(let [trans (fn [ent]
(reduce
#(assoc %1 (:id %2) (:val %2))
{}
ent))]
(for [i (merge-with * (trans xs) (trans ys))]
{:id (first i) :val (second i)}))
you can sort on the result of above expression to get sorted vector.
Thanks,
Di Xu
2014-06-17 20:24 GMT+08:00 Shoeb Bhinderwala <[email protected]>:
> 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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