From: Martin DeMello <martindemello@...>
Date: 2004-08-17T14:50:59+09:00
Subject: Re: Q: Shifting a hash anf and array

Meino Christian Cramer <Meino.Cramer@gmx.de> wrote:
> 
>  Contents of the array before the trick:
> 
>  1 2 3 4 5 6 7 8 9 0        index
>  A B C D E F G H I J            contents
> 
>  (execute *trick*)
> 
>  Contents of the array after the trick:
> 
>  1 2 3 4 5 6 7 8 9 0        index
>  J A B C D E F G H I            contents

array.unshift(array.pop)

>  And now the shift of an hash:
> 
>  Contents of the hash before the trick:
> 
>  A B C D E F G H I J            key
>  1 2 3 4 5 6 7 8 9 0        value
> 
>  (execute *trick*)
> 
>  Contents of the hash after the trick:
> 
>  A B C D E F G H I J            key
>  0 1 2 3 4 5 6 7 8 9        value
> 
>  Both are very similiar. 

Not really :) Hashes are inherently unordered, so the concept of a
rotation is a bit trickier. This works on the assumption that
Hash#values returns values in positions corresponding to the keys in
Hash#keys...

class Array
  def rot1
    unshift(pop)
  end
end

Hash[*(hash.keys.rot1.zip(hash.values.rot1).flatten)]

martin