//Threshold based
public static LightWeightGraph GetGeometricGraph(DistanceMatrix distances, double threshold)
{
//construct the geo graph
int numNodes = distances.Count;
var nodes = new LightWeightNode[numNodes];
List <int>[] edges = new List <int> [numNodes];
List <double>[] weights = new List <double> [numNodes];
for (int i = 0; i < numNodes; i++)
{
edges[i] = new List <int>();
}
//Add Edges
for (int i = 0; i < numNodes - 1; i++)
{
for (int j = i + 1; j < numNodes; j++)
{
if (distances[i, j] <= threshold)
{
edges[i].Add(j);
edges[j].Add(i);
}
}
}
for (int i = 0; i < numNodes; i++)
{
nodes[i] = new LightWeightNode(i, true, edges[i], weights[i]);
}
return(new LightWeightGraph(nodes, true));
}
public LightWeightGraph()
{
Nodes = new LightWeightNode[1];
NumNodes = 1;
Nodes[0] = new LightWeightNode(0, false, new List <int>());
IsWeighted = false;
}
/// <summary>
/// Copy Constructor
/// </summary>
/// <param name="n">LightWeightNode to copy</param>
public LightWeightNode(LightWeightNode n)
{
Id = n.Id;
Label = n.Label;
Edge = (int[])n.Edge.Clone();
EdgeWeights = (double[])n.EdgeWeights.Clone();
//NodeWeight = n.NodeWeight;
Count = n.Count;
}
public static LWGWithNodeDescriptors GetGraphFromNetFile(String file)
{
using (StreamReader sr = new StreamReader(file))
{
String vertCountPattern = "[*]Vertices\\s+(?<vert>\\d+)";
String firstLine = sr.ReadLine();
var match = Regex.Match(firstLine, vertCountPattern, RegexOptions.IgnoreCase);
int numVert = int.Parse(match.Groups["vert"].Value);
String vertPattern =
"\\s+(?<vertid>\\d+)\\s+\"(?<vertName>[^\"]+)\"\\s+(?<x>\\d[.]\\d+)\\s+(?<y>\\d+[.]\\d+)";
NetVertDesciption[] verts = new NetVertDesciption[numVert];
for (int i = 0; i < numVert; i++)
{
String line = sr.ReadLine();
match = Regex.Match(line, vertPattern, RegexOptions.IgnoreCase);
String vertID = match.Groups["vertid"].Value;
String vertName = match.Groups["vertName"].Value;
String x = match.Groups["x"].Value;
String y = match.Groups["y"].Value;
verts[i] = (new NetVertDesciption(int.Parse(vertID) - 1, vertName, double.Parse(x), double.Parse(y)));
}
while (!sr.ReadLine().Contains("*Edges"))
{
}
List <int>[] edges = new List <int> [numVert];
List <double>[] edgeWeights = new List <double> [numVert];
for (int i = 0; i < numVert; i++)
{
edges[i] = new List <int>();
edgeWeights[i] = new List <double>();
}
String edgePattern =
"\\s+(?<fIndex>\\d+)\\s+(?<tIndex>\\d+)\\s+(?<dist>\\d[.]\\d+)";
while (!sr.EndOfStream)
{
String line = sr.ReadLine();
match = Regex.Match(line, edgePattern, RegexOptions.IgnoreCase);
int from = int.Parse(match.Groups["fIndex"].Value) - 1;
int to = int.Parse(match.Groups["tIndex"].Value) - 1;
double dist = double.Parse(match.Groups["dist"].Value);
edges[from].Add(to); edgeWeights[from].Add(dist);
edges[to].Add(from); edgeWeights[to].Add(dist);
}
LightWeightNode[] nodes = new LightWeightNode[numVert];
for (int i = 0; i < numVert; i++)
{
nodes[i] = (new LightWeightNode(i, true, edges[i], edgeWeights[i]));
}
return(new LWGWithNodeDescriptors(verts, new LightWeightGraph(nodes, true)));
}
}
/// <summary>
/// Make a deep Copy of a Graph
/// </summary>
/// <param name="g">LightWeightGraph to copy</param>
public LightWeightGraph(LightWeightGraph g)
: base(DataType.Graph)
{
NumNodes = g.NumNodes;
Nodes = new LightWeightNode[NumNodes];
for (int i = 0; i < NumNodes; i++)
{
Nodes[i] = new LightWeightNode(g[i]);
}
IsWeighted = g.IsWeighted;
}
//override for the sake of dictionary
public override bool Equals(Object obj)
{
LightWeightNode n = obj as LightWeightNode;
if (n == null)
{
return(false);
}
return(n.Id == Id);
}
public static LightWeightGraph GetGraphFromFile(String file)
{
DelimitedFile parsedFile = new DelimitedFile(file, false, true);
int parsedFileRowCount = parsedFile.Data.Count;
//Ensure it has atleast 1 point and lists if it is weighted
if (parsedFileRowCount < 2)
{
throw new InvalidDataException("file");
}
String weightString = parsedFile.Data[0][0];
bool isWeighted = true;
if (weightString == "unweighted")
{
isWeighted = false;
}
else if (weightString != "weighted")
{
throw new InvalidDataException("Invalid Weight Type");
}
//Start parsing the file
List <List <NodeWeightPair> > nodes = new List <List <NodeWeightPair> >();
for (int i = 1; i < parsedFileRowCount; i++)
{
var row = parsedFile.Data[i];
List <NodeWeightPair> nList = new List <NodeWeightPair>();
nodes.Add(nList);
int edgeSize = (isWeighted) ? 2 : 1;
for (int j = 1; j < row.Length; j += edgeSize)
{
int from = int.Parse(row[j]);
double weight = (isWeighted) ? double.Parse(row[j + 1]) : 1.0f;
nList.Add(new NodeWeightPair {
Node = from, Weight = weight
});
}
}
//Construct the graph
var lwn = new LightWeightNode[nodes.Count];
List <int>[] edges = new List <int> [nodes.Count];
List <double>[] edgeWeights = new List <double> [nodes.Count];
for (int i = 0; i < nodes.Count; i++)
{
edges[i] = new List <int>();
edgeWeights[i] = new List <double>();
}
for (int i = 0; i < lwn.Length; i++)
{
int count = nodes[i].Count;
for (int j = 0; j < count; j++)
{
var a = nodes[i][j];
edges[i].Add(a.Node);
edgeWeights[i].Add(a.Weight);
}
}
for (int i = 0; i < lwn.Length; i++)
{
lwn[i] = new LightWeightNode(i, true, edges[i], edgeWeights[i]);
}
return(new LightWeightGraph(lwn, isWeighted));
}
//construct a subgraph using some exclusion rules
public LightWeightGraph(LightWeightGraph lwg, bool[] S)
: base(DataType.Graph)
{
int sSize = S.Count(c => c);
//Setup our node array to be filled
Nodes = new LightWeightNode[lwg.NumNodes - sSize];
NumNodes = Nodes.Length;
IsWeighted = lwg.IsWeighted;
int nodeID = 0;
int[] oldIDToNewID = new int[lwg.NumNodes];
int[] oldLabel = new int[NumNodes];
//Now we need to itterate over each node in lwg
for (int v = 0; v < lwg.NumNodes; v++)
{
if (!S[v])
{
oldIDToNewID[v] = nodeID;
oldLabel[nodeID] = lwg.Nodes[v].Label;
nodeID++;
}
}
List <int>[] edgesList = new List <int> [NumNodes];
List <double>[] edgeWeightList = new List <double> [NumNodes];
for (int i = 0; i < lwg.NumNodes - sSize; i++)
{
edgesList[i] = new List <int>();
edgeWeightList[i] = new List <double>();
}
//now we should add our edges
nodeID = 0;
for (int v = 0; v < lwg.NumNodes; v++)
{
if (!S[v]) //if this is not a removed node we should add the edges
{
var edges = lwg.Nodes[v].Edge;
var edgeWeights = lwg.Nodes[v].EdgeWeights;
//Go through all of the edges and only add those not removed
for (int u = 0; u < lwg.Nodes[v].Count; u++)
{
int edgeTo = edges[u];
if (!S[edgeTo]) //this edge is still valid so we should add it
{
edgesList[nodeID].Add(oldIDToNewID[edgeTo]);
if (lwg.IsWeighted)
{
edgeWeightList[nodeID].Add(edgeWeights[u]);
}
}
}
nodeID++;
}
}
for (int i = 0; i < NumNodes; i++)
{
Nodes[i] = new LightWeightNode(i, oldLabel[i], lwg.IsWeighted, edgesList[i], (IsWeighted) ? edgeWeightList[i] : null);
}
}
//Knn based
public static LightWeightGraph GetKNNGraph(DistanceMatrix distances, int numNeighbors)
{
int numNodes = distances.Count;
var nodes = new LightWeightNode[numNodes];
List <int>[] edgeLists = new List <int> [numNodes];
List <double>[] edgeWeights = new List <double> [numNodes];
for (int i = 0; i < numNodes; i++)
{
edgeLists[i] = new List <int>();
edgeWeights[i] = new List <double>();
}
//prevent redundant edges
HashSet <Tuple <int, int> > addedEdges = new HashSet <Tuple <int, int> >();
//Our comparator
MinHeapPriorityQueue <Tuple <int, double> > .isGreaterThan comp =
new MinHeapPriorityQueue <Tuple <int, double> > .isGreaterThan((x, y) => { return(x.Item2 > y.Item2); });
//Add Edges
for (int i = 0; i < numNodes; i++)
{
//get list of edges
List <Tuple <int, double> > edges = new List <Tuple <int, double> >();
for (int j = 0; j < numNodes; j++)
{
//Make sure we don't load our heap with repeated edges
if (i != j)
{
edges.Add(new Tuple <int, double>(j, distances[i, j]));
}
}
//Build the heap
MinHeapPriorityQueue <Tuple <int, double> > heap = new MinHeapPriorityQueue <Tuple <int, double> >(comp);
heap.addAll(edges);
//Now add all of the neighbors
for (int edgeNum = 0; edgeNum < numNeighbors; edgeNum++)
{
if (heap.isEmpty())
{
break;
}
Tuple <int, double> e = heap.extractMin();
Tuple <int, int> edgeNodePair = (e.Item1 < i)
? new Tuple <int, int>(e.Item1, i)
: new Tuple <int, int>(i, e.Item1);
//if (!addedEdges.Contains(edgeNodePair))
if (!addedEdges.Contains(edgeNodePair))
{
//make sure we don't add this edge again in the future
//addedEdges.Add(edgeNodePair);
addedEdges.Add(edgeNodePair);
//Add the double edge now
edgeLists[i].Add(e.Item1);
edgeLists[e.Item1].Add(i);
edgeWeights[i].Add((double)e.Item2);
edgeWeights[e.Item1].Add((double)e.Item2);
}
}
}
for (int i = 0; i < numNodes; i++)
{
nodes[i] = new LightWeightNode(i, true, edgeLists[i], edgeWeights[i]);
}
return(new LightWeightGraph(nodes, true));
}
//Stacked MST
public static LightWeightGraph GetStackedMST(DistanceMatrix distances, int numMSTs)
{
int numNodes = distances.Count;
//in a complete graph, there are n*(n-1)/2 edges
//an MST contains n-1 edges
//number of msts is n/2
if (numMSTs > numNodes / 2)
{
numMSTs = numNodes / 2;
}
LightWeightNode[] nodes = new LightWeightNode[numNodes];
List <int>[] edges = new List <int> [numNodes];
List <double>[] weights = new List <double> [numNodes];
//List<double>[] edgeWeights = new List<double>[numNodes];
for (int i = 0; i < numNodes; i++)
{
edges[i] = new List <int>();
weights[i] = new List <double>();
}
//Add all of the distances to the Heap
List <distXY> points = new List <distXY>();
for (int x = 0; x < numNodes - 1; x++)
{
for (int y = x + 1; y < numNodes; y++)
{
points.Add(new distXY(x, y, distances[x, y]));
}
}
//Now we need to start making our MST
for (int n = 0; n < numMSTs; n++)
{
MinHeapPriorityQueue <distXY> minheap = new MinHeapPriorityQueue <distXY>(((x, y) => x.Dist > y.Dist));
minheap.addAll(points);
DisjointSet ds = new DisjointSet(numNodes);
int k = 0;
while (k < numNodes - 1)
{
distXY e = minheap.extractMin();
if (ds.diff(e.X, e.Y)) //different
{
ds.union(e.X, e.Y);
//change the dist
e.Dist = double.MaxValue;
//Add it
edges[e.X].Add(e.Y);
edges[e.Y].Add(e.X);
weights[e.X].Add(distances[e.X, e.Y]);
weights[e.Y].Add(distances[e.X, e.Y]);
k++;
}
}
}
for (int i = 0; i < numNodes; i++)
{
nodes[i] = new LightWeightNode(i, true, edges[i], weights[i]);
}
return(new LightWeightGraph(nodes, true));
}