/// <summary>
/// Clears the votings for a given node representative, but leaves the index references.
/// </summary>
/// <param name="nodeVoting"></param>
void ClearVoting(NodeVoting nodeVoting)
{
foreach (VoteBlock block in nodeVoting.VotingBlocks)
{
block.Votings.Clear();
}
}
/// <summary>
/// Local optimization for a given node, as described in Graph Drawing by Stress Majorization by Gansner et. al. (Sect. 2.3).
/// </summary>
/// <param name="nodeVoting"></param>
/// <returns></returns>
Point LocalizedOptimization(NodeVoting nodeVoting)
{
Point currentPosition = Positions[nodeVoting.VotedNodeIndex];
double nextX = 0;
double nextY = 0;
double sumWeights = 0;
// if there is not voting vlock, the position of this node will not change
if (nodeVoting.VotingBlocks == null || nodeVoting.VotingBlocks.Count == 0)
{
return(currentPosition);
}
foreach (VoteBlock votingBlock in nodeVoting.VotingBlocks)
{
double blockWeight = votingBlock.BlockWeight;
foreach (Vote vote in votingBlock.Votings)
{
Point voterPos = Positions[vote.VoterIndex];
double votingDistance = vote.Distance;
double diffX = currentPosition.X - voterPos.X;
double diffY = currentPosition.Y - voterPos.Y;
double euclidDistance = Math.Sqrt(diffX * diffX + diffY * diffY);
double weight = blockWeight * vote.Weight;
double voteX = voterPos.X + votingDistance * diffX / euclidDistance;
nextX += voteX * weight;
double voteY = voterPos.Y + votingDistance * diffY / euclidDistance;
nextY += voteY * weight;
sumWeights += weight;
}
}
if (sumWeights == 0)
{
// there was no single voting, just return the current position
return(currentPosition);
}
return(new Point(nextX / sumWeights, nextY / sumWeights));
}
/// <summary>
/// Iterates only once.
/// </summary>
/// <returns></returns>
public List <Point> IterateSingleLocalizedMethod()
{
List <Point> newPositions;
if (Settings.UpdateMethod == UpdateMethod.Serial)
{
newPositions = Positions;
}
else
{
newPositions = new List <Point>(Positions.Count);
}
// For each node compute the new position by averaging over all votes.
for (int i = 0; i < NodeVotings.Count; i++)
{
NodeVoting nodeVoting = NodeVotings[i];
int votedIndex = nodeVoting.VotedNodeIndex;
Point newPos = LocalizedOptimization(nodeVoting);
if (Settings.UpdateMethod == UpdateMethod.Serial)
{
newPositions[votedIndex] = newPos;
}
else
{
newPositions.Add(newPos);
}
}
if (Settings.UpdateMethod == UpdateMethod.Parallel)
{
for (int i = 0; i < NodeVotings.Count; i++)
{
NodeVoting nodeVoting = NodeVotings[i];
int index = nodeVoting.VotedNodeIndex;
Positions[index] = newPositions[i];
}
}
return(newPositions);
}
/// <summary>
/// Clears the votings for a given node representative, but leaves the index references.
/// </summary>
/// <param name="nodeVoting"></param>
void ClearVoting(NodeVoting nodeVoting) {
foreach (VoteBlock block in nodeVoting.VotingBlocks) {
block.Votings.Clear();
}
}
/// <summary>
/// Local optimization for a given node, as described in Graph Drawing by Stress Majorization by Gansner et. al. (Sect. 2.3).
/// </summary>
/// <param name="nodeVoting"></param>
/// <returns></returns>
Point LocalizedOptimization(NodeVoting nodeVoting) {
Point currentPosition = Positions[nodeVoting.VotedNodeIndex];
double nextX = 0;
double nextY = 0;
double sumWeights = 0;
// if there is not voting vlock, the position of this node will not change
if (nodeVoting.VotingBlocks == null || nodeVoting.VotingBlocks.Count == 0) {
return currentPosition;
}
foreach (VoteBlock votingBlock in nodeVoting.VotingBlocks) {
double blockWeight = votingBlock.BlockWeight;
foreach (Vote vote in votingBlock.Votings) {
Point voterPos = Positions[vote.VoterIndex];
double votingDistance = vote.Distance;
double diffX = currentPosition.X - voterPos.X;
double diffY = currentPosition.Y - voterPos.Y;
double euclidDistance = Math.Sqrt(diffX*diffX + diffY*diffY);
double weight = blockWeight*vote.Weight;
double voteX = voterPos.X + votingDistance*diffX/euclidDistance;
nextX += voteX*weight;
double voteY = voterPos.Y + votingDistance*diffY/euclidDistance;
nextY += voteY*weight;
sumWeights += weight;
}
}
if (sumWeights == 0) {
// there was no single voting, just return the current position
return currentPosition;
}
return new Point(nextX/sumWeights, nextY/sumWeights);
}
/// <summary>
/// Example on how to use Stress Majorization with a small graph and Localized method.
/// </summary>
public static void RunStressMajorizationExample()
{
//create a star graph where three nodes are connected to the center
GeometryGraph graph = new GeometryGraph();
graph.Nodes.Add(new Node());
graph.Nodes.Add(new Node());
graph.Nodes.Add(new Node());
graph.Nodes.Add(new Node());
//set initial positions, e.g., random
graph.Nodes[0].BoundaryCurve = CurveFactory.CreateRectangle(20, 10, new Point(5, 5));
graph.Nodes[1].BoundaryCurve = CurveFactory.CreateRectangle(20, 10, new Point(7, 10));
graph.Nodes[2].BoundaryCurve = CurveFactory.CreateRectangle(20, 10, new Point(7, 2));
graph.Nodes[3].BoundaryCurve = CurveFactory.CreateRectangle(20, 10, new Point(35, 1));
graph.Edges.Add(new Edge(graph.Nodes[0], graph.Nodes[1]));
graph.Edges.Add(new Edge(graph.Nodes[0], graph.Nodes[2]));
graph.Edges.Add(new Edge(graph.Nodes[0], graph.Nodes[3]));
//array with desired distances between the nodes for every edge
double[] idealEdgeLength = new double[graph.Edges.Count];
for (int i = 0; i < graph.Edges.Count; i++)
{
idealEdgeLength[i] = 100; //all edges should have this euclidean length
}
//create stress majorization class and set the desired distances on the edges
StressMajorization majorizer = new StressMajorization();
majorizer.Positions = new List <Point>(graph.Nodes.Select(v => v.Center));
majorizer.NodeVotings = new List <NodeVoting>(graph.Nodes.Count);
// initialize for every node an empty block
for (int i = 0; i < graph.Nodes.Count; i++)
{
var nodeVote = new NodeVoting(i); //by default there is already a block with weighting 1
//optional: add second block with different type of edges, e.g., with stronger weight
//var secondBlock = new VoteBlock(new List<Vote>(), 100);
//nodeVote.VotingBlocks.Add(secondBlock);
//var block2=nodeVote.VotingBlocks[1]; //block could be accessed like this in a later stage
majorizer.NodeVotings.Add(nodeVote);
}
// for every edge set the desired distances by setting votings among the two end nodes.
Dictionary <Node, int> posDict = new Dictionary <Node, int>();
for (int i = 0; i < graph.Nodes.Count; i++)
{
posDict[graph.Nodes[i]] = i;
}
var edges = graph.Edges.ToArray();
for (int i = 0; i < graph.Edges.Count; i++)
{
var edge = edges[i];
int nodeId1 = posDict[edge.Source];
int nodeId2 = posDict[edge.Target];
double idealDistance = idealEdgeLength[i];
double weight = 1 / (idealDistance * idealDistance);
var voteFromNode1 = new Vote(nodeId1, idealDistance, weight); // vote from node1 for node2
var voteFromNode2 = new Vote(nodeId2, idealDistance, weight); // vote from node2 for node1
// add vote of node1 to list of node2 (in first voting block)
majorizer.NodeVotings[nodeId2].VotingBlocks[0].Votings.Add(voteFromNode1);
// add vote of node2 to list of node1 (in first voting block)
majorizer.NodeVotings[nodeId1].VotingBlocks[0].Votings.Add(voteFromNode2);
}
//used localized method to reduce stress
majorizer.Settings = new StressMajorizationSettings();
majorizer.Settings.SolvingMethod = SolvingMethod.Localized;
List <Point> result = majorizer.IterateAll();
for (int i = 0; i < result.Count; i++)
{
graph.Nodes[i].Center = result[i];
}
#if DEBUG && !SHARPKIT
LayoutAlgorithmSettings.ShowGraph(graph);
#endif
}
/// <summary>
/// Example on how to use Stress Majorization with a small graph and Localized method.
/// </summary>
public static void RunStressMajorizationExample() {
//create a star graph where three nodes are connected to the center
GeometryGraph graph = new GeometryGraph();
graph.Nodes.Add(new Node());
graph.Nodes.Add(new Node());
graph.Nodes.Add(new Node());
graph.Nodes.Add(new Node());
//set initial positions, e.g., random
graph.Nodes[0].BoundaryCurve = CurveFactory.CreateRectangle(20, 10, new Point(5, 5));
graph.Nodes[1].BoundaryCurve = CurveFactory.CreateRectangle(20, 10, new Point(7, 10));
graph.Nodes[2].BoundaryCurve = CurveFactory.CreateRectangle(20, 10, new Point(7, 2));
graph.Nodes[3].BoundaryCurve = CurveFactory.CreateRectangle(20, 10, new Point(35, 1));
graph.Edges.Add(new Edge(graph.Nodes[0], graph.Nodes[1]));
graph.Edges.Add(new Edge(graph.Nodes[0], graph.Nodes[2]));
graph.Edges.Add(new Edge(graph.Nodes[0], graph.Nodes[3]));
//array with desired distances between the nodes for every edge
double[] idealEdgeLength=new double[graph.Edges.Count];
for (int i = 0; i < graph.Edges.Count; i++) {
idealEdgeLength[i] = 100; //all edges should have this euclidean length
}
//create stress majorization class and set the desired distances on the edges
StressMajorization majorizer = new StressMajorization();
majorizer.Positions = new List<Point>(graph.Nodes.Select(v=>v.Center));
majorizer.NodeVotings = new List<NodeVoting>(graph.Nodes.Count);
// initialize for every node an empty block
for (int i = 0; i < graph.Nodes.Count; i++) {
var nodeVote = new NodeVoting(i); //by default there is already a block with weighting 1
//optional: add second block with different type of edges, e.g., with stronger weight
//var secondBlock = new VoteBlock(new List<Vote>(), 100);
//nodeVote.VotingBlocks.Add(secondBlock);
//var block2=nodeVote.VotingBlocks[1]; //block could be accessed like this in a later stage
majorizer.NodeVotings.Add(nodeVote);
}
// for every edge set the desired distances by setting votings among the two end nodes.
Dictionary<Node,int> posDict=new Dictionary<Node, int>();
for (int i = 0; i < graph.Nodes.Count; i++) {
posDict[graph.Nodes[i]] = i;
}
var edges = graph.Edges.ToArray();
for (int i=0; i<graph.Edges.Count;i++) {
var edge = edges[i];
int nodeId1 = posDict[edge.Source];
int nodeId2 = posDict[edge.Target];
double idealDistance = idealEdgeLength[i];
double weight = 1 / (idealDistance * idealDistance);
var voteFromNode1 = new Vote(nodeId1, idealDistance, weight); // vote from node1 for node2
var voteFromNode2 = new Vote(nodeId2, idealDistance, weight); // vote from node2 for node1
// add vote of node1 to list of node2 (in first voting block)
majorizer.NodeVotings[nodeId2].VotingBlocks[0].Votings.Add(voteFromNode1);
// add vote of node2 to list of node1 (in first voting block)
majorizer.NodeVotings[nodeId1].VotingBlocks[0].Votings.Add(voteFromNode2);
}
//used localized method to reduce stress
majorizer.Settings=new StressMajorizationSettings();
majorizer.Settings.SolvingMethod=SolvingMethod.Localized;
List<Point> result = majorizer.IterateAll();
for (int i = 0; i < result.Count; i++) {
graph.Nodes[i].Center = result[i];
}
#if DEBUG && !SILVERLIGHT && !SHARPKIT
LayoutAlgorithmSettings.ShowGraph(graph);
#endif
}
/// <summary>
/// Inits the datastructures, later forces can be defined on the nodes.
/// </summary>
/// <param name="majorizer"></param>
/// <param name="nodes"></param>
/// <param name="nodePositions"></param>
static void InitStressWithGraph(StressMajorization majorizer, Node[] nodes, Point[] nodePositions) {
majorizer.Positions = new List<Point>(nodePositions);
majorizer.NodeVotings = new List<NodeVoting>(nodes.Length);
for (int i = 0; i < nodes.Length; i++) {
var nodeVote = new NodeVoting(i);
//add second block for separate weighting of the overlap distances
var voteBlock = new VoteBlock(new List<Vote>(), 100);
// nodeVote.VotingBlocks[0].BlockWeight = 0;
nodeVote.VotingBlocks.Add(voteBlock);
majorizer.NodeVotings.Add(nodeVote);
}
}