From: William Djaja Tjokroaminata <billtj@...>
Date: 2002-09-20T05:58:18+09:00
Subject: Re: How to Efficiently Calculate the Pattern of Zeros and Ones?

Hi,

If the "shifts data through it" is accomplished using Ruby
Array#push() and Array#shift(), then probably the code is indeed very easy
to write, but probably not very efficient in the background.  I like the
answer given in the first response, as I think it mimics how regular
expression works (using some "states").

Regards,

Bill
===========================================================================
Joel VanderWerf <vjoel@path.berkeley.edu> wrote:
> I had to go back and check whether each_with_neighbors generated lots of 
> arrays or not. It turns out that it doesn't. Instead, it keeps a single 
> array, shifts data through it, and yields the array. So it should be 
> fairly efficient as pure ruby code goes.

> However, this may surprise users who modify the array in the iterator 
> block, so I'll slip a warning into the docs.

> If your rows are short, each_with_neighbors is not very efficient 
> because of the "warm up" and "cool down" to deal with the cases near the 
> edge.