From: Paul <tester.paul@...>
Date: 2009-08-30T15:30:11+09:00
Subject: Sorting an array by multiple elements?

Hi there, I have an array of arrays that I want to sort by multiple
elements.

Sample data in the array looks like: [ [ id, date, num, name ], [ id,
date, num, name ], ... ]

I need to sort by : (1) name, (2) date, and (3) id.

I can sort by any one element in the array no problem using something
like :
> summary_data.sort! { |a,b| a[ 3 ] <=> b[ 3 ] }

Unfortunately, I can't do this line more than once because it blows
away any previous sorting.

I found a few pages on the internet that describe how to "sort an
array of Ruby objects by multiple class fields", however, I don't know
how to create a "class field".  I'm looking at an array, not a class.

Is there a way to do this or do I need to convert my data to something
else so I can do what I need?

Please help.

Thanks.