Merge branch 'main' into issue-37210-to-sql-truncate

Author: gmcrocetti

Diff for: doc/source/whatsnew/v2.3.0.rst

@@ -37,6 +37,7 @@ Other enhancements
   updated to work correctly with NumPy >= 2 (:issue:`57739`)
 - :meth:`Series.str.decode` result now has ``StringDtype`` when ``future.infer_string`` is True (:issue:`60709`)
 - :meth:`~Series.to_hdf` and :meth:`~DataFrame.to_hdf` now round-trip with ``StringDtype``  (:issue:`60663`)
+- The :meth:`Series.str.decode` has gained the argument ``dtype`` to control the dtype of the result (:issue:`60940`)
 - The :meth:`~Series.cumsum`, :meth:`~Series.cummin`, and :meth:`~Series.cummax` reductions are now implemented for ``StringDtype`` columns when backed by PyArrow (:issue:`60633`)
 - The :meth:`~Series.sum` reduction is now implemented for ``StringDtype`` columns (:issue:`59853`)
 

Diff for: pandas/_libs/algos.pyx

@@ -818,33 +818,7 @@ def is_monotonic(const numeric_object_t[:] arr, bint timelike):
     if timelike and <int64_t>arr[0] == NPY_NAT:
         return False, False, False
 
-    if numeric_object_t is not object:
-        with nogil:
-            prev = arr[0]
-            for i in range(1, n):
-                cur = arr[i]
-                if timelike and <int64_t>cur == NPY_NAT:
-                    is_monotonic_inc = 0
-                    is_monotonic_dec = 0
-                    break
-                if cur < prev:
-                    is_monotonic_inc = 0
-                elif cur > prev:
-                    is_monotonic_dec = 0
-                elif cur == prev:
-                    is_unique = 0
-                else:
-                    # cur or prev is NaN
-                    is_monotonic_inc = 0
-                    is_monotonic_dec = 0
-                    break
-                if not is_monotonic_inc and not is_monotonic_dec:
-                    is_monotonic_inc = 0
-                    is_monotonic_dec = 0
-                    break
-                prev = cur
-    else:
-        # object-dtype, identical to above except we cannot use `with nogil`
+    with nogil(numeric_object_t is not object):
         prev = arr[0]
         for i in range(1, n):
             cur = arr[i]

Diff for: pandas/_libs/hashtable_func_helper.pxi.in

@@ -415,20 +415,7 @@ def mode(ndarray[htfunc_t] values, bint dropna, const uint8_t[:] mask=None):
 
     modes = np.empty(nkeys, dtype=values.dtype)
 
-    if htfunc_t is not object:
-        with nogil:
-            for k in range(nkeys):
-                count = counts[k]
-                if count == max_count:
-                    j += 1
-                elif count > max_count:
-                    max_count = count
-                    j = 0
-                else:
-                    continue
-
-                modes[j] = keys[k]
-    else:
+    with nogil(htfunc_t is not object):
         for k in range(nkeys):
             count = counts[k]
             if count == max_count:

Diff for: pandas/_libs/internals.pyx

@@ -502,7 +502,7 @@ def get_concat_blkno_indexers(list blknos_list not None):
 @cython.boundscheck(False)
 @cython.wraparound(False)
 def get_blkno_indexers(
-    int64_t[:] blknos, bint group=True
+    const int64_t[:] blknos, bint group=True
 ) -> list[tuple[int, slice | np.ndarray]]:
     """
     Enumerate contiguous runs of integers in ndarray.
@@ -596,8 +596,8 @@ def get_blkno_placements(blknos, group: bool = True):
 @cython.boundscheck(False)
 @cython.wraparound(False)
 cpdef update_blklocs_and_blknos(
-    ndarray[intp_t, ndim=1] blklocs,
-    ndarray[intp_t, ndim=1] blknos,
+    const intp_t[:] blklocs,
+    const intp_t[:] blknos,
     Py_ssize_t loc,
     intp_t nblocks,
 ):

Diff for: pandas/_libs/join.pyx

@@ -225,7 +225,10 @@ def full_outer_join(const intp_t[:] left, const intp_t[:] right,
 
 @cython.wraparound(False)
 @cython.boundscheck(False)
-cdef void _get_result_indexer(intp_t[::1] sorter, intp_t[::1] indexer) noexcept nogil:
+cdef void _get_result_indexer(
+    const intp_t[::1] sorter,
+    intp_t[::1] indexer,
+) noexcept nogil:
     """NOTE: overwrites indexer with the result to avoid allocating another array"""
     cdef:
         Py_ssize_t i, n, idx
@@ -681,8 +684,8 @@ def outer_join_indexer(ndarray[numeric_object_t] left, ndarray[numeric_object_t]
 from pandas._libs.hashtable cimport Int64HashTable
 
 
-def asof_join_backward_on_X_by_Y(ndarray[numeric_t] left_values,
-                                 ndarray[numeric_t] right_values,
+def asof_join_backward_on_X_by_Y(const numeric_t[:] left_values,
+                                 const numeric_t[:] right_values,
                                  const int64_t[:] left_by_values,
                                  const int64_t[:] right_by_values,
                                  bint allow_exact_matches=True,
@@ -752,8 +755,8 @@ def asof_join_backward_on_X_by_Y(ndarray[numeric_t] left_values,
     return left_indexer, right_indexer
 
 
-def asof_join_forward_on_X_by_Y(ndarray[numeric_t] left_values,
-                                ndarray[numeric_t] right_values,
+def asof_join_forward_on_X_by_Y(const numeric_t[:] left_values,
+                                const numeric_t[:] right_values,
                                 const int64_t[:] left_by_values,
                                 const int64_t[:] right_by_values,
                                 bint allow_exact_matches=1,
@@ -824,8 +827,8 @@ def asof_join_forward_on_X_by_Y(ndarray[numeric_t] left_values,
     return left_indexer, right_indexer
 
 
-def asof_join_nearest_on_X_by_Y(ndarray[numeric_t] left_values,
-                                ndarray[numeric_t] right_values,
+def asof_join_nearest_on_X_by_Y(const numeric_t[:] left_values,
+                                const numeric_t[:] right_values,
                                 const int64_t[:] left_by_values,
                                 const int64_t[:] right_by_values,
                                 bint allow_exact_matches=True,

Diff for: pandas/_libs/lib.pyx

@@ -981,16 +981,14 @@ def get_level_sorter(
 
 @cython.boundscheck(False)
 @cython.wraparound(False)
-def count_level_2d(ndarray[uint8_t, ndim=2, cast=True] mask,
+def count_level_2d(const uint8_t[:, :] mask,
                    const intp_t[:] labels,
                    Py_ssize_t max_bin,
                    ):
     cdef:
-        Py_ssize_t i, j, k, n
+        Py_ssize_t i, j, k = mask.shape[1], n = mask.shape[0]
         ndarray[int64_t, ndim=2] counts
 
-    n, k = (<object>mask).shape
-
     counts = np.zeros((n, max_bin), dtype="i8")
     with nogil:
         for i in range(n):

Diff for: pandas/_libs/reshape.pyx

@@ -40,27 +40,7 @@ def unstack(const numeric_object_t[:, :] values, const uint8_t[:] mask,
     cdef:
         Py_ssize_t i, j, w, nulls, s, offset
 
-    if numeric_object_t is not object:
-        # evaluated at compile-time
-        with nogil:
-            for i in range(stride):
-
-                nulls = 0
-                for j in range(length):
-
-                    for w in range(width):
-
-                        offset = j * width + w
-
-                        if mask[offset]:
-                            s = i * width + w
-                            new_values[j, s] = values[offset - nulls, i]
-                            new_mask[j, s] = 1
-                        else:
-                            nulls += 1
-
-    else:
-        # object-dtype, identical to above but we cannot use nogil
+    with nogil(numeric_object_t is not object):
         for i in range(stride):
 
             nulls = 0

Diff for: pandas/core/strings/accessor.py

@@ -34,6 +34,7 @@
     is_numeric_dtype,
     is_object_dtype,
     is_re,
+    is_string_dtype,
 )
 from pandas.core.dtypes.dtypes import (
     ArrowDtype,
@@ -2102,7 +2103,9 @@ def slice_replace(self, start=None, stop=None, repl=None):
         result = self._data.array._str_slice_replace(start, stop, repl)
         return self._wrap_result(result)
 
-    def decode(self, encoding, errors: str = "strict"):
+    def decode(
+        self, encoding, errors: str = "strict", dtype: str | DtypeObj | None = None
+    ):
         """
         Decode character string in the Series/Index using indicated encoding.
 
@@ -2116,6 +2119,12 @@ def decode(self, encoding, errors: str = "strict"):
         errors : str, optional
             Specifies the error handling scheme.
             Possible values are those supported by :meth:`bytes.decode`.
+        dtype : str or dtype, optional
+            The dtype of the result. When not ``None``, must be either a string or
+            object dtype. When ``None``, the dtype of the result is determined by
+            ``pd.options.future.infer_string``.
+
+            .. versionadded:: 2.3.0
 
         Returns
         -------
@@ -2137,6 +2146,10 @@ def decode(self, encoding, errors: str = "strict"):
         2   ()
         dtype: object
         """
+        if dtype is not None and not is_string_dtype(dtype):
+            raise ValueError(f"dtype must be string or object, got {dtype=}")
+        if dtype is None and get_option("future.infer_string"):
+            dtype = "str"
         # TODO: Add a similar _bytes interface.
         if encoding in _cpython_optimized_decoders:
             # CPython optimized implementation
@@ -2146,7 +2159,6 @@ def decode(self, encoding, errors: str = "strict"):
             f = lambda x: decoder(x, errors)[0]
         arr = self._data.array
         result = arr._str_map(f)
-        dtype = "str" if get_option("future.infer_string") else None
         return self._wrap_result(result, dtype=dtype)
 
     @forbid_nonstring_types(["bytes"])

Diff for: pandas/tests/strings/test_strings.py

@@ -601,6 +601,30 @@ def test_decode_errors_kwarg():
     tm.assert_series_equal(result, expected)
 
 
+def test_decode_string_dtype(string_dtype):
+    # https://github.com/pandas-dev/pandas/pull/60940
+    ser = Series([b"a", b"b"])
+    result = ser.str.decode("utf-8", dtype=string_dtype)
+    expected = Series(["a", "b"], dtype=string_dtype)
+    tm.assert_series_equal(result, expected)
+
+
+def test_decode_object_dtype(object_dtype):
+    # https://github.com/pandas-dev/pandas/pull/60940
+    ser = Series([b"a", rb"\ud800"])
+    result = ser.str.decode("utf-8", dtype=object_dtype)
+    expected = Series(["a", r"\ud800"], dtype=object_dtype)
+    tm.assert_series_equal(result, expected)
+
+
+def test_decode_bad_dtype():
+    # https://github.com/pandas-dev/pandas/pull/60940
+    ser = Series([b"a", b"b"])
+    msg = "dtype must be string or object, got dtype='int64'"
+    with pytest.raises(ValueError, match=msg):
+        ser.str.decode("utf-8", dtype="int64")
+
+
 @pytest.mark.parametrize(
     "form, expected",
     [