add utility for joining path on windows

xarray/core/datatree.py

@@ -113,10 +113,6 @@ def _to_new_dataset(data: Dataset | Coordinates | None) -> Dataset:
     return ds
 
 
-def _join_path(root: str, name: str) -> str:
-    return str(NodePath(root) / name)
-
-
 def _inherited_dataset(ds: Dataset, parent: Dataset) -> Dataset:
     return Dataset._construct_direct(
         variables=parent._variables | ds._variables,

xarray/core/treenode.py

@@ -1,7 +1,6 @@
 from __future__ import annotations
 
 import collections
-import os
 import sys
 from collections.abc import Iterator, Mapping
 from pathlib import PurePosixPath
@@ -45,6 +44,10 @@ def __init__(self, *pathsegments):
         # TODO should we also forbid suffixes to avoid node names with dots in them?
 
 
+def join_path(base: str, name: str, /) -> str:
+    return str(NodePath(base) / name)
+
+
 Tree = TypeVar("Tree", bound="TreeNode")
 
 
@@ -435,8 +438,7 @@ def subtree_with_keys(self: Tree) -> Iterator[tuple[str, Tree]]:
             path, node = queue.popleft()
             yield path, node
             queue.extend(
-                (os.path.join(path, name), child)
-                for name, child in node.children.items()
+                (join_path(path, name), child) for name, child in node.children.items()
             )
 
     @property
@@ -870,7 +872,7 @@ def group_subtrees(
 
         for name in first_node.children:
             child_nodes = tuple(node.children[name] for node in active_nodes)
-            queue.append((os.path.join(path, name), child_nodes))
+            queue.append((join_path(path, name), child_nodes))
 
 
 def zip_subtrees(