生成长度为N的相同项的向量

Question

我想根据项目和计数生成相同项目的向量.这似乎是一个比循环更容易做的事情.任何使功能更紧凑/精简的想法？

;take an object and a nubmer n and return a vector of those objects that is n-long
(defn return_multiple_items [item number-of-items]
    (loop [x 0
           items [] ]
      (if (= x number-of-items)
           items
           (recur (+ x 1)
                  (conj items item)))))

>(return_multiple_items "A" 5 )
>["A" "A" "A" "A" "A"]
>(return_multiple_items {:years 3} 3)
>[{:years 3} {:years 3} {:years 3}]

Answer 1

有一个内置函数重复,专门为这种情况设计:

> (repeat 5 "A")
("A" "A" "A" "A" "A")

如您所见,它产生一系列相同的元素.如果你需要一个向量,你可以用vec转换它:

> (vec (repeat 5 "A"))
["A" "A" "A" "A" "A"]