Class: Hobix::Search::Simple::Searcher

Inherits:
Object
  • Object
show all
Defined in:
lib/hobix/search/simple.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(dict, document_vectors, cache_file) ⇒ Searcher

Returns a new instance of Searcher.



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# File 'lib/hobix/search/simple.rb', line 63

def initialize(dict, document_vectors, cache_file)
  @dict = dict
  @document_vectors = document_vectors
  @cache_file = cache_file
end

Class Method Details

.load(cache_file, wash = false) ⇒ Object

Serialization support. At some point we’ll need to do incremental indexing. For now, however, the following seems to work fairly effectively on 1000 entry blogs, so I’ll defer the change until later.



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# File 'lib/hobix/search/simple.rb', line 128

def Searcher.load(cache_file, wash=false)
  dict = document_vectors = nil
  modified = false
  loaded   = false
  begin
    File.open(cache_file, "r") do |f| 
      unless wash
        dict = Marshal.load(f)
        document_vectors = Marshal.load(f)
        loaded = true
      end
    end
  rescue
  ;
  end
    
  unless loaded
    dict = Dictionary.new
    document_vectors = {}
    modified = true
  end
  
  s = Searcher.new(dict, document_vectors, cache_file)
  s.dump if modified
  s
end

Instance Method Details

#catalog(entry) ⇒ Object

Create a new dictionary and document vectors from a blog archive



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# File 'lib/hobix/search/simple.rb', line 176

def catalog(entry)
  unless has_entry? entry.identifier, entry.mtime
    vector = Vector.new
    vector.at = entry.mtime
    extract_words_for_searcher(entry.content.downcase) do |word|
      word_index = @dict.add_word(word, entry.classifications)
      if word_index
        vector.add_word_index(word_index) 
      end
    end
    @document_vectors[entry.identifier] = vector
  end
end

#classifications(text) ⇒ Object 



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# File 'lib/hobix/search/simple.rb', line 190

def classifications(text)
  score = Hash.new
  @dict.clsf.each do |category, category_words|
    score[category] = 0
    total = category_words.values.inject(0) {|sum, element| sum+element}
    extract_words_for_searcher(text) do |word|
      s = category_words.has_key?(word) ? category_words[word] : 0.1
      score[category] += Math.log(s/total.to_f)
    end
  end
  score
end

#classify(text) ⇒ Object 



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# File 'lib/hobix/search/simple.rb', line 203

def classify(text)
  (classifications(text).sort_by { |a| -a[1] })[0][0]
end

#dump ⇒ Object 



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# File 'lib/hobix/search/simple.rb', line 155

def dump
  File.open(@cache_file, "w") do |fileInstance|
    Marshal.dump(@dict, fileInstance)
    Marshal.dump(@document_vectors, fileInstance)
  end
end

#extract_words_for_searcher(text) ⇒ Object 



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# File 'lib/hobix/search/simple.rb', line 162

def extract_words_for_searcher(text)
  text.scan(/[-+]?\w[\-\w:\\]{2,}/) do |word|
    yield word
  end
end

#find_words(words) ⇒ Object

Return SearchResults based on trying to find the array of words in our document vectors

A word beginning ‘+’ must appear in the target documents A word beginning ‘-’ must not appear other words are scored. The documents with the highest scores are returned first



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# File 'lib/hobix/search/simple.rb', line 77

def find_words(words)
  search_results = SearchResults.new
    
  general = Vector.new
  must_match = Vector.new
  must_not_match = Vector.new
  not_found = false
  
  extract_words_for_searcher(words.join(' ')) do |word|
    case word[0]
    when ?+
      word = word[1,99]
      vector = must_match
    when ?-
   word = word[1,99]
      vector = must_not_match
    else
   vector = general
    end
    
    index = @dict.find(word.downcase)
    if index
      vector.add_word_index(index)
    else
      not_found = true
   search_results.add_warning "'#{word}' does not occur in the documents"
    end
  end
    
  if (general.num_bits + must_match.num_bits).zero? 
    search_results.add_warning "No valid search terms given"
  elsif not not_found
    res = []
    @document_vectors.each do |entry, (dvec, mtime)|
      score = dvec.score_against(must_match, must_not_match, general)
      res << [ entry, score ] if score > 0
    end
    
    res.sort {|a,b| b[1] <=> a[1] }.each {|name, score|
      search_results.add_result(name, score)
    }
    
    search_results.add_warning "No matches" unless search_results.contains_matches
  end
  search_results
end

#has_entry?(id, mtime) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/hobix/search/simple.rb', line 168

def has_entry? id, mtime
  dvec = @document_vectors[id]
  return true if dvec and dvec.at.to_i >= mtime.to_i
end