CLN: Port x_rotation_conv.c to python

src/clib/xtg/libxtg.h

@@ -178,8 +178,6 @@ double
 x_avg_angles(double *swig_np_dbl_in_v1,  // *angles
              long n_swig_np_dbl_in_v1);  // nsize,
 
-double
-x_rotation_conv(double ain, int aimode, int mode, int option);
 
 double
 x_tetrahedron_volume(double *swig_np_dbl_inplaceflat_v1,

src/xtgeo/common/_angles.py

@@ -0,0 +1,29 @@
+from math import degrees, radians
+
+
+def _deg_angle2azimuth(deg: float) -> float:
+    """Converts an angle from X-axis anti-clockwise orientation
+    to Y-axis clockwise azimuth.
+    """
+    return (-deg + 90) % 360
+
+
+def _deg_azimuth2angle(deg: float) -> float:
+    """Converts azimuth from Y-axis clockwise orientation to X-axis
+    anti-clockwise angle.
+    """
+    return (450 - deg) % 360
+
+
+def _rad_angle2azimuth(rad: float) -> float:
+    """Converts an angle from X-axis anti-clockwise orientation to Y-axis clockwise
+    azimuth in radians.
+    """
+    return radians(_deg_angle2azimuth(degrees(rad)))
+
+
+def _rad_azimuth2angle(deg: float) -> float:
+    """Converts azimuth from Y-axis clockwise orientation to X-axis anti-clockwise
+    angle in radians.
+    """
+    return radians(_deg_azimuth2angle(degrees(deg)))

src/xtgeo/common/calc.py

@@ -8,7 +8,7 @@
 import numpy as np
 
 from xtgeo import XTGeoCLibError, _cxtgeo
-from xtgeo.common import XTGeoDialog, null_logger
+from xtgeo.common import XTGeoDialog, _angles, null_logger
 
 xtg = XTGeoDialog()
 logger = null_logger(__name__)
@@ -207,13 +207,11 @@ def angle2azimuth(
     Return:
         Azimuth angle (in degrees or radian)
     """
-    nmode1 = 0
-    nmode2 = 2
-    if mode == "radians":
-        nmode1 += 1
-        nmode2 += 1
-
-    return _cxtgeo.x_rotation_conv(inangle, nmode1, nmode2, 0)
+    return (
+        _angles._deg_angle2azimuth(inangle)
+        if mode == "degrees"
+        else _angles._rad_angle2azimuth(inangle)
+    )
 
 
 def azimuth2angle(
@@ -232,13 +230,11 @@ def azimuth2angle(
     Return:
         Angle (in degrees or radians)
     """
-    nmode1 = 2
-    nmode2 = 0
-    if mode == "radians":
-        nmode1 += 1
-        nmode2 += 1
-
-    return _cxtgeo.x_rotation_conv(inangle, nmode1, nmode2, 0)
+    return (
+        _angles._deg_azimuth2angle(inangle)
+        if mode == "degrees"
+        else _angles._rad_azimuth2angle(inangle)
+    )
 
 
 def tetrehedron_volume(vertices: Sequence[float]) -> float:

tests/test_common/test_calc.py

@@ -4,6 +4,8 @@
 
 import numpy as np
 import pytest
+from hypothesis import given
+from hypothesis import strategies as st
 
 import xtgeo
 import xtgeo.common.calc as xcalc
@@ -190,6 +192,36 @@ def test_azimuth2angle():
     assert res == 120
 
 
+@given(
+    x=st.floats(
+        min_value=0,
+        max_value=180,
+        allow_infinity=False,
+        allow_nan=False,
+    )
+)
+def test_angle2azimuth_azimuth2angle_deg(x: float) -> None:
+    assert (
+        pytest.approx(xcalc.azimuth2angle(xcalc.angle2azimuth(x, "degrees"), "degrees"))
+        == x
+    )
+
+
+@given(
+    x=st.floats(
+        min_value=0,
+        max_value=math.pi,
+        allow_infinity=False,
+        allow_nan=False,
+    )
+)
+def test_angle2azimuth_azimuth2angle_rad(x: float) -> None:
+    assert (
+        pytest.approx(xcalc.azimuth2angle(xcalc.angle2azimuth(x, "radians"), "radians"))
+        == x
+    )
+
+
 def test_averageangle():
     """Test finding an average angle"""