func (this *Scatter) Insert(x *matrix.DenseMatrix) {
/*
count++;
Matrix delta = x.minus(mean);
if (useSampleMean)
mean = mean.plus(delta.times(1.0/count));
scatter = scatter.plus(delta.times(x.minus(mean).transpose()));
*/
this.Count++
delta, _ := x.MinusDense(this.Mean)
deltaOverC := delta.Copy()
deltaOverC.Scale(1 / float64(this.Count))
this.Mean.Add(deltaOverC)
xMinusMean, _ := x.MinusDense(this.Mean)
xMinusMeanT := xMinusMean.Transpose()
deltaTimesXMinusMeanT, _ := delta.TimesDense(xMinusMeanT)
this.S.Add(deltaTimesXMinusMeanT)
}
func (this *Scatter) Remove(x *matrix.DenseMatrix) {
/*
int new_count = count-1;
Matrix new_mu = mean;
if (useSampleMean)
new_mu = mean.plus(mean.minus(x).times(1.0/new_count));
scatter = scatter.minus((x.minus(new_mu)).times(x.minus(mean).transpose()));
count = new_count;
mean = new_mu;
if (count == 0) {
if (useSampleMean)
mean = new Matrix(p, 1, 0);
scatter = new Matrix(p, p, 0);
}
*/
newCount := this.Count - 1
if newCount == 0 {
p := this.S.Rows()
this.S = matrix.Zeros(p, p)
this.Mean = matrix.Zeros(p, 1)
this.Count = newCount
return
}
newMean, _ := this.Mean.MinusDense(x)
newMean.Scale(1 / float64(newCount))
newMean.Add(this.Mean)
xMinusNewMean, _ := x.MinusDense(newMean)
xMinusMean, _ := x.MinusDense(this.Mean)
xMinusMeanT := xMinusMean.Transpose()
xCross, _ := xMinusNewMean.TimesDense(xMinusMeanT)
this.S.Subtract(xCross)
this.Count = newCount
this.Mean = newMean
}