This probably won't help with your garbage collection worries, but it's a
bit more flexible.
*(defn find-assoc-in [pred coll k v & kvs]*
* (let [f #(if (pred %) (apply assoc % k v kvs) %)]*
* (into (empty coll) (map f coll))))*
On Tuesday, July 30, 2013 10:53:48 AM UTC-7, 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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