From: Logan Capaldo <logancapaldo@...>
Date: 2006-02-09T10:32:36+09:00
Subject: Re: can map/collect return fewer values than are found in the target?


On Feb 8, 2006, at 8:18 PM, Kelly Dwight Felkins wrote:

> Is there a way for collect to return fewer items than the  
> enumerable the
> collect is running on? It looks to me like
> map/collect will return at least one value for each item in the  
> array --
> I've seen examples of how to return more items, but
> not less.
>
> Is there a way to do this more succinctly:
>
> VOWELS = %w{a e i o u}
> items = %w{ a b c d e f g h i}
> new_items = []
> items.each do |item|
>   new_items << item unless VOWELS.include(item)
> end
> new_items
>
> map/collect in ruby seems very similar to map in perl except that  
> in perl
> the block can return zero or more elements. Is there an method in  
> ruby that
> is similar to perl's map?
>
> Thanks,
>
> -Kelly

new_items = items.reject { |item| VOWELS.include?(item) }

or

new_items = items.select { |item| true unless VOWELS.include?(item) }

or

new_items = items.inject([]) { |list, item| list << item unless  
VOWELS.include?(item); list }