So I take in two Sets and wanna iterate through them in order to return a new set containing the cross product of the two sets.
(defn cartesian
"computes Cartesian product of A and B"
[A B]
use "set", "for")
I'm very new to Clojure so I'm not sure why use "set, "for" is included at all. But A and B will be Sets. Now I wanna iterate through each one and return the Cartesian product of them. Example:
(cartesian #{1 2} #{3 4 5}) => #{[1 3] [1 4] [1 5] [2 3] [2 4] [2 5]}
I'm not sure on the steps to get there though. I have looked through documentation etc but can't find what I'm looking for. Other answer to this deal with lists etc. But I have to use 2 Sets.
What I'm looking at atm is using doseq[e A]
and inside that doseq[x B]
then add each vector-pair [ex]
to a new Set and then return it. This doesn't seem like a standard functional solution though. Am I on the right track? How do I add it to a new Set?
You can accomplish that using for
:
(defn cartesian [A B]
(set (for [a A
b B]
[a b])))
(cartesian #{1 2} #{3 4 5})
;; => #{[2 3] [2 5] [1 4] [1 3] [1 5] [2 4]}
Use cartesian-product from clojure.math.combinatorics . To get exact result you want (set of vectors), use into
with map
transducer:
(into #{} (map vec) (clojure.math.combinatorics/cartesian-product #{1 2} #{3 4 5}))
=> #{[2 3] [2 5] [1 4] [1 3] [1 5] [2 4]}
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