window-by-time transducer

time-window.clj

=> (require '[net.cgrand.xforms :as x]) ; https://github.com/cgrand/xforms
=> (into []
     (x/window-by-time
       :ts ; normalized time function -- window length is always 1.0
       4 ; number of steps to slide the window
       (fn ; initializing/snapshooting/reducing function
         ([] clojure.lang.PersistentQueue/EMPTY)
         ([q] (vec q))
         ([q x] (conj q x)))
       (fn [q _] (pop q))) ; inverse reducing function
     (map (fn [x] {:ts x}) (concat (range 0 2 0.5) (range 3 5 0.25)))) ; input with "holes"
 [[{:ts 0}] ; t =  0
  [{:ts 0}] ; t =  0.25
  [{:ts 0} {:ts 0.5}] ; t =  0.5
  [{:ts 0} {:ts 0.5}] ; t =  0.75
  [{:ts 0.5} {:ts 1.0}] ; t =  1.0
  [{:ts 0.5} {:ts 1.0}] ; t =  1.25
  [{:ts 1.0} {:ts 1.5}] ; t =  1.5
  [{:ts 1.0} {:ts 1.5}] ; t =  1.75
  [{:ts 1.5}] ; t =  2.0
  [{:ts 1.5}] ; t =  2.25
  [] ; t =  2.5
  [] ; t =  2.75
  [{:ts 3}] ; t =  3.0
  [{:ts 3} {:ts 3.25}] ; t =  3.25
  [{:ts 3} {:ts 3.25} {:ts 3.5}] ; t =  3.5
  [{:ts 3} {:ts 3.25} {:ts 3.5} {:ts 3.75}] ; t =  3.75
  [{:ts 3.25} {:ts 3.5} {:ts 3.75} {:ts 4.0}] ; t =  4.0
  [{:ts 3.5} {:ts 3.75} {:ts 4.0} {:ts 4.25}] ; t =  4.25
  [{:ts 3.75} {:ts 4.0} {:ts 4.25} {:ts 4.5}] ; t =  4.5
  [{:ts 4.0} {:ts 4.25} {:ts 4.5} {:ts 4.75}]] ; t =  4.75