group-location solution for the problem in clojure in thai FB group

group-location.clj

(def local
      [{:province :a, :district :b, :amphoe :c}
       {:province :a, :district :k, :amphoe :g} ])

(defn group-by-fn
  ([func groupping]
   (fn [hmap]
       (group-by-fn func groupping hmap)))
  ([func groupping hmap]
   (->> hmap
       (group-by groupping)
       (map (fn [[k v]] [k (func v)]))
       (into {}))))

(def group-location
  (-> #(mapv :district %)
      (group-by-fn :amphoe)
      (group-by-fn :province)))
     
(group-location local)