This builds on and refactors sentence-prep.rb, yielding an inverted index for a list of documents passed in as string arguments on the command line.

build_inverted_index.rb

#!/usr/bin/ruby

require 'rubygems'
require 'fast_stemmer'

def doc_prep(docs)
  prepped_docs = {}
	doc_id = 0
	stop_words = "a,able,about,across,after,all,almost,also,am,among,an,and,any,are,as,at,be,because,been,but,by,can,cannot,could,dear,did,do,does,either,else,ever,every,for,from,get,got,had,has,have,he,her,hers,him,his,how,however,i,if,in,into,is,it,its,just,least,let,like,likely,may,me,might,most,must,my,neither,no,nor,not,of,off,often,on,only,or,other,our,own,rather,said,say,says,she,should,since,so,some,than,that,the,their,them,then,there,these,they,this,tis,to,too,twas,us,wants,was,we,were,what,when,where,which,while,who,whom,why,will,with,would,yet,you,your,use,used".split(',')

	docs.each do |doc|
		doc_id += 1
		unstemmed_words =  doc.gsub(/[[:punct:]]/, '').downcase.split.select { |word| !stop_words.include?(word) }
		stemmed_words = []
		unstemmed_words.each { |word| stemmed_words << word.stem }
		prepped_docs[doc_id] = stemmed_words
	end

	return prepped_docs
end

def create_posting
end

def create_dictionary_and_postings(docs)
	dictionary = {}
	postings = 
	term_id = 0
	docs.each do |doc_id, doc|
		words_in_this_doc = []
		doc.each do |word|
			symbolized_word = word.to_sym
			if dictionary.has_key?(symbolized_word)
				dictionary[symbolized_word][:cf] += 1
				if !words_in_this_doc.include?(symbolized_word)
					words_in_this_doc << symbolized_word
					dictionary[symbolized_word][:df] += 1
					dictionary[symbolized_word][:postings] << {doc_id: doc_id, tf: 1}
				else
					dictionary[symbolized_word][:postings].each do |posting|
						posting[:tf] = posting[:tf] += 1 if posting[:doc_id] == doc_id
					end
				end	
			else
				dictionary[symbolized_word] = {term_id: term_id += 1, cf: 1, df: 1, postings: [{doc_id: doc_id, tf: 1}]}
				words_in_this_doc << symbolized_word
			end
		end
	end

	return dictionary
end


docs = []
ARGV.each do |doc|
	docs << doc
end
docs = doc_prep(docs)
puts docs.inspect
index = create_dictionary_and_postings(docs)
# index.each { |term, values| puts "#{term}=>#{values}\n" }
sorted_index = index.to_a.sort
sorted_index.each { |dp| puts "#{dp[0]}=>#{dp[1]}" }