Wikipedia Parser

Wikipedia parser lets you parse .bz2 and .xml dumps of Wikipedia articles without decompressing the .bz2 file. The Parser functions as an enumerator over the pages to stream-parse the dumps (which can take several hours to read).

Usage

To get started gem install wikipedia_parser, then head over to the Wikipedia dumps, and now you can:

require 'wikipedia_parser'

parser = WikiParser.new :path => File.dirname(__FILE__)+"/enwiki.bz2" # path to wikipedia dump

loop do
	page = parser.get_next_page
	if !page              then break
	else
		puts page.title
		puts page.internal_links
	end
end

The internal links contain the title and the uri of the destination page:

loop do
	page = parser.get_next_page
	if !page              then break
	else
		page.internal_links.each do |link|
			puts link[:title][page.language] + "points to" + link[:uri]
		end
	end
end

For larger pages, such as Barack Obama or United States reading all the internal links takes a long time. If you are only interested in certain pages, say those that start with the letter A, then you could skip those pages you don't want without incuring the cost of reading the entire article since the title is at the top of the xml file. Here's one way of implementing this check:

loop do
	page = parser.get_next_page :until => "title" # or "id" or "redirect" (boolean)
	if !page then break
	else
		if page.title ~= /^[aA]/ # starts with A
			page.finish_processing # reads the remainder of the nodes.
			page.internal_links.each do |link|
				puts link[:title][page.language] + "points to" + link[:uri]
			end
		end
	end
end

Testing

Simply run:

rake test

Issues

On Mac and Linux bzip2 is included, but it appears that on Windows a seperate bzip2 reader is needed.