Class: Ferret::Search::Spans::SpanScorer

Inherits:
Ferret::Search::Scorer show all
Includes:
Ferret::Search
Defined in:
lib/ferret/search/spans/span_scorer.rb

Constant Summary

Constants inherited from Ferret::Search::Scorer

Ferret::Search::Scorer::MAX_DOCS

Instance Attribute Summary

Attributes inherited from Ferret::Search::Scorer

#similarity

Instance Method Summary collapse

Methods inherited from Ferret::Search::Scorer

#each_hit, #each_hit_up_to

Constructor Details

#initialize(spans, weight, similarity, norms) ⇒ SpanScorer

Returns a new instance of SpanScorer.



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# File 'lib/ferret/search/spans/span_scorer.rb', line 5

def initialize(spans, weight, similarity, norms)
  @first_time = true
  @more = true
 
  super(similarity)
  @spans = spans
  @norms = norms
  @weight = weight
  @value = weight.value()
  @freq = 0.0
end

Instance Method Details

#doc ⇒ Object 



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# File 'lib/ferret/search/spans/span_scorer.rb', line 37

def doc() return @doc end

#explain(doc) ⇒ Object 



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# File 'lib/ferret/search/spans/span_scorer.rb', line 61

def explain(doc)
  tf_explanation = Explanation.new()

  skip_to(doc)

  phrase_freq = ((doc() == doc) ? @freq : 0.0)
  tf_explanation.value = similarity().tf(phrase_freq)
  tf_explanation.description = "tf(phrase_freq=#{phrase_freq})"

  return tf_explanation
end

#next? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/ferret/search/spans/span_scorer.rb', line 17

def next?
  if (@first_time) 
    @more = @spans.next?
    @first_time = false
  end

  return false if not @more

  @freq = 0.0
  @doc = @spans.doc

  while (@more and @doc == @spans.doc) 
    match_length = @spans.finish - @spans.start
    @freq += similarity().sloppy_freq(match_length)
    @more = @spans.next?
  end

  return (@more or @freq != 0.0)
end

#score ⇒ Object 



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# File 'lib/ferret/search/spans/span_scorer.rb', line 39

def score()
  raw = similarity().tf(@freq) * @value           # raw score
  # normalize
  return raw * Similarity.decode_norm(@norms[@doc])
end

#skip_to(target) ⇒ Object 



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# File 'lib/ferret/search/spans/span_scorer.rb', line 45

def skip_to(target)
  @more = @spans.skip_to(target)

  return false if not @more

  @freq = 0.0
  @doc = @spans.doc()

  while (@more and @spans.doc() == target) 
    @freq += similarity().sloppy_freq(@spans.finish - @spans.start)
    @more = @spans.next?
  end

  return (@more or @freq != 0.0)
end