ENH/PERF: add ExtensionArray.duplicated

asv_bench/benchmarks/algorithms.py

@@ -1,6 +1,7 @@
 from importlib import import_module
 
 import numpy as np
+import pyarrow as pa
 
 import pandas as pd
 
@@ -80,7 +81,7 @@ class Duplicated:
             "datetime64[ns]",
             "datetime64[ns, tz]",
             "timestamp[ms][pyarrow]",
-            "duration[s][pyarrow]",
+            "string[pyarrow]",
         ],
     ]
     param_names = ["unique", "keep", "dtype"]
@@ -97,11 +98,9 @@ def setup(self, unique, keep, dtype):
                 "2011-01-01", freq="H", periods=N, tz="Asia/Tokyo"
             ),
             "timestamp[ms][pyarrow]": pd.Index(
-                np.arange(N), dtype="timestamp[ms][pyarrow]"
-            ),
-            "duration[s][pyarrow]": pd.Index(
-                np.arange(N), dtype="duration[s][pyarrow]"
+                np.arange(N), dtype=pd.ArrowDtype(pa.timestamp("ms"))
             ),
+            "string[pyarrow]": tm.makeStringIndex(N).astype(pd.ArrowDtype(pa.string())),
         }[dtype]
         if not unique:
             data = data.repeat(5)

doc/source/whatsnew/v2.2.0.rst

@@ -76,6 +76,7 @@ Other enhancements
 
 - :func:`read_csv` now supports ``on_bad_lines`` parameter with ``engine="pyarrow"``. (:issue:`54480`)
 - :meth:`ExtensionArray._explode` interface method added to allow extension type implementations of the ``explode`` method (:issue:`54833`)
+- :meth:`ExtensionArray.duplicated` added to allow extension type implementations of the ``duplicated`` method (:issue:`55255`)
 - DataFrame.apply now allows the usage of numba (via ``engine="numba"``) to JIT compile the passed function, allowing for potential speedups (:issue:`54666`)
 -
 
@@ -239,7 +240,7 @@ Performance improvements
 - Performance improvement in :meth:`DataFrame.groupby` when aggregating pyarrow timestamp and duration dtypes (:issue:`55031`)
 - Performance improvement in :meth:`DataFrame.sort_index` and :meth:`Series.sort_index` when indexed by a :class:`MultiIndex` (:issue:`54835`)
 - Performance improvement in :meth:`Index.difference` (:issue:`55108`)
-- Performance improvement in :meth:`Series.duplicated` for pyarrow timestamp and duration dtypes (:issue:`55255`)
+- Performance improvement in :meth:`Series.duplicated` for pyarrow dtypes (:issue:`55255`)
 - Performance improvement when indexing with more than 4 keys (:issue:`54550`)
 - Performance improvement when localizing time to UTC (:issue:`55241`)
 

pandas/core/algorithms.py

@@ -55,7 +55,6 @@
 )
 from pandas.core.dtypes.concat import concat_compat
 from pandas.core.dtypes.dtypes import (
-    ArrowDtype,
     BaseMaskedDtype,
     CategoricalDtype,
     ExtensionDtype,
@@ -979,40 +978,32 @@ def value_counts_arraylike(
 
 
 def duplicated(
-    values: ArrayLike, keep: Literal["first", "last", False] = "first"
+    values: ArrayLike,
+    keep: Literal["first", "last", False] = "first",
+    mask: npt.NDArray[np.bool_] | None = None,
 ) -> npt.NDArray[np.bool_]:
     """
     Return boolean ndarray denoting duplicate values.
 
     Parameters
     ----------
-    values : nd.array, ExtensionArray or Series
+    values : np.ndarray or ExtensionArray
         Array over which to check for duplicate values.
     keep : {'first', 'last', False}, default 'first'
         - ``first`` : Mark duplicates as ``True`` except for the first
           occurrence.
         - ``last`` : Mark duplicates as ``True`` except for the last
           occurrence.
         - False : Mark all duplicates as ``True``.
+    mask : ndarray[bool]
+        array indicating which elements to exclude from checking
 
     Returns
     -------
     duplicated : ndarray[bool]
     """
-    if hasattr(values, "dtype"):
-        if isinstance(values.dtype, ArrowDtype):
-            if values.dtype.kind in "ifub":
-                values = values._to_masked()  # type: ignore[union-attr]
-            else:
-                values = (
-                    values._maybe_convert_datelike_array()  # type: ignore[union-attr]
-                )
-        if isinstance(values.dtype, BaseMaskedDtype):
-            values = cast("BaseMaskedArray", values)
-            return htable.duplicated(values._data, keep=keep, mask=values._mask)
-
     values = _ensure_data(values)
-    return htable.duplicated(values, keep=keep)
+    return htable.duplicated(values, keep=keep, mask=mask)
 
 
 def mode(

pandas/core/arrays/arrow/array.py

@@ -42,6 +42,7 @@
 from pandas.core.dtypes.missing import isna
 
 from pandas.core import (
+    algorithms as algos,
     missing,
     roperator,
 )
@@ -1289,6 +1290,30 @@ def to_numpy(
             result[~mask] = data[~mask]._pa_array.to_numpy()
         return result
 
+    @doc(ExtensionArray.duplicated)
+    def duplicated(
+        self, keep: Literal["first", "last", False] = "first"
+    ) -> npt.NDArray[np.bool_]:
+        pa_type = self._pa_array.type
+        if pa.types.is_floating(pa_type) or pa.types.is_integer(pa_type):
+            values = self.to_numpy(na_value=0)
+        elif pa.types.is_boolean(pa_type):
+            values = self.to_numpy(na_value=False)
+        elif pa.types.is_temporal(pa_type):
+            if pa_type.bit_width == 32:
+                pa_type = pa.int32()
+            else:
+                pa_type = pa.int64()
+            arr = self.astype(ArrowDtype(pa_type))
+            values = arr.to_numpy(na_value=0)
+        else:
+            # factorize the values to avoid the performance penalty of
+            # converting to object dtype
+            values = self.factorize()[0]
+
+        mask = self.isna() if self._hasna else None
+        return algos.duplicated(values, keep=keep, mask=mask)
+
     def unique(self) -> Self:
         """
         Compute the ArrowExtensionArray of unique values.

pandas/core/arrays/base.py

@@ -61,6 +61,7 @@
     roperator,
 )
 from pandas.core.algorithms import (
+    duplicated,
     factorize_array,
     isin,
     map_array,
@@ -125,6 +126,7 @@ class ExtensionArray:
     astype
     copy
     dropna
+    duplicated
     factorize
     fillna
     equals
@@ -1116,6 +1118,30 @@ def dropna(self) -> Self:
         # error: Unsupported operand type for ~ ("ExtensionArray")
         return self[~self.isna()]  # type: ignore[operator]
 
+    def duplicated(
+        self, keep: Literal["first", "last", False] = "first"
+    ) -> npt.NDArray[np.bool_]:
+        """
+        Return boolean ndarray denoting duplicate values.
+
+        Parameters
+        ----------
+        keep : {'first', 'last', False}, default 'first'
+            - ``first`` : Mark duplicates as ``True`` except for the first occurrence.
+            - ``last`` : Mark duplicates as ``True`` except for the last occurrence.
+            - False : Mark all duplicates as ``True``.
+
+        Returns
+        -------
+        ndarray[bool]
+
+        Examples
+        --------
+        >>> pd.array([1, 1, 2, 3, 3], dtype="Int64").duplicated()
+        array([False,  True, False, False,  True])
+        """
+        return duplicated(values=self, keep=keep)
+
     def shift(self, periods: int = 1, fill_value: object = None) -> ExtensionArray:
         """
         Shift values by desired number.

pandas/core/arrays/masked.py

@@ -952,6 +952,14 @@ def copy(self) -> Self:
         mask = self._mask.copy()
         return self._simple_new(data, mask)
 
+    @doc(ExtensionArray.duplicated)
+    def duplicated(
+        self, keep: Literal["first", "last", False] = "first"
+    ) -> npt.NDArray[np.bool_]:
+        values = self._data
+        mask = self._mask
+        return algos.duplicated(values, keep=keep, mask=mask)
+
     def unique(self) -> Self:
         """
         Compute the BaseMaskedArray of unique values.

pandas/core/base.py

@@ -1365,7 +1365,10 @@ def drop_duplicates(self, *, keep: DropKeep = "first"):
 
     @final
     def _duplicated(self, keep: DropKeep = "first") -> npt.NDArray[np.bool_]:
-        return algorithms.duplicated(self._values, keep=keep)
+        arr = self._values
+        if isinstance(arr, ExtensionArray):
+            return arr.duplicated(keep=keep)
+        return algorithms.duplicated(arr, keep=keep)
 
     def _arith_method(self, other, op):
         res_name = ops.get_op_result_name(self, other)

pandas/tests/extension/base/methods.py

@@ -248,6 +248,18 @@ def test_sort_values_frame(self, data_for_sorting, ascending):
         )
         tm.assert_frame_equal(result, expected)
 
+    @pytest.mark.parametrize("keep", ["first", "last", False])
+    def test_duplicated(self, data, keep):
+        arr = data.take([0, 1, 0, 1])
+        result = arr.duplicated(keep=keep)
+        if keep == "first":
+            expected = np.array([False, False, True, True])
+        elif keep == "last":
+            expected = np.array([True, True, False, False])
+        else:
+            expected = np.array([True, True, True, True])
+        tm.assert_numpy_array_equal(result, expected)
+
     @pytest.mark.parametrize("box", [pd.Series, lambda x: x])
     @pytest.mark.parametrize("method", [lambda x: x.unique(), pd.unique])
     def test_unique(self, data, box, method):