CODEWITHSUNDEEP
clojure
user3602477
user3602477

Reputation: 99

Clojure loop through a vector starting from the nth element not 0

I would like to loop through a vector starting from the nth element not 0;

How it looks like in Java:

for(int i = firstIndex; i <= lastIndex; i++) {
    newText += contents[i] + " ";
}

Upvotes: 0

Views: 579

Answers (2)

Nathan Davis
Nathan Davis

Reputation: 5766

If you are always dealing with a vector, then subvec is a good choice. For example:

(subvec contents firstIndex)

If you want to be compatible with sequences in general, you'll want to use drop. drop is O(n) w.r.t. the number of elements dropped, which subvec is always O(1). If you're only ever dropping a few elements, the difference is negligible. But for dropping a large number of elements (i.e., large firstIndex), subvec will be a clear winner. But subvec is only available on vectors.

Upvotes: 5

lest
lest

Reputation: 8100

You can use the drop function to skip first n elements and then loop over the result. For example, if you want to skip two first elements:

user=> (drop 2 [1 2 3 4])
(3 4)

The following can possibly do the same that the Java form you provided:

(require '[clojure.string :as str])
(str/join " " (drop first-index contents))

Upvotes: 1

Related Questions