Question

I’m working on a problem where I need to create a CartesianProduct class. I should be able to pass this class 2 lists, and then output the Cartesian product (all possible combinations) of these lists.

So far I can create an object out of this class, create all possible combinations, but when I try to output these results to screen I get each item on its own row as if it doesnt realize it is an array.

My code:

class CartesianProduct
    include Enumerable
    # Your code here
    def initialize(a,b)
        @output = []
        a.each do |x|
            b.each do |y|
                if !(output.include? [x,y])
                    output << [x,y]
                end
            end
        end
    end

    #getter
    def output
        @output
    end

    def each
        @output.each do |a| puts a end
    end

    #setter
    def output=(a,b)
        a.each do |x|
            b.each do |y|
                if !(output.include? [a,b])
                    output << [a,b]
                end
            end
        end
    end
end

What Im using to test:

c = CartesianProduct.new([:a,:b], [4,5])
=> #<CartesianProduct:0x93569f8 @output=[[:a, 4], [:a, 5], [:b, 4], [:b, 5]]>

Testing is done via the following command: c.each { |elt| puts elt.inspect }

I get:

irb(main):1403:0> c.each { |elt| puts elt.inspect }
a
4
a
5
b
4
b
5
=> [[:a, 4], [:a, 5], [:b, 4], [:b, 5]]

but I should be getting:

# [:a, 4]
# [:a, 5]
# [:b, 4]
# [:b, 5]

My output is not printing the symbols as symbols but rather converting to string, and its print each item on its own line…

This is homework, so I’m not looking for an answer, but a nudge in the right direction would help quite a bit.

EDIT ========================================================================
Changing my definition of each in the class resolved this issue.

def each
    @output.map do |x|
        yield x
    end
end

Answer 1

Changing my definition of each in the class resolved this issue.

def each
    @output.map do |x|
        yield x
    end
end