From: Paul Carvalho <tester.paul@...>
Date: 2009-08-31T02:25:05+09:00
Subject: Re: Sorting an array by multiple elements?

On Aug 30, 11:41 am, "David A. Black" wrote:
>
> The nothing result seems strange. This:
[snip]
>
>   data = [ [2, "2009-08-21", 2, "alfie"],
>            [6, "2009-08-23", 3, "alfie"],
>            [1, "2009-08-21", 4, "barny"],
>            [3, "2009-08-23", 3, "alfie"],
>            [5, "2009-08-24", 1, "cliff"],
>            [4, "2009-08-21", 1, "cliff", "bob"] ]
>
>    data.sort_by {|id, date, num, name| [name, date, id] }
>
> gives me:
>
>         [2, "2009-08-21", 2, "alfie"]
>         [3, "2009-08-23", 3, "alfie"]
>         [6, "2009-08-23", 3, "alfie"]
>         [1, "2009-08-21", 4, "barny"]
>         [4, "2009-08-21", 1, "cliff", "bob"]
>         [5, "2009-08-24", 1, "cliff"]
>

Thanks David,

I think I know what the happened now.  When I tried the other
approach, I sorted in place using:  data.sort!

But when I used "data.sort_by" it might have sorted it but didn't save
it back to the same array.

"sort_by!" doesn't exist so I'll need to save the sorted data to
another variable.

The sort with the sample data above works as I expect, but for some
reason it still isn't sorting correctly with my real data.  I'll keep
looking at it.  I must be missing something else, although I can't
think what it might be right now.

Sort the data, write it out to file.  Should be straightforward.

Cheers.