From: mortee <mortee.lists@...>
Date: 2007-10-26T06:58:28+09:00
Subject: Re: Intervals in Ruby

ara.t.howard wrote:
> yes.  the most obvious one is needing adjacent entries and/or
> self-modification.  something along the lines of
> 
> pixels.size.times do |i|
>   pixel = pixels[i]
>   left = pixels[i - 1]
>   right = pixels[i + 1]
> 
>   if left.nil? and condition(right) or
>      condition(left) and condition(right) or
>      condition(left) and right.nil?
> 
>     pixel = transformation left, pixel, right
>   end
> end

What about #each_with_index for this case? Using pixels.size.times and
accessing each element by the yielded integer indexes explicitely
assumes that the index space is continuous - however, the same algorithm
using #each_with_index would only assume that each item yielded by it
has two adjacent neighbors.

> min = [a.size, b.size].min
> 
> min.times do |i|
>   something_with a[i] and b[i]
> end
> 
> which is to say iterating datasets in parallel.
> 
> yes there is zip - fantastic if you are into duplicating both datasets
> in memory *and* are iterating over n=2 data structures but otherwise
> useless.

Hmmm, are you sure that zip duplicates all the involved arrays even if
passed a block?

mortee