document.rb
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#!/usr/bin/env ruby
#--
# This file is a part of the mirimiri library
#
# Copyright (C) 2010-2011 Romain Deveaud <romain.deveaud@gmail.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#++
# General module
module Mirimiri
# A Document is a bag of words and is constructed from a string.
class Document
attr_reader :words, :doc_content, :xcount
# Any non-word characters are removed from the words (see http://perldoc.perl.org/perlre.html
# and the \\W special escape).
#
# Protected function, only meant to by called at the initialization.
def format_words
wo = []
@doc_content.split.each do |w|
w.split(/\W/).each do |sw|
wo.push(sw.downcase) if sw =~ /[[:alpha:]]/
end
end
wo
end
# Returns an Array containing the +n+-grams (words) from the current Document.
#
# ngrams(2) #=> ["the free", "free encyclopedia", "encyclopedia var", "var skin", ...]
def ngrams(n)
window = []
ngrams_array = []
if @ngrams[n].nil?
@words.each do |w|
window.push(w)
if window.size == n
ngrams_array.push window.join(" ")
window.delete_at(0)
end
end
@ngrams[n] = ngrams_array
end
@ngrams[n]
end
# Returns a Hash containing the words and their associated counts in the current Document.
#
# count_words #=> { "guitar"=>1, "bass"=>3, "album"=>20, ... }
def count_words
counts = Hash.new { |h,k| h[k] = 0 }
@words.each { |w| counts[w] += 1 }
counts
end
# Old entropy function.
# TODO: remove.
def entropy0(s)
en = 0.0
s.split.each do |w|
p_wi = @xcount[w].to_f/@words.count.to_f
en += p_wi*Math.log2(p_wi)
end
en *= -1
en
end
# Computes the entropy of a given string +s+ inside the document.
#
# If the string parameter is composed of many words (i.e. tokens separated
# by whitespace(s)), it is considered as an ngram.
#
# entropy("guitar") #=> 0.014348983965324762
# entropy("dillinger escape plan") #=> 0.054976093116768154
def entropy(s)
en = 0.0
size = s.split.size
if size == 1
p_wi = @xcount[s].to_f/@words.count.to_f
en += p_wi*Math.log(p_wi)
elsif size > 1
ng_size = ngrams(size)
p_wi = ng_size.count(s).to_f/ng_size.count.to_f
en += p_wi*Math.log(p_wi)
end
en *= -1
en
end
# Computes the term frequency of a given *word* +s+.
#
# tf("guitar") #=> 0.000380372765310004
def tf(s)
@xcount[s].to_f/@words.size.to_f
end
# Computes the KL divergence between the language model of the +self+
# and the language model of +doc+.
#
# KL is not symmetric, see http://en.wikipedia.org/wiki/Kullback-Leibler_divergence
# for more information.
#
# d1.kl(d2) #=> 0.2971808085725761
def kl(doc)
raise ArgumentError, 'Argument is not a Mirimiri::Document' unless doc.is_a? Mirimiri::Document
vocab = self.words & doc.words
vocab.inject(0.0) { |res,w| res + self.tf(w)*Math.log(self.tf(w)/doc.tf(w)) }
end
def initialize(content="")
@doc_content = content
@words = format_words
@xcount = count_words
@ngrams = {}
end
protected :format_words, :count_words
end
# A WebDocument is a Document with a +url+.
class WebDocument < Document
attr_reader :url
# Returns the HTML text from the page of a given +url+.
def self.get_content(url)
require 'net/http'
Net::HTTP.get(URI.parse(url))
end
# WebDocument constructor, the content of the Document is the HTML page
# without the tags.
def initialize(url,only_tags=nil)
require 'sanitize'
@url = url
content = only_tags.nil? ? WebDocument.get_content(url) : WebDocument.get_content(url).extract_xmltags_values(only_tags).join("")
super Sanitize.clean(content, :remove_contents => ['script','style'])
end
end
# A WikipediaPage is a WebDocument.
class WikipediaPage < WebDocument
require 'rexml/document'
require 'net/http'
require 'kconv'
def self.search_wikipedia_titles(name)
# raise ArgumentError, "Bad encoding", name unless name.isutf8
res = REXML::Document.new(Net::HTTP.get( URI.parse "http://en.wikipedia.org/w/api.php?action=query&list=search&srsearch=#{URI.escape name}&srlimit=20&format=xml" ).force_encoding("ISO-8859-1").encode("UTF-8")).elements['api/query/search']
res.collect { |e| e.attributes['title'] } unless res.nil?
end
def self.get_url(name)
raise ArgumentError, "Bad encoding", name unless name.isutf8
atts = REXML::Document.new(Net::HTTP.get( URI.parse "http://en.wikipedia.org/w/api.php?action=query&titles=#{URI.escape name}&inprop=url&prop=info&format=xml" ).unaccent.toutf8).elements['api/query/pages/page'].attributes
atts['fullurl'] if atts['missing'].nil?
end
def self.search_homepage(name)
title = WikipediaPage.search_wikipedia_titles name
WikipediaPage.get_url(title[0]) unless title.nil? || title.empty?
end
def self.extract_anchors(url)
self.get_content(url).extract_xmltags_values('p').join(' ').scan(/<a href="(.+?)" title=.*?>(.+?)<\/a>/).delete_if { |a| a[0] =~ /^\/wiki\/.*$/.negated }
end
end
class FreebasePage < WebDocument
require 'net/http'
require 'kconv'
require 'json'
def self.search_article_ids query,limit
raise ArgumentError, "Bad encoding", name unless name.isutf8
JSON.parse(Net::HTTP.get( URI.parse "http://api.freebase.com/api/service/search?query=#{query.gsub(" ","+")}&limit=#{limit}" ))['result'].collect { |a| a['article']['id'] unless a['article'].nil? }.compact
end
def self.get_url id
"http://api.freebase.com/api/trans/raw#{id}"
end
end
end