✨ Add pyiem.grid.nav.get_nav

src/pyiem/grid/nav.py

@@ -95,6 +95,13 @@
 }
 
 
+def get_nav(name: str, dom: str) -> CartesianGridNavigation:
+    """Helper to remove some boilerplate for fetching gridnav."""
+    extra = f"_{dom.upper()}" if dom != "" else ""
+    key = f"{name.upper()}{extra}"
+    return CartesianGridNavigation(**_GRID_CONFIGS[key])
+
+
 def __getattr__(name: str):
     """Build stuff on the fly."""
     if name in _GRID_CONFIGS:

src/pyiem/grid/nav.pyi

@@ -12,3 +12,5 @@ class STAGE4(CartesianGridNavigation): ...
 class STAGE4_PRE2002(CartesianGridNavigation): ...
 class MRMS_IEMRE(CartesianGridNavigation): ...
 class PRISM(CartesianGridNavigation): ...
+
+def get_nav(name: str, region: str) -> CartesianGridNavigation: ...

tests/grid/test_grid_nav.py

@@ -14,3 +14,9 @@ def test_api():
 def test_prism_calc():
     """Test that PRISM works out to what we expect."""
     assert (nav.PRISM.right - -66.50) < 0.01
+
+
+def test_get_nav():
+    """Test that we can get a helper."""
+    assert nav.get_nav("iemRE", "")
+    assert nav.get_nav("era5LAND", "china")

tests/models/test_models_gridnav.py

@@ -31,18 +31,32 @@ def test_non_even_spacing():
         )
 
 
+def test_computing_dxdy():
+    """Test that we can get a dx and dy."""
+    _cgn = CartesianGridNavigation(
+        left_edge=0,
+        bottom_edge=0,
+        nx=10,
+        ny=10,
+        right_edge=10,
+        top_edge=10,
+    )
+    assert _cgn.dx == 1
+    assert _cgn.dy == 1
+
+
 def test_computing_nxny():
     """Test that ny and ny can be computed."""
-    cgn = CartesianGridNavigation(
+    _cgn = CartesianGridNavigation(
         left_edge=0,
         bottom_edge=0,
         dx=1,
         dy=1,
         right_edge=10,
         top_edge=10,
     )
-    assert cgn.nx == 10
-    assert cgn.ny == 10
+    assert _cgn.nx == 10
+    assert _cgn.ny == 10
 
 
 def test_api(cgn):