Is this the best way to grab common elements from a Hash of arrays?

Question

I\'m trying to get a common element from a group of arrays in Ruby. Normally, you can use the & operator to compare two arrays, which returns elements

Answer 1

Can't you just do a comparison of the first two, take the result and compare it to the next one etc? That seems to meet your criteria.

Answer 2

Behold the power of inject! ;)

[[1,2,3],[1,3,5],[1,5,6]].inject(&:&)
=> [1]

As Jordan mentioned, if your version of Ruby lacks support for &-notation, just use

inject{|acc,elem| acc & elem}

Answer 3

Why not do this:

def get_common_elements_for_hash_of_arrays(hash)
    ret = nil
    hash.each do |key, array|
        if ret.nil? then
            ret = array
        else
            ret = array & ret
        end
    end
    ret = Array.new if ret.nil? # give back empty array if passed empty hash
    return ret
end