def weightings(records_size)
      out = ActiveSupport::OrderedHash.new

      ## phurni 2012-09-21 when records_size is exactly the @records.size (all records are matches), the Math.log would
      ## return 0 which means the frequency (pos.size) will have no effect. Cheat to make it like the matching
      ## record is one less, so that we still can weight on frequency.
      matching_records_size = (records_size == @records.size ? @records.size - 1 : @records.size)

      @records.each do |r_id, pos|

        # Fixes a bug when the records_size is zero. i.e. The only record
        # contaning the word has been deleted.
        if records_size < 1
          out[r_id] = 0.0
          next
        end

        # weighting = frequency * log (records.size / records_with_atom)
        ## parndt 2010/05/03 changed to records_size.to_f to avoid -Infinity Errno::ERANGE exceptions
        ## which would happen for example Math.log(1 / 20) == -Infinity but Math.log(1.0 / 20) == -2.99573227355399
        out[r_id] = pos.size * Math.log(records_size.to_f / matching_records_size)
      end

      out
    end
def weightings(records_size)
      out = ActiveSupport::OrderedHash.new

      ## phurni 2012-09-21 when records_size is exactly the @records.size (all records are matches), the Math.log would
      ## return 0 which means the frequency (pos.size) will have no effect. Cheat to make it like the matching
      ## record is one less, so that we still can weight on frequency.
      matching_records_size = (records_size == @records.size ? @records.size - 1 : @records.size)

      @records.each do |r_id, pos|

        # Fixes a bug when the records_size is zero. i.e. The only record
        # contaning the word has been deleted.
        if records_size < 1
          out[r_id] = 0.0
          next
        end

        # weighting = frequency * log (records.size / records_with_atom)
        ## parndt 2010/05/03 changed to records_size.to_f to avoid -Infinity Errno::ERANGE exceptions
        ## which would happen for example Math.log(1 / 20) == -Infinity but Math.log(1.0 / 20) == -2.99573227355399
        out[r_id] = pos.size * Math.log(records_size.to_f / matching_records_size)
      end

      out
    end
Returns a hash of record_ids and weightings for each record in the
 atom.