CLN: Enforce read_csv(keep_date_col, parse_dates) deprecations

asv_bench/benchmarks/io/csv.py

@@ -445,16 +445,6 @@ def setup(self, engine):
         data = data.format(*two_cols)
         self.StringIO_input = StringIO(data)
 
-    def time_multiple_date(self, engine):
-        read_csv(
-            self.data(self.StringIO_input),
-            engine=engine,
-            sep=",",
-            header=None,
-            names=list(string.digits[:9]),
-            parse_dates=[[1, 2], [1, 3]],
-        )
-
     def time_baseline(self, engine):
         read_csv(
             self.data(self.StringIO_input),

doc/source/user_guide/io.rst

@@ -270,15 +270,9 @@ parse_dates : boolean or list of ints or names or list of lists or dict, default
   * If ``True`` -> try parsing the index.
   * If ``[1, 2, 3]`` ->  try parsing columns 1, 2, 3 each as a separate date
     column.
-  * If ``[[1, 3]]`` -> combine columns 1 and 3 and parse as a single date
-    column.
-  * If ``{'foo': [1, 3]}`` -> parse columns 1, 3 as date and call result 'foo'.
 
   .. note::
      A fast-path exists for iso8601-formatted dates.
-keep_date_col : boolean, default ``False``
-  If ``True`` and parse_dates specifies combining multiple columns then keep the
-  original columns.
 date_parser : function, default ``None``
   Function to use for converting a sequence of string columns to an array of
   datetime instances. The default uses ``dateutil.parser.parser`` to do the
@@ -823,71 +817,8 @@ The simplest case is to just pass in ``parse_dates=True``:
 
 It is often the case that we may want to store date and time data separately,
 or store various date fields separately. the ``parse_dates`` keyword can be
-used to specify a combination of columns to parse the dates and/or times from.
-
-You can specify a list of column lists to ``parse_dates``, the resulting date
-columns will be prepended to the output (so as to not affect the existing column
-order) and the new column names will be the concatenation of the component
-column names:
-
-.. ipython:: python
-   :okwarning:
-
-   data = (
-       "KORD,19990127, 19:00:00, 18:56:00, 0.8100\n"
-       "KORD,19990127, 20:00:00, 19:56:00, 0.0100\n"
-       "KORD,19990127, 21:00:00, 20:56:00, -0.5900\n"
-       "KORD,19990127, 21:00:00, 21:18:00, -0.9900\n"
-       "KORD,19990127, 22:00:00, 21:56:00, -0.5900\n"
-       "KORD,19990127, 23:00:00, 22:56:00, -0.5900"
-   )
-
-   with open("tmp.csv", "w") as fh:
-       fh.write(data)
-
-   df = pd.read_csv("tmp.csv", header=None, parse_dates=[[1, 2], [1, 3]])
-   df
-
-By default the parser removes the component date columns, but you can choose
-to retain them via the ``keep_date_col`` keyword:
-
-.. ipython:: python
-   :okwarning:
-
-   df = pd.read_csv(
-       "tmp.csv", header=None, parse_dates=[[1, 2], [1, 3]], keep_date_col=True
-   )
-   df
+used to specify columns to parse the dates and/or times.
 
-Note that if you wish to combine multiple columns into a single date column, a
-nested list must be used. In other words, ``parse_dates=[1, 2]`` indicates that
-the second and third columns should each be parsed as separate date columns
-while ``parse_dates=[[1, 2]]`` means the two columns should be parsed into a
-single column.
-
-You can also use a dict to specify custom name columns:
-
-.. ipython:: python
-   :okwarning:
-
-   date_spec = {"nominal": [1, 2], "actual": [1, 3]}
-   df = pd.read_csv("tmp.csv", header=None, parse_dates=date_spec)
-   df
-
-It is important to remember that if multiple text columns are to be parsed into
-a single date column, then a new column is prepended to the data. The ``index_col``
-specification is based off of this new set of columns rather than the original
-data columns:
-
-
-.. ipython:: python
-   :okwarning:
-
-   date_spec = {"nominal": [1, 2], "actual": [1, 3]}
-   df = pd.read_csv(
-       "tmp.csv", header=None, parse_dates=date_spec, index_col=0
-   )  # index is the nominal column
-   df
 
 .. note::
    If a column or index contains an unparsable date, the entire column or
@@ -901,10 +832,6 @@ data columns:
    for your data to store datetimes in this format, load times will be
    significantly faster, ~20x has been observed.
 
-.. deprecated:: 2.2.0
-   Combining date columns inside read_csv is deprecated. Use ``pd.to_datetime``
-   on the relevant result columns instead.
-
 
 Date parsing functions
 ++++++++++++++++++++++
@@ -920,12 +847,6 @@ Performance-wise, you should try these methods of parsing dates in order:
    then use ``to_datetime``.
 
 
-.. ipython:: python
-   :suppress:
-
-   os.remove("tmp.csv")
-
-
 .. _io.csv.mixed_timezones:
 
 Parsing a CSV with mixed timezones

doc/source/whatsnew/v3.0.0.rst

@@ -254,8 +254,10 @@ Removal of prior version deprecations/changes
 - Enforced deprecation of :meth:`offsets.Tick.delta`, use ``pd.Timedelta(obj)`` instead (:issue:`55498`)
 - 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 ``keep_date_col`` keyword in :func:`read_csv` (:issue:`55569`)
 - 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 combining parsed datetime columns in :func:`read_csv` in ``parse_dates`` (:issue:`55569`)
 - 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`)