CODEWITHSUNDEEP
clojureseqsliding-window
pmf
pmf

Reputation: 7749

Sliding window over seq

In Clojure, what would be the nicest way to have a sliding window over a (finite, not too large) seq? Should I just use drop and take and keep track of the current index or is there a nicer way I'm missing?

Upvotes: 19

Views: 4130

Answers (3)

little-dude
little-dude

Reputation: 1674

I didn't know partition could do this so I implemented it this way

(defn sliding-window [seq length]
  (loop [result ()
         remaining seq]
    (let [chunk (take length remaining)]
      (if (< (count chunk) length)
        (reverse result)
        (recur (cons chunk result) (rest remaining))))))

Upvotes: 1

Timothy Pratley
Timothy Pratley

Reputation: 10662

If you want to operate on the windows, it can also be convenient to do this with map:

user=> (def a [3 1 4 1 5 9])
user=> (map (partial apply +) (partition 3 1 a))
(8 6 10 15)
user=> (map + a (next a) (nnext a))
(8 6 10 15)

Upvotes: 3

Jonas
Jonas

Reputation: 19642

I think that partition with step 1 does it:

user=> (partition 3 1 [3 1 4 1 5 9])
((3 1 4) (1 4 1) (4 1 5) (1 5 9))

Upvotes: 33

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