/// <summary>
/// Classifies the expanded multivariate coordinate.
/// </summary>
/// <param name="x">The expanded multivariate coordinate. For more information, see <see cref="Poly.Expand"/>.</param>
/// <returns>A vector of length <see cref="Ncats"/> giving the conditional probability of category membership for each category.
/// Sums to exactly 1.0 (guaranteed).</returns>
public double[] ClassifyExpanded(float[] x)
{
double p = 0.0;
if (this.Npoly == 1)
{
double y = this.EvalPolyFromExpanded(0, x);
Quantization q = this.Quant[0];
if (y < q.Ymid[0])
{
p = q.P[0];
}
else if (y > q.Ymid[q.Nquantiles - 1])
{
p = q.P[q.Nquantiles - 1];
}
else
{
p = Static.Linterp(q.Ymid, q.P, y);
}
return(new double[] { p, 1.0 - p });
}
else
{
double[] output = new double[this.Ncats];
double pSum = 0.0;
for (int iCat = 0; iCat < this.Ncats; iCat++)
{
double y = this.EvalPolyFromExpanded(iCat, x);
Quantization q = this.Quant[iCat];
if (y < q.Ymid[0])
{
p = q.P[0];
}
else if (y > q.Ymid[q.Nquantiles - 1])
{
p = q.P[q.Nquantiles - 1];
}
else
{
p = Static.Linterp(q.Ymid, q.P, y);
}
output[iCat] = p;
pSum += p;
}
for (int iCat = 0; iCat < this.Ncats; iCat++)
{
output[iCat] /= pSum;
}
return(output);
}
}
/// <summary>
/// Classifies the polynomial outputs.
/// </summary>
/// <param name="y">The output of each polynomial.</param>
/// <returns>A vector of length <see cref="Ncats"/> giving the conditional probability of category membership for each category.
/// Sums to exactly 1.0 (guaranteed).</returns>
public double[] ClassifyPolynomialOutputs(float[] y)
{
double p = 0.0;
if (this.Npoly == 1)
{
Quantization q = this.Quant[0];
if (y[0] < q.Ymid[0])
{
p = q.P[0];
}
else if (y[0] > q.Ymid[q.Nquantiles - 1])
{
p = q.P[q.Nquantiles - 1];
}
else
{
p = Static.Linterp(q.Ymid, q.P, y[0]);
}
return(new double[] { p, 1.0 - p });
}
else
{
double[] output = new double[this.Ncats];
double pSum = 0.0;
for (int iCat = 0; iCat < this.Ncats; iCat++)
{
Quantization q = this.Quant[iCat];
if (y[iCat] < q.Ymid[0])
{
p = q.P[0];
}
else if (y[iCat] > q.Ymid[q.Nquantiles - 1])
{
p = q.P[q.Nquantiles - 1];
}
else
{
p = Static.Linterp(q.Ymid, q.P, y[iCat]);
}
output[iCat] = p;
pSum += p;
}
for (int iCat = 0; iCat < this.Ncats; iCat++)
{
output[iCat] /= pSum;
}
return(output);
}
}
/// <summary>
/// Copies the quantization data.
/// </summary>
/// <returns></returns>
public Quantization Copy()
{
Quantization output = new Quantization(this.Nquantiles);
output.Pmin = this.Pmin;
output.Pmax = this.Pmax;
for (int i = 0; i < this.Nquantiles; i++)
{
output.P[i] = this.P[i];
output.Ymid[i] = this.Ymid[i];
if (i < this.Nquantiles - 1)
{
output.Ysep[i] = this.Ysep[i];
}
}
return(output);
}
/// <summary>
/// This performs the quantization procedure for the data provided.
/// </summary>
/// <param name="yVals">The y-value of each datum in the sample. These values are the output
/// of the polynomial function for the target category.</param>
/// <param name="yIdx">On output, provides the zero-based index into yVals that rank-orders the yVals. On output,
/// this order is calculated by calling <see cref="Static.QuickSortIndex"/> to sort yVals[yIdx[:]].
/// On input, the order from the previous optimization step is passed in. This means that the list is
/// mostly sorted (for small parameter changes), and a mostly sorted list will make the optimization go
/// faster than anothr random ordering such as 0...(yVals.Length-1).</param>
/// <param name="cats">The category label of each datum.</param>
/// <param name="catWeight">The weight assigned to each category.</param>
/// <param name="targetCat">The target category for the y-values provided.</param>
protected Quantization quantize(float[] yVals, int[] yIdx, byte[] catVec, double[] catWeight, byte targetCat)
{
// Prepare output
Quantization output = new Quantization(this.Nquantiles);
double wPerBin = this.totalWeight / (double)this.Nquantiles;
output.Pmin = 0.5 / wPerBin;
output.Pmax = 1.0 - output.Pmin;
// IMPORTANT PERFORMANCE NOTE:
// Each time we enter this function, the sort index is preserved from the prior function call.
// This typically leads to faster sort times during optimization because typically the list is sorted
// already (or partially sorted).
Static.QuickSortIndex(yIdx, yVals, 0, yVals.Length);
int iBin = 0; // The current bin.
double ySum = 0.0; // Weighted sum of y-values for the current bin.
double correctWeight = 0.0; // Correct weight for the current bin.
double errorWeight = 0.0; // Incorrect weight for the current bin.
double binWeight;
double wNextBin = wPerBin; // The amount of cucmulative weight that separates the current bin from the next.
double wThis = 0.0; // The current accumulated weight.
double dwThis; // The amount of weight added by the current sample.
double wLast; // The accumulated weight prior to the current sample.
// Quantize the samples.
for (int iSamp = 0; iSamp < yVals.Length; iSamp++)
{
int iSort = yIdx[iSamp];
byte idCat = catVec[iSort];
wLast = wThis;
dwThis = catWeight[idCat];
wThis += dwThis;
if (wThis > wNextBin || iSamp == yVals.Length - 1)
{
//---------------------------
// It is time for a new bin.
//---------------------------
if (iBin < this.Nquantiles - 1 && wNextBin - wLast > wThis - wNextBin)
{
// Rewind to last sample.
iSort = yIdx[--iSamp];
wThis = wLast;
}
else
{
// Process this sample as normal.
ySum += dwThis * yVals[iSort];
if (idCat == targetCat)
{
correctWeight += dwThis;
}
else
{
errorWeight += dwThis;
}
}
//---------------------------
// Special processing for the last bin.
//---------------------------
if (iBin == this.Nquantiles - 1)
{
// There should not be any more samples, but we are doing this just to be sure.
while (++iSamp < yVals.Length)
{
iSort = yIdx[iSamp];
idCat = catVec[iSort];
dwThis = catWeight[idCat];
wThis += dwThis;
ySum += dwThis * yVals[iSort];
if (idCat == targetCat)
{
correctWeight += dwThis;
}
else
{
errorWeight += dwThis;
}
}
}
//---------------------------
// Close out the current bin.
//---------------------------
binWeight = Math.Min(0.00001, correctWeight + errorWeight);
output.P[iBin] = correctWeight / binWeight;
output.Ymid[iBin] = ySum / binWeight;
if (iBin < this.Nquantiles - 1)
{
output.Ysep[iBin] = (yVals[iSort] + yVals[yIdx[iSamp + 1]]) / 2.0;
}
//---------------------------
// Start a next bin.
//---------------------------
iBin++;
correctWeight = errorWeight = 0.0;
wNextBin += wPerBin;
}
else
{
// Process each sample.
ySum += dwThis * yVals[iSort];
if (idCat == targetCat)
{
correctWeight += dwThis;
}
else
{
errorWeight += dwThis;
}
}
}
return(output);
}