Question

In Clojure, how do I enter a vector of vectors and print the specified index in each vector? i.e. I enter [1 2 3 4] [5 6 7 8] and my function gives me [1 5] when I call (index vector 0)?

Answer 1

check out the solution and do COMMENT if any doubts.

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(ns clojure.examples.program1
(:gen-class))

(defn index [v n]
(def cnt (count v)) ; count the number of vectors present in 'v' and store it in 'cnt'
(loop [i 0 mat []] ; loop begins from i=0 and an empty vector called 'mat'
(if (< i cnt) ; check if i < cnt
(recur (inc i) (conj mat (get-in v [i n]))) ; increment i and get the specified indexed element 'n' of vector 'v' and concat to vector 'mat' using 'conj'
(println mat)))) ; print the final vector as resultant   

; the below is the way to enter vector of vectors
(def vect [[1 2 3 4] [5 6 7 8]])
; pass the defined vector of vectors 'vect' and index '0' to function 'index'
; call #1
(index vect 0)
; call #2
(index vect 2)

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OUTPUT ::