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clojuresequence

How can i get the second to last element of a Sequence? Clojure

i know how to get the last element with the function last but is it possible to get the second to last element of a Sequence?

(defn last
  [args]
   (last args))
(last [1 2 3 4]) ;;--> 4 but i want it to return 3
Solution

  • Use reverse, take-last, butlast or nth (this one seems to be the fastest):

    (defn second-to-last1 [s]
  (second (reverse s)))

(second-to-last1 (range 100))
=> 98

(defn second-to-last2 [s]
  (first (take-last 2 s)))

(second-to-last2 (range 100))
=> 98

(defn second-to-last3 [s]
  (last (butlast s)))

(second-to-last3 (range 100))
=> 98

(defn second-to-last4 [s]
  (nth s (- (count s) 2) nil))

(second-to-last4 (range 100))
=> 98