From: James Edward Gray II <james@...>
Date: 2005-10-12T00:00:36+09:00
Subject: Re: Sort pseudo-lists

On Oct 11, 2005, at 9:51 AM, Robert Klemme wrote:

> Martin DeMello wrote:
>
>> pete boardman <pete.boardman@pobox.com> wrote:
>>
>>> 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:
>>>
>>
>> That's actually the default behaviour, so you can just say arr.sort
>>
>
> Strictly speaking that's wrong: the code above and arr.sort are not
> equivalent because arr.sort will evaluate all elements of embedded  
> arrays
> while the code above will only honor the first one:

I showed how to do just the first, then Pete said:

>>> Is it easy to sort the array of arrays by their second, third,  
>>> and fourth entries
>>> as well

Making Martin's answer right on.

James Edward Gray II