How to filter a persistent map in Clojure?

Question

I have a persistent map which I want to filter. Something like this:

(filter #(-> % val (= 1)) {:a 1 :b 1 :c 2})

The above comes out as

Answer 1

Here's another one using reduce-kv

(defn filter-kv [pred map]
  (reduce-kv (fn [accumulator key value]
               (if (pred key value)
                 (assoc accumulator key value)
                 accumulator)) {} map))

Usage

(filter-kv (fn [key _]
             (not (= key "a"))) {"a" {:some "a"}
                                 "b" {:some "b"}
                                 "c" {:some "c"}})

>> {"b" {:some "b"}
    "c" {:some "c"}}