From: Robert Klemme <shortcutter@...>
Date: 2010-09-09T15:25:09+09:00
Subject: Re: Key Associated w/ Maximum Value in Hash

On 09.09.2010 05:23, Josh Cheek wrote:

> On Wed, Sep 8, 2010 at 9:57 PM, Timothy Baron<timothy.baron@gmail.com>wrote:
>
>> Simple question:  what's the cleanest way to retrieve a key associated
>> with the maximum value of a hash.  For instance, how do I retrieve 'b'
>> from the following example:
>>
>> hash = Hash.new
>> hash['a']=4
>> hash['b']=10
>> hash['c']=7
>> --
>> Posted via http://www.ruby-forum.com/.
>>
>>
> How about Enumerable#max
>
> hash = {'a'=>4,'b'=>10,'c'=>7}
> max_record = hash.max { |a,b| a.last<=>  b.last } # =>  ["b", 10]
> max_index = max_record&&  max_record.first # =>  "b"

In 1.9.x you can even spare the #last:

irb(main):001:0> hash = {'a'=>4,'b'=>10,'c'=>7}
=> {"a"=>4, "b"=>10, "c"=>7}
irb(main):002:0> hash.max {|(k1,v1),(k2,v2)| v1 <=> v2}
=> ["b", 10]

Here's a version with #inject

irb(main):004:0> hash.inject([nil,0]) {|(maxk,maxv),(k,v)| v > maxv ? 
[k,v] : [maxk,maxv]}.last
=> 10

Kind regards

	robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/