public VariableOrdersSampler(List <string> labels, DirectedGraph directedAcyclicGraph, int seed)
{
new VariableOrdersSampler(labels, directedAcyclicGraph, new Random(seed));
}
public VariableOrdersSampler(List <string> labels, DirectedGraph directedAcyclicGraph, Random randomNumbers)
{
HashSet <Tuple <string, string> > restrictions = null;
List <GraphNode> nodes = new List <GraphNode>();
List <DirectedGraphEdge> edges = new List <DirectedGraphEdge>();
this._bestModel = null;
this._bestModelScore = double.NegativeInfinity;
this._randomNumbers = randomNumbers;
restrictions = directedAcyclicGraph.GetOrderRestrictions();
this._standardRestrictionMatrix = new int[labels.Count][];
this._C = new double[labels.Count][];
this._R = new double[labels.Count][];
this._M = new double[labels.Count][];
for (int i = 0; i < labels.Count; ++i)
{
this._standardRestrictionMatrix[i] = new int[labels.Count];
this._C[i] = new double[labels.Count];
this._R[i] = new double[i + 1];
this._M[i] = new double[labels.Count];
}
// allowing all edges except self edges (identity matrix)
// and initializing C, R and M
for (int i = 0; i < labels.Count; ++i)
{
for (int j = i; j < labels.Count; ++j)
{
if (i != j)
{
this._standardRestrictionMatrix[i][j] = 0;
this._standardRestrictionMatrix[j][i] = 0;
this._C[i][j] = double.NegativeInfinity;
this._C[j][i] = double.NegativeInfinity;
this._R[j][i] = double.NegativeInfinity;
this._M[i][j] = 0;
this._M[j][i] = 0;
}
else
{
this._standardRestrictionMatrix[i][j] = 1;
this._C[i][j] = double.NegativeInfinity;
this._R[j][i] = double.NegativeInfinity;
this._M[i][j] = 0;
}
}
}
uint counter = 0;
this._nameToIndex = new Dictionary <string, uint>();
this._indexToName = new Dictionary <uint, string>();
foreach (string label in labels)
{
this._nameToIndex.Add(label, counter);
this._indexToName.Add(counter, label);
++counter;
}
foreach (Tuple <string, string> restriction in restrictions)
{
this._standardRestrictionMatrix[_nameToIndex[restriction.Item2]][_nameToIndex[restriction.Item1]] = 1;
this._standardRestrictionMatrix[_nameToIndex[restriction.Item1]][_nameToIndex[restriction.Item2]] = 1;
edges.Add(new DirectedGraphEdge(restriction.Item1, restriction.Item2, 0));
}
foreach (string node in labels)
{
nodes.Add(new GraphNode(node));
}
this._restrictionGraph = new DirectedGraph(nodes, edges);
}
public List <string> SampleOrder()
{
DirectedGraph tempGraph = (DirectedGraph)this._restrictionGraph.Clone();
List <string> orderedNodes = new List <string>();
int[][] tempRestrictionMatrix = (int[][])this._standardRestrictionMatrix.Clone();
double sum = 0;
double randomNumber = 0;
double tempSum = 0;
int index = 0;
List <Tuple <double, Tuple <uint, uint> > > choices = _getPossibleChoices(tempRestrictionMatrix, ref sum);
while (choices.Count > 0)
{
index = 0;
// if all allowed choices in M are zero, we draw the index from a uniform distribution
// otherwise, the entry M[i,j] is proportional to its probability to be chosen
if (sum - 0.0001 < 0 && sum + 0.0001 > 0)
{
index = _randomNumbers.Next(choices.Count);
}
else
{
randomNumber = ((double)this._randomNumbers.Next()) / Int32.MaxValue * sum;
//find choice that corresponds to random number
tempSum = 0;
do
{
tempSum += choices[index++].Item1;
}while (index < choices.Count && tempSum < randomNumber - 0.0001);
// this should not happen
if (index == choices.Count)
{
--index;
}
}
//add edge to restriction graph
DirectedGraphEdge chosenEdge = new DirectedGraphEdge(this._indexToName[choices[index].Item2.Item1],
this._indexToName[choices[index].Item2.Item2],
0);
tempGraph.AddEdge(chosenEdge);
//update restrictions
HashSet <string> newChildren = tempGraph.GetReachableNodes(chosenEdge.To);
newChildren.Add(chosenEdge.To);
tempRestrictionMatrix[this._nameToIndex[chosenEdge.From]][this._nameToIndex[chosenEdge.To]] = 1;
HashSet <string> ancestors = tempGraph.GetAncestors(chosenEdge.From);
foreach (string newChild in newChildren)
{
tempRestrictionMatrix[this._nameToIndex[newChild]][this._nameToIndex[chosenEdge.From]] = 1;
foreach (string ancestor in ancestors)
{
tempRestrictionMatrix[this._nameToIndex[newChild]][this._nameToIndex[ancestor]] = 1;
}
}
// prepare next round
sum = 0;
choices = _getPossibleChoices(tempRestrictionMatrix, ref sum);
}
// if there are no free choices, tempGraph contains all choices and has therefore a unique topological order
return(tempGraph.GetTopologicalOrder());
}
