From: pete boardman <pete.boardman@...>
Date: 2005-10-11T17:46:32+09:00
Subject: Re: Sort pseudo-lists

On 10 Oct 2005, at 22:53, James Edward Gray II wrote:

> arr = eval "{{3.1, 1.3, 2.5, 2.1}, {2.1, 3.1, 2.4, 2.2}, {1.4, 2.2,  
> 2.1, 4.2}}".tr("{}", "[]")
> arr.sort { |a, b| a.first <=> b.first }

Thanks, James - simple, elegant, and nearly perfect! Is it easy to  
sort the array of arrays by their second, third, and fourth entries  
as well:

ie such that

[[2.1, 2.2, 9.5, 2.1], [2.1, 2.2, 2.4, 2.2], [2.1, 2.2, 2.1, 4.2]]

sorts to

[[2.1, 2.2, 2.1, 4.2],[2.1, 2.2, 2.4, 2.2],[2.1, 2.2, 9.5, 2.1]]

rather than

[[2.1, 2.2, 9.5, 2.1], [2.1, 2.2, 2.4, 2.2], [2.1, 2.2, 2.1, 4.2]]

thanks

Pete