public static _SparseFeature[] MergeSpVcts(ArrayList<_SparseFeature[]> vcts) {
HashMap<Integer, Double> vct = new HashMap<Integer, Double>();
for (_SparseFeature[] fv : vcts) {
for (_SparseFeature f : fv) {
int x = f.getIndex();
if (vct.containsKey(x)) {
vct.put(x, vct.get(x) + f.getValue());
} else {
vct.put(x, f.getValue());
}
}
}
return Utils.createSpVct(vct);
}
void ComputeEmissionProbsForDoc(_Doc d) {
for (int i = 0; i < d.getSenetenceSize(); i++) {
_Stn stn = d.getSentence(i);
Arrays.fill(emission[i], 0);
int start = 0, end = this.number_of_topics;
if (i == 0 && d.getSourceType() == 2) { // first sentence is specially handled for newEgg
// get the sentiment label of the first sentence
int sentimentLabel = stn.getSentenceSenitmentLabel();
if (sentimentLabel == 0) { // positive sentiment in the first half
end = this.number_of_topics / 2;
for (int k = end; k < this.number_of_topics; k++)
emission[i][k] = Double.NEGATIVE_INFINITY;
} else if (sentimentLabel == 1) { // negative sentiment in the second half
start = this.number_of_topics / 2;
for (int k = 0; k < start; k++) emission[i][k] = Double.NEGATIVE_INFINITY;
}
}
for (int k = start; k < end; k++) {
for (_SparseFeature w : stn.getFv()) {
emission[i][k] +=
w.getValue() * topic_term_probabilty[k][w.getIndex()]; // all in log-space
}
}
}
}
// Dot product of the random vector and document sparse vector.
public static double dotProduct(double[] vct, _SparseFeature[] sf) {
if (sf[sf.length - 1].getIndex() > vct.length)
System.err.print("Error in computing dot product between a sparse vector and a full vector");
double value = 0;
for (_SparseFeature fv : sf) value += vct[fv.getIndex()] * fv.getValue();
return value;
}
public static Feature[] createLibLinearFV(HashMap<Integer, Double> spVct) {
Feature[] node = new Feature[spVct.size()];
int fid = 0;
for (_SparseFeature fv : createSpVct(spVct))
node[fid++] =
new FeatureNode(1 + fv.getIndex(), fv.getValue()); // svm's feature index starts from 1
return node;
}
// Calculate the similarity between two sparse vectors.
public static double calculateSimilarity(_SparseFeature[] spVct1, _SparseFeature[] spVct2) {
if (spVct1 == null || spVct2 == null) return 0; // What is the minimal value of similarity?
double similarity = 0;
int pointer1 = 0, pointer2 = 0;
while (pointer1 < spVct1.length && pointer2 < spVct2.length) {
_SparseFeature temp1 = spVct1[pointer1];
_SparseFeature temp2 = spVct2[pointer2];
if (temp1.getIndex() == temp2.getIndex()) {
similarity += temp1.getValue() * temp2.getValue();
pointer1++;
pointer2++;
} else if (temp1.getIndex() > temp2.getIndex()) pointer2++;
else pointer1++;
}
return similarity;
}
// L2 normalization: fsValue/sqrt(sum of fsValue*fsValue)
public static double sumOfFeaturesL2(_SparseFeature[] fs) {
if (fs == null) return 0;
double sum = 0;
for (_SparseFeature feature : fs) {
double value = feature.getValue();
sum += value * value;
}
return Math.sqrt(sum);
}
// Get projectSpVct by building a hashmap<Integer, String> filter, added by Lin.
public static _SparseFeature[] projectSpVct(
_SparseFeature[] fv, HashMap<Integer, String> filter) {
ArrayList<_SparseFeature> pFv = new ArrayList<_SparseFeature>();
for (_SparseFeature f : fv) {
if (filter.containsKey(f.getIndex())) {
pFv.add(new _SparseFeature(f.getIndex(), f.getValue()));
}
}
if (pFv.isEmpty()) return null;
else return pFv.toArray(new _SparseFeature[pFv.size()]);
}
public static void L2Normalization(_SparseFeature[] fs) {
double sum = sumOfFeaturesL2(fs);
if (sum > 0) {
for (_SparseFeature f : fs) {
double normValue = f.getValue() / sum;
f.setValue(normValue);
}
} else {
for (_SparseFeature f : fs) {
f.setValue(0.0);
}
}
}
public static Feature[] createLibLinearFV(_SparseFeature[] spVct, int fSize) {
Feature[] node;
if (fSize > 0) // include bias term in the end
node = new Feature[1 + spVct.length];
else // ignore bias term
node = new Feature[spVct.length];
int fid = 0;
for (_SparseFeature fv : spVct)
node[fid++] =
new FeatureNode(1 + fv.getIndex(), fv.getValue()); // svm's feature index starts from 1
if (fSize > 0) node[fid] = new FeatureNode(1 + fSize, 1.0);
return node;
}
// probabilities of topic assignment
void accPhiStat(_Doc d) {
double prob;
for (int t = 0; t < d.getSenetenceSize(); t++) {
_Stn s = d.getSentence(t);
for (_SparseFeature f : s.getFv()) {
int wid = f.getIndex();
double v = f.getValue(); // frequency
for (int i = 0; i < number_of_topics; i++) {
prob = this.p_dwzpsi[t][i];
for (int j = 1; j < constant; j++) prob += this.p_dwzpsi[t][i + j * number_of_topics];
this.sstat[i][wid] += v * prob;
}
}
}
}
// x_i - x_j
public static _SparseFeature[] diffVector(_SparseFeature[] spVcti, _SparseFeature[] spVctj) {
// first deal with special case
if (spVcti == null && spVctj == null) return null;
else if (spVctj == null) return spVcti;
else if (spVcti == null) return negSpVct(spVctj);
ArrayList<_SparseFeature> vectorList = new ArrayList<_SparseFeature>();
int i = 0, j = 0;
_SparseFeature fi = spVcti[i], fj = spVctj[j];
double fv;
while (i < spVcti.length && j < spVctj.length) {
fi = spVcti[i];
fj = spVctj[j];
if (fi.getIndex() == fj.getIndex()) {
fv = fi.getValue() - fj.getValue();
if (Math.abs(fv) > Double.MIN_VALUE) // otherwise it is too small
vectorList.add(new _SparseFeature(fi.getIndex(), fv));
i++;
j++;
} else if (fi.getIndex() > fj.getIndex()) {
vectorList.add(new _SparseFeature(fj.getIndex(), -fj.getValue()));
j++;
} else {
vectorList.add(new _SparseFeature(fi.getIndex(), fi.getValue()));
i++;
}
}
while (i < spVcti.length) {
fi = spVcti[i];
vectorList.add(new _SparseFeature(fi.getIndex(), fi.getValue()));
i++;
}
while (j < spVctj.length) {
fj = spVctj[j];
vectorList.add(new _SparseFeature(fj.getIndex(), -fj.getValue()));
j++;
}
return vectorList.toArray(new _SparseFeature[vectorList.size()]);
}
// L1 normalization: fsValue/sum(abs(fsValue))
public static double sumOfFeaturesL1(_SparseFeature[] fs) {
double sum = 0;
for (_SparseFeature feature : fs) sum += Math.abs(feature.getValue());
return sum;
}