Thank you all for your help. This helps so much!
I did try using into a number of times, but didnt get that to work. I
have to admit that, except for the rudamentary examples I have not
used reduce too much yet. I was reviewing Stu Halloways code on group-
by and was trying to come up with a way to use reduce in this
application, but am not quite there yet. I will study up!
Thanks again for the help!
Base
On Jun 22, 2:56 am, Justin Kramer <jkkra...@gmail.com> wrote:
> I took a crack at it. Whenever I think of building up a structure, I
> think of reduce or into. Like Meikel, I create a nested, sorted-map
> tree first, then convert to the vector-of-maps format you describe.
>
> (defn add-path [root path]
> (let [add-child (fn [parent child-path]
> (if (get-in parent child-path)
> parent
> (assoc-in parent child-path
> {:data (peek child-path)
> :children (sorted-map)})))
> ancestor-paths (for [i (range 1 (inc (count path)))]
> (vec (interpose :children (take i path))))]
> (reduce add-child root ancestor-paths)))
>
> (defn rows->tree [rows]
> {:data :root
> :children (reduce add-path (sorted-map) rows)})
>
> ;; Note: consumes stack space
> (defn tree-map->vec [node]
> (vec
> (for [[k v] node]
> (if (zero? (count (:children v)))
> (dissoc v :children)
> (assoc v :children (tree-map->vec (:children v)))))))
>
> ;; Example
>
> (def data1 [[:a1 :b1 :c1]
> [:a1 :b1 :c2]
> [:a1 :b2 :c3]
> [:a1 :b2 :c4]
> [:a2 :b3 :c5]
> [:a2 :b3 :c6]
> [:a2 :b4 :c7]
> [:a2 :b4 :c8]])
> (use 'clojure.contrib.pprint)
> (pprint (rows->tree data))
> (pprint (tree-map->vec (:children (rows->tree data))))
>
> Seehttp://gist.github.com/448120for example output.
>
> Hope that helps,
>
> Justin
>
> On Jun 21, 10:55 pm, Base <basselh...@gmail.com> wrote:
>
> > Hi all -
>
> > This seems like it should be easy, but for some reason i have thought
> > myself into a box on this and now am stuck.
>
> > I have a data set of rows/ columns that has some hierarchical data in
> > it:
>
> > COLUMN A B C
>
> > A1 B1 C1
> > A1 B1 C2
> > A1 B2 C3
> > A1 B2 C4
> > A2 B3 C5
> > A2 B3 C6
> > A2 B4 C7
> > A2 B4 C8
>
> > and i want to convert this to a nested map structure:
> > [
> > {:data A1
> > :children [{:data B1 :children [{:data C1} {:data C2}]]}
> > {:data B2 :children [{:data C3} {:data C4}]]}
>
> > {:data A2
> > :children [{:data B3 :children [{:data C5} {:data C6}]]}
> > {:data B4 :children [{:data C7} {:data C8}]]} ]
>
> > I have tried various methods and have frustrated myself to no end.
> > Any help on this would be most greatly appreciated.
>
> > 3 additional notes:
> > 1. It would be really awesome if i could somehow specify the
> > hierarchical structure so that I can reuse this (as i will have to)
> > 2. I will be using this on some fairly large data sets (the largest is
> > maybe 50K records).
> > 3. I think that the largest number of nodes in the tree will be 3,
> > but this *could* change in the future.
>
> > As always, any help is most appreciated.
>
> > Thanks
>
> > Base
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