private void PrecomputeAllDistances()
{
Parallel.For(0, centroidDistances.Length, i =>
{
for (int j = 0; j < i; j++)
{
// precompute distance
centroidDistances[i][j] = WeightedCentroid.GetDistance(weightedCentroids[i], weightedCentroids[j]);
// precompute minimal distance in a row
if (centroidDistances[i][j] < rowMinimalDistances[i])
{
rowMinimalDistances[i] = centroidDistances[i][j];
rowMinimalDistanceIds[i] = j;
}
}
});
}
private void ComputeNewDistances(int mergedCentroidId, int droppedCentroidId)
{
// invalidate dropped data
rowMinimalDistances[droppedCentroidId] = double.NaN;
rowMinimalDistanceIds[droppedCentroidId] = -1;
Parallel.For(0, droppedCentroidId, j =>
{
centroidDistances[droppedCentroidId][j] = double.NaN;
});
Parallel.For(droppedCentroidId + 1, centroidDistances.Length, i =>
{
centroidDistances[i][droppedCentroidId] = double.NaN;
});
// compute new distances and minimal value in mergedId row
rowMinimalDistances[mergedCentroidId] = double.MaxValue;
Parallel.For(0, mergedCentroidId, j =>
{
if (!isDropped[j])
{
centroidDistances[mergedCentroidId][j]
= WeightedCentroid.GetDistance(weightedCentroids[j], weightedCentroids[mergedCentroidId]);
// update minimal distances
if (centroidDistances[mergedCentroidId][j] < rowMinimalDistances[mergedCentroidId])
{
rowMinimalDistances[mergedCentroidId] = centroidDistances[mergedCentroidId][j];
rowMinimalDistanceIds[mergedCentroidId] = j;
}
}
});
if (rowMinimalDistances[mergedCentroidId] == double.MaxValue)
{
rowMinimalDistances[mergedCentroidId] = double.NaN;
}
// compute new distances in mergedId column
Parallel.For(mergedCentroidId + 1, centroidDistances.Length, i =>
{
if (!isDropped[i])
{
centroidDistances[i][mergedCentroidId]
= WeightedCentroid.GetDistance(weightedCentroids[i], weightedCentroids[mergedCentroidId]);
// update minimal distances
if (centroidDistances[i][mergedCentroidId] < rowMinimalDistances[i])
{
rowMinimalDistances[i] = centroidDistances[i][mergedCentroidId];
rowMinimalDistanceIds[i] = mergedCentroidId;
}
}
});
// find new minimal value in the row if the value from dropped column was minimal
for (int i = droppedCentroidId + 1; i < centroidDistances.Length; i++)
{
if (!isDropped[i] && rowMinimalDistanceIds[i] == droppedCentroidId)
{
rowMinimalDistances[i] = double.MaxValue;
rowMinimalDistanceIds[i] = -1;
for (int j = 0; j < i; j++)
{
if (!isDropped[j] && centroidDistances[i][j] < rowMinimalDistances[i])
{
rowMinimalDistances[i] = centroidDistances[i][j];
rowMinimalDistanceIds[i] = j;
}
}
if (rowMinimalDistances[i] == double.MaxValue)
{
rowMinimalDistances[i] = double.NaN;
}
}
}
}
