/*******************************************************************************
* 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.schedulers.schedule;
import static com.analog.lyric.dimple.environment.DimpleEnvironment.*;
import java.util.Iterator;
import java.util.Objects;
import org.eclipse.jdt.annotation.NonNull;
import org.eclipse.jdt.annotation.Nullable;
import com.analog.lyric.dimple.model.core.FactorGraph;
import com.analog.lyric.dimple.schedulers.GibbsSequentialScanScheduler;
import com.analog.lyric.dimple.schedulers.IScheduler;
import com.analog.lyric.dimple.schedulers.scheduleEntry.BlockScheduleEntry;
import com.analog.lyric.dimple.schedulers.scheduleEntry.IScheduleEntry;
import com.google.common.collect.Iterators;
/**
* @author jeffb
*
* This is a dynamic schedule, which updates only one variable that is
* randomly chosen. This allows one iteration to correspond to exactly
* one variable update. In the Gibbs solver, factors do not need to be
* explicitly updated in the schedule.
*
* WARNING: This schedule DOES NOT respect any existing sub-graph
* scheduler associations. That is, if any sub-graph already has an
* associated scheduler, that scheduler is ignored in creating this
* schedule. I believe this is a necessary limitation for Gibbs sampling
* to operate properly.
*
*/
public class GibbsRandomScanSchedule extends ScheduleBase implements IGibbsSchedule
{
private static final long serialVersionUID = 1L;
/*-------
* State
*/
protected FixedSchedule _scheduleEntryPool;
/*--------------
* Construction
*/
public GibbsRandomScanSchedule(FactorGraph factorGraph)
{
this(null, factorGraph);
}
@SuppressWarnings("null")
public GibbsRandomScanSchedule(@Nullable IScheduler scheduler, FactorGraph factorGraph)
{
super(scheduler, factorGraph);
initialize();
}
/*-------------------
* ISchedule methods
*/
@Override
public void attach(FactorGraph factorGraph)
{
super.attach(factorGraph);
initialize();
}
protected void initialize()
{
// Create a pool of schedule entries that will be randomly chosen from
// By default, this is the same set of nodes in a sequential-scan schedule
_scheduleEntryPool = (FixedSchedule)new GibbsSequentialScanScheduler().createSchedule(getFactorGraph());
++_version;
}
@Override
public @NonNull FactorGraph getFactorGraph()
{
return Objects.requireNonNull(_factorGraph);
}
@Override
public Iterator<IScheduleEntry> iterator()
{
// Choose an entry in the list of schedule entries uniformly at random
// Note: the DimpleRandomGenerator is used here so that if a fixed seed is set in the solver,
// then the schedule will also be repeatable
int entryIndex = activeRandom().nextInt(_scheduleEntryPool.size());
// Create a single schedule entry that includes all of the selected variable
return Iterators.singletonIterator(_scheduleEntryPool.get(entryIndex));
}
// Add a block schedule entry, which will replace individual variable updates included in the block
@Override
public void addBlockScheduleEntry(BlockScheduleEntry blockScheduleEntry)
{
_scheduleEntryPool.addBlockScheduleEntry(blockScheduleEntry);
}
@Override
public final long scheduleVersion()
{
return _scheduleEntryPool.scheduleVersion();
}
// Indicate the number of entries in the schedule entry pool
@Override
public int size()
{
return _scheduleEntryPool.size();
}
}