Some cleanup

spatz/sensors/__init__.py

@@ -1,4 +1,8 @@
 from spatz.sensors.sensor import Sensor
+from spatz.sensors.gps import GPS
 from spatz.sensors.imu import Accelerometer, Gyroscope, IMU
 from spatz.sensors.pressure import PressureSensor
-from spatz.sensors.compound import CompoundSensor
+from spatz.sensors.compound import CompoundSensor
+
+
+from pandas import NA

spatz/sensors/gps/__init__.py

@@ -0,0 +1 @@
+from spatz.sensors.gps.gps import GPS

spatz/transforms/transform.py

@@ -5,7 +5,7 @@ from typing import Any, Tuple
 
 
 class Transform:
-    def apply(self, t: float, x: np.array):
+    def apply(self, t: float, x: ArrayLike):
         y = self(t, x)
         assert x.shape == y.shape, "Transform has to maintain the array's shape."