A quick moving average

gistfile1.clj

(defn sma [n s]
  {:pre [(pos? n)]}
  (concat
   (repeat (dec n) nil)
   (map #(/ (reduce + %) n) (partition n 1 s))))

 (defn simple-moving-average                                                                                                                            
   "Calculates the moving average of 's with window size 'w.                                                                                     

    Returns a list with length less 'w than the original."                                                                                       
   [xs w]                                                                                                                                        
   (map #(/ (reduce + %) w)                                                                                                                      
         (partition w 1 xs)))