/**
* SVMOutput of an instance in the training set, m_data This uses the cache, unlike
* SVMOutput(Instance)
*
* @param index index of the training instance in m_data
* @return the SVM output
* @throws Exception if something goes wrong
*/
protected double SVMOutput(int index) throws Exception {
double result = -m_b;
for (int i = m_supportVectors.getNext(-1); i != -1; i = m_supportVectors.getNext(i)) {
result += (m_alpha[i] - m_alphaStar[i]) * m_kernel.eval(index, i, m_data.instance(index));
}
return result;
}
/**
* wrap up various variables to save memeory and do some housekeeping after optimization has
* finished.
*
* @throws Exception if something goes wrong
*/
protected void wrapUp() throws Exception {
m_target = null;
m_nEvals = m_kernel.numEvals();
m_nCacheHits = m_kernel.numCacheHits();
if ((m_SVM.getKernel() instanceof PolyKernel)
&& ((PolyKernel) m_SVM.getKernel()).getExponent() == 1.0) {
// convert alpha's to weights
double[] weights = new double[m_data.numAttributes()];
for (int k = m_supportVectors.getNext(-1); k != -1; k = m_supportVectors.getNext(k)) {
for (int j = 0; j < weights.length; j++) {
if (j != m_classIndex) {
weights[j] += (m_alpha[k] - m_alphaStar[k]) * m_data.instance(k).value(j);
}
}
}
m_weights = weights;
// release memory
m_alpha = null;
m_alphaStar = null;
m_kernel = null;
}
m_bModelBuilt = true;
}
/**
* @param inst
* @return
* @throws Exception
*/
public double SVMOutput(Instance inst) throws Exception {
double result = -m_b;
// Is the machine linear?
if (m_weights != null) {
// Is weight vector stored in sparse format?
for (int i = 0; i < inst.numValues(); i++) {
if (inst.index(i) != m_classIndex) {
result += m_weights[inst.index(i)] * inst.valueSparse(i);
}
}
} else {
for (int i = m_supportVectors.getNext(-1); i != -1; i = m_supportVectors.getNext(i)) {
result += (m_alpha[i] - m_alphaStar[i]) * m_kernel.eval(-1, i, inst);
}
}
return result;
}
