public void iterateSample(VocabWord w1, VocabWord w2, double currentSentenceAlpha) {
if (w1 == null || w2 == null || w2.getIndex() < 0 || w2.getIndex() == w1.getIndex()) return;
final int currentWordIndex = w2.getIndex();
// error for current word and context
INDArray neu1e = Nd4j.create(vectorLength);
// First iteration Syn0 is random numbers
INDArray l1 = null;
if (indexSyn0VecMap.containsKey(vocab.elementAtIndex(currentWordIndex))) {
l1 = indexSyn0VecMap.get(vocab.elementAtIndex(currentWordIndex));
} else {
l1 = getRandomSyn0Vec(vectorLength, (long) currentWordIndex);
}
//
for (int i = 0; i < w1.getCodeLength(); i++) {
int code = w1.getCodes().get(i);
int point = w1.getPoints().get(i);
if (point < 0) throw new IllegalStateException("Illegal point " + point);
// Point to
INDArray syn1;
if (pointSyn1VecMap.containsKey(point)) {
syn1 = pointSyn1VecMap.get(point);
} else {
syn1 = Nd4j.zeros(1, vectorLength); // 1 row of vector length of zeros
pointSyn1VecMap.put(point, syn1);
}
// Dot product of Syn0 and Syn1 vecs
double dot = Nd4j.getBlasWrapper().level1().dot(vectorLength, 1.0, l1, syn1);
if (dot < -maxExp || dot >= maxExp) continue;
int idx = (int) ((dot + maxExp) * ((double) expTable.length / maxExp / 2.0));
if (idx > expTable.length) continue;
// score
double f = expTable[idx];
// gradient
double g =
(1 - code - f)
* (useAdaGrad
? w1.getGradient(i, currentSentenceAlpha, currentSentenceAlpha)
: currentSentenceAlpha);
Nd4j.getBlasWrapper().level1().axpy(vectorLength, g, syn1, neu1e);
Nd4j.getBlasWrapper().level1().axpy(vectorLength, g, l1, syn1);
}
int target = w1.getIndex();
int label;
// negative sampling
if (negative > 0)
for (int d = 0; d < negative + 1; d++) {
if (d == 0) label = 1;
else {
nextRandom.set(nextRandom.get() * 25214903917L + 11);
int idx = Math.abs((int) (nextRandom.get() >> 16) % negativeHolder.getTable().length());
target = negativeHolder.getTable().getInt(idx);
if (target <= 0) target = (int) nextRandom.get() % (vocab.numWords() - 1) + 1;
if (target == w1.getIndex()) continue;
label = 0;
}
if (target >= negativeHolder.getSyn1Neg().rows() || target < 0) continue;
double f = Nd4j.getBlasWrapper().dot(l1, negativeHolder.getSyn1Neg().slice(target));
double g;
if (f > maxExp)
g = useAdaGrad ? w1.getGradient(target, (label - 1), alpha) : (label - 1) * alpha;
else if (f < -maxExp)
g = label * (useAdaGrad ? w1.getGradient(target, alpha, alpha) : alpha);
else {
int idx = (int) ((f + maxExp) * (expTable.length / maxExp / 2));
if (idx >= expTable.length) continue;
g =
useAdaGrad
? w1.getGradient(target, label - expTable[idx], alpha)
: (label - expTable[idx]) * alpha;
}
Nd4j.getBlasWrapper().axpy((float) g, negativeHolder.getSyn1Neg().slice(target), neu1e);
Nd4j.getBlasWrapper().axpy((float) g, l1, negativeHolder.getSyn1Neg().slice(target));
}
// Updated the Syn0 vector based on gradient. Syn0 is not random anymore.
Nd4j.getBlasWrapper().level1().axpy(vectorLength, 1.0f, neu1e, l1);
if (aff.get() == 0) {
synchronized (this) {
cid.set(EnvironmentUtils.buildCId());
aff.set(EnvironmentUtils.buildEnvironment().getAvailableMemory());
}
}
VocabWord word = vocab.elementAtIndex(currentWordIndex);
word.setVocabId(cid.get());
word.setAffinityId(aff.get());
indexSyn0VecMap.put(word, l1);
}
