clojure.core/split-with

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Type: function Added: Clojure 1.0 Examples: 3 Runnable: 1

([pred coll])

Returns a vector of [(take-while pred coll) (drop-while pred coll)]

Examples

by gstamp on 2010-08-11 . May have evaluation errors. ▶

(split-with (partial >= 3) [1 2 3 4 5]) [(1 2 3) (4 5)] (split-with (partial > 3) [1 2 3 2 1]) [(1 2) (3 2 1)] (split-with (partial > 10) [1 2 3 2 1]) [(1 2 3 2 1) ()]

by achesnais on 2016-08-10 . May have evaluation errors. ▶

;; If your plan is to split based on a certain value, using sets as ;; predicates here isn't entirely straightforward. (split-with #{:c} [:a :b :c :d]) [() (:a :b :c :d)] ;; This is because the split happens at the first false/nil predicate result. ;; Your predicate should thus return false upon hitting the desired split value! (split-with (complement #{:c}) [:a :b :c :d]) [(:a :b) (:c :d)] ;; In short, the predicate defines an attribute valid for the whole left ;; side of the split. There's no such guarantee for the right side! (split-with odd? [1 3 5 6 7 9]) [(1 3 5) (6 7 9)] ;; Except if your predicate never returns false. (split-with (complement #{:e}) [:a :b :c :d]) [(:a :b :c :d) ()]

by reborg on 2020-02-15 ▶

;; The following split-by builds on top of split-with. Instead of ;; splitting only the first time pred returns false, it splits (lazily) ;; every time it turns from true to false. (defn split-by [pred coll] (lazy-seq (when-let [s (seq coll)] (let [[xs ys] (split-with pred s)] (if (seq xs) (cons xs (split-by pred ys)) (let [!pred (complement pred) skip (take-while !pred s) others (drop-while !pred s) [xs ys] (split-with pred others)] (cons (concat skip xs) (split-by pred ys)))))))) (split-by #(zero? (mod % 2)) [1 1 2 3 3 4 5 6 7 9]) ;; => ((1 1 2) (3 3 4) (5 6) (7 9))

See also

• clojure.core/split-at (2)
• clojure.string/split (4)
• clojure.core/take-while (3)
• clojure.core/drop-while (2)
• clojure.core/partition-by (3)

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