pydata · eshort0401 · Nov 21, 2025 · Nov 21, 2025 · Nov 21, 2025 · Nov 21, 2025
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
@@ -24,13 +24,13 @@ repos:
       - id: rst-inline-touching-normal
       - id: text-unicode-replacement-char
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.14.3
+    rev: v0.14.6
     hooks:
       - id: ruff-check
         args: ["--fix", "--show-fixes"]
       - id: ruff-format
   - repo: https://github.com/keewis/blackdoc
-    rev: v0.4.5
+    rev: v0.4.6
     hooks:
       - id: blackdoc
         exclude: "generate_aggregations.py"
@@ -76,6 +76,6 @@ repos:
       - id: validate-pyproject
         additional_dependencies: ["validate-pyproject-schema-store[all]"]
   - repo: https://github.com/adhtruong/mirrors-typos
-    rev: v1.39.0
+    rev: v1.39.2
     hooks:
       - id: typos
diff --git a/doc/api/dataarray.rst b/doc/api/dataarray.rst
@@ -162,6 +162,7 @@ Aggregation
    DataArray.min
    DataArray.mean
    DataArray.median
+   DataArray.nunique
    DataArray.prod
    DataArray.sum
    DataArray.std

diff --git a/doc/api/dataset.rst b/doc/api/dataset.rst
@@ -169,6 +169,7 @@ Aggregation
    Dataset.min
    Dataset.mean
    Dataset.median
+   Dataset.nunique
    Dataset.prod
    Dataset.sum
    Dataset.std

diff --git a/doc/api/datatree.rst b/doc/api/datatree.rst
@@ -266,6 +266,7 @@ Aggregate data in all nodes in the subtree simultaneously.
    DataTree.min
    DataTree.mean
    DataTree.median
+   DataTree.nunique
    DataTree.prod
    DataTree.sum
    DataTree.std

diff --git a/doc/whats-new.rst b/doc/whats-new.rst
@@ -22,6 +22,10 @@ New Features
 - :py:func:`combine_nested` now support :py:class:`DataTree` objects
   (:pull:`10849`).
   By `Stephan Hoyer <https://github.com/shoyer>`_.
+- Add :py:func:`nunique` reduction function (:issue:`9548`), which behaves like
+  :py:func:`pandas.DataFrame.nunique` applied along specific dimensions.
+  By `Ewan Short <https://github.com/eshort0401>`_.
+
 
 Breaking Changes
 ~~~~~~~~~~~~~~~~