/** Subtracts a vector from this vector. Assumes equal dimensions. */
public void Subtract(RealVector other)
{
double[] u = other.GetFeatures();
for (int i = 0; i < u.Length; ++i) {
w[i] -= u[i];
}
}
private static RealVector BatchGradient(double[] logloss, TrainingInstance[] batch)
{
int dimensions = batch[0].GetFeatureCount();
int batchSize = batch.Length;
RealVector toReplicate = new RealVector(logloss);
RealVector labels = new RealVector(batchSize);
for (int i = 0 ; i < batchSize; i++)
{
labels.GetFeatures()[i] = batch[i].GetLabel();
}
labels.Add(1).ScaleThis(0.5);
toReplicate.Subtract(labels);
RealVector[] repmat = new RealVector[dimensions];
for (int i = 0; i < dimensions; i++) {
repmat[i] = new RealVector(toReplicate);
}
for (int i = 0; i < dimensions; i++) {
for(int j = 0; j < batchSize; j++) {
repmat[i].w[j] *= batch[j].GetFeatures().w[i];
}
}
RealVector result = new RealVector(dimensions);
for (int i = 0; i < dimensions;i++) {
result.w[i] = repmat[i].Average();
}
return result;
}
/** Dot-product between two vectors. Assumes equal dimensions. */
public double DotProduct(RealVector other)
{
double result = 0.0;
double[] u = other.GetFeatures();
for (int i = 0; i < u.Length; ++i) {
result += u[i] * this.w[i];
}
return result;
}
