Fix getting Ellipsoid.semi_minor_metre when not computed (#506)

docs/history.rst

@@ -9,6 +9,7 @@ Change Log
 * ENH: Added :class:`pyproj.crs.CoordinateSystem` to `pyproj.crs` namespace (pull #501)
 * ENH: Added :meth:`pyproj.crs.CoordinateSystem.from_user_input`, :meth:`pyproj.crs.CoordinateOperation.from_user_input`, :meth:`pyproj.crs.Datum.from_user_input`, :meth:`pyproj.crs.PrimeMeridian.from_user_input`, :meth:`pyproj.crs.Ellipsoid.from_user_input` (pull #502)
 * ENH: Added :meth:`pyproj.crs.CoordinateSystem.from_name`, :meth:`pyproj.crs.CoordinateOperation.from_name`, :meth:`pyproj.crs.Datum.from_name`, :meth:`pyproj.crs.PrimeMeridian.from_name`, :meth:`pyproj.crs.Ellipsoid.from_name` (pull #505)
+* BUG: Fix getting :attr:`pyproj.crs.Ellipsoid.semi_minor_metre` when not computed (issue #457)
 
 2.4.2
 ~~~~~

pyproj/_crs.pxd

@@ -40,11 +40,10 @@ cdef class _CRSParts(Base):
 
 
 cdef class Ellipsoid(_CRSParts):
-    cdef double _semi_major_metre
-    cdef double _semi_minor_metre
+    cdef readonly double semi_major_metre
+    cdef readonly double semi_minor_metre
     cdef readonly object is_semi_minor_computed
-    cdef double _inv_flattening
-    cdef readonly object ellipsoid_loaded
+    cdef readonly double inverse_flattening
 
     @staticmethod
     cdef create(PJ_CONTEXT* context, PJ* ellipsoid_pj)

pyproj/_crs.pyx

@@ -718,17 +718,20 @@ cdef class Ellipsoid(_CRSParts):
         The name of the ellipsoid.
     is_semi_minor_computed: int
         1 if True, 0 if False
-    ellipsoid_loaded: bool
-        True if it is loaded without errors.
+    semi_major_metre: float
+        The semi major axis in meters of the ellipsoid.
+    semi_minor_metre: float
+        The semi minor axis in meters of the ellipsoid.
+    inverse_flattening: float
+        The inverse flattening of the ellipsoid.
 
     """
     def __cinit__(self):
         # load in ellipsoid information if applicable
-        self._semi_major_metre = float("NaN")
-        self._semi_minor_metre = float("NaN")
+        self.semi_major_metre = float("NaN")
+        self.semi_minor_metre = float("NaN")
         self.is_semi_minor_computed = False
-        self._inv_flattening = float("NaN")
-        self.ellipsoid_loaded = False
+        self.inverse_flattening = float("NaN")
 
     def __init__(self):
         raise RuntimeError(
@@ -742,14 +745,13 @@ cdef class Ellipsoid(_CRSParts):
         ellips.projobj = ellipsoid_pj
         cdef int is_semi_minor_computed = 0
         proj_ellipsoid_get_parameters(
-            ellips.context,
-            ellips.projobj,
-            &ellips._semi_major_metre,
-            &ellips._semi_minor_metre,
+            context,
+            ellipsoid_pj,
+            &ellips.semi_major_metre,
+            &ellips.semi_minor_metre,
             &is_semi_minor_computed,
-            &ellips._inv_flattening,
+            &ellips.inverse_flattening,
         )
-        ellips.ellipsoid_loaded = True
         ellips.is_semi_minor_computed = is_semi_minor_computed == 1
         ellips._set_base_info()
         CRSError.clear()
@@ -954,47 +956,6 @@ cdef class Ellipsoid(_CRSParts):
         CRSError.clear()
         return Ellipsoid.create(context, ellipsoid_pj)
 
-    @property
-    def semi_major_metre(self):
-        """
-        The ellipsoid semi major metre.
-
-        Returns
-        -------
-        float or None: The semi major metre if the projection is an ellipsoid.
-        """
-        if self.ellipsoid_loaded:
-            return self._semi_major_metre
-        return float("NaN")
-
-    @property
-    def semi_minor_metre(self):
-        """
-        The ellipsoid semi minor metre.
-
-        Returns
-        -------
-        float or None: The semi minor metre if the projection is an ellipsoid
-            and the value was com
-            puted.
-        """
-        if self.ellipsoid_loaded and self.is_semi_minor_computed:
-            return self._semi_minor_metre
-        return float("NaN")
-
-    @property
-    def inverse_flattening(self):
-        """
-        The ellipsoid inverse flattening.
-
-        Returns
-        -------
-        float or None: The inverse flattening if the projection is an ellipsoid.
-        """
-        if self.ellipsoid_loaded:
-            return self._inv_flattening
-        return float("NaN")
-
 
 cdef class PrimeMeridian(_CRSParts):
     """

pyproj/crs.py

@@ -463,14 +463,13 @@ def get_geod(self):
         -------
         pyproj.geod.Geod: Geod object based on the ellipsoid.
         """
-        if self.ellipsoid is None or not self.ellipsoid.ellipsoid_loaded:
+        if self.ellipsoid is None:
             return None
         in_kwargs = {
             "a": self.ellipsoid.semi_major_metre,
             "rf": self.ellipsoid.inverse_flattening,
+            "b": self.ellipsoid.semi_minor_metre,
         }
-        if self.ellipsoid.is_semi_minor_computed:
-            in_kwargs["b"] = self.ellipsoid.semi_minor_metre
         return Geod(**in_kwargs)
 
     @classmethod

test/test_crs.py

@@ -422,6 +422,13 @@ def test_ellipsoid():
     assert "{:.3f}".format(crs1.ellipsoid.semi_minor_metre) == "6356752.314"
 
 
+def test_ellipsoid__semi_minor_not_computed():
+    cc = CRS("+proj=geos +lon_0=-89.5 +a=6378137.0 +b=6356752.31 h=12345")
+    assert cc.datum.ellipsoid.semi_minor_metre == 6356752.31
+    assert cc.datum.ellipsoid.semi_major_metre == 6378137.0
+    assert not cc.datum.ellipsoid.is_semi_minor_computed
+
+
 def test_area_of_use():
     crs1 = CRS.from_epsg(4326)
     assert crs1.area_of_use.bounds == (-180.0, -90.0, 180.0, 90.0)