Example usage for org.apache.commons.collections15.comparators ReverseComparator ReverseComparator

Introduction

In this page you can find the example usage for org.apache.commons.collections15.comparators ReverseComparator ReverseComparator.

Prototype

public ReverseComparator(Comparator<T> comparator) 

Source Link

Document

Creates a comparator that inverts the comparison of the given comparator.

Usage

From source file:net.sf.jtmt.summarizers.LuceneSummarizer.java

/**
 * Compute top term query./*from   ww  w  .ja  v a  2  s.  co  m*/
 *
 * @param ramdir the ramdir
 * @return the query
 * @throws Exception the exception
 */
private Query computeTopTermQuery(Directory ramdir) throws Exception {
    final Map<String, Integer> frequencyMap = new HashMap<String, Integer>();
    List<String> termlist = new ArrayList<String>();
    IndexReader reader = IndexReader.open(ramdir, true);
    TermEnum terms = reader.terms();
    while (terms.next()) {
        Term term = terms.term();
        String termText = term.text();
        int frequency = reader.docFreq(term);
        frequencyMap.put(termText, frequency);
        termlist.add(termText);
    }
    reader.close();
    // sort the term map by frequency descending
    Collections.sort(termlist,
            new ReverseComparator<String>(new ByValueComparator<String, Integer>(frequencyMap)));
    // retrieve the top terms based on topTermCutoff
    List<String> topTerms = new ArrayList<String>();
    float topFreq = -1.0F;
    for (String term : termlist) {
        if (topFreq < 0.0F) {
            // first term, capture the value
            topFreq = (float) frequencyMap.get(term);
            topTerms.add(term);
        } else {
            // not the first term, compute the ratio and discard if below
            // topTermCutoff score
            float ratio = (float) ((float) frequencyMap.get(term) / topFreq);
            if (ratio >= topTermCutoff) {
                topTerms.add(term);
            } else {
                break;
            }
        }
    }
    StringBuilder termBuf = new StringBuilder();
    BooleanQuery q = new BooleanQuery();
    for (String topTerm : topTerms) {
        termBuf.append(topTerm).append("(").append(frequencyMap.get(topTerm)).append(");");
        q.add(new TermQuery(new Term("text", topTerm)), Occur.SHOULD);
    }
    System.out.println(">>> top terms: " + termBuf.toString());
    System.out.println(">>> query: " + q.toString());
    return q;
}

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