Method to match node paths via glob xarray-contrib/datatree#267

* test

* implementation

* documentation

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* whatsnew

* API

* correct faulty test

* remove newline

* search-> match

* format continuation lines correctly

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

datatree/datatree.py

@@ -1242,8 +1242,13 @@ def filter(self: DataTree, filterfunc: Callable[[DataTree], bool]) -> DataTree:
         filterfunc: function
             A function which accepts only one DataTree - the node on which filterfunc will be called.
 
+        Returns
+        -------
+        DataTree
+
         See Also
         --------
+        match
         pipe
         map_over_subtree
         """
@@ -1252,6 +1257,51 @@ def filter(self: DataTree, filterfunc: Callable[[DataTree], bool]) -> DataTree:
         }
         return DataTree.from_dict(filtered_nodes, name=self.root.name)
 
+    def match(self, pattern: str) -> DataTree:
+        """
+        Return nodes with paths matching pattern.
+
+        Uses unix glob-like syntax for pattern-matching.
+
+        Parameters
+        ----------
+        pattern: str
+            A pattern to match each node path against.
+
+        Returns
+        -------
+        DataTree
+
+        See Also
+        --------
+        filter
+        pipe
+        map_over_subtree
+
+        Examples
+        --------
+        >>> dt = DataTree.from_dict(
+        ...     {
+        ...         "/a/A": None,
+        ...         "/a/B": None,
+        ...         "/b/A": None,
+        ...         "/b/B": None,
+        ...     }
+        ... )
+        >>> dt.match("*/B")
+        DataTree('None', parent=None)
+        ├── DataTree('a')
+        │   └── DataTree('B')
+        └── DataTree('b')
+            └── DataTree('B')
+        """
+        matching_nodes = {
+            node.path: node.ds
+            for node in self.subtree
+            if NodePath(node.path).match(pattern)
+        }
+        return DataTree.from_dict(matching_nodes, name=self.root.name)
+
     def map_over_subtree(
         self,
         func: Callable,

datatree/tests/test_datatree.py

@@ -678,6 +678,25 @@ def f(x, tree, y):
 
 
 class TestSubset:
+    def test_match(self):
+        # TODO is this example going to cause problems with case sensitivity?
+        dt = DataTree.from_dict(
+            {
+                "/a/A": None,
+                "/a/B": None,
+                "/b/A": None,
+                "/b/B": None,
+            }
+        )
+        result = dt.match("*/B")
+        expected = DataTree.from_dict(
+            {
+                "/a/B": None,
+                "/b/B": None,
+            }
+        )
+        dtt.assert_identical(result, expected)
+
     def test_filter(self):
         simpsons = DataTree.from_dict(
             d={

docs/source/api.rst

@@ -102,6 +102,7 @@ For manipulating, traversing, navigating, or mapping over the tree structure.
    DataTree.find_common_ancestor
    map_over_subtree
    DataTree.pipe
+   DataTree.match
    DataTree.filter
 
 DataTree Contents

docs/source/hierarchical-data.rst

@@ -379,7 +379,23 @@ Subsetting Tree Nodes
 
 We can subset our tree to select only nodes of interest in various ways.
 
-The :py:meth:`DataTree.filter` method can be used to retain only the nodes of a tree that meet a certain condition.
+Similarly to on a real filesystem, matching nodes by common patterns in their paths is often useful.
+We can use :py:meth:`DataTree.match` for this:
+
+.. ipython:: python
+
+    dt = DataTree.from_dict(
+        {
+            "/a/A": None,
+            "/a/B": None,
+            "/b/A": None,
+            "/b/B": None,
+        }
+    )
+    result = dt.match("*/B")
+
+We can also subset trees by the contents of the nodes.
+:py:meth:`DataTree.filter` retains only the nodes of a tree that meet a certain condition.
 For example, we could recreate the Simpson's family tree with the ages of each individual, then filter for only the adults:
 First lets recreate the tree but with an `age` data variable in every node:
 

docs/source/whats-new.rst

@@ -23,6 +23,8 @@ v0.0.13 (unreleased)
 New Features
 ~~~~~~~~~~~~
 
+- New :py:meth:`DataTree.match` method for glob-like pattern matching of node paths. (:pull:`267`)
+  By `Tom Nicholas <https://github.com/TomNicholas>`_.
 - Indicate which node caused the problem if error encountered while applying user function using :py:func:`map_over_subtree`
   (:issue:`190`, :pull:`264`). Only works when using python 3.11 or later.
   By `Tom Nicholas <https://github.com/TomNicholas>`_.