@Override
public void createWeight(QueryContext context, IndexSearcher searcher) throws IOException {
TFIDFSimilarity sim = asTFIDF(searcher.getSimilarity(), field);
if (sim == null) {
throw new UnsupportedOperationException(
"requires a TFIDFSimilarity (such as DefaultSimilarity)");
}
int docfreq = searcher.getIndexReader().docFreq(new Term(indexedField, indexedBytes));
float idf = sim.idf(docfreq, searcher.getIndexReader().maxDoc());
FuncValues result = new ConstDoubleDocValues(idf, this);
context.put(this, result);
}
/**
* Create a PriorityQueue from a word->tf map.
*
* @param words a map of words keyed on the word(String) with Int objects as the values.
* @param fieldNames an array of field names to override defaults.
*/
private PriorityQueue<ScoreTerm> createQueue(Map<String, Int> words, String... fieldNames)
throws IOException {
// have collected all words in doc and their freqs
int numDocs = ir.numDocs();
final int limit = Math.min(maxQueryTerms, words.size());
FreqQ queue = new FreqQ(limit); // will order words by score
for (String word : words.keySet()) { // for every word
int tf = words.get(word).x; // term freq in the source doc
if (minTermFreq > 0 && tf < minTermFreq) {
continue; // filter out words that don't occur enough times in the source
}
// go through all the fields and find the largest document frequency
String topField = fieldNames[0];
int docFreq = 0;
for (String fieldName : fieldNames) {
int freq = ir.docFreq(new Term(fieldName, word));
topField = (freq > docFreq) ? fieldName : topField;
docFreq = (freq > docFreq) ? freq : docFreq;
}
if (minDocFreq > 0 && docFreq < minDocFreq) {
continue; // filter out words that don't occur in enough docs
}
if (docFreq > maxDocFreq) {
continue; // filter out words that occur in too many docs
}
if (docFreq == 0) {
continue; // index update problem?
}
float idf = similarity.idf(docFreq, numDocs);
float score = tf * idf;
if (queue.size() < limit) {
// there is still space in the queue
queue.add(new ScoreTerm(word, topField, score, idf, docFreq, tf));
} else {
ScoreTerm term = queue.top();
if (term.score < score) { // update the smallest in the queue in place and update the queue.
term.update(word, topField, score, idf, docFreq, tf);
queue.updateTop();
}
}
}
return queue;
}
/**
* Create a PriorityQueue from a word->tf map.
*
* @param perFieldTermFrequencies a per field map of words keyed on the word(String) with Int
* objects as the values.
*/
private PriorityQueue<ScoreTerm> createQueue(
Map<String, Map<String, Int>> perFieldTermFrequencies) throws IOException {
// have collected all words in doc and their freqs
int numDocs = ir.numDocs();
final int limit = Math.min(maxQueryTerms, this.getTermsCount(perFieldTermFrequencies));
FreqQ queue = new FreqQ(limit); // will order words by score
for (Map.Entry<String, Map<String, Int>> entry : perFieldTermFrequencies.entrySet()) {
Map<String, Int> perWordTermFrequencies = entry.getValue();
String fieldName = entry.getKey();
for (Map.Entry<String, Int> tfEntry : perWordTermFrequencies.entrySet()) { // for every word
String word = tfEntry.getKey();
int tf = tfEntry.getValue().x; // term freq in the source doc
if (minTermFreq > 0 && tf < minTermFreq) {
continue; // filter out words that don't occur enough times in the source
}
int docFreq = ir.docFreq(new Term(fieldName, word));
if (minDocFreq > 0 && docFreq < minDocFreq) {
continue; // filter out words that don't occur in enough docs
}
if (docFreq > maxDocFreq) {
continue; // filter out words that occur in too many docs
}
if (docFreq == 0) {
continue; // index update problem?
}
float idf = similarity.idf(docFreq, numDocs);
float score = tf * idf;
if (queue.size() < limit) {
// there is still space in the queue
queue.add(new ScoreTerm(word, fieldName, score, idf, docFreq, tf));
} else {
ScoreTerm term = queue.top();
if (term.score
< score) { // update the smallest in the queue in place and update the queue.
term.update(word, fieldName, score, idf, docFreq, tf);
queue.updateTop();
}
}
}
}
return queue;
}
private void addTerms(IndexReader reader, FieldVals f, ScoreTermQueue q) throws IOException {
if (f.queryString == null) return;
final Terms terms = MultiFields.getTerms(reader, f.fieldName);
if (terms == null) {
return;
}
try (TokenStream ts = analyzer.tokenStream(f.fieldName, f.queryString)) {
CharTermAttribute termAtt = ts.addAttribute(CharTermAttribute.class);
int corpusNumDocs = reader.numDocs();
HashSet<String> processedTerms = new HashSet<>();
ts.reset();
while (ts.incrementToken()) {
String term = termAtt.toString();
if (!processedTerms.contains(term)) {
processedTerms.add(term);
ScoreTermQueue variantsQ =
new ScoreTermQueue(
MAX_VARIANTS_PER_TERM); // maxNum variants considered for any one term
float minScore = 0;
Term startTerm = new Term(f.fieldName, term);
AttributeSource atts = new AttributeSource();
MaxNonCompetitiveBoostAttribute maxBoostAtt =
atts.addAttribute(MaxNonCompetitiveBoostAttribute.class);
SlowFuzzyTermsEnum fe =
new SlowFuzzyTermsEnum(terms, atts, startTerm, f.minSimilarity, f.prefixLength);
// store the df so all variants use same idf
int df = reader.docFreq(startTerm);
int numVariants = 0;
int totalVariantDocFreqs = 0;
BytesRef possibleMatch;
BoostAttribute boostAtt = fe.attributes().addAttribute(BoostAttribute.class);
while ((possibleMatch = fe.next()) != null) {
numVariants++;
totalVariantDocFreqs += fe.docFreq();
float score = boostAtt.getBoost();
if (variantsQ.size() < MAX_VARIANTS_PER_TERM || score > minScore) {
ScoreTerm st =
new ScoreTerm(
new Term(startTerm.field(), BytesRef.deepCopyOf(possibleMatch)),
score,
startTerm);
variantsQ.insertWithOverflow(st);
minScore = variantsQ.top().score; // maintain minScore
}
maxBoostAtt.setMaxNonCompetitiveBoost(
variantsQ.size() >= MAX_VARIANTS_PER_TERM ? minScore : Float.NEGATIVE_INFINITY);
}
if (numVariants > 0) {
int avgDf = totalVariantDocFreqs / numVariants;
if (df == 0) // no direct match we can use as df for all variants
{
df = avgDf; // use avg df of all variants
}
// take the top variants (scored by edit distance) and reset the score
// to include an IDF factor then add to the global queue for ranking
// overall top query terms
int size = variantsQ.size();
for (int i = 0; i < size; i++) {
ScoreTerm st = variantsQ.pop();
st.score = (st.score * st.score) * sim.idf(df, corpusNumDocs);
q.insertWithOverflow(st);
}
}
}
}
ts.end();
}
}