parameter values
if (_parameters.getSize() != alpha.length)
_parameters = new DirichletParameters(alpha.length);
_parameters.setAlpha(alpha);
}
return _parameters.evalNormalizedEnergy(arguments, index);
}
@Override
public final boolean isDirected() {return true;}
@Override
public final int[] getDirectedToIndices(int numEdges)
{
// All edges except the parameter edges (if present) are directed-to edges
return FactorFunctionUtilities.getListOfIndices(_firstDirectedToIndex, numEdges-1);
}
/*-----------------------------------
* IParametricFactorFunction methods
*/
@Override
public int copyParametersInto(Map<String, Object> parameters)
{
if (_parametersConstant)
{
parameters.put("alpha", getParameter("alpha"));
return 1;
}
return 0;
}
@Override
public @Nullable Object getParameter(String parameterName)
{
if (_parametersConstant)
{
switch (parameterName)
{
case "alpha":
case "alphas":
return _parameters.getAlphas();
}
}
return null;
}
@Override
public DirichletParameters getParameterizedMessage()
{
return _parameters;
}
@Override
public final boolean hasConstantParameters()
{
return _parametersConstant;
}
/*-------------------------
* Factor-specific methods
*/
public final double[] getAlphaMinusOneArray()
{
return _parameters.getAlphaMinusOneArray();
}
public final int getDimension()
{
return _parameters.getSize();
}
}