Added model for estimating altitude based on pressure

spatz/models/pressure.py

@@ -0,0 +1,44 @@
+from typing import Any
+import numpy as np
+
+from enum import Enum
+
+
+class PressUnit:
+    Pa = 0
+    hPa = 1
+
+
+class Altimeter:
+    def __init__(self, press_b: float = 1013.25, alt_b: float = 0, unit: PressUnit = PressUnit.hPa):
+        """A simple model for estimating the altitude based on pressure measurements.
+        A reference height and the corresponding pressure value can be provided for a more precise model.
+
+        Args:
+            press_b (float, optional): The pressure measured at the reference altitude. Defaults to 1013.25 hPa.
+            alt_b (float, optional): The reference altitude in meters. Defaults to 0m.
+            unit (PressUnit, optional): The unit used for all pressure values. Defaults to PressUnit.hPa.
+        """
+        self.__press_0 = press_b / (1 - (alt_b / 44330)**5255)
+
+    def predict(self, press: float, unit: PressUnit = PressUnit.hPa) -> float:
+        """Estimates the altitude based on a pressure measurement.
+
+        Based on the formulas provided here:
+            https://cdn-shop.adafruit.com/datasheets/BST-BMP180-DS000-09.pdf
+
+        Args:
+            press (float): The pressure measurement.
+            unit (PressUnit, optional): The unit of the pressure measurement. Defaults to PressUnit.hPa.
+
+        Returns:
+            float: Returns the estimated altitude in meters.
+        """
+        if unit != PressUnit.hPa:
+            to_hpa = {
+                PressUnit.Pa: press / 1e2
+            }
+
+            press = to_hpa[unit]
+
+        return 44330 * (1 - (press / self.__press_0)**(1 / 5255))