DEPR: convert_datetime64 parameter in to_records() (pandas-dev#18902)

Author: reidy-p

doc/source/whatsnew/v0.23.0.txt

@@ -842,6 +842,7 @@ Deprecations
 - ``pandas.tseries.plotting.tsplot`` is deprecated. Use :func:`Series.plot` instead (:issue:`18627`)
 - ``Index.summary()`` is deprecated and will be removed in a future version (:issue:`18217`)
 - ``NDFrame.get_ftype_counts()`` is deprecated and will be removed in a future version (:issue:`18243`)
+- The ``convert_datetime64`` parameter in :func:`DataFrame.to_records` has been deprecated and will be removed in a future version. The NumPy bug motivating this parameter has been resolved. The default value for this parameter has also changed from ``True`` to ``None`` (:issue:`18160`).
 
 .. _whatsnew_0230.prior_deprecations:
 

pandas/core/frame.py

@@ -1311,7 +1311,7 @@ def from_records(cls, data, index=None, exclude=None, columns=None,
 
         return cls(mgr)
 
-    def to_records(self, index=True, convert_datetime64=True):
+    def to_records(self, index=True, convert_datetime64=None):
         """
         Convert DataFrame to a NumPy record array.
 
@@ -1322,7 +1322,9 @@ def to_records(self, index=True, convert_datetime64=True):
         ----------
         index : boolean, default True
             Include index in resulting record array, stored in 'index' field.
-        convert_datetime64 : boolean, default True
+        convert_datetime64 : boolean, default None
+            .. deprecated:: 0.23.0
+
             Whether to convert the index to datetime.datetime if it is a
             DatetimeIndex.
 
@@ -1376,6 +1378,13 @@ def to_records(self, index=True, convert_datetime64=True):
                    ('2018-01-01T09:01:00.000000000', 2, 0.75)],
                   dtype=[('index', '<M8[ns]'), ('A', '<i8'), ('B', '<f8')])
         """
+
+        if convert_datetime64 is not None:
+            warnings.warn("The 'convert_datetime64' parameter is "
+                          "deprecated and will be removed in a future "
+                          "version",
+                          FutureWarning, stacklevel=2)
+
         if index:
             if is_datetime64_any_dtype(self.index) and convert_datetime64:
                 ix_vals = [self.index.to_pydatetime()]

pandas/tests/frame/test_convert_to.py

@@ -79,10 +79,23 @@ def test_to_records_dt64(self):
         df = DataFrame([["one", "two", "three"],
                         ["four", "five", "six"]],
                        index=date_range("2012-01-01", "2012-01-02"))
-        assert df.to_records()['index'][0] == df.index[0]
 
-        rs = df.to_records(convert_datetime64=False)
-        assert rs['index'][0] == df.index.values[0]
+        # convert_datetime64 defaults to None
+        expected = df.index.values[0]
+        result = df.to_records()['index'][0]
+        assert expected == result
+
+        # check for FutureWarning if convert_datetime64=False is passed
+        with tm.assert_produces_warning(FutureWarning):
+            expected = df.index.values[0]
+            result = df.to_records(convert_datetime64=False)['index'][0]
+            assert expected == result
+
+        # check for FutureWarning if convert_datetime64=True is passed
+        with tm.assert_produces_warning(FutureWarning):
+            expected = df.index[0]
+            result = df.to_records(convert_datetime64=True)['index'][0]
+            assert expected == result
 
     def test_to_records_with_multindex(self):
         # GH3189