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      subvec

      clojure.core

      自 1.0 起提供 (源)
      • (subvec v start)
      • (subvec v start end)
      Returns a persistent vector of the items in vector from
start (inclusive) to end (exclusive).  If end is not supplied,
defaults to (count vector). This operation is O(1) and very fast, as
the resulting vector shares structure with the original and no
trimming is done.
      © Rich Hickey。保留所有权利。Eclipse 公共许可证 1.0
      4 Examples
      ;; not supplying 'end' returns vector from 'start' to (count vector)
user=> (subvec [1 2 3 4 5 6 7] 2)
[3 4 5 6 7]

;; supplying 'end' returns vector from 'start' to element (- end 1)
user=> (subvec [1 2 3 4 5 6 7] 2 4)
[3 4]
      ;; Remove one item by index

(let [coll [0 1 2 3 4 5]
      i 3]
  (concat (subvec coll 0 i)
          (subvec coll (inc i))))
;; => (0 1 2 4 5)
      ;; To query the indices of a subvec:
(def foo (vec (range 10)))
(def bar (subvec foo 3 7)) 
=> (.start bar)
3
=> (.end bar)
7

;; Increments with repeated slicing:
(def baz (subvec bar 2))
=> (.start baz)
5

;; Return the original vector:
=> (.v bar)
[0 1 2 3 4 5 6 7 8 9]
=> (.v baz)
[0 1 2 3 4 5 6 7 8 9]
      ;; IndexOutOfBoundsException for bad indices
=> (subvec [0 1 2 3 4 5] 8 9)
Execution error (IndexOutOfBoundsException) at ...
      See Also
      clojure.core/vector

      Creates a new vector containing the args.

      Added by alimoeeny
      clojure.core/vector?

      Return true if x implements IPersistentVector

      Added by alimoeeny
      1 Note
        By , created 7.1 years ago
        ;; Note that subvec holds a reference to the original vector. If you plan 
;; to split a large vector and never using it again, consider freeing up
;; the reference.

(let [v1 (subvec (vec (range 1e7)) 0 5)
      v2 (subvec (vec (range 1e7)) 5 10)]
      (into v1 v2))
;; OutOfMem

(let [v1 (into [] (subvec (vec (range 1e7)) 0 5))
      v2 (into [] (subvec (vec (range 1e7)) 5 10))]
      (into v1 v2))
;; [0 1 2 3 4 5 6 7 8 9]