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From "Dmitry Goldenberg" <dmitry.goldenb...@weblayers.com>
Subject How to map terms to frequencies for a doc - ?
Date Tue, 07 Feb 2006 15:33:53 GMT
Hello,

Given a query, I want to be able to, for each query term, get the number of occurrences of
the term.  I have tried what I'm including below and it does not seem to provide reliable
results.  Seems to work fine with exact matching but as soon as stemming kicks in, all bets
are off as to value of the number of occurrences returned.  E.g. if the query is "refer" the
following tokens are found: "refer", "referred", etc but the actual number of occurrences
in the document differs from what getTermFrequencies reports.

Any ideas, anyone?  Can this be written in a simpler and/or more efficient way?
Thanks -

      int totalOccurrences = 0;

      reader = IndexReader.open(getDirectory(indexDirPath));
      HashSet terms = new HashSet();
      query.extractTerms(terms);

      TermFreqVector[] tfvs = reader.getTermFreqVectors(docId);
      if (tfvs != null) {

        // For each term frequency vector (i.e. for each field)
        for (int i = 0; i < tfvs.length; i++) {
          String field = tfvs[i].getField();
          String[] strTerms = tfvs[i].getTerms();
          int[] tfs = tfvs[i].getTermFrequencies();

          if (strTerms != null) {

            // For each term in the query
            for (Iterator iter = terms.iterator(); iter.hasNext();) {

              Term term = (Term) iter.next();
              // For each term in the vector
              for (int j = 0; j < strTerms.length; j++) {

                // If found the query term among the vector terms
                if (field.equals(term.field()) && strTerms[j].equals(term.text()))
{

                  // Add the term frequency to the total
                  totalOccurrences += tfs[j];

                }
              }
            }
          }
        }
      }


 

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