(def app-state
  (atom {:sensors
          {{:kind :temperature :label-id 1} [[21.0, 0]]
           {:kind :temperature :label-id 2} [[32.0, 0]]}
         :labels {}}))

(swap! app-state assoc-in [:sensors] (update-in (:sensors @app-state) [{:kind :temperature :label-id 1}] conj [99.9 1]))