From: Gary Wright <gwtmp01@...>
Date: 2011-01-19T13:28:05+09:00
Subject: Re: Improving performance of hash math


On Jan 18, 2011, at 9:55 PM, dblock wrote:

> I am trying to improve performance of Euclidian distance between two
> hash maps. The code is pretty straightforward:
> 
> def self.euclidian_distance(lhs, rhs)
>    @s = lhs.inject(0.0) do |s, (k,v)|
>      rhs.has_key?(k) ? (s + (v - rhs[k])**2) : (s + v**2)
>    end
>    @s = rhs.inject(@s) do |s, (k,v)|
>      lhs.has_key?(k) ? s : (s + v**2)
>    end
>    @s
> end
> 
> Any suggestions?
> 

Switch to using #each with an explicit accumulator variable instead of #inject.

Gary Wright