Function 为 clojure 中向量的最大索引

Question

Hi I'd like to ask how to get the maximum value of index from Vector in clojure?

(def dummyvector [190 260 300 310 250])

I have dummyvector here, index 0 = 190, 1 = 260... I know the maximum is index 4 = 250. Does clojure have function to get the index value of 4?

Answer 1

Please see the list of documentation in this template project , especially Getting Clojure, Brave Clojure, and the Clojure CheatSheet.

As for your particular question, just type something like:

> (count [5 4 3 2 1])
5

You can then use the dec function (decrement by 1) to get 4 .

> (dec (count [5 4 3 2 1]))
4

If you are instead trying to search for an arbitrary value in the list, you may wish to use Java interop like:

(.indexOf  [0 2 4 1 3 5]  4) => 2

Answer 2

Indexes are zero-based in Clojure so you could use

(dec (count dummyvector))

or

(->> dummyvector count dec)

or if you really want to go the long way around the barn to find this

(last (keys (zipmap (range 1 (count dummyvector)) dummyvector)))