From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-10-11T18:36:00+09:00
Subject: Re: Testing for subarrays

On Mon, Oct 11, 2010 at 11:27 AM, Michel Demazure <michel@demazure.com> wrote:
> I want to check whether a given array contains a given subarray and
> return the corresponding range.
> Is there a builtin method ? If not, do you have better than this :
>
> class Array
>  def look_up(sub_array)
>    len = sub_array.size
>    self.each_cons(len).with_index do |cons, index|
>      return Range.new(index, index + len - 1) if cons == sub_array
>    end
>    nil
>  end
> end

Not necessarily better:

irb(main):001:0> a = [1,2,3,4,5,6,7,8]
=> [1, 2, 3, 4, 5, 6, 7, 8]
irb(main):002:0> b = [4,5,6]
=> [4, 5, 6]
irb(main):004:0> a.each_cons(b.size).to_a.index(b)
=> 3
irb(main):005:0> a.each_cons(b.size).to_a.index([5,1,2])
=> nil

Jesus.