Class: Ferret::Search::MultiPhraseQuery::MultiPhraseWeight

Inherits:
Weight
  • Object
show all
Includes:
Index
Defined in:
lib/ferret/search/multi_phrase_query.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(query, searcher) ⇒ MultiPhraseWeight

Returns a new instance of MultiPhraseWeight.



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# File 'lib/ferret/search/multi_phrase_query.rb', line 60

def initialize(query, searcher)
  @query = query
  @term_arrays = query.term_arrays
  @positions = query.positions
  @similarity = query.similarity(searcher)
  @idf = 0.0

  # compute idf
  query.term_arrays.each do |terms|
    terms.each do |term|
      @idf += @similarity.idf_term(term, searcher)
    end
  end
end

Instance Attribute Details

#query ⇒ Object (readonly)

Returns the value of attribute query.



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# File 'lib/ferret/search/multi_phrase_query.rb', line 58

def query
  @query
end

#value ⇒ Object (readonly)

Returns the value of attribute value.



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# File 'lib/ferret/search/multi_phrase_query.rb', line 58

def value
  @value
end

Instance Method Details

#explain(reader, doc) ⇒ Object 



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# File 'lib/ferret/search/multi_phrase_query.rb', line 111

def explain(reader, doc)
 
  result = Explanation.new()
  result.description = "weight(#{@query} in #{doc}), product of:"

  idf_expl = Explanation.new(@idf, "idf(#{@query})")
  
  # explain query weight
  query_expl = Explanation.new()
  query_expl.description = "query_weight(#{@query}), product of:"

  boost_expl = Explanation.new(@query.boost(), "boost")
  (query_expl << boost_expl) if (@query.boost() != 1.0)

  query_expl << idf_expl
  
  query_norm_expl = Explanation.new(@query_norm,"query_norm")
  query_expl << query_norm_expl
  
  query_expl.value =
    boost_expl.value * idf_expl.value * query_norm_expl.value

  result << query_expl
 
  # explain field weight
  field_expl = Explanation.new()
  field_expl.description =
    "field_weight(#{@query} in #{doc}), product of:"

  tf_expl = scorer(reader).explain(doc)
  field_expl << tf_expl
  field_expl << idf_expl

  field_norm_expl = Explanation.new()
  field_norms = reader.get_norms(@query.field)
  field_norm =
    field_norms ? Similarity.decode_norm(field_norms[doc]) : 0.0
  field_norm_expl.value = field_norm
  field_norm_expl.description =
    "field_norm(field=#{@query.field}, doc=#{doc})"
  field_expl << field_norm_expl

  field_expl.value = tf_expl.value * idf_expl.value * field_norm_expl.value 
  result << field_expl

  if (query_expl.value == 1.0)
    return field_expl
  else
    result.value = query_expl.value * field_expl.value
    return result
  end
end

#normalize(query_norm) ⇒ Object 



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# File 'lib/ferret/search/multi_phrase_query.rb', line 80

def normalize(query_norm) 
  @query_norm = query_norm
  @query_weight *= query_norm                # normalize query weight
  @value = @query_weight * @idf              # idf for document 
end

#scorer(reader) ⇒ Object 



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# File 'lib/ferret/search/multi_phrase_query.rb', line 86

def scorer(reader)
  return nil if (@term_arrays.size == 0) # optimize zero-term case
  tps = []
  @term_arrays.each do |terms|
    p = []
    if (terms.length > 1)
      p = MultipleTermDocPosEnum.new(reader, terms)
    else
      p = reader.term_positions_for(terms[0])
    end
  
    return nil if (p == nil)
  
    tps << p
  end

  if (@query.slop == 0)
    return ExactPhraseScorer.new(self, tps, @positions, @similarity,
                                 reader.get_norms(@query.field))
  else
    return SloppyPhraseScorer.new(self, tps, @positions, @similarity,
                                  @query.slop, reader.get_norms(@query.field))
  end
end

#sum_of_squared_weights ⇒ Object 



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# File 'lib/ferret/search/multi_phrase_query.rb', line 75

def sum_of_squared_weights() 
  @query_weight = @idf * @query.boost()      # compute query weight
  return @query_weight * @query_weight       # square it
end