From: "(r.*n){2}" <perl2ruby@...>
Date: 2010-09-24T05:45:09+09:00
Subject: Re: Sorting problem with an Array of Arrays

On Sep 23, 11:27 am, Jeremy Bopp <jer...@bopp.net> wrote:
> On 9/22/2010 11:30 PM, Paul wrote:
>
> > Hi Jeremy, thanks for the reply.
>
> > On Sep 22, 6:54 pm, Jeremy Bopp <jer...@bopp.net> wrote:
>
> >>> You could define a class to represent each of your inner array elements.
> >>>  That class could then define the <=> method in which you could compare
> >>> each item in the order you desire.  Then your outer array, consisting of
> >>> instances of your class, could be trivially sorted with Array#sort.
>
> > I'm afraid I don't understand what you are saying here.  All I
> > understood was "could be trivially sorted with Array#sort."  I don't
> > understand classes.
>
> Classes are rather a central concept in Ruby, so it would be a really
> good idea to learn about them; however, they are not necessary here.
> I'll keep this short and say that using an array of arrays such as what
> you have here can make your code cryptic and brittle as it grows and
> ages.  Using a class to represent your inner array items will help avoid
> these issues. :-)
>
> I see that you have more details about your problem in a later reply, so
> I'll see about addressing more issues there.
>
> -Jeremy

$cat h1.rb
#!/usr/bin/ruby
puts [
 ["DEF-1", 1271772000, 1],
 ["ABC-2", 1271773800, 1],
 ["ABC-3", 1271863200, 2],
 ["AAA-1", 1271862000, 2],
 ["ABC-4", 1271869200, 2],
 ["ABC-1", 1271768400, 2]
].sort{ |x,y| (x[1] <=> y[1]) * 10 + (x[0] <=> y[0]) }.inspect


$./h1.rb
[["ABC-1", 1271768400, 2], ["DEF-1", 1271772000, 1], ["ABC-2",
1271773800, 1], ["AAA-1", 1271862000, 2], ["ABC-3", 1271863200, 2],
["ABC-4", 1271869200, 2]]
$