From: Joel VanderWerf <vjoel@...>
Date: 2002-02-27T08:29:54+09:00
Subject: Re: fiddly little array manipulation question

Phil Mitchell wrote:
> 
> Is there a nicer way to take the intersection of an array of arrays, other
> than:
> 
> intersection = arrOfArrays[0]
> for i in 1...arrOfArrays.length
>   intersection &= arrOfArrays[i]
> end
> 
> Am I missing some rubyism?

Enumerable#inject helps a little:

[ [1,2,3], [2,3,4] ].inject([0,1,2]) { |x, y| x & y }

# ==> [2]

inject is defined in the pickaxe book, but IIRC it's going to become
standard eventually. You can also get it in my enumerable tools package
in RAA:

http://www.ruby-lang.org/en/raa-list.rhtml?name=Enumerable+tools