@Override
public double[][] getKernelMatrix(List<TrainingSample<T>> list) {
final List<TrainingSample<T>> l = list;
// init matrix with ones
double matrix[][] = new double[l.size()][l.size()];
for (double[] lines : matrix) Arrays.fill(lines, 1.);
for (final Kernel<T> k : kernels.keySet()) {
final double w = kernels.get(k);
// check w
if (w == 0) continue;
final double[][] m = k.getKernelMatrix(l);
// specific factory
ThreadedMatrixOperator tmo =
new ThreadedMatrixOperator() {
@Override
public void doLine(int index, double[] line) {
for (int i = line.length - 1; i >= 0; i--) {
line[i] *= Math.pow(m[index][i], w);
}
};
};
tmo.getMatrix(matrix);
}
return matrix;
}
public IndexedCacheKernel(Kernel<T> k, final Map<S, T> signatures) {
this.kernel = k;
matrix = new double[signatures.size()][signatures.size()];
// adding index
map = new HashMap<S, Integer>(signatures.size());
int index = 0;
for (S s : signatures.keySet()) {
map.put(s, index);
index++;
}
// computing matrix
ThreadedMatrixOperator factory =
new ThreadedMatrixOperator() {
@Override
public void doLine(int index, double[] line) {
// reverse search through mapping S <-> index
S s1 = null;
for (S s : map.keySet())
if (map.get(s) == index) {
s1 = s;
break;
}
// mapped signature
T t1 = signatures.get(s1);
// all mapping S <-> T
for (S s2 : map.keySet()) {
// get index of s2
int j = map.get(s2);
// get signature of s2
T t2 = signatures.get(s2);
// add value of kernel
line[j] = kernel.valueOf(t1, t2);
}
};
};
/* do the actuel computing of the matrix */
matrix = factory.getMatrix(matrix);
}