How to swap 2 elements in Vector of Vector

Question

How do I extend this: What is the idiomatic way to swap two elements in a vector

to essentially a 2D array?

[[1 2 3] [4 5 6] [7 8 9]] --> [[1 2 5] [4 3 6] [7 8 9]]

Answer 1

Use get-in and assoc-in:

(defn swap-in [vv p1 p2]
  (let [v1 (get-in vv p1)
        v2 (get-in vv p2)
    (-> vv 
        (assoc-in p1 v2)
        (assoc-in p2 v1))))

So now:

(def my-vec [[1 2 3] [4 5 6] [7 8 9]])
(swap-in my-vec [0 2] [1 1])
=> [[1 2 5] [4 3 6] [7 8 9]]

This will work with vectors nested to any "depth", so long as the specified positions in my-vec actually exist.