From: "Marcel Molina Jr." <marcel@...>
Date: 2006-02-09T10:38:06+09:00
Subject: Re: can map/collect return fewer values than are found in the target?

On Thu, Feb 09, 2006 at 10:18:46AM +0900, 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?

Looks like you want Arry#select. In fact, take a look at the docs ;)

----------------------------------------------------------- Array#select
     array.select {|item| block } -> an_array
------------------------------------------------------------------------
     Invokes the block passing in successive elements from _array_,
     returning an array containing those elements for which the block
     returns a true value (equivalent to +Enumerable#select+).

        a = %w{ a b c d e f }
        a.select {|v| v =~ /[aeiou]/}   #=> ["a", "e"]

marcel
-- 
Marcel Molina Jr. <marcel@vernix.org>