private void GetShortestGraph(DirectedGraphNode sourceNode, DirectedGraphNode targetNode, DirectedGraph graph)
{
if (sourceNode.Name == targetNode.Name)
{
return;
}
var predecessorNodes = this.GetShortestPathPredecessors(targetNode);
foreach (var predecessor in predecessorNodes)
{
var node = new DistanceNode(predecessor.Name)
{
Tag = predecessor.Tag,
};
if (!graph.TryAddNode(node))
{
node = (DistanceNode)graph.GetNode(node.Name);
}
var distance = _distances[predecessor.Name];
node.Distance = distance;
_graph.TryGetEdge(predecessor, targetNode, out var edge);
if (graph.TryAddEdge(predecessor.Name, targetNode.Name, edge.Weight, false, out _))
{
GetShortestGraph(sourceNode, predecessor, graph);
}
}
}
protected DirectedGraph BuildShortestPathGraph(DirectedGraphNode sourceNode, DirectedGraphNode targetNode)
{
if (_distances[targetNode.Name] == double.PositiveInfinity)
{
throw new PathNotFoundException(sourceNode.Name, targetNode.Name);
}
var graph = new DirectedGraph();
//Set start Node
var distanceNode = new DistanceNode(targetNode.Name)
{
Tag = targetNode.Tag
};
var distance = _distances[targetNode.Name];
distanceNode.Distance = distance;
graph.AddNode(distanceNode);
GetShortestGraph(sourceNode, targetNode, graph);
//set node distances
foreach (var node in graph.Nodes)
{
node.Description = node.Name + Environment.NewLine + "Distance:" + _distances[node.Name].ToString();
}
//set edge description
foreach (var edge in graph.Edges)
{
edge.Description = edge.Weight.ToString();
}
return(graph);
}
/// <summary>
/// Searches the shortest path to the Source node
/// via the DeepFirst-Search Algorithm
/// </summary>
public static bool TryGetDistanceNode(this DirectedGraph graph, string nodeName, out DistanceNode distanceNode)
{
var result = graph.TryGetNode(nodeName, out var existingNode);
if (result == true && existingNode is DistanceNode node)
{
distanceNode = node;
return(true);
}
else
{
distanceNode = null;
return(false);
}
}