public IPathResult FindPaths(int node1Id, int node2Id, IPathFinderSettings settings)
{
if (settings == null) settings = PathFinderSettings.Default;
var pathSteps = _pathFinderAuxiliaries.CacheService.GetMonitored(_graphDescriptor, MakeCacheKey("FindPaths.PathSteps." + node1Id + "/" + node2Id, settings), () =>
{
TryInit();
var paths = _graphClient.Cypher
.Start(
new CypherStartBitWithNodeIndexLookupWithSingleParameter("n", WellKnownConstants.NodeIdIndexName, "id:" + node1Id),
new CypherStartBitWithNodeIndexLookupWithSingleParameter("t", WellKnownConstants.NodeIdIndexName, "id:" + node2Id)
)
.Match("path = (n)-[:" + WellKnownConstants.RelationshipTypeKey + "*1.." + settings.MaxDistance + "]-(t)")
.Return<Path>("nodes(path) AS Nodes", CypherResultMode.Projection) // Taken from: http://craigbrettdevden.blogspot.co.uk/2013/03/retrieving-paths-in-neo4jclient.html
.Results;
return PathsToPathSteps(paths);
});
return new Associativy.Services.PathFinderAuxiliaries.PathResult
{
SucceededPaths = pathSteps,
SucceededGraph = PathToGraph(pathSteps, "PathToGraph:" + node1Id + "/" + node2Id, settings)
};
}
public IQueryableGraph<int> GetPartialGraph(int centralNodeId, IPathFinderSettings settings)
{
if (settings == null) settings = PathFinderSettings.Default;
return _pathFinderAuxiliaries.QueryableFactory.Create<int>((parameters) =>
{
var graph = _pathFinderAuxiliaries.CacheService.GetMonitored(_graphDescriptor, QueryableGraphHelper.MakeCacheKey(MakeCacheKey("GetPartialGraph.BaseGraph." + centralNodeId, settings), parameters), () =>
{
TryInit();
var paths = _graphClient.Cypher
.StartWithNodeIndexLookup("n", WellKnownConstants.NodeIdIndexName, "id:" + centralNodeId)
.Match("path = (n)-[:" + WellKnownConstants.RelationshipTypeKey + "*1.." + settings.MaxDistance + "]-()")
.Return<Path>("nodes(path) AS Nodes", CypherResultMode.Projection) // Taken from: http://craigbrettdevden.blogspot.co.uk/2013/03/retrieving-paths-in-neo4jclient.html
.Skip(parameters.Paging.SkipConnections)
.Limit(parameters.Paging.TakeConnections)
.Results;
return _pathFinderAuxiliaries.PathToGraph(PathsToPathSteps(paths));
});
return QueryableGraphHelper.LastSteps(new LastStepParams
{
CacheService = _pathFinderAuxiliaries.CacheService,
GraphEditor = _pathFinderAuxiliaries.GraphEditor,
GraphDescriptor = _graphDescriptor,
ExecutionParameters = parameters,
Graph = graph,
BaseCacheKey = MakeCacheKey("GetPartialGraph." + centralNodeId + ".PathToGraph.", settings)
});
});
}
/// <summary>
/// Returns a partial graph of the graph that starts from the center node and contains all paths within the specified range, containing the ids of the content items
/// </summary>
/// <param name="centralNodeId">The node paths will be calculated from</param>
/// <param name="settings"></param>
public static IQueryableGraph<int> GetPartialGraph(this IPathFinder pathFinder, IContent centralNode, IPathFinderSettings settings)
{
return pathFinder.GetPartialGraph(centralNode.ContentItem.Id, settings);
}
private IQueryableGraph<int> PathToGraph(IEnumerable<IList<int>> succeededPaths, string baseCacheKey, IPathFinderSettings settings)
{
return _pathFinderAuxiliaries.QueryableFactory.Create<int>((parameters) =>
{
var graph = _pathFinderAuxiliaries.CacheService.GetMonitored(_graphDescriptor, MakeCacheKey(baseCacheKey + "BaseGraph.", settings), () =>
{
return _pathFinderAuxiliaries.PathToGraph(succeededPaths);
});
return LastStepsWithPaging(parameters, graph, baseCacheKey, settings);
});
}
private string MakeCacheKey(string name, IPathFinderSettings settings)
{
return CacheKeyPrefix + _graphDescriptor.Name + "." + name + ".PathFinderSettings:" + settings.MaxDistance + ".";
}
private dynamic LastStepsWithPaging(IExecutionParams parameters, IUndirectedGraph<int, IUndirectedEdge<int>> graph, string cacheName, IPathFinderSettings settings)
{
return QueryableGraphHelper.LastStepsWithPaging(new LastStepParams
{
CacheService = _pathFinderAuxiliaries.CacheService,
GraphEditor = _pathFinderAuxiliaries.GraphEditor,
GraphDescriptor = _graphDescriptor,
ExecutionParameters = parameters,
Graph = graph,
BaseCacheKey = MakeCacheKey(cacheName, settings)
});
}
public virtual IPathResult FindPaths(int node1Id, int node2Id, IPathFinderSettings settings)
{
if (settings == null) settings = PathFinderSettings.Default;
// This way we'll use the same cache no matter in which order the arguments are specified
if (node2Id < node1Id)
{
var temp = node2Id;
node2Id = node1Id;
node1Id = temp;
}
var paths = _pathFinderAuxiliaries.CacheService.GetMonitored(_graphDescriptor, MakeCacheKey("FindPaths.Paths." + _graphDescriptor.Name + "/" + node1Id.ToString() + "/" + node2Id.ToString(), settings), () =>
{
// This below is a depth-first search that tries to find all paths to the target node that are within the maximal length (maxDistance) and
// keeps track of the paths found.
var connectionManager = _graphDescriptor.Services.ConnectionManager;
var explored = new Dictionary<int, PathNode>();
var succeededPaths = new List<List<int>>();
var frontier = new Stack<FrontierNode>();
var startNodeId = node1Id;
var targetNodeId = node2Id;
if (connectionManager.GetNeighbourCount(startNodeId) > connectionManager.GetNeighbourCount(targetNodeId))
{
startNodeId = node2Id;
targetNodeId = node1Id;
}
explored[startNodeId] = new PathNode(startNodeId) { MinDistance = 0 };
frontier.Push(new FrontierNode { Node = explored[startNodeId] });
FrontierNode frontierNode;
PathNode currentNode;
List<int> currentPath;
int currentDistance;
while (frontier.Count != 0)
{
frontierNode = frontier.Pop();
currentNode = frontierNode.Node;
currentPath = frontierNode.Path;
currentPath.Add(currentNode.Id);
currentDistance = frontierNode.Distance;
// We can't traverse the graph further
if (currentDistance == settings.MaxDistance - 1)
{
// Target will be only found if it's the direct neighbour of current
if (connectionManager.AreNeighbours(currentNode.Id, targetNodeId))
{
if (!explored.ContainsKey(targetNodeId))
{
explored[targetNodeId] = new PathNode(targetNodeId);
}
if (explored[targetNodeId].MinDistance > currentDistance + 1)
{
explored[targetNodeId].MinDistance = currentDistance + 1;
}
currentNode.Neighbours.Add(explored[targetNodeId]);
currentPath.Add(targetNodeId);
succeededPaths.Add(currentPath);
}
}
// We can traverse the graph further
else
{
// If we haven't already fetched current's neighbours, fetch them
if (currentNode.Neighbours.Count == 0)
{
var neighbourIds = connectionManager.GetNeighbourIds(currentNode.Id);
currentNode.Neighbours = new List<PathNode>(neighbourIds.Count());
foreach (var neighbourId in neighbourIds)
{
currentNode.Neighbours.Add(new PathNode(neighbourId));
}
}
foreach (var neighbour in currentNode.Neighbours)
{
// Target is a neighbour
if (neighbour.Id == targetNodeId)
{
var succeededPath = new List<int>(currentPath) { targetNodeId }; // Since we will use currentPath in further iterations too
succeededPaths.Add(succeededPath);
}
// We can traverse further, push the neighbour onto the stack
else if (neighbour.Id != startNodeId)
{
neighbour.MinDistance = currentDistance + 1;
if (!explored.ContainsKey(neighbour.Id) || neighbour.MinDistance >= currentDistance + 1)
{
frontier.Push(new FrontierNode { Distance = currentDistance + 1, Path = new List<int>(currentPath), Node = neighbour });
}
}
if (neighbour.Id != startNodeId)
{
// If this is the shortest path to the node, overwrite its minDepth
if (neighbour.MinDistance > currentDistance + 1)
{
neighbour.MinDistance = currentDistance + 1;
}
explored[neighbour.Id] = neighbour;
}
}
}
}
return succeededPaths;
});
return new Associativy.Services.PathFinderAuxiliaries.PathResult
{
SucceededPaths = paths,
SucceededGraph = PathToGraph(paths, "PathToGraph:" + node1Id + "/" + node2Id, settings)
};
}
public virtual IQueryableGraph<int> GetPartialGraph(int centralNodeId, IPathFinderSettings settings)
{
if (settings == null) settings = PathFinderSettings.Default;
return _pathFinderAuxiliaries.QueryableFactory.Create<int>((parameters) =>
{
var graph = _pathFinderAuxiliaries.CacheService.GetMonitored(_graphDescriptor, MakeCacheKey("GetPartialGraph.BaseGraph." + centralNodeId, settings), () =>
{
var connectionManager = _graphDescriptor.Services.ConnectionManager;
var g = _pathFinderAuxiliaries.GraphEditor.GraphFactory<int>();
var visited = new Dictionary<int, PathNode>();
var frontier = new Stack<PathNode>();
frontier.Push(new PathNode(centralNodeId) { MinDistance = 0 });
while (frontier.Count != 0)
{
var current = frontier.Pop();
if (current.MinDistance == settings.MaxDistance) continue;
if (!visited.ContainsKey(current.Id))
{
visited[current.Id] = current;
foreach (var neighbourId in connectionManager.GetNeighbourIds(current.Id))
{
var neighbour = visited.ContainsKey(neighbourId) ? visited[neighbourId] : new PathNode(neighbourId);
current.Neighbours.Add(neighbour);
g.AddVerticesAndEdge(new UndirectedEdge<int>(current.Id, neighbourId));
}
}
var neighbourMinDistance = current.MinDistance + 1;
foreach (var neighbour in current.Neighbours)
{
if (neighbourMinDistance < neighbour.MinDistance)
{
neighbour.MinDistance = neighbourMinDistance;
frontier.Push(neighbour);
}
}
}
return g;
});
return LastStepsWithPaging(parameters, graph, "GetPartialGraph." + centralNodeId + ".PathToGraph.", settings);
});
}
