I would not use an atom. Think about it as doing a reduce while passing
along a set of the names you've seen so far. You might also look at the
implementation of "distinct" in clojure.core which is similar (you want to
detect duplicates in the same way, but emit new names instead of omitting
dupes).
On Friday, January 10, 2014 8:59:10 AM UTC-6, Colin Yates wrote:
>
> I have a sequence of file names and I want to make them unique. (uniquify
> ["a" "b" "c" "a"]) => ["a" "b" "c" "a_1"])
>
> This is what I have come up with, but surely there is a better way?
>
> What would you all do? Feedback welcome (including the word 'muppet' as I
> am sure I have missed something simple) :)
>
> (defn uniquify
> "Return a sequence, in the same order as s containing every element
> of s. If s (which is presumed to be a string) occurs more than once
> then every subsequent occurrence will be made unique.
>
> Items will be updated to include an incrementing numeric count using
> the specified formatter function. The formatter function will be
> given the name and the number and should return a combination of the
> two.
>
> The set of unique s's in the returned sequence will be the count of
> s's in s."
> ([s] (uniquify s (fn [item duplicates] (str item "_" duplicates))))
> ([s formatter]
> (let [occurrences (atom {})
> register-occurrence (fn [item]
> (if (get @occurrences item)
> (swap! (get @occurrences item) inc)
> (swap! occurrences assoc item (atom 1)))
> @(get @occurrences item))
> process (fn [item]
> (let [duplicates (dec (register-occurrence item))]
> (if (> duplicates 0)
> (formatter item duplicates)
> item)))
> unique-s (map process s)]
> unique-s)))
>
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