In Clojure, how do I make a nested map return a map with an inner map all set to 0?

Question

So basically how do I make a function given the input {:A 1 :B 2 :C {:X 5 :Y 5 :Z 5} :D 1} and the key :C return {:A 1 :B 2 :C {:X 0 :Y 0 :Z 0} :D 1}? It's the same mapping but with the nested map all set to 0. Given that we know that the key :C has the nested values.

I'm very new to clojure and I'm struggling with loops and iterations so any help would be appreciated.

Thanks.

Answer 1

(defn with-zero-vals-at-key
  [m k]
  (update m k (fn [m2] (zipmap (keys m2) (repeat 0)))))

(with-zero-vals-at-key {:A 1 :B 2 :C {:X 5 :Y 5 :Z 5} :D 1} :C)
;; => {:A 1, :B 2, :C {:X 0, :Y 0, :Z 0}, :D 1}

;; OR

(defn with-zero-vals
  [m]
  (zipmap (keys m) (repeat 0)))

(update {:A 1 :B 2 :C {:X 5 :Y 5 :Z 5} :D 1}
        :C
        with-zero-vals)
;; => {:A 1, :B 2, :C {:X 0, :Y 0, :Z 0}, :D 1}