/// <summary>
/// getSegmentActiveSynapses(c, i, t, s, newSynapses= false)
/// Return a segmentUpdate data structure containing a list of proposed changes to segment s.
/// Let activeSynapses be the list of active synapses where the originating cells have their
/// activeState output = 1 at time step t. (This list is empty if s = -1 since the segment doesn't exist.)
/// newSynapses is an optional argument that defaults to false. If newSynapses is true,
/// then newSynapseCount - count(activeSynapses) synapses are added to activeSynapses.
/// These synapses are randomly chosen from the set of cells that have learnState output = 1 at time step t.
/// </summary>
/// <param name="segment"></param>
/// <param name="cell"></param>
/// <param name="time"></param>
/// <param name="newSynapses"></param>
/// <returns></returns>
private SegmentUpdate GetSegmentActiveSynapses(Segment segment, Cell cell, Time time, bool newSynapses = false)
{
IEnumerable<Synapse> activeSynapses = null;
if (segment != null)
{
activeSynapses = segment.Synapses.Where(synapse => synapse.GetIsActive(ActiveMode.ActiveState, time)).ToArray();
}
activeSynapses = activeSynapses ?? Enumerable.Empty<Synapse>();
if (newSynapses
&& Network.Instance.Parameters.NewSynapseCount - activeSynapses.Count() > 0)
{
var potentialSynapses =
Cells.Where(c => c.GetIsLearningState(time)
&& c != cell)
.SelectMany(c => c.Segments.SelectMany(s => s.Synapses))
.Except(cell.Segments.SelectMany(c => c.Synapses));
activeSynapses = activeSynapses.Concat
(potentialSynapses.OrderBy(ps => Guid.NewGuid())
.Take(Network.Instance.Parameters.NewSynapseCount - activeSynapses.Count()));
}
return new SegmentUpdate(cell, segment, activeSynapses);
}
/// <summary>
/// getBestMatchingCell(c)
/// For the given column, return the cell with the best matching segment (as defined above).
/// If no cell has a matching segment, then return the cell with the fewest number of segments.
/// </summary>
/// <param name="time"></param>
/// <param name="cell"></param>
/// <param name="segment"></param>
private void CalculateBestMatchingCellAndSegment(Time time, out Cell foundCell, out Segment foundSegment)
{
var foundItem = Cells.Select
(cell =>
{
Segment segment;
int score;
GetBestMatchingSegment(cell, time, out segment, out score);
return new
{
Cell = cell,
Segment = segment,
SegmentScore = score
};
}).OrderByDescending(item => item.SegmentScore).FirstOrDefault();
if (foundItem == null)
{
foundCell = Cells.OrderBy(cell => cell.Segments.Count()).First();
foundSegment = null;
}
else
{
foundCell = foundItem.Cell;
foundSegment = foundItem.Segment;
}
}
/// <summary>
/// getBestMatchingSegment(c, i, t)
/// For the given column c cell i at time t, find the segment with the largest number of active synapses.
/// This routine is aggressive in finding the best match.
/// The permanence value of synapses is allowed to be below connectedPerm.
/// The number of active synapses is allowed to be below activationThreshold, but must be above minThreshold.
/// The routine returns the segment index. If no segments are found, then an index of -1 is returned.
/// </summary>
/// <param name="cell"></param>
/// <param name="time"></param>
private void GetBestMatchingSegment(Cell cell, Time time, out Segment segmentFound, out int score)
{
segmentFound = null;
score = int.MinValue;
var segmentWithScore = cell.Segments
.Select(segment =>
new
{
Segment = segment,
Score = segment.GetIsSegmentActiveScore
(ActiveMode.ActiveState, time,
Network.Instance.Parameters.AbsoluteMinPermanence,
Network.Instance.Parameters.MinActivationThreshold)
})
.Where(item => item.Score >= 0).
OrderByDescending(item => item.Score).FirstOrDefault();
if (segmentWithScore != null)
{
segmentFound = segmentWithScore.Segment;
score = segmentWithScore.Score;
}
}
public SegmentUpdate(Cell cell, Segment segment, IEnumerable<Synapse> activeSynapses)
{
Cell = cell;
ActiveSynapses = activeSynapses;
Segment = segment;
}