/// <summary>
/// Step 3: Remove dangling links from graph
/// </summary>
protected void UnDangleGraph()
{
if (_danglingLinksPurger != null && _dangleThreshold > 0)
{
DeBruijnPathList danglingNodes = null;
// Observe lenghts of dangling links in the graph
// This is an optimization - instead of incrementing threshold by 1 and
// running the purger iteratively, we first determine the lengths of the
// danglings links found in the graph and run purger only for those lengths.
_danglingLinksPurger.LengthThreshold = _dangleThreshold - 1;
IEnumerable <int> danglingLengths;
IGraphEndsEroder graphEndsEroder = _danglingLinksPurger as IGraphEndsEroder;
if (graphEndsEroder != null && _isErosionEnabled)
{
// If eroder is implemented, while getting lengths of dangling links,
// it also erodes the low coverage ends.
danglingLengths = graphEndsEroder.ErodeGraphEnds(_graph, _erosionThreshold);
}
else
{
// Perform dangling purger at all incremental values till dangleThreshold.
danglingLengths = Enumerable.Range(1, _dangleThreshold - 1);
}
// Erosion is to be only once. Reset erode threshold to -1.
_erosionThreshold = -1;
// Start removing dangling links
foreach (int threshold in danglingLengths)
{
if (_graph.Nodes.Count >= threshold)
{
_danglingLinksPurger.LengthThreshold = threshold;
danglingNodes = _danglingLinksPurger.DetectErroneousNodes(_graph);
_danglingLinksPurger.RemoveErroneousNodes(_graph, danglingNodes);
}
}
// Removing dangling links can in turn create more dangling links
// In order to remove all links within threshold, we therefore run
// purger at threshold length until there is no more change in graph.
do
{
danglingNodes = null;
if (_graph.Nodes.Count >= _dangleThreshold)
{
_danglingLinksPurger.LengthThreshold = _dangleThreshold;
danglingNodes = _danglingLinksPurger.DetectErroneousNodes(_graph);
_danglingLinksPurger.RemoveErroneousNodes(_graph, danglingNodes);
}
}while (danglingNodes != null && danglingNodes.Paths.Count > 0);
}
}
/// <summary>
/// Step 4: Remove redundant paths from graph
/// </summary>
protected void RemoveRedundancy()
{
if (_redundantPathsPurger != null)
{
DeBruijnPathList redundantNodes;
do
{
redundantNodes = _redundantPathsPurger.DetectErroneousNodes(_graph);
_redundantPathsPurger.RemoveErroneousNodes(_graph, redundantNodes);
} while (redundantNodes.Paths.Count > 0);
}
}