From: brabuhr@...
Date: 2009-06-09T03:55:17+09:00
Subject: Re: How to sort array ascending, except zero ?

On 6/8/09, Robert Klemme <shortcutter@googlemail.com> wrote:
> On 08.06.2009 17:07, andrea wrote:
>> irb(main):003:0> a=[0,3,2,-5,0,4]
>> => [0, 3, 2, -5, 0, 4]
>> irb(main):004:0> a.sort{|x,y| x.zero? ? 1 : x<=>y}
>> => [-5, 2, 3, 4, 0, 0]
>
> irb(main):003:0> a=[1,0]
> => [1, 0]
> irb(main):004:0> a.sort{|x,y| x.zero? ? 1 : x<=>y}
> => [0, 1]
> irb(main):005:0>

Assuming a stable sorting algorithm, sort twice is an option:

irb(main):001:0> [1, 0].sort.sort_by{|n| n.zero? ? 1 : 0}
=> [1, 0]
irb(main):002:0> [0,3,2,-5,0,4].sort.sort_by{|n| n.zero? ? 1 : 0}
=> [-5, 4, 3, 2, 0, 0]
irb(main):003:0> a = (1..10).map{|n| rand(5) - 2}
=> [-1, 2, -1, 0, 0, 2, 0, 2, 2, -2]
irb(main):004:0> a.sort.sort_by{|n| n.zero? ? 1 : 0}
=> [-2, -1, -1, 2, 2, 2, 2, 0, 0, 0]
irb(main):033:0> a.sort.sort_by{|n| n.zero?.to_s}
=> [-2, -1, -1, 2, 2, 2, 2, 0, 0, 0]