[asdf] Do not copy array data (#456)

* only cast to ndarray, if not a time type. This makes asdf copy_arrays flag effective again.
* explicitly set DataArray.name to None, to prevent it being derived from ndarray.name (which is used for asdf.NDarraytype wrapper).


Co-authored-by: Cagtay Fabry <43667554+CagtayFabry@users.noreply.github.com>

weldx/asdf/tags/weldx/core/common_types.py

@@ -134,7 +134,12 @@ def from_tree(cls, tree, ctx):
 
         """
         dtype = np.dtype(tree["dtype"])
-        data = np.array(tree["data"], dtype=dtype)
+        # TODO: it would be ideal, if asdf would handle time types natively.
+        if dtype.char in ("M", "m"):  # handle np.timedelta64 and np.datetime64
+            data = np.array(tree["data"], dtype=dtype)
+            # assert data.base is tree["data"]
+        else:
+            data = tree["data"]  # let asdf handle np arrays with its own wrapper.
         if "unit" in tree:  # convert to pint.Quantity
             data = Q_(data, tree["unit"])
 

weldx/asdf/tags/weldx/core/data_array.py

@@ -73,4 +73,7 @@ def from_tree(cls, tree, ctx):
         attrs = tree["attributes"]
 
         da = DataArray(data=data, coords=coords, dims=dims, attrs=attrs)
+        da.name = None  # we currently do not use the name attribute
+        # (but since it gets automatically derived if not set, we define it now.
+
         return da