From: dblack@...
Date: 2006-03-14T08:33:59+09:00
Subject: Re: array element access

Hi --

On Tue, 14 Mar 2006, Mike Austin wrote:

> Tomas Fischer wrote:
>> Hi,
>> 
>> I've got an array a= [1,2,3,4,5,6] and want to access each second element:
>> b=[2,4,6]. How is this done in ruby?
>> 
>> I know, that I can use a for-loob and modulo operator, but I think there is 
>> a "ruby way" of doing this.
>> 
>> Thanks.
>> tomas
>
> I've always been intrigued by creating a generalized enumeration system. 
> Have you guys seen this: http://www.rubyweeklynews.org/20050710 : accessing 
> index inside map.  For example:
>
> (1..10).collect.with_index { |v, i| v * i }
>
> I think that is sweet!  I wonder if it can be generalized enough to do this:
>
> file.collect.each_byte.with_index { |b, i| b + 1 }

I'm not sure why, but to my eye this has always looked somewhat
obscure.  I guess it's something about having to read to the right,
even to the extent of not seeing a block, before I know what's being
returned (array vs. enumerator).  It's almost as if the call to
collect wasn't a "real" call to collect, but rather a kind of
place-holder for a collect operation.  I'm not sure.


David

-- 
David A. Black (dblack@wobblini.net)
Ruby Power and Light, LLC (http://www.rubypowerandlight.com)

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