From: dblack@...
Date: 2006-01-05T04:27:22+09:00
Subject: Re: Question on iterating a hash

Hi --

On Thu, 5 Jan 2006, James Edward Gray II wrote:

> On Jan 4, 2006, at 12:46 PM, phil swenson wrote:
>
>> I have a hash that looks like this : {"1"=>"0, "3"="1", "45"=>"1",
>> "101"=>"0"}
>> 
>> What I want is an array of all the keys that have hash values equal to
>> "1" ["3","45"] in this case.
>> 
>> Yeah, i can just iterate the keys... but it seems like there is a "ruby"
>> way to do this.  Any thoughts?
>
>>> h = Hash[*%w{1 0 3 1 45 1 101 0}]
> => {"45"=>"1", "1"=>"0", "101"=>"0", "3"=>"1"}
>>> h.select { |key, value| value == "1" }.map { |key, value| key }
> => ["45", "3"]

Wouldn't it be easier to iterate through the keys?  I'm not sure why
Phil didn't want to.  (Phil?)

   h.keys.select {|k| h[k] == 1}


David

-- 
David A. Black
dblack@wobblini.net

"Ruby for Rails", from Manning Publications, coming April 2006!
http://www.manning.com/books/black