adding nvector module

Author: ryanpavlick

src/pymap3d/nvector.py

@@ -0,0 +1,101 @@
+import numpy as np
+import pymap3d as pm
+
+def geodetic2nvector(lat, lon, ell=None, deg=True):
+    """
+    Convert geodetic coordinates (latitude, longitude) to an n-vector.
+
+    Parameters:
+        lat : float or array-like
+            Geodetic latitude(s).
+        lon : float or array-like
+            Geodetic longitude(s).
+        ell : str or tuple, optional
+            Reference ellipsoid (default is None, which uses WGS84).
+        deg : bool, optional
+            If True (default), inputs are in degrees. If False, use radians.
+
+    Returns:
+        n1, n2, n3 : ndarray
+            Components of the n-vector in the Earth-Centered Earth-Fixed (ECEF) coordinate system.
+    """
+    lat, lon = np.atleast_1d(lat), np.atleast_1d(lon)
+
+    if deg:
+        lat, lon = np.radians(lat), np.radians(lon)
+
+    sin_lat, cos_lat = np.sin(lat), np.cos(lat)
+    sin_lon, cos_lon = np.sin(lon), np.cos(lon)
+
+    n1 = cos_lat * cos_lon
+    n2 = cos_lat * sin_lon
+    n3 = sin_lat
+
+    return n1, n2, n3
+
+def nvector2geodetic(n1, n2, n3, ell=None, deg=True):
+    """
+    Convert an n-vector back to geodetic coordinates (latitude, longitude).
+
+    Parameters:
+        n1, n2, n3 : float or array-like
+            Components of the n-vector in the Earth-Centered Earth-Fixed (ECEF) coordinate system.
+        ell : str or tuple, optional
+            Reference ellipsoid (default is None, which uses WGS84).
+        deg : bool, optional
+            If True (default), returns latitude and longitude in degrees. If False, in radians.
+
+    Returns:
+        lat, lon : ndarray
+            Geodetic latitude(s) and longitude(s).
+    """
+    n1, n2, n3 = np.atleast_1d(n1), np.atleast_1d(n2), np.atleast_1d(n3)
+
+    # Compute latitude and longitude from n-vector
+    lat = np.arcsin(n3)
+    lon = np.arctan2(n2, n1)
+
+    if deg:
+        lat, lon = np.degrees(lat), np.degrees(lon)
+
+    return lat, lon
+
+def ecef2nvector(x, y, z, ell=None, deg=True):
+    """
+    Convert ECEF coordinates to an n-vector.
+
+    Parameters:
+        x, y, z : float or array-like
+            ECEF coordinates in meters.
+        ell : str or tuple, optional
+            Reference ellipsoid (default is None, which uses WGS84).
+        deg : bool, optional
+            If True (default), geodetic2nvector() inputs are in degrees. If False, in radians.
+
+    Returns:
+        n1, n2, n3 : ndarray
+            Components of the n-vector in the Earth-Centered Earth-Fixed (ECEF) coordinate system.
+    """
+    lat, lon, _ = pm.ecef2geodetic(x, y, z, ell=ell, deg=deg)
+    return geodetic2nvector(lat, lon, ell=ell, deg=deg)
+
+def nvector2ecef(n1, n2, n3, alt=0, ell=None, deg=True):
+    """
+    Convert an n-vector to ECEF coordinates.
+
+    Parameters:
+        n1, n2, n3 : float or array-like
+            Components of the n-vector in the Earth-Centered Earth-Fixed (ECEF) coordinate system.
+        alt : float or array-like, optional
+            Altitude in meters (default is 0).
+        ell : str or tuple, optional
+            Reference ellipsoid (default is None, which uses WGS84).
+        deg : bool, optional
+            If True (default), nvector2geodetic() outputs are in degrees. If False, in radians.
+
+    Returns:
+        x, y, z : ndarray
+            ECEF coordinates in meters.
+    """
+    lat, lon = nvector2geodetic(n1, n2, n3, ell=ell, deg=deg)
+    return pm.geodetic2ecef(lat, lon, alt, ell=ell, deg=deg)