From: Erwin <yves_dufour@...>
Date: 2008-06-01T15:34:33+09:00
Subject: Re: how to sort a multi-elements array

On 31 mai, 19:40, Robert Klemme <shortcut...@googlemail.com> wrote:
> 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

thanks Robert , I'll write that in my NoteTaker Ruby book !!