From: "Simon Kröger" <SimonKroeger@...>
Date: 2006-01-05T04:53:40+09:00
Subject: Re: Question on iterating a hash

dblack@wobblini.net wrote:

> 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

Don't know, but here is another one:

h.select{|k, v| v == "1" }.transpose.first

cheers

Simon