From: Phrogz <gavin@...>
Date: 2006-11-06T12:55:08+09:00
Subject: Re: array sorting question

Giles Bowkett wrote:
> I have an array of arrays. the interior arrays can be of any arbitrary
> length including zero. I want to sort the array of arrays in such a
> way that the interior arrays with the most elements are closest to the
> middle of the main array.

main = (-4..12).map{ |i| (0..i).to_a }

sorted = main.sort_by{ |sub| sub.length }
i = 0
half1, half2 = sorted.partition{ (i+=1) % 2 == 0 }
pyramid = half1 + half2.reverse

require 'pp'
pp pyramid

#=> [[],
#=>  [],
#=>  [0, 1],
#=>  [0, 1, 2, 3],
#=>  [0, 1, 2, 3, 4, 5],
#=>  [0, 1, 2, 3, 4, 5, 6, 7],
#=>  [0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
#=>  [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11],
#=>  [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12],
#=>  [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
#=>  [0, 1, 2, 3, 4, 5, 6, 7, 8],
#=>  [0, 1, 2, 3, 4, 5, 6],
#=>  [0, 1, 2, 3, 4],
#=>  [0, 1, 2],
#=>  [0],
#=>  [],
#=>  []]