Here's what I came up with:
(require '[clojure.set :as set])
(let [->map-fn (fn [s] (->> s (map (juxt :id :val)) (into {})))
xs-m (->map-fn xs)
ys-m (->map-fn ys)]
(->> (set/union (keys xs-m) (keys ys-m))
(map (fn [k] {:id k :val (* (get xs-m k 1) (get ys-m k 1))}))))
On Tue, Jun 17, 2014 at 7:24 AM, Shoeb Bhinderwala <[email protected]>
wrote:
> Can someone help me write the following function:
>
> I have two lists of maps as inputs:
>
> (def xs [{:id 1 :val 10}
> {:id 2 :val 20}
> {:id 3 :val 30}
> {:id 4 :val 40}])
>
> (def ys [{:id 2 :val 20}
> {:id 3 :val 30}
> {:id 5 :val 50}
> {:id 6 :val 60}])
>
> I want to create a result zs which is the union of xs and ys, except that
> if the :id occurs in BOTH then I want to multiply the corresponding :val.
>
> The result zs should be:
>
> [{:id 1 :val 10}
> {:id 2 :val 400} <-- :id 2 occurs in both collections, so multiply the
> :val fields
> {:id 3 :val 900} <-- :id 3 occurs in both collections, so multiply the
> :val fields
> {:id 4 :val 40}
> {:id 5 :val 50}
> {:id 6 :val 60}]
>
> Thanks in advance,
> Shoeb
>
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