Merge pull request #2077 from guziy/z-coord-for-crs

Calculate vertical coord, even if not explicitely requested

lib/cartopy/crs.py

@@ -47,13 +47,13 @@ def _get_transformer_from_crs(src_crs, tgt_crs):
 
 def _safe_pj_transform(src_crs, tgt_crs, x, y, z=None, trap=True):
     transformer = _get_transformer_from_crs(src_crs, tgt_crs)
-    transformed_coords = transformer.transform(x, y, z, errcheck=trap)
+
+    # if a projection is essentially 2d there
+    # should be no harm in setting its z to 0
     if z is None:
-        xx, yy = transformed_coords
-        zz = 0
-    else:
-        xx, yy, zz = transformed_coords
-    return xx, yy, zz
+        z = np.zeros_like(x)
+
+    return transformer.transform(x, y, z, errcheck=trap)
 
 
 class Globe:

lib/cartopy/tests/test_crs.py

@@ -303,8 +303,7 @@ def test_transform_points_outside_domain():
     crs = ccrs.Orthographic()
     result = crs.transform_points(ccrs.PlateCarree(),
                                   np.array([-120]), np.array([80]))
-    assert np.all(np.isnan(result[..., :2]))
-    assert result[..., -1] == 0
+    assert np.all(np.isnan(result))
     result = crs.transform_points(ccrs.PlateCarree(),
                                   np.array([-120]), np.array([80]),
                                   trap=True)