Hi Mark,
Here is a version runs about 1.3x faster on my setup.
(defn flatten-keys [thing]
(letfn [(-map-key [prefix k] (str prefix "." (name k)))
(-seq-key [prefix i] (str prefix "[" i "]"))
(-flatten-entry [make-key prefix result entry]
(let [[k v] entry]
(-flatten-thing result (make-key prefix k) v)))
(-flatten-thing [result key thing]
(cond (map? thing)
(reduce (partial -flatten-entry -map-key key)
result
(seq thing))
(sequential? thing)
(reduce (partial -flatten-entry -seq-key key)
result
(map-indexed vector thing))
:else (assoc! result key thing)))]
(persistent!
(-flatten-thing (transient {}) (if (map? thing) "$" "") thing))))
And it can take an empty collection as argument.
Sebastien
Le mardi 17 février 2015 17:14:29 UTC+1, Mark Watson a écrit :
>
> I want to flatten a map of nested maps/vecs
>
> Currently I'm using the fn's:
>
> (defn- flatten-keys* [a ks m]
>
> (cond
>
> (map? m) (reduce into
>
> (map (fn [[k v]]
>
> (flatten-keys* a (if-not (empty? ks)
>
> (str ks "." (name k))
>
> (str "$." (name k))) v)) (seq
> m)))
>
> (and (sequential? m)
>
> (not (instance? clojure.lang.MapEntry m))) (reduce into
>
> (map-indexed (fn
> [idx itm]
>
>
> (flatten-keys* a
>
>
> (str ks "[" idx "]")
>
>
> itm))
>
> (seq
> m)))
>
> :else (assoc a ks m)))
>
> (defn flatten-keys [m] (flatten-keys* {} "" m))
>
> (flatten-keys {:name {:first "Rich" :last "Hickey"} :number [1 415 123 4567]})
>
> ;; => {"$.number[0]" 1, "$.number[1]" 415, "$.number[2]" 123, "$.number[3]"
> 4567, "$.name.first" "Rich", "$.name.last" "Hickey"}
>
>
> However, I was wondering if anyone had suggestions on a more performant fn?
>
> I have a white-list of possible flattened keys. But, the list is big
> (~1200), and with with most (~95%) of the keys having corresponding vals =
> nil it was much less performant using get-in on every possible key.
>
> Thanks for the help!
>
>
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