From: Robert Klemme <shortcutter@...>
Date: 2008-06-01T02:44:37+09:00
Subject: Re: how to sort a multi-elements array

On 31.05.2008 19:31, Erwin wrote:
> I know how to sort an array with 2 elements... that's the only example
> I could fin on Array#sort...
> but what if ... I need to sort an array like this one :
> 
> anArray = [ [1, "joe", 4], [2, "arthur", 2], [5, "william", 3], [16,
> "bob", 1], [20, "ernesto", 17], [27, "julia", 1], [28, "barbara", 2] ]
> 
> sorting on third-element (highest ranking) , and second-element
> (nickname)
> 
> aSortedArray = [ [20, "ernesto", 17], [1, "joe", 4], 5, "william", 3],
> [2, "arthur", 2],  [28, "barbara", 2], [16, "bob", 1] ]
> 
> any doc link where this is explained ?

As always, use #sort with a block or #sort_by - the number of elements 
in those arrays is irrelevant, you just need to decide which elements 
you want to pick as sort key.

an_array.sort_by {|a,b,c| [c,b]}
an_array.sort {|(a,b,c),(d,e,f)| [c,b] <=> [f,e]}
an_array.sort do |(a,b,c),(d,e,f)|
   x = c <=> f
   x == 0 ? b <=> e : x
end

Btw, your data looks like it could benefit from using Struct and also 
benefit from the automatically implemented <=>, i.e.

Person = Struct.new :age, :name, :position

an_array = [
   Person.new(4, "joe", 1),
   Person.new(2, "arthur", 2),
   Person.new(3, "william", 5),
]

Kind regards

	robert