swap-sub.clj

swap-sub.clj

  (def qs {1 [:a :b] 2 [:a] 3 [:b] 4 [:b :c] 5 [:a] 6 [:a :c]})
  (defn swap-sub [m]
    (->> m
         (mapcat (fn [[k v]] (zipmap v (repeat k))))
         (group-by first)
         (map (fn [[k v]] [k (mapv second v)]))
         (into {})))
  (swap-sub qs) ;=> {:a [1 2 5 6], :b [1 3 4], :c [4 6]}