On Wed, Nov 18, 2009 at 8:19 AM, Robert Campbell <rrc...@gmail.com> wrote:
> Hey guys,
>
> I'm having some trouble finding a nice way to perform a map
> transformation I need. I need to transform this:
>
> [ {:a 1 :b 2 :c 3} {:a 4 :b 5 :c 6} {:a 7 :b 8 :c 9} ]
>
> into this:
>
> { {:a 1 :b 2} 3 {:a 4 :b 5} 6 {:a 7 :b 8} 9 }
>
> I wanted to use map, but each f in map only returns one value, so I
> couldn't figure it out. Here is what I have now:
>
> (def result (ref {}))
> (for [item coll]
> (dosync (alter result assoc (dissoc item :c) (item :c))))
> ; result should now have correct value
>
> I also wrote a recursive version to build the map without using a ref,
> but I feel like I'm missing a simpler way..
>
(into {}
(map (fn [m] [(dissoc m :c) (:c m)])
[{:a 1 :b 2 :c 3} {:a 4 :b 5 :c 6} {:a 7 :b 8 :c 9}]))
-> {{:a 1, :b 2} 3, {:a 4, :b 5} 6, {:a 7, :b 8} 9}
Rich
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