public PairwiseGenerator(int[] counts)
{
this.counts = counts;
dimensions = counts.Length;
coveringTables = new CoveringTable[dimensions][];
for (int i = 0; i < dimensions; i++)
{
coveringTables[i] = new CoveringTable[dimensions];
for (int j = 0; j < i; j++)
{
int[,] coverings = new int[counts[i], counts[j]];
coveringTables[i][j] = new CoveringTable(coverings, false);
coveringTables[j][i] = new CoveringTable(coverings, true);
}
}
tieBreaker = new Random(0); // Note: Uses a constant seed to be deterministic.
}
public bool Next(int[] indices)
{
for (int i = 0; i < dimensions; i++)
{
indices[i] = -1;
}
bool foundUncovered = false;
for (int firstDimension = 0; firstDimension < dimensions; firstDimension++)
{
if (indices[firstDimension] >= 0)
{
continue;
}
// Find the value in the first dimension that produces the best score over all values in all other dimensions.
int firstCount = counts[firstDimension];
int bestFirstScore = 0;
int bestFirstIndex = 0;
int ties = 0;
for (int firstIndex = 0; firstIndex < firstCount; firstIndex++)
{
int firstScore = 0;
for (int secondDimension = 0; secondDimension < dimensions; secondDimension++)
{
if (firstDimension == secondDimension)
{
continue;
}
CoveringTable coverings = coveringTables[firstDimension][secondDimension];
if (firstDimension < secondDimension)
{
int secondCount = counts[secondDimension];
for (int secondIndex = 0; secondIndex < secondCount; secondIndex++)
{
if (coverings.GetCoveringCount(firstIndex, secondIndex) == 0)
{
firstScore += 1;
break;
}
}
}
else
{
if (coverings.GetCoveringCount(firstIndex, indices[secondDimension]) == 0)
{
firstScore += 1;
}
}
}
if (firstScore < bestFirstScore)
{
continue;
}
if (firstScore == bestFirstScore)
{
// Randomly choose which of the ties to keep with equal probability.
// This helps to reduce the variance between covered pairs.
ties += 1;
if (tieBreaker.Next(ties) != 0)
{
continue;
}
}
else
{
bestFirstScore = firstScore;
}
bestFirstIndex = firstIndex;
}
if (bestFirstScore != 0)
{
// If the best score is non-zero, then we know there exists an uncovered pair that will be
// covered by this choice of first index because we always prefer indexes that produce new coverings.
foundUncovered = true;
indices[firstDimension] = bestFirstIndex;
}
else
{
// If the best score is zero, then it makes no difference which index we choose so we
// pick one at random. This helps to reduce the variance between covered pairs
// as otherwise we'd constantly be choosing the 0th element.
indices[firstDimension] = tieBreaker.Next(firstCount);
}
}
// If we did not find any uncovered pairs, then there are none to be found.
if (!foundUncovered)
{
return(false);
}
// Mark all pairs that were covered.
for (int i = 0; i < dimensions; i++)
{
for (int j = i + 1; j < dimensions; j++)
{
coveringTables[i][j].IncrementCoveringCount(indices[i], indices[j]);
}
}
return(true);
}
public PairwiseGenerator(int[] counts)
{
this.counts = counts;
dimensions = counts.Length;
coveringTables = new CoveringTable[dimensions][];
for (int i = 0; i < dimensions; i++)
{
coveringTables[i] = new CoveringTable[dimensions];
for (int j = 0; j < i; j++)
{
int[,] coverings = new int[counts[i], counts[j]];
coveringTables[i][j] = new CoveringTable(coverings, false);
coveringTables[j][i] = new CoveringTable(coverings, true);
}
}
tieBreaker = new Random(0); // Note: Uses a constant seed to be deterministic.
}
