(defun doc->point (doc)
  (geo:point-deg
   (/ (get-element "latitudeE7" doc) 1d7)
   (/ (get-element "longitudeE7" doc) 1d7)))

(defun doc->ts (doc)
  (local-time:unix-to-timestamp
   (floor (get-element "timestampMs" doc) 1000)))

(defun day-kv (date)
  (let* ((ts (local-time:parse-timestring date))
         (nd (local-time:timestamp+ ts 1 :day)))
    ($between "timestampMs"
              (* 1000 (local-time:timestamp-to-unix ts))
              (* 1000 (local-time:timestamp-to-unix nd)))))

(defun extract-places (docs)
  (loop
     for doc in docs
     for point = (doc->point doc)     
     with last-place and moved and need-add
     when last-place do (setf moved
                              (geo:distance>=
                               (geo:distance-between
                                point
                                (doc->point last-place))
                               (geo:distance-meters 200)))
     when moved do (setf last-place doc
                         need-add t)
     when (and need-add
               (> (local-time:timestamp-difference
                   (doc->ts doc)
                   (doc->ts last-place))
                  400))
     collect (cons (doc->ts last-place) (doc->point last-place))
     and do (setf need-add nil)
     when (not last-place) do (setf last-place doc)
       ))