public QryResult evaluateIndri(RetrievalModelIndri r) throws IOException {
QryResult result = args.get(0).evaluate(r);
double score = 0;
double lam = r.lambda;
double mu = r.mu;
this.field = result.invertedList.field;
this.C = (double) QryEval.corpus.get(field);
this.ctf = (double) result.invertedList.ctf;
long doclen;
InvList.DocPosting docp;
double Pmle = this.ctf / this.C;
for (int i = 0; i < result.invertedList.df; i++) {
docp = result.invertedList.postings.get(i);
doclen = QryEval.dls.getDocLength(this.field, docp.docid);
score = (1.0 - lam) * ((double) docp.tf + mu * Pmle) / ((double) doclen + mu) + lam * Pmle;
result.docScores.add(docp.docid, score);
}
// The SCORE operator should not return a populated inverted list.
// If there is one, replace it with an empty inverted list.
if (result.invertedList.df > 0) result.invertedList = new InvList();
return result;
}
// for Ranked model
public QryResult evaluateBooleanRanked(RetrievalModel r) throws IOException {
// Evaluate the query argument.
QryResult result = args.get(0).evaluate(r);
// Each pass of the loop computes a score for one document. Note:
// If the evaluate operation above returned a score list (which is
// very possible), this loop gets skipped.
for (int i = 0; i < result.invertedList.df; i++) {
// DIFFERENT RETRIEVAL MODELS IMPLEMENT THIS DIFFERENTLY.
// Unranked Boolean. All matching documents get a score of 1.0.
result.docScores.add(
result.invertedList.postings.get(i).docid, result.invertedList.postings.get(i).tf);
}
// The SCORE operator should not return a populated inverted list.
// If there is one, replace it with an empty inverted list.
if (result.invertedList.df > 0) result.invertedList = new InvList();
return result;
}
// for BM25
public QryResult evaluateBM25(RetrievalModelBM25 r) throws IOException {
// Evaluate the query argument.
QryResult result = args.get(0).evaluate(r);
DocLengthStore dls = new DocLengthStore(QryEval.READER);
int N = QryEval.READER.getDocCount(result.invertedList.field);
long doclen;
float avg_doclen =
QryEval.READER.getSumTotalTermFreq(result.invertedList.field)
/ (float) QryEval.READER.getDocCount(result.invertedList.field);
double rsj = Math.log((N - result.invertedList.df + 0.5) / (result.invertedList.df + 0.5));
double score = 0;
// Each pass of the loop computes a score for one document. Note:
// If the evaluate operation above returned a score list (which is
// very possible), this loop gets skipped.
for (int i = 0; i < result.invertedList.df; i++) {
doclen =
dls.getDocLength(result.invertedList.field, result.invertedList.postings.get(i).docid);
score =
rsj
* result.invertedList.postings.get(i).tf
/ (result.invertedList.postings.get(i).tf
+ r.k1 * ((1 - r.b) + r.b * doclen / avg_doclen));
result.docScores.add(result.invertedList.postings.get(i).docid, score);
}
// The SCORE operator should not return a populated inverted list.
// If there is one, replace it with an empty inverted list.
if (result.invertedList.df > 0) result.invertedList = new InvList();
return result;
}
