/// <summary>
/// Contracts the given vertex.
/// </summary>
/// <param name="vertex"></param>
public void Contract(uint vertex)
{
if (this.IsContracted(vertex))
{
throw new Exception("Is already contracted!");
}
// get all information from the source.
var edges = _target.GetEdges(vertex).ToList();
// report the before contraction event.
this.OnBeforeContraction(vertex, edges);
// build the list of edges to replace.
var allNeigbours = new List <Edge <CHEdgeData> >(edges.Count);
var tos = new List <uint>(edges.Count);
var tosSet = new HashSet <uint>();
foreach (var edge in edges)
{
// use this edge for contraction.
allNeigbours.Add(edge);
tos.Add(edge.Neighbour);
tosSet.Add(edge.Neighbour);
// remove the edge in downwards direction and on the edge with the same data.
_target.RemoveEdge(edge.Neighbour, vertex);
}
//// build the list of pairs and make sure duplicates don't count.
//var allNeighbourPairs = new Dictionary<Tuple<uint, uint>, Tuple<float, float>>();
//for(int x = 1; x < allNeigbours.Count; x++)
//{
// var xEdge = allNeigbours[x];
// var xEdgeForwardWeight = xEdge.EdgeData.CanMoveBackward ? xEdge.EdgeData.Weight : float.MaxValue;
// var xEdgeBackwardWeight = xEdge.EdgeData.CanMoveForward ? xEdge.EdgeData.Weight : float.MaxValue;
// for(int y = 0; y < x; y++)
// {
// var yEdge = allNeigbours[x];
// //var yEdgeForwardWeight = yEdge.EdgeData.CanMoveBackward ? yEdge.EdgeData.Weight : float.MaxValue;
// //var yEdgeBackwardWeight = yEdge.EdgeData.CanMoveForward ? yEdge.EdgeData.Weight : float.MaxValue;
// float forwardWeight = float.MaxValue;
// float backwardWeight = float.MaxValue;
// if(xEdge.Neighbour < yEdge.Neighbour)
// {
// if (xEdge.EdgeData.CanMoveBackward && yEdge.EdgeData.CanMoveForward)
// {
// forwardWeight = xEdgeBackwardWeight + yEdge.EdgeData.Weight;
// }
// if (xEdge.EdgeData.CanMoveForward && yEdge.EdgeData.CanMoveBackward)
// {
// backwardWeight = xEdgeForwardWeight + yEdge.EdgeData.Weight;
// }
// }
// else if(xEdge.Neighbour > yEdge.Neighbour)
// {
// if (xEdge.EdgeData.CanMoveBackward && yEdge.EdgeData.CanMoveForward)
// {
// backwardWeight = xEdgeBackwardWeight + yEdge.EdgeData.Weight;
// }
// if (xEdge.EdgeData.CanMoveForward && yEdge.EdgeData.CanMoveBackward)
// {
// forwardWeight = xEdgeForwardWeight + yEdge.EdgeData.Weight;
// }
// }
// Tuple<float, float> existingWeights;
// Tuple<uint, uint> neighbourPair = new Tuple<uint,uint>(xEdge.Neighbour, yEdge.Neighbour);
// if(!allNeighbourPairs.TryGetValue(neighbourPair, out existingWeights))
// {
// if (existingWeights.Item1 < forwardWeight)
// {
// forwardWeight = existingWeights.Item1;
// }
// if (existingWeights.Item2 < backwardWeight)
// {
// backwardWeight = existingWeights.Item2;
// }
// }
// allNeighbourPairs[neighbourPair] = new Tuple<float, float>(forwardWeight, backwardWeight);
// }
//}
var toRequeue = new HashSet <uint>();
var forwardEdges = new CHEdgeData?[2];
var backwardEdges = new CHEdgeData?[2];
var existingEdgesToRemove = new HashSet <CHEdgeData>();
// loop over each combination of edges just once.
var forwardWitnesses = new bool[allNeigbours.Count];
var backwardWitnesses = new bool[allNeigbours.Count];
var weights = new List <float>(allNeigbours.Count);
var edgesToY = new Dictionary <uint, Tuple <CHEdgeData?, CHEdgeData?, CHEdgeData?, float, float> >(allNeigbours.Count);
for (int x = 1; x < allNeigbours.Count; x++)
{ // loop over all elements first.
var xEdge = allNeigbours[x];
// get edges.
edgesToY.Clear();
var rawEdgesToY = _target.GetEdges(xEdge.Neighbour);
while (rawEdgesToY.MoveNext())
{
var rawEdgeNeighbour = rawEdgesToY.Neighbour;
if (tosSet.Contains(rawEdgeNeighbour))
{
var rawEdgeData = rawEdgesToY.EdgeData;
var rawEdgeForwardWeight = rawEdgeData.CanMoveForward ? rawEdgeData.Weight : float.MaxValue;
var rawEdgeBackwardWeight = rawEdgeData.CanMoveBackward ? rawEdgeData.Weight : float.MaxValue;
Tuple <CHEdgeData?, CHEdgeData?, CHEdgeData?, float, float> edgeTuple;
if (!edgesToY.TryGetValue(rawEdgeNeighbour, out edgeTuple))
{
edgeTuple = new Tuple <CHEdgeData?, CHEdgeData?, CHEdgeData?, float, float>(rawEdgeData, null, null,
rawEdgeForwardWeight, rawEdgeBackwardWeight);
edgesToY.Add(rawEdgeNeighbour, edgeTuple);
}
else if (!edgeTuple.Item2.HasValue)
{
edgesToY[rawEdgeNeighbour] = new Tuple <CHEdgeData?, CHEdgeData?, CHEdgeData?, float, float>(
edgeTuple.Item1, rawEdgeData, null,
rawEdgeForwardWeight < edgeTuple.Item4 ? rawEdgeForwardWeight : edgeTuple.Item4,
rawEdgeBackwardWeight < edgeTuple.Item5 ? rawEdgeBackwardWeight : edgeTuple.Item5);
}
else
{
edgesToY[rawEdgeNeighbour] = new Tuple <CHEdgeData?, CHEdgeData?, CHEdgeData?, float, float>(
edgeTuple.Item1, edgeTuple.Item2, rawEdgeData,
rawEdgeForwardWeight < edgeTuple.Item4 ? rawEdgeForwardWeight : edgeTuple.Item4,
rawEdgeBackwardWeight < edgeTuple.Item5 ? rawEdgeBackwardWeight : edgeTuple.Item5);
}
}
}
// calculate max weight.
weights.Clear();
var forwardUnknown = false;
var backwardUnknown = false;
for (int y = 0; y < x; y++)
{
// update maxWeight.
var yEdge = allNeigbours[y];
if (xEdge.Neighbour != yEdge.Neighbour)
{
// reset witnesses.
var forwardWeight = (float)xEdge.EdgeData.Weight + (float)yEdge.EdgeData.Weight;
forwardWitnesses[y] = !xEdge.EdgeData.CanMoveBackward || !yEdge.EdgeData.CanMoveForward;
backwardWitnesses[y] = !xEdge.EdgeData.CanMoveForward || !yEdge.EdgeData.CanMoveBackward;
weights.Add(forwardWeight);
Tuple <CHEdgeData?, CHEdgeData?, CHEdgeData?, float, float> edgeTuple;
if (edgesToY.TryGetValue(yEdge.Neighbour, out edgeTuple))
{
if (!forwardWitnesses[y])
{ // check 1-hop witnesses.
if (edgeTuple.Item4 <= forwardWeight)
{
forwardWitnesses[y] = true;
}
}
if (!backwardWitnesses[y])
{ // check 1-hop witnesses.
if (edgeTuple.Item5 <= forwardWeight)
{
backwardWitnesses[y] = true;
}
}
}
forwardUnknown = !forwardWitnesses[y] || forwardUnknown;
backwardUnknown = !backwardWitnesses[y] || backwardUnknown;
}
else
{ // already set this to true, not use calculating it's witness.
forwardWitnesses[y] = true;
backwardWitnesses[y] = true;
weights.Add(0);
}
}
// calculate witnesses.
if (forwardUnknown || backwardUnknown)
{
_contractionWitnessCalculator.Exists(_target, xEdge.Neighbour, tos, weights, int.MaxValue,
ref forwardWitnesses, ref backwardWitnesses);
}
for (int y = 0; y < x; y++)
{ // loop over all elements.
var yEdge = allNeigbours[y];
// add the combinations of these edges.
if (xEdge.Neighbour != yEdge.Neighbour)
{ // there is a connection from x to y and there is no witness path.
// create x-to-y data and edge.
var canMoveForward = !forwardWitnesses[y] && (xEdge.EdgeData.CanMoveBackward && yEdge.EdgeData.CanMoveForward);
var canMoveBackward = !backwardWitnesses[y] && (xEdge.EdgeData.CanMoveForward && yEdge.EdgeData.CanMoveBackward);
if (canMoveForward || canMoveBackward)
{ // add the edge if there is usefull info or if there needs to be a neighbour relationship.
// calculate the total weights.
var weight = (float)xEdge.EdgeData.Weight + (float)yEdge.EdgeData.Weight;
// there are a few options now:
// 1) No edges yet between xEdge.Neighbour and yEdge.Neighbour.
// 1) There is no other contracted edge: just add as a duplicate.
// 2) There is at least on other contracted edge: optimize information because there can only be 4 case between two vertices:
// - One bidirectional edge.
// - Two directed edges with different weights.
// - One forward edge.
// - One backward edge.
// => all available information needs to be combined.
// check existing data.
var existingForwardWeight = float.MaxValue;
var existingBackwardWeight = float.MaxValue;
uint existingForwardContracted = 0;
uint existingBackwardContracted = 0;
var existingCanMoveForward = false;
var existingCanMoveBackward = false;
var existingEdges = _target.GetEdges(xEdge.Neighbour, yEdge.Neighbour);
existingEdgesToRemove.Clear();
while (existingEdges.MoveNext())
{
var existingEdgeData = existingEdges.EdgeData;
if (existingEdgeData.IsContracted)
{ // this edge is contracted, collect it's information.
existingEdgesToRemove.Add(existingEdgeData);
if (existingEdgeData.CanMoveForward)
{ // can move forward, so at least one edge that can move forward.
existingCanMoveForward = true;
if (existingForwardWeight > existingEdgeData.Weight)
{ // update forward weight.
existingForwardWeight = existingEdgeData.Weight;
existingForwardContracted = existingEdgeData.ContractedId;
}
}
if (existingEdgeData.CanMoveBackward)
{ // can move backward, so at least one edge that can move backward.
existingCanMoveBackward = true;
if (existingBackwardWeight > existingEdgeData.Weight)
{ // update backward weight.
existingBackwardWeight = existingEdgeData.Weight;
existingBackwardContracted = existingEdgeData.ContractedId;
}
}
}
}
if (existingCanMoveForward || existingCanMoveBackward)
{ // there is already another contraced edge.
uint forwardContractedId = vertex;
float forwardWeight = weight;
// merge with existing data.
if (existingCanMoveForward &&
((weight > existingForwardWeight) || !canMoveForward))
{ // choose the smallest weight.
canMoveForward = true;
forwardContractedId = existingForwardContracted;
forwardWeight = existingForwardWeight;
}
uint backwardContractedId = vertex;
float backwardWeight = weight;
// merge with existing data.
if (existingCanMoveBackward &&
((weight > existingBackwardWeight) || !canMoveBackward))
{ // choose the smallest weight.
canMoveBackward = true;
backwardContractedId = existingBackwardContracted;
backwardWeight = existingBackwardWeight;
}
// add one of the 4 above case.
forwardEdges[0] = null;
forwardEdges[1] = null;
backwardEdges[0] = null;
backwardEdges[1] = null;
if (canMoveForward && canMoveBackward && forwardWeight == backwardWeight && forwardContractedId == backwardContractedId)
{ // just add one edge.
forwardEdges[0] = new CHEdgeData(forwardContractedId, true, true, forwardWeight);
//_target.AddEdge(xEdge.Neighbour, yEdge.Neighbour, new CHEdgeData(forwardContractedId, true, true, forwardWeight));
backwardEdges[0] = new CHEdgeData(backwardContractedId, true, true, backwardWeight);
//_target.AddEdge(yEdge.Neighbour, xEdge.Neighbour, new CHEdgeData(backwardContractedId, true, true, backwardWeight));
}
else if (canMoveBackward && canMoveForward)
{ // add two different edges.
forwardEdges[0] = new CHEdgeData(forwardContractedId, true, false, forwardWeight);
//_target.AddEdge(xEdge.Neighbour, yEdge.Neighbour, new CHEdgeData(forwardContractedId, true, false, forwardWeight));
backwardEdges[0] = new CHEdgeData(forwardContractedId, false, true, forwardWeight);
//_target.AddEdge(yEdge.Neighbour, xEdge.Neighbour, new CHEdgeData(forwardContractedId, false, true, forwardWeight));
forwardEdges[1] = new CHEdgeData(backwardContractedId, false, true, backwardWeight);
//_target.AddEdge(xEdge.Neighbour, yEdge.Neighbour, new CHEdgeData(backwardContractedId, false, true, backwardWeight));
backwardEdges[1] = new CHEdgeData(backwardContractedId, true, false, backwardWeight);
//_target.AddEdge(yEdge.Neighbour, xEdge.Neighbour, new CHEdgeData(backwardContractedId, true, false, backwardWeight));
}
else if (canMoveForward)
{ // only add one forward edge.
forwardEdges[0] = new CHEdgeData(forwardContractedId, true, false, forwardWeight);
//_target.AddEdge(xEdge.Neighbour, yEdge.Neighbour, new CHEdgeData(forwardContractedId, true, false, forwardWeight));
backwardEdges[0] = new CHEdgeData(forwardContractedId, false, true, forwardWeight);
//_target.AddEdge(yEdge.Neighbour, xEdge.Neighbour, new CHEdgeData(forwardContractedId, false, true, forwardWeight));
}
else if (canMoveBackward)
{ // only add one backward edge.
forwardEdges[0] = new CHEdgeData(backwardContractedId, false, true, backwardWeight);
//_target.AddEdge(xEdge.Neighbour, yEdge.Neighbour, new CHEdgeData(backwardContractedId, false, true, backwardWeight));
backwardEdges[0] = new CHEdgeData(backwardContractedId, true, false, backwardWeight);
//_target.AddEdge(yEdge.Neighbour, xEdge.Neighbour, new CHEdgeData(backwardContractedId, true, false, backwardWeight));
}
// remove all existing stuff.
foreach (var existingEdgeToRemove in existingEdgesToRemove)
{
if (forwardEdges[0].Equals(existingEdgeToRemove))
{ // this forward edge is to be kept.
forwardEdges[0] = null; // it's already there.
}
else if (forwardEdges[1] != null &&
!forwardEdges[1].Equals(existingEdgeToRemove))
{ // this forward edge is to be kept.
forwardEdges[1] = null; // it's already there.
}
else
{ // yup, just remove it now.
_target.RemoveEdge(xEdge.Neighbour, yEdge.Neighbour, existingEdgeToRemove);
}
var existingEdgeToRemoveBackward = (CHEdgeData)existingEdgeToRemove.Reverse();
if (backwardEdges[0].Equals(existingEdgeToRemoveBackward))
{ // this backward edge is to be kept.
backwardEdges[0] = null; // it's already there.
}
else if (backwardEdges[1] != null &&
!backwardEdges[1].Equals(existingEdgeToRemoveBackward))
{ // this backward edge is to be kept.
backwardEdges[1] = null; // it's already there.
}
else
{ // yup, just remove it now.
_target.RemoveEdge(yEdge.Neighbour, xEdge.Neighbour, existingEdgeToRemoveBackward);
}
}
// add remaining edges.
if (forwardEdges[0].HasValue)
{
_target.AddEdge(xEdge.Neighbour, yEdge.Neighbour, forwardEdges[0].Value);
}
if (forwardEdges[1].HasValue)
{
_target.AddEdge(xEdge.Neighbour, yEdge.Neighbour, forwardEdges[1].Value);
}
if (backwardEdges[0].HasValue)
{
_target.AddEdge(yEdge.Neighbour, xEdge.Neighbour, backwardEdges[0].Value);
}
if (backwardEdges[1].HasValue)
{
_target.AddEdge(yEdge.Neighbour, xEdge.Neighbour, backwardEdges[1].Value);
}
toRequeue.Add(xEdge.Neighbour);
toRequeue.Add(yEdge.Neighbour);
}
else
{ // there is no edge, just add the data.
// add contracted edges like normal.
_target.AddEdge(xEdge.Neighbour, yEdge.Neighbour, new CHEdgeData(vertex, canMoveForward, canMoveBackward, weight));
_target.AddEdge(yEdge.Neighbour, xEdge.Neighbour, new CHEdgeData(vertex, canMoveBackward, canMoveForward, weight));
toRequeue.Add(xEdge.Neighbour);
toRequeue.Add(yEdge.Neighbour);
}
}
}
}
}
// mark the vertex as contracted.
this.MarkContracted(vertex);
// notify a contracted neighbour.
_calculator.NotifyContracted(vertex);
// report the after contraction event.
this.OnAfterContraction(vertex, allNeigbours);
//// update priority of direct neighbours.
//foreach (var neighbour in toRequeue)
//{
// this.ReQueue(neighbour);
//}
}
/// <summary>
/// Contracts the given vertex.
/// </summary>
/// <param name="vertex"></param>
public void Contract(uint vertex)
{
if (_contracted.Length > vertex && _contracted[vertex])
{
throw new Exception("Is already contracted!");
}
// keep the neighbours.
HashSet <KeyValuePair <uint, CHEdgeData> > neighbours =
new HashSet <KeyValuePair <uint, CHEdgeData> >();
// get all information from the source.
KeyValuePair <uint, CHEdgeData>[] edges = _target.GetArcs(vertex);
// remove all informative edges.
edges = edges.RemoveInformativeEdges();
// report the before contraction event.
this.OnBeforeContraction(vertex, edges);
// remove the edges from the neighbours to the target.
foreach (KeyValuePair <uint, CHEdgeData> edge in edges)
{ // remove the edge.
_target.DeleteArc(edge.Key, vertex);
// keep the neighbour.
if (_keepDirectNeighbours && !edge.Value.HasContractedVertex)
{ // edge does represent a neighbour relation.
neighbours.Add(
new KeyValuePair <uint, CHEdgeData>(edge.Key, edge.Value.ConvertToInformative()));
}
}
// loop over each combination of edges just once.
for (int x = 1; x < edges.Length; x++)
{ // loop over all elements first.
KeyValuePair <uint, CHEdgeData> xEdge = edges[x];
if (xEdge.Value.IsInformative)
{
continue;
}
for (int y = 0; y < x; y++)
{ // loop over all elements.
KeyValuePair <uint, CHEdgeData> yEdge = edges[y];
if (yEdge.Value.IsInformative)
{
continue;
}
// calculate the total weight.
float weight = xEdge.Value.Weight + yEdge.Value.Weight;
// add the combinations of these edges.
if (((xEdge.Value.Backward && yEdge.Value.Forward) ||
(yEdge.Value.Backward && xEdge.Value.Forward)) &&
(xEdge.Key != yEdge.Key))
{ // there is a connection from x to y and there is no witness path.
bool witnessXToY = _witnessCalculator.Exists(_target, xEdge.Key,
yEdge.Key, vertex, weight, 100);
bool witnessYToX = _witnessCalculator.Exists(_target, yEdge.Key,
xEdge.Key, vertex, weight, 100);
// create x-to-y data and edge.
CHEdgeData dataXToY = new CHEdgeData();
bool forward = (xEdge.Value.Backward && yEdge.Value.Forward) &&
!witnessXToY;
bool backward = (yEdge.Value.Backward && xEdge.Value.Forward) &&
!witnessYToX;
dataXToY.SetDirection(forward, backward, true);
dataXToY.Weight = weight;
dataXToY.ContractedVertexId = vertex;
if ((dataXToY.Forward || dataXToY.Backward) ||
!_target.HasArc(xEdge.Key, yEdge.Key))
{ // add the edge if there is usefull info or if there needs to be a neighbour relationship.
_target.AddArc(xEdge.Key, yEdge.Key, dataXToY, _comparer);
}
// create y-to-x data and edge.
CHEdgeData dataYToX = new CHEdgeData();
forward = (yEdge.Value.Backward && xEdge.Value.Forward) &&
!witnessYToX;
backward = (xEdge.Value.Backward && yEdge.Value.Forward) &&
!witnessXToY;
dataYToX.SetDirection(forward, backward, true);
dataYToX.Weight = weight;
dataYToX.ContractedVertexId = vertex;
if ((dataYToX.Forward || dataYToX.Backward) ||
!_target.HasArc(yEdge.Key, xEdge.Key))
{ // add the edge if there is usefull info or if there needs to be a neighbour relationship.
_target.AddArc(yEdge.Key, xEdge.Key, dataYToX, _comparer);
}
}
}
}
// mark the vertex as contracted.
this.MarkContracted(vertex);
// notify a contracted neighbour.
_calculator.NotifyContracted(vertex);
// add contracted neighbour edges again.
if (_keepDirectNeighbours)
{
foreach (KeyValuePair <uint, CHEdgeData> neighbour in neighbours)
{
_target.AddArc(neighbour.Key, vertex, neighbour.Value, null);
}
}
// report the after contraction event.
this.OnAfterContraction(vertex, edges);
}
/// <summary>
/// Contracts the given vertex.
/// </summary>
/// <param name="vertex"></param>
public void Contract(uint vertex)
{
if (_contracted.Length > vertex && _contracted[vertex])
{
throw new Exception("Is already contracted!");
}
// keep the neighbours.
var neighbours = new HashSet <KeyValuePair <uint, CHEdgeData> >();
// get all information from the source.
var edges = _target.GetEdges(vertex);
// report the before contraction event.
this.OnBeforeContraction(vertex, edges);
// replace the adjacent edges with edges that are point up.
var edgesForContractions = new List <KeyValuePair <uint, CHEdgeData> >(edges.Length);
foreach (var edge in edges)
{
if (!edge.Value.ToLower && !edge.Value.ToHigher)
{ // the edge is not to lower or higher.
// use this edge for contraction.
edgesForContractions.Add(edge);
// overwrite the old edge making it point 'to higher' only.
_target.AddEdge(vertex, edge.Key,
new CHEdgeData(edge.Value.Weight, edge.Value.Forward, edge.Value.Backward, true, edge.Value.ContractedVertexId, edge.Value.Tags), null);
}
}
// loop over each combination of edges just once.
for (int x = 1; x < edgesForContractions.Count; x++)
{ // loop over all elements first.
var xEdge = edgesForContractions[x];
for (int y = 0; y < x; y++)
{ // loop over all elements.
var yEdge = edgesForContractions[y];
// calculate the total weight.
var weight = xEdge.Value.Weight + yEdge.Value.Weight;
// add the combinations of these edges.
if (((xEdge.Value.Backward && yEdge.Value.Forward) ||
(yEdge.Value.Backward && xEdge.Value.Forward)) &&
(xEdge.Key != yEdge.Key))
{ // there is a connection from x to y and there is no witness path.
var witnessXToY = _contractionWitnessCalculator.Exists(_target, xEdge.Key,
yEdge.Key, vertex, weight, int.MaxValue);
var witnessYToX = _contractionWitnessCalculator.Exists(_target, yEdge.Key,
xEdge.Key, vertex, weight, int.MaxValue);
// create x-to-y data and edge.
var dataXToY = new CHEdgeData();
var forward = (xEdge.Value.Backward && yEdge.Value.Forward) &&
!witnessXToY;
var backward = (yEdge.Value.Backward && xEdge.Value.Forward) &&
!witnessYToX;
if ((forward || backward) ||
!_target.ContainsEdge(xEdge.Key, yEdge.Key))
{ // add the edge if there is usefull info or if there needs to be a neighbour relationship.
dataXToY.SetDirection(forward, backward);
dataXToY.Weight = weight;
dataXToY.ContractedVertexId = vertex;
_target.AddEdge(xEdge.Key, yEdge.Key, dataXToY, null, _comparer);
}
}
}
}
// mark the vertex as contracted.
this.MarkContracted(vertex);
// notify a contracted neighbour.
_calculator.NotifyContracted(vertex);
// report the after contraction event.
this.OnAfterContraction(vertex, edges);
}
