From: Robert Klemme <shortcutter@...>
Date: 2006-08-06T17:35:12+09:00
Subject: Re: Iterating over an array n element at a time

Trans wrote:
> Kim Pedersen wrote:
>> Is there an elegant way to iterate over an array n elements at a time?
>> e.g. something like...
>>
>> a = [1,1,1,2,2,2,3,3,3]
>>
>> a.each(3) do |x,y,z|
>>     print x,y,z,"\n"
>> end
>>
>> prints...
>> 111
>> 222
>> 333
>>
>> //kim
> 
> enumerator is probably better since it is built-in, but...
> 
>   require 'facet/enumerable/each_by'
>   a = [1,1,1,2,2,2,3,3,3]
>   a.each_by(3) { |x,y,z| print x,y,z,"\n" }
>   111
>   222
>   333
> 
> But why not have Ruby fill those arguments out automatically? This
> already does:
> 
>   a = [[1,1,1],[2,2,2],[3,3,3]]
>   a.each { |x,y,z| print x,y,z,"\n" }
> 
> So couldn't some "slurping" indicator be used?
> 
>   a = [1,1,1,2,2,2,3,3,3]
>   a.each { |(x,y,z)| print x,y,z,"\n" }
> 
> Or something.
> 
> T.
> 
> 
Note though that your code does something different than each_cons which 
moves a sliding window while your code iterates in chunks!  See:

robert@fussel ~
$ ruby -r enumerator -e'  %w( 1 2 3 4 5 ).each_cons(2){|a, b| p a, b, 
"-"}  '
"1"
"2"
"-"
"2"
"3"
"-"
"3"
"4"
"-"
"4"
"5"
"-"

robert@fussel ~
$

Kind regards

	robert