README

This is my solution to RPCFN #13: Economics 101
http://rubylearning.com/blog/2010/08/31/rpcfn-economics-101-13

I used 3 ways to solve it:
- using Hpricot and Nokogiri 
- using RegExp
- parsing the questions (and even write them in pure Ruby (no String))

hpricot18.rb

# 1 What is the population of the country with the most people? Yes, we know it’s China, but just how many people lived there in 1996?
# 2 What are the five countries with the highest inflation rates, and what were those rates in 1996?
# 3 What are the six continents in the file and which countries belong to which continent? Can you also produce them in alphabetical order?

# Idea: parse these sentences to make the search :p

require 'rubygems'
require 'hpricot'

doc = open('cia-1996.xml') { |f| Hpricot(f) }

# Countries without population (25/260)
# p countries.select { |country| country['population'].nil? }.map { |country| country['name'] }

# 1 What is the population of the country with the most people? Yes, we know it’s China, but just how many people lived there in 1996?
# China
# 1 210 004 956
countries = doc / :country # or doc.xpath('/cia/country')
china = countries.max_by { |country| country[:population].to_i }
puts china[:name]
puts china[:population].reverse.chars.each_slice(3).map(&:join).join(' ').reverse

puts
# 2 What are the five countries with the highest inflation rates, and what were those rates in 1996?
# {"Belarus"=>244.0, "Turkey"=>94.0, "Azerbaijan"=>85.0, "Malawi"=>83.3, "Yemen"=>71.3}

cc = countries.dup
p 5.times.inject({}) { |h,_|  
  c = cc.delete cc.max_by { |c| c[:inflation].to_f }
  h[c[:name]] = c[:inflation].to_f
  h
}

p countries.sort_by { |country| - country[:inflation].to_f }[0...5].inject({}) { |h,c| h[c[:name]] = c[:inflation].to_f and h }

puts
# 3 What are the six continents in the file and which countries belong to which continent? Can you also produce them in alphabetical order?
# ["Europe", "Asia", "North America", "Australia/Oceania", "South America", "Africa"]

p continents = (doc / :continent).map { |continent| continent[:name] }
puts
countries_by_continent = countries.inject(Hash.new { |h,k| h[k] = [] }) { |h,country|
  h[country[:continent]] << country[:name]
  h
}
p Hash[countries_by_continent.sort_by { |continent, countries| countries.sort and continent }]

nokogiri.rb

# 1 What is the population of the country with the most people? Yes, we know it’s China, but just how many people lived there in 1996?
# 2 What are the five countries with the highest inflation rates, and what were those rates in 1996?
# 3 What are the six continents in the file and which countries belong to which continent? Can you also produce them in alphabetical order?

# Idea: parse these sentences to make the search :p

require 'nokogiri'
doc = Nokogiri open 'cia-1996.xml'

# Countries without population (25/260)
# p countries.select { |country| country['population'].nil? }.map { |country| country['name'] }

# 1 What is the population of the country with the most people? Yes, we know it’s China, but just how many people lived there in 1996?
# China
# 1 210 004 956
countries = (doc / :country)
china = countries.max_by { |country| country[:population].to_i }
puts china[:name]
puts china[:population].reverse.chars.each_slice(3).map(&:join).join(' ').reverse

puts
# 2 What are the five countries with the highest inflation rates, and what were those rates in 1996?
# {"Belarus"=>244.0, "Turkey"=>94.0, "Azerbaijan"=>85.0, "Malawi"=>83.3, "Yemen"=>71.3}

cc = countries.dup
p 5.times.with_object({}) { |_,h|  
  c = cc.delete cc.max_by { |c| c[:inflation].to_f }
  h[c[:name]] = c[:inflation].to_f
}

p countries.sort_by { |country| - country[:inflation].to_f }[0...5].each_with_object({}) { |c,h| h[c[:name]] = c[:inflation].to_f }

#max = Float::INFINITY
#countries.inject([]) { |best, country|
#}

puts
# 3 What are the six continents in the file and which countries belong to which continent? Can you also produce them in alphabetical order?
# ["Europe", "Asia", "North America", "Australia/Oceania", "South America", "Africa"]

p continents = (doc / :continent).map { |continent| continent[:name] }
puts
countries_by_continent = countries.each_with_object(Hash.new { |h,k| h[k] = [] }) { |country,h|
  h[country[:continent]] << country[:name]
}
#p Hash[countries_by_continent.sort_by { |continent, countries| countries.sort and continent }]

puts
p Hash[countries.group_by { |country| country[:continent] }.map { |continent,countries| [continent,countries.map { |c| c[:name] }] }.sort_by { |continent, countries| countries.sort and continent }]

parse.rb

# encoding: utf-8

# 1 What is the population of the country with the most people? Yes, we know it’s China, but just how many people lived there in 1996?
# 2 What are the five countries with the highest inflation rates, and what were those rates in 1996?
# 3 What are the six continents in the file and which countries belong to which continent? Can you also produce them in alphabetical order?

require 'nokogiri'
require 'ap'

class String
  PLURALS = { "country" => "countries" }
  NUMBERS = { "three" => 3, "four" => 4, "five" => 5 }
  def singularize
    PLURALS.key self
  end
  def convert
    case self
    when /\A-?\d+\z/; to_i
    when /\A-?\d+\.\d+\z/; to_f
    when /\A\d{2} \d{2} \d{4}\z/; Time.new *split.reverse
    end
  end
  alias _to_i to_i
  def to_i
    NUMBERS[self] || _to_i
  end
  def === node
    node[self]
  end
  def inspect
    dup
  end
end

class Time
  def inspect
    strftime('%d %B %Y')
  end
end

class Integer
  def inspect
    to_s.reverse.chars.each_slice(3).map(&:join).join(' ').reverse
  end
end

POS_SUPERLATIVES, NEG_SUPERLATIVES = %w[most biggest highest newest], %w[oldest]
SUPERLATIVES = (POS_SUPERLATIVES+NEG_SUPERLATIVES).join '|'

def read question, doc
  puts question
  case question
  when /What is the (?<attribute>[\w ]+) of the (?<element>\w+) with the (?:#{SUPERLATIVES})/
    attribute, element = $~[:attribute].tr(' ','_'), $~[:element]
    best = (doc / element).grep(attribute).max_by { |e| e[attribute].convert }
    puts best[:name]
    ap best[attribute].convert
  when /What are the (?<n>\w+) (?<elements>\w+) with the (?<sup>#{SUPERLATIVES}) (?<attribute>[\w ]+(?=\?)|\w+)/
    n, elements, attribute = $~[:n], $~[:elements], $~[:attribute].tr(' ','_')
    ap (doc / elements.singularize)
            .grep(attribute) 
            .sort_by { |e| e[attribute].convert }
            .tap { |a| a.reverse! if POS_SUPERLATIVES.include?($~[:sup]) }
            .take(n.to_i)
            .each_with_object({}) { |e,h| h[e[:name]] = e[attribute].convert }
  when /What are the \w+ \w+ .+ which (?<elements>\w+) (belong to|has) which (?<group>\w+)/
    _ = (doc / $~[:elements].singularize)
    . grep($~[:group])
    . each_with_object(Hash.new { |h,k| h[k] = [] }) { |e,h| h[e[$~[:group]]] << e[:name] }
    
    _ = Hash[_.sort_by { |group, elements| elements.sort and group }] if question =~ /in alphabetical order/
    _.each_pair { |group, elements|
      puts "  \e[34m#{group.inspect}:\e[0m #{elements.join ', '}"
    }
  end
  puts
end

if __FILE__ == $0
  doc = Nokogiri open 'cia-1996.xml'

  read "What is the population of the country with the most people? Yes, we know it’s China, but just how many people lived there in 1996?", doc
  read "What are the five countries with the highest inflation rates, and what were those rates in 1996?", doc
  #read "What are the six continents in the file and which countries belong to which continent? Can you also produce them in alphabetical order?", doc

  read "What is the total area of the country with the biggest territory?", doc
  read "What is the infant mortality of the country with the highest infant mortality?", doc

  read "What are the three countries with the highest population growth?", doc
  read "What are the three countries with the newest indep date?", doc
  read "What are the three countries with the oldest indep date?", doc
  read "What are the five countries with the biggest gdp total?", doc

  #read "What are the different governments and which countries has which government?", doc
end

question.rb

# This heavily use method_missing to not have any String
require './parse'

class Question
  def initialize(&block)
    @question = []
    instance_exec(&block)
  end
  
  def method_missing(meth, *args)
    @question << meth
  end
  
  def to_s
    @question.reverse.join ' '
  end

  def inspect
    "#<Question: #{to_s}>"
  end
  
  def ask doc
    read to_s, doc
  end
end
def ask(&block)
  Question.new(&block).ask(@doc)
end

@doc = Nokogiri open 'cia-1996.xml'

ask { What is the population of the country with the most people? }

ask { What are the five countries with the highest inflation rates }

ask { What are the six continents within the file _and which countries belong to which continent? }

regexp.rb

doc = open 'cia-1996.xml', &:read

class Array
  def to_h
    Hash[self]
  end
end

# 1 What is the population of the country with the most people? Yes, we know it’s China, but just how many people lived there in 1996?
puts doc.scan(/<country.+? name='(.+?)'.+? population='(\d+)'/m).max_by { |country, population| population.to_i }.join ' '

puts
# 2 What are the five countries with the highest inflation rates, and what were those rates in 1996?

# p countries.sort_by { |country| - country[:inflation].to_f }[0...5].map.with_object({}) { |c,h| h[c[:name]] = c[:inflation].to_f }
p doc.scan(/<country.+? name='(.+?)'.+? inflation='([\d.]+)'/m).sort_by { |country,inflation| -inflation.to_f }[0...5].to_h

puts
# 3 What are the six continents in the file and which countries belong to which continent? Can you also produce them in alphabetical order?
p doc.scan(/<country.+? continent='(.+?)'.+? name='(.+?)'/m)
     .group_by(&:first)
     .map { |continent,countries| [continent, countries.map(&:last)] }
     .sort_by { |continent, countries| countries.sort and continent }.to_h