/// <summary>
/// Search strict dangling vertices, for example
/// |\
/// | \
/// |__\Y_________Z
/// In the above draft, Z is a dangling vertex, but Y is not.
/// </summary>
/// <returns></returns>
public IEnumerable <CurveVertex> SearchDanglingVertices()
{
// Search none loop vertices.
var noneLoopVertices = SearchNoneLoopVertices();
// Depth first search the graph, and find all the path end vertices.
var result = new HashSet <CurveVertex>();
var observer = new VertexPredecessorPathRecorderObserver <CurveVertex, SEdge <CurveVertex> >();
var dfs = new DepthFirstSearchAlgorithm <CurveVertex, SEdge <CurveVertex> >((IVertexListGraph <CurveVertex, SEdge <CurveVertex> >)_graph);
using (observer.Attach(dfs))
{
dfs.Compute();
}
// Dangling vertex must be an end path vertex.
foreach (var curveVertex in observer.EndPathVertices)
{
if (!noneLoopVertices.Contains(curveVertex))
{
continue;
}
result.Add(curveVertex);
// Check whether this path's root point is a dangling vertex.
var root = GetRootVertex(observer.VertexPredecessors, curveVertex);
if (root != null && noneLoopVertices.Contains(root.Value))
{
result.Add(root.Value);
}
}
return(result);
}
public IEnumerable <IEnumerable <SEdge <CurveVertex> > > SearchDanglingPaths()
{
// Search all none loop vertices
var noneLoopVertices = SearchNoneLoopVertices();
var danglingEdges = new List <SEdge <CurveVertex> >();
foreach (var vertex in noneLoopVertices)
{
IEnumerable <SEdge <CurveVertex> > edges = null;
if (_graph.TryGetOutEdges(vertex, out edges))
{
danglingEdges.AddRange(edges);
}
}
// Create a small graph.
var tempGraph = danglingEdges.ToAdjacencyGraph <CurveVertex, SEdge <CurveVertex> >();
// Deep first search the graph and get all its paths.
var observer = new VertexPredecessorPathRecorderObserver <CurveVertex, SEdge <CurveVertex> >();
var dfs = new DepthFirstSearchAlgorithm <CurveVertex, SEdge <CurveVertex> >((IVertexListGraph <CurveVertex, SEdge <CurveVertex> >)tempGraph);
using (observer.Attach(dfs))
{
dfs.Compute();
}
return(observer.AllPaths());
}
public static IList <IEnumerable <TaggedEdge <string, string> > > GetPaths(AdjacencyGraph <string, TaggedEdge <string, string> > g)
{
var dfs = new DepthFirstSearchAlgorithm <string, TaggedEdge <string, string> >(g);
var recorder = new VertexPredecessorPathRecorderObserver <string, TaggedEdge <string, string> >();
List <IEnumerable <TaggedEdge <string, string> > > results = new List <IEnumerable <TaggedEdge <string, string> > >();
using (recorder.Attach(dfs))
{
dfs.Compute();
var paths = recorder.AllPaths();
foreach (var p in paths)
{
results.Add(p);
}
}
return(results);
}
public void Attach()
{
// DFS is used for tests but result may change if using another search algorithm
// or another starting point
{
var recorder = new VertexPredecessorPathRecorderObserver <int, Edge <int> >();
var graph = new AdjacencyGraph <int, Edge <int> >();
var dfs = new DepthFirstSearchAlgorithm <int, Edge <int> >(graph);
using (recorder.Attach(dfs))
{
dfs.Compute();
CollectionAssert.IsEmpty(recorder.VerticesPredecessors);
CollectionAssert.IsEmpty(recorder.EndPathVertices);
}
}
{
var recorder = new VertexPredecessorPathRecorderObserver <int, Edge <int> >();
var graph = new AdjacencyGraph <int, Edge <int> >();
graph.AddVertexRange(new[] { 1, 2 });
var dfs = new DepthFirstSearchAlgorithm <int, Edge <int> >(graph);
using (recorder.Attach(dfs))
{
dfs.Compute();
CollectionAssert.IsEmpty(recorder.VerticesPredecessors);
CollectionAssert.AreEquivalent(new[] { 1, 2 }, recorder.EndPathVertices);
}
}
{
var recorder = new VertexPredecessorPathRecorderObserver <int, Edge <int> >();
// Graph without cycle
var edge12 = new Edge <int>(1, 2);
var edge13 = new Edge <int>(1, 3);
var edge14 = new Edge <int>(1, 4);
var edge24 = new Edge <int>(2, 4);
var edge31 = new Edge <int>(3, 1);
var edge33 = new Edge <int>(3, 3);
var edge34 = new Edge <int>(3, 4);
var graph = new AdjacencyGraph <int, Edge <int> >();
graph.AddVerticesAndEdgeRange(new[]
{
edge12, edge13, edge14, edge24, edge31, edge33, edge34
});
var dfs = new DepthFirstSearchAlgorithm <int, Edge <int> >(graph);
using (recorder.Attach(dfs))
{
dfs.Compute();
CollectionAssert.AreEqual(
new Dictionary <int, Edge <int> >
{
[2] = edge12,
[3] = edge13,
[4] = edge24
},
recorder.VerticesPredecessors);
CollectionAssert.AreEquivalent(new[] { 3, 4 }, recorder.EndPathVertices);
}
}
{
var recorder = new VertexPredecessorPathRecorderObserver <int, Edge <int> >();
// Graph with cycle
var edge12 = new Edge <int>(1, 2);
var edge13 = new Edge <int>(1, 3);
var edge14 = new Edge <int>(1, 4);
var edge24 = new Edge <int>(2, 4);
var edge31 = new Edge <int>(3, 1);
var edge33 = new Edge <int>(3, 3);
var edge34 = new Edge <int>(3, 4);
var edge41 = new Edge <int>(4, 1);
var graph = new AdjacencyGraph <int, Edge <int> >();
graph.AddVerticesAndEdgeRange(new[]
{
edge12, edge13, edge14, edge24, edge31, edge33, edge34, edge41
});
var dfs = new DepthFirstSearchAlgorithm <int, Edge <int> >(graph);
using (recorder.Attach(dfs))
{
dfs.Compute();
CollectionAssert.AreEqual(
new Dictionary <int, Edge <int> >
{
[2] = edge12,
[3] = edge13,
[4] = edge24
},
recorder.VerticesPredecessors);
CollectionAssert.AreEquivalent(new[] { 3, 4 }, recorder.EndPathVertices);
}
}
}
public void AllPaths()
{
{
var recorder = new VertexPredecessorPathRecorderObserver <int, Edge <int> >();
var graph = new AdjacencyGraph <int, Edge <int> >();
var dfs = new DepthFirstSearchAlgorithm <int, Edge <int> >(graph);
using (recorder.Attach(dfs))
{
dfs.Compute();
CollectionAssert.IsEmpty(recorder.AllPaths());
}
}
{
var recorder = new VertexPredecessorPathRecorderObserver <int, Edge <int> >();
var graph = new AdjacencyGraph <int, Edge <int> >();
graph.AddVertexRange(new[] { 1, 2 });
var dfs = new DepthFirstSearchAlgorithm <int, Edge <int> >(graph);
using (recorder.Attach(dfs))
{
dfs.Compute();
CollectionAssert.IsEmpty(recorder.AllPaths());
}
}
{
var recorder = new VertexPredecessorPathRecorderObserver <int, Edge <int> >();
// Graph without cycle
var edge12 = new Edge <int>(1, 2);
var edge13 = new Edge <int>(1, 3);
var edge14 = new Edge <int>(1, 4);
var edge24 = new Edge <int>(2, 4);
var edge31 = new Edge <int>(3, 1);
var edge33 = new Edge <int>(3, 3);
var edge34 = new Edge <int>(3, 4);
var graph = new AdjacencyGraph <int, Edge <int> >();
graph.AddVerticesAndEdgeRange(new[]
{
edge12, edge13, edge14, edge24, edge31, edge33, edge34
});
var dfs = new DepthFirstSearchAlgorithm <int, Edge <int> >(graph);
using (recorder.Attach(dfs))
{
dfs.Compute();
CollectionAssert.AreEquivalent(
new IEnumerable <Edge <int> >[]
{
new[] { edge13 },
new[] { edge12, edge24 }
},
recorder.AllPaths());
}
}
{
var recorder = new VertexPredecessorPathRecorderObserver <int, Edge <int> >();
// Graph with cycle
var edge12 = new Edge <int>(1, 2);
var edge13 = new Edge <int>(1, 3);
var edge14 = new Edge <int>(1, 4);
var edge24 = new Edge <int>(2, 4);
var edge31 = new Edge <int>(3, 1);
var edge33 = new Edge <int>(3, 3);
var edge34 = new Edge <int>(3, 4);
var edge41 = new Edge <int>(4, 1);
var graph = new AdjacencyGraph <int, Edge <int> >();
graph.AddVerticesAndEdgeRange(new[]
{
edge12, edge13, edge14, edge24, edge31, edge33, edge34, edge41
});
var dfs = new DepthFirstSearchAlgorithm <int, Edge <int> >(graph);
using (recorder.Attach(dfs))
{
dfs.Compute();
CollectionAssert.AreEquivalent(
new IEnumerable <Edge <int> >[]
{
new[] { edge13 },
new[] { edge12, edge24 }
},
recorder.AllPaths());
}
}
}