clojure.core/subvec

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Type: function Added: Clojure 1.0 Examples: 4 Runnable: 2

([v start] [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.

Examples

by zmila on 2010-08-11 ▶

;; not supplying 'end' returns vector from 'start' to (count vector) (subvec [1 2 3 4 5 6 7] 2) [3 4 5 6 7] ;; supplying 'end' returns vector from 'start' to element (- end 1) (subvec [1 2 3 4 5 6 7] 2 4) [3 4]

by freckletonj on 2016-10-18 ▶

;; 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)

by Sophia-Gold on 2017-08-28 . May have evaluation errors. ▶

;; 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]

by jonathan-chen-tda on 2019-11-11 . May have evaluation errors. ▶

;; IndexOutOfBoundsException for bad indices => (subvec [0 1 2 3 4 5] 8 9) Execution error (IndexOutOfBoundsException) at ...

Note by reborg

;; 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]

See also

• clojure.core/vector (3)
• clojure.core/vector? (2)

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