Method: TFIDF.idf

Defined in:
lib/zipf/tfidf.rb

.idf(list_of_hashes) ⇒ Object

returns idf value for each word in a vocabulary



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# File 'lib/zipf/tfidf.rb', line 24

def TFIDF::idf list_of_hashes
  vocab = list_of_hashes.values.flatten.uniq
  n = list_of_hashes.size.to_f
  idf = {}
  vocab.each { |i|
    df = list_of_hashes.values.flatten.count i
    idf[i] = Math.log(n/df)
  }
  return idf
end