From: Siep Korteling <s.korteling@...>
Date: 2008-08-07T05:25:32+09:00
Subject: Re: Need help detecting overlapping ranges

Bryan Richardson wrote:
> Hello all,
> 
> I am writing some code where I create a bunch of ranges, then at the end
> I want to create new ranges out of any ranges that overlap one another.
> For example, say I have the following ranges:
> 
> (1..5) (7..11) (22..29) (5..8)
> 
> Given the ranges above, I want to end up with the following ranges:
> 
> (1..11) (22..29)
> 
(...)
> This code works, but it is *EXTREMELY* slow (my current array of ranges
> is averaging out to ~24000 range elements).  Anyone have an idea of how
> to speed it up?
> 
> --
> Thanks!
> Bryan

Sets are usually much faster then large arrays and sets have a divide 
method.

require 'set'
ranges=[(1..5),(7..11),(22..29),(5..8)]
set=Set.new
  ranges.each do|range|
  range.each do|el|
set<<el
end
end
sets = set.divide { |i,j| (i - j).abs == 1 } #straight from the 
documentation!

p sets
#<Set: {#<Set: {27, 22, 28, 23, 29, 24, 25, 26}>, #<Set: {5, 11, 6, 1, 
7, 2, 8, 3, 9, 4, 10}>}>

hth,

Siep

-- 
Posted via http://www.ruby-forum.com/.