Clojure zip function

Question

I need to build a seq of seqs (vec of vecs) by combining first, second, etc elements of the given seqs.

After a quick searching and looking at the cheat sheet. I haven't found one and finished with writing my own:

(defn zip 
  "From the sequence of sequences return a another sequence of sequenses
  where first result sequense consist of first elements of input sequences
  second element consist of second elements of input sequenses etc.

  Example:

  [[:a 0 \\a] [:b 1 \\b] [:c 2 \\c]] => ([:a :b :c] [0 1 2] [\\a \\b \\c])"
  [coll]
  (let [num-elems (count (first coll))
        inits (for [_ (range num-elems)] [])]
    (reduce (fn [cols elems] (map-indexed
                              (fn [idx coll] (conj coll (elems idx))) cols))
        inits coll)))

I'm interested if there is a standard method for this?

Answer 1

(apply map vector [[:a 0 \a] [:b 1 \b] [:c 2 \c]])
;; ([:a :b :c] [0 1 2] [\a \b \c])

You can use the variable arity of map to accomplish this.

From the map docstring:

... Returns a lazy sequence consisting of the result of applying f to the set of first items of each coll, followed by applying f to the set of second items in each coll, until any one of the colls is exhausted. Any remaining items in other colls are ignored....