Hi,
how about ....
(vec
(for [{:keys [a b c] :as m} aa]
(if (= a 50) (assoc m :c 3) m)))
:)
Jim
On 30/07/13 18:53, cej38 wrote:
Suppose I have a vector of maps (this could also be a vector of records)
(def aa [{:a 0 :b 0 :c 0} {:a 50 :b 0 :c 0} {:a 100 :b 0 :c 0}])
and I want to go in an change the value of associated with :c when :a
has a value of 50, so that the final col of maps looks like
[{:a 0 :b 0 :c 0} {:a 50 :b 0 :c 3} {:a 100 :b 0 :c 0}].
I came up with a function that does this:
(defn find-assoc-in
[k v mv]
(let [f #(if (= ((first k) %) (first v))
(assoc % (second k) (second v))
%)]
(map f mv)))
(find-assoc-in [:a :c] [50 3] aa)
The problem with this function is that it potentially does a lot
of unnecessary copying of elements that aren't changed, and thus has a
lot of garbage collection. I would like help coming up with something
that does much less garbage collection.
Will someone please point out a better way of doing this?
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