CLN: Remove deprecated read_csv(infer_datetime_format=) (pandas-dev#58620)

Author: mroeschke

doc/source/user_guide/io.rst

@@ -276,12 +276,6 @@ parse_dates : boolean or list of ints or names or list of lists or dict, default
 
   .. note::
      A fast-path exists for iso8601-formatted dates.
-infer_datetime_format : boolean, default ``False``
-  If ``True`` and parse_dates is enabled for a column, attempt to infer the
-  datetime format to speed up the processing.
-
-  .. deprecated:: 2.0.0
-   A strict version of this argument is now the default, passing it has no effect.
 keep_date_col : boolean, default ``False``
   If ``True`` and parse_dates specifies combining multiple columns then keep the
   original columns.
@@ -1639,7 +1633,6 @@ Options that are unsupported by the pyarrow engine which are not covered by the
 * ``decimal``
 * ``iterator``
 * ``dayfirst``
-* ``infer_datetime_format``
 * ``verbose``
 * ``skipinitialspace``
 * ``low_memory``

doc/source/whatsnew/v3.0.0.rst

@@ -255,6 +255,7 @@ Removal of prior version deprecations/changes
 - Enforced deprecation of ``axis=None`` acting the same as ``axis=0`` in the DataFrame reductions ``sum``, ``prod``, ``std``, ``var``, and ``sem``, passing ``axis=None`` will now reduce over both axes; this is particularly the case when doing e.g. ``numpy.sum(df)`` (:issue:`21597`)
 - Enforced deprecation of ``core.internals`` members ``Block``, ``ExtensionBlock``, and ``DatetimeTZBlock`` (:issue:`58467`)
 - Enforced deprecation of ``quantile`` keyword in :meth:`.Rolling.quantile` and :meth:`.Expanding.quantile`, renamed to ``q`` instead. (:issue:`52550`)
+- Enforced deprecation of argument ``infer_datetime_format`` in :func:`read_csv`, as a strict version of it is now the default (:issue:`48621`)
 - Enforced deprecation of non-standard (``np.ndarray``, :class:`ExtensionArray`, :class:`Index`, or :class:`Series`) argument to :func:`api.extensions.take` (:issue:`52981`)
 - Enforced deprecation of parsing system timezone strings to ``tzlocal``, which depended on system timezone, pass the 'tz' keyword instead (:issue:`50791`)
 - Enforced deprecation of passing a dictionary to :meth:`SeriesGroupBy.agg` (:issue:`52268`)

pandas/io/parsers/readers.py

@@ -118,7 +118,6 @@ class _read_shared(TypedDict, Generic[HashableT], total=False):
         na_filter: bool
         skip_blank_lines: bool
         parse_dates: bool | Sequence[Hashable] | None
-        infer_datetime_format: bool | lib.NoDefault
         keep_date_col: bool | lib.NoDefault
         date_parser: Callable | lib.NoDefault
         date_format: str | dict[Hashable, str] | None
@@ -323,15 +322,6 @@ class _read_shared(TypedDict, Generic[HashableT], total=False):
     :func:`~pandas.read_csv`.
 
     Note: A fast-path exists for iso8601-formatted dates.
-infer_datetime_format : bool, default False
-    If ``True`` and ``parse_dates`` is enabled, pandas will attempt to infer the
-    format of the ``datetime`` strings in the columns, and if it can be inferred,
-    switch to a faster method of parsing them. In some cases this can increase
-    the parsing speed by 5-10x.
-
-    .. deprecated:: 2.0.0
-        A strict version of this argument is now the default, passing it has no effect.
-
 keep_date_col : bool, default False
     If ``True`` and ``parse_dates`` specifies combining multiple columns then
     keep the original columns.
@@ -758,7 +748,6 @@ def read_csv(
     skip_blank_lines: bool = True,
     # Datetime Handling
     parse_dates: bool | Sequence[Hashable] | None = None,
-    infer_datetime_format: bool | lib.NoDefault = lib.no_default,
     keep_date_col: bool | lib.NoDefault = lib.no_default,
     date_parser: Callable | lib.NoDefault = lib.no_default,
     date_format: str | dict[Hashable, str] | None = None,
@@ -822,17 +811,6 @@ def read_csv(
                 stacklevel=find_stack_level(),
             )
 
-    if infer_datetime_format is not lib.no_default:
-        warnings.warn(
-            "The argument 'infer_datetime_format' is deprecated and will "
-            "be removed in a future version. "
-            "A strict version of it is now the default, see "
-            "https://pandas.pydata.org/pdeps/0004-consistent-to-datetime-parsing.html. "
-            "You can safely remove this argument.",
-            FutureWarning,
-            stacklevel=find_stack_level(),
-        )
-
     if delim_whitespace is not lib.no_default:
         # GH#55569
         warnings.warn(
@@ -949,7 +927,6 @@ def read_table(
     skip_blank_lines: bool = True,
     # Datetime Handling
     parse_dates: bool | Sequence[Hashable] | None = None,
-    infer_datetime_format: bool | lib.NoDefault = lib.no_default,
     keep_date_col: bool | lib.NoDefault = lib.no_default,
     date_parser: Callable | lib.NoDefault = lib.no_default,
     date_format: str | dict[Hashable, str] | None = None,
@@ -1004,17 +981,6 @@ def read_table(
             stacklevel=find_stack_level(),
         )
 
-    if infer_datetime_format is not lib.no_default:
-        warnings.warn(
-            "The argument 'infer_datetime_format' is deprecated and will "
-            "be removed in a future version. "
-            "A strict version of it is now the default, see "
-            "https://pandas.pydata.org/pdeps/0004-consistent-to-datetime-parsing.html. "
-            "You can safely remove this argument.",
-            FutureWarning,
-            stacklevel=find_stack_level(),
-        )
-
     if delim_whitespace is not lib.no_default:
         # GH#55569
         warnings.warn(

pandas/tests/io/parser/test_parse_dates.py

@@ -1383,25 +1383,6 @@ def test_parse_dates_empty_string(all_parsers):
     tm.assert_frame_equal(result, expected)
 
 
-@pytest.mark.parametrize(
-    "reader", ["read_csv_check_warnings", "read_table_check_warnings"]
-)
-def test_parse_dates_infer_datetime_format_warning(all_parsers, reader):
-    # GH 49024, 51017
-    parser = all_parsers
-    data = "Date,test\n2012-01-01,1\n,2"
-
-    getattr(parser, reader)(
-        FutureWarning,
-        "The argument 'infer_datetime_format' is deprecated",
-        StringIO(data),
-        parse_dates=["Date"],
-        infer_datetime_format=True,
-        sep=",",
-        raise_on_extra_warnings=False,
-    )
-
-
 @pytest.mark.parametrize(
     "reader", ["read_csv_check_warnings", "read_table_check_warnings"]
 )