flexible to the case that numpy change convention

Author: Emma Ai

odc/stats/plugins/_base.py

@@ -53,7 +53,7 @@ def native_transform(self, xx: xr.Dataset) -> xr.Dataset:
                 xx[var].attrs.get("nodata") is None
                 and np.dtype(xx[var].dtype).kind == "f"
             ):
-                xx[var].attrs["nodata"] = np.nan
+                xx[var].attrs["nodata"] = xx[var].dtype.type(None)
         return xx
 
     def fuser(self, xx: xr.Dataset) -> xr.Dataset:

odc/stats/plugins/lc_veg_class_a1.py

@@ -200,15 +200,14 @@ def l3_class(self, xx: xr.Dataset):
 
         # Mask nans with NODATA
         l3_mask = expr_eval(
-            "where((a!=a)|((b>=_n)&(_n==_n))|(b!=b), nodata, e)",
+            "where((a!=a), nodata, e)",
             {
                 "a": si5,
-                "b": xx.veg_frequency.data,
                 "e": l3_mask,
             },
             name="mark_nodata",
             dtype="uint8",
-            **{"_n": xx.veg_frequency.attrs["nodata"], "nodata": NODATA},
+            **{"nodata": NODATA},
         )
 
         # Now add the water frequency