Class: PlagiarismChecker

Inherits:
Object
  • Object
show all
Defined in:
lib/automated_metareview/plagiarism_check.rb

Instance Method Summary collapse

Instance Method Details

#check_for_plagiarism(review_text, subm_text) ⇒ Object

reviewText and submText are array containing review and submission texts



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# File 'lib/automated_metareview/plagiarism_check.rb', line 10

def check_for_plagiarism(review_text, subm_text)
  result = false
  for l in 0..review_text.length - 1 #iterating through the review's sentences
    review = review_text[l].to_s
    # puts "review.class #{review.to_s.class}.. review - #{review}"
    for m in 0..subm_text.length - 1 #iterating though the submission's sentences
      submission = subm_text[m].to_s  
      # puts "submission.class #{submission.to_s.class}..submission - #{submission}"
      rev_len = 0
      
      rev = review.split(" ") #review's tokens, taking 'n' at a time
      array = review.split(" ")
      
      while(rev_len < array.length) do
        if(array[rev_len] == " ") #skipping empty
          rev_len+=1
          next
        end
        
        #generating the sentence segment you'd like to compare
        rev_phrase = array[rev_len]
        add = 0 #add on to this when empty strings found  
        for j in rev_len+1..(NGRAM+rev_len+add-1) #concatenating 'n' tokens
          if(j < array.length)
            if(array[j] == "") #skipping empty
              add+=1
              next
            end
            rev_phrase = rev_phrase +" "+  array[j]
          end
        end
        
        if(j == array.length)
          #if j has reached the end of the array, then reset rev_len to the end of array to, or shorter strings will be compared
          rev_len = array.length
        end
        
        #replacing punctuation
        tp = TextPreprocessing.new
        submission = tp.contains_punct(submission)
        rev_phrase = tp.contains_punct(rev_phrase)
        #puts "Review phrase: #{rev_phrase} .. #{rev_phrase.split(" ").length}"
        
        #checking if submission contains the review and that only NGRAM number of review tokens are compared
        if(rev_phrase.split(" ").length == NGRAM and submission.downcase.include?(rev_phrase.downcase))
          result = true
          break
        end
        #System.out.println("^^^ Plagiarism result:: "+result);
        rev_len+=1
      end #end of the while loop
      if(result == true)
        break
      end  
    end #end of for loop for submission
    if(result == true)
      break
    end
  end #end of for loop for reviews    
  return result
end

#compare_reviews_with_questions_responses(auto_metareview, map_id) ⇒ Object

Checking if the response has been copied from the review questions or from other responses submitted.



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# File 'lib/automated_metareview/plagiarism_check.rb', line 76

def compare_reviews_with_questions_responses(auto_metareview, map_id)
  review_text_arr = auto_metareview.review_array
  response = Response.find(:first, :conditions => ["map_id = ?", map_id])
  scores = Score.find(:all, :conditions => ["response_id = ?", response.id])
  questions = Array.new
  #fetching the questions for the responses
  for i in 0..scores.length - 1
    questions << Question.find_by_sql(["Select * from questions where id = ?", scores[i].question_id])[0].txt
  end
  
  count_copies = 0 #count of the number of responses that are copies either of questions of other responses
  rev_array = Array.new #holds the non-plagiairised responses
  #comparing questions with text
  for i in 0..scores.length - 1
    if(!questions[i].nil? and !review_text_arr[i].nil? and questions[i].downcase == review_text_arr[i].downcase)
      count_copies+=1
      next #skip comparing with other responses
    end
    
    #comparing response with other responses
    flag = 0
    for j in 0..review_text_arr.length - 1
      if(i != j and !review_text_arr[i].nil? and !review_text_arr[j].nil? and review_text_arr[i].downcase == review_text_arr[j].downcase)
        count_copies+=1
        flag = 1
        break
      end
    end

    if(flag == 0) #ensuring no match with any of the review array's responses
      rev_array << review_text_arr[i]
    end
  end
  
  #setting @review_array as rev_array
  if(count_copies > 0) #resetting review_array only when plagiarism was found
     auto_metareview.review_array = rev_array
  end
  
  if(count_copies > 0 and count_copies == scores.length)
    return ALL_RESPONSES_PLAGIARISED #plagiarism, with all other metrics 0
  elsif(count_copies > 0)
    return SOME_RESPONSES_PLAGIARISED #plagiarism, while evaluating other metrics
  end
end

#google_search_response(auto_metareview) ⇒ Object

Checking if the response was copied from google



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# File 'lib/automated_metareview/plagiarism_check.rb', line 125

def google_search_response(auto_metareview)
  review_text_arr = auto_metareview.review_array
  # require 'ruby-web-search'
  count = 0
  temp_array = Array.new
  review_text_arr.each{
    |rev_text|
    if(!rev_text.nil?)
      #placing the search text within quotes to search exact match for the complete text
      response = RubyWebSearch::Google.search(:query => "\""+ rev_text +"\"") 
      #if the results are greater than 0, then the text has been copied
      if(response.results.length > 0)
        count+=1
      else
        temp_array << rev_text #copying the non-plagiarised text for evaluation
      end
    end
  }
  #setting temp_array as the @review_array
  auto_metareview.review_array = temp_array
  
  if(count > 0)
    return true
  else
    return false
  end
end