ansaurus

Question

Nokogiri: Sort Array of IDs according to order in HTML document.

Answer 1

+1 A:

I don't know what Nokogiri is, but if you have the HTML code as a String, than it would be possible to get the order with regexp matching, for example:

var str = '<html>...</html>'; // the HTML code to check
var ids = ['bar', 'para-3', 'para-2', 'para-7']; // the array with all IDs to check
var reg = new RegExp('(?:id=[\'"])('+ids.join('|')+')(?:[\'"])','g') // the regexp
var result = [], tmp; // array holding the result and a temporary variable
while((tmp = reg.exec(str))!==null)result.push(tmp[1]); // matching the IDs
console.log(result); // ['para-2', 'para-3', 'bar', 'para-7']

using this code you have to be careful with IDs containing regexp meta-characters. They should be escaped first.

Rafael 2009-05-06 16:31:53

Answer 2

A:

Here's one way to do it in Nokogiri - there may be others which are more efficient, as this ends up walking the entire DOM.

require 'set'

#Using a set here to make lookup O(1), because we don't care about the initial order
id_set = ['bar', 'para-3', 'para-2', 'para-7'].to_set
sorted = []

value.root.traverse do |node|
  node_id = node['id']
  sorted << node_id if node_id && id_set.delete?(node_id)
end
# sorted is now ['para-2', 'para-3', 'bar', 'para-7']

EDIT: Here's a one-liner that gets the same results, but I haven't done benchmarking to see which is faster.

ids = ['bar', 'para-3', 'para-2', 'para-7']
value.xpath("//*[@id]").collect {|node| node['id']} & ids

Greg Campbell 2009-05-06 16:37:29

Answer 3

A:

This is the solution a coworker and I came up with:

parent = value.css('body').first
indexes = []
parent.children.each do |child|
  indexes << child['id']
end

puts @un_array.sort! { |x,y| indexes.index(x) <=> indexes.index(y) }

First I fetch all IDs of the HTML document into an Array, than I sort @un_array according to the IDs-Array I created before.

Javier 2009-05-07 13:39:53

ansaurus

tags:

views:

answers:

Nokogiri: Sort Array of IDs according to order in HTML document.

related questions