From: Albert Wagner <alwagner@...>
Date: 2002-09-13T08:47:54+09:00
Subject: Re: Multi-level sort idiom?

On Tuesday 10 September 2002 01:35 pm, Brett Williams wrote:
> Let's say I have an array, each element of which is a 2-dimensional array
> of ints.
>
> I want to sort with the first element in the 2D array taking precedence,
> but using the second as a tiebreaker.
>
> So far, I haven't come up with a nice idiom that doesn't seem a bit kludgy:
> What I tried was to do something like:
> x.sort {|a,b| a[0]<=>b[0] || a[1]<=>b[1]}
> but 0 is not false in Ruby so this doesn't work.
>
> x.sort {|a,b| 2*(a[0]<=>b[0]) + (a[1]<=>b[1])}
> works, but is non-intuitive and not pretty.
>
> Does anyone have a nice clean rubyesque idiom for this?

Rubyesque idiom? Probably not, but this is readable:

y = x.sort{|a,b|	
	if (result = a[0]<=>b[0]) != 0
		result
	else
		a[1]<=>b[1]
	end
	}