From: Reuben Grinberg <reuben.grinberg@...>
Date: 2007-04-10T02:00:09+09:00
Subject: Re: Creating an array of differences

Here's another way of doing it:

(a.zip(a[1..a.length])[0...a.length-1]).map { |a,b| b-a }

This things makes an array of pairs of the elements:

irb(main):007:0> a = [1000, 1100, 1200]
=> [1000, 1100, 1200]
irb(main):029:0> a.zip(a[1..a.length])[0...a.length-1]
=> [[1000, 1100], [1100, 1200]]
irb(main):030:0> (a.zip(a[1..a.length])[0...a.length-1]).map { |a,b| b-a }
=> [100, 100]

-Reuben

Jason Madigan wrote:
> Hey there,
> 
> I'm pretty new to Ruby so perhaps some of you could help me out with a
> little problem I've come up against. I have an array consisting of
> integers (called session[:octets_in]). What I want to do is create an
> array comprising of the difference between the current element and the
> previous element (e.g. ["1000", "1100", "1200"] would become ["100",
> "200"]). I'm not entirely sure how to go about this, so any pointers
> would be welcome.
>