Added some variables to add clarity

mappingbot/encoder.py

@@ -7,6 +7,9 @@ print(GPIO.VERSION)
 
 class Encoder:
 
+    PULSES_PER_ROTATION = 40  # How many edges you would detect in a full rotation
+    WHEEL_DIAMETER = 6  # TODO: Move this into another file which holds constants like this
+
     def __init__(self, name, encoder_pin: int):
         """Initialize some stuff"""
         self.name = name
@@ -50,7 +53,7 @@ class Encoder:
     def get_speed(self) -> float:
         """Convert pulse speed to cm/s"""
         pulse_per_second = self.get_current_pulse_speed()
-        return pulse_per_second * (6 * 2 * math.pi) / 40
+        return pulse_per_second * (self.WHEEL_DIAMETER * 2 * math.pi) / self.PULSES_PER_ROTATION
 
     def init_callback(self):
         """Initialize the interrupt"""