1 files changed, 75 insertions, 14 deletions
diff --git a/numpy/array_api/_set_functions.py b/numpy/array_api/_set_functions.py
index 357f238f5..05ee7e555 100644
--- a/numpy/array_api/_set_functions.py
+++ b/numpy/array_api/_set_functions.py
@@ -2,19 +2,82 @@ from __future__ import annotations
 
 from ._array_object import Array
 
-from typing import Tuple, Union
+from typing import NamedTuple
 
 import numpy as np
 
+# Note: np.unique() is split into four functions in the array API:
+# unique_all, unique_counts, unique_inverse, and unique_values (this is done
+# to remove polymorphic return types).
 
-def unique(
-    x: Array,
-    /,
-    *,
-    return_counts: bool = False,
-    return_index: bool = False,
-    return_inverse: bool = False,
-) -> Union[Array, Tuple[Array, ...]]:
+# Note: The various unique() functions are supposed to return multiple NaNs.
+# This does not match the NumPy behavior, however, this is currently left as a
+# TODO in this implementation as this behavior may be reverted in np.unique().
+# See https://github.com/numpy/numpy/issues/20326.
+
+# Note: The functions here return a namedtuple (np.unique() returns a normal
+# tuple).
+
+class UniqueAllResult(NamedTuple):
+    values: Array
+    indices: Array
+    inverse_indices: Array
+    counts: Array
+
+
+class UniqueCountsResult(NamedTuple):
+    values: Array
+    counts: Array
+
+
+class UniqueInverseResult(NamedTuple):
+    values: Array
+    inverse_indices: Array
+
+
+def unique_all(x: Array, /) -> UniqueAllResult:
+    """
+    Array API compatible wrapper for :py:func:`np.unique <numpy.unique>`.
+
+    See its docstring for more information.
+    """
+    res = np.unique(
+        x._array,
+        return_counts=True,
+        return_index=True,
+        return_inverse=True,
+    )
+
+    return UniqueAllResult(*[Array._new(i) for i in res])
+
+
+def unique_counts(x: Array, /) -> UniqueCountsResult:
+    res = np.unique(
+        x._array,
+        return_counts=True,
+        return_index=False,
+        return_inverse=False,
+    )
+
+    return UniqueCountsResult(*[Array._new(i) for i in res])
+
+
+def unique_inverse(x: Array, /) -> UniqueInverseResult:
+    """
+    Array API compatible wrapper for :py:func:`np.unique <numpy.unique>`.
+
+    See its docstring for more information.
+    """
+    res = np.unique(
+        x._array,
+        return_counts=False,
+        return_index=False,
+        return_inverse=True,
+    )
+    return UniqueInverseResult(*[Array._new(i) for i in res])
+
+
+def unique_values(x: Array, /) -> Array:
     """
     Array API compatible wrapper for :py:func:`np.unique <numpy.unique>`.
 
@@ -22,10 +85,8 @@ def unique(
     """
     res = np.unique(
         x._array,
-        return_counts=return_counts,
-        return_index=return_index,
-        return_inverse=return_inverse,
+        return_counts=False,
+        return_index=False,
+        return_inverse=False,
     )
-    if isinstance(res, tuple):
-        return tuple(Array._new(i) for i in res)
     return Array._new(res)