clojure.core/replace

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Type: function Added: Clojure 1.0 Examples: 5 Runnable: 3

([smap] [smap coll])

Given a map of replacement pairs and a vector/collection, returns a vector/seq with any elements = a key in smap replaced with the corresponding val in smap. Returns a transducer when no collection is provided.

Examples

by jneira on 2010-07-28 ▶

;; Vectors in the first argument are implicitly treated like maps ;; from zero-based indexes to values so this is equivalent to ;; ;; (replace {0 :zeroth, 1 :first, 2 :second, 3 :third, 4 :fourth} [0 2 4 0]) (replace [:zeroth :first :second :third :fourth] [0 2 4 0]) [:zeroth :second :fourth :zeroth] (replace [10 9 8 7 6] [0 2 4]) [10 8 6]

by huahaiy on 2011-05-11 . May have evaluation errors. ▶

(replace {2 :two, 4 :four} [4 2 3 4 5 6 2]) [:four :two 3 :four 5 6 :two] (replace '{0 ZERO, 1 ONE, 2 TWO} '(This is the code 0 1 2 0)) (This is the code ZERO ONE TWO ZERO)

by Alexey Tarasevich on 2013-11-30 . May have evaluation errors. ▶

; Behaves somewhat similar to map, but notice the differences (map [:zeroth :first :second :third :fourth] [0 2 4 0]) (:zeroth :second :fourth :zeroth) ; 1. replace returns a vector, while map returns a seq ; 2. replace keeps unmatched values, while map replace with nil (map {} [0]) (nil) (map [] [0]) IndexOutOfBoundsException clojure.lang.PersistentVector.arrayFor (PersistentVector.java:107)

by ertugrulcetin on 2016-08-26 ▶

(replace {2 :a, 4 :b} [1 2 3 4]) ;;=> [1 :a 3 :b]

by reborg on 2018-02-06 ▶

;; On hash-maps: (def user {:name "jack" :city "London" :id 123}) (defn entry [k v] (clojure.lang.MapEntry/create k v)) (def sub {(entry :city "London") [:postcode "WD12"]}) (into {} (replace sub user)) ;; {:name "jack", :postcode "WD12", :id 123}

Note by jneira

The behaviour for vectors was a little strange for me. I'd say replace "selects" from "smap" the indexes which are in "coll"

See also

• clojure.walk/prewalk-replace
• clojure.walk/postwalk-replace
• clojure.core/map (13)
• clojure.string/replace (8)

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