From: Tom Verbeure <hombre@...>
Date: 2008-11-12T15:42:23+09:00
Subject: Re: 1.upto(4) in ruby 1.8.6

On Nov 11, 10:13 pm, Peņa, Botp <b...@delmonte-phil.com> wrote:
> From: Tom Verbeure [mailto:hom...@gmail.com]
> # indices     = 1.upto(points.size)
> # zipped = indices.zip(distances, points)
>
>   (1..points.size).zip(distances,points)
>
> but arrays have builtin indices, why not
>
>   distances.zip(points)
>
> ?

In later steps, the list gets sorted by the 'distance' field, then
truncated and then sorted back in the original order, but with some
inside points removed.
Like this:

        indices   = (1..points.size).to_a
	zipped = indices.zip(distances, points)
        zipped = zipped.delete_if { |x| x[1].nil? }
        zipped.sort! { |x,y| y[1] <=> x[1] }
        zipped = zipped.slice(0, max_nr_points)

	# Sort back in original order
	zipped.sort! { |x,y| x[0] <=> y[0] }
	points = zipped.collect { |p| p[2] }

Tom