DEPR: Deprecate method argument of reindex_like (#58724)

* deprecate 'method' argument in NDFrame.reindex_like

* fix whatsnew order

* included FutureWarning assertion in test_datetime_index.py

* repositioned deprecation in docstring

doc/source/whatsnew/v3.0.0.rst

@@ -206,6 +206,7 @@ Other Deprecations
 - Deprecated allowing non-keyword arguments in :meth:`Series.to_markdown` except ``buf``. (:issue:`57280`)
 - Deprecated allowing non-keyword arguments in :meth:`Series.to_string` except ``buf``. (:issue:`57280`)
 - Deprecated behavior of :meth:`Series.dt.to_pytimedelta`, in a future version this will return a :class:`Series` containing python ``datetime.timedelta`` objects instead of an ``ndarray`` of timedelta; this matches the behavior of other :meth:`Series.dt` properties. (:issue:`57463`)
+- Deprecated parameter ``method`` in :meth:`DataFrame.reindex_like` / :meth:`Series.reindex_like` (:issue:`58667`)
 - Deprecated using ``epoch`` date format in :meth:`DataFrame.to_json` and :meth:`Series.to_json`, use ``iso`` instead. (:issue:`57063`)
 -
 

pandas/conftest.py

@@ -158,6 +158,7 @@ def pytest_collection_modifyitems(items, config) -> None:
         ("SeriesGroupBy.idxmin", "The behavior of Series.idxmin"),
         ("SeriesGroupBy.idxmax", "The behavior of Series.idxmax"),
         ("to_pytimedelta", "The behavior of TimedeltaProperties.to_pytimedelta"),
+        ("NDFrame.reindex_like", "keyword argument 'method' is deprecated"),
         # Docstring divides by zero to show behavior difference
         ("missing.mask_zero_div_zero", "divide by zero encountered"),
         (

pandas/core/generic.py

@@ -93,7 +93,10 @@
     InvalidIndexError,
 )
 from pandas.errors.cow import _chained_assignment_method_msg
-from pandas.util._decorators import doc
+from pandas.util._decorators import (
+    deprecate_kwarg,
+    doc,
+)
 from pandas.util._exceptions import find_stack_level
 from pandas.util._validators import (
     check_dtype_backend,
@@ -4301,6 +4304,8 @@ def _check_copy_deprecation(copy):
                 stacklevel=find_stack_level(),
             )
 
+    # issue 58667
+    @deprecate_kwarg("method", None)
     @final
     def reindex_like(
         self,
@@ -4328,6 +4333,8 @@ def reindex_like(
             Please note: this is only applicable to DataFrames/Series with a
             monotonically increasing/decreasing index.
 
+            .. deprecated:: 3.0.0
+
             * None (default): don't fill gaps
             * pad / ffill: propagate last valid observation forward to next
               valid

pandas/io/formats/style.py

@@ -3800,7 +3800,7 @@ def _validate_apply_axis_arg(
             f"operations is a Series with 'axis in [0,1]'"
         )
     if isinstance(arg, (Series, DataFrame)):  # align indx / cols to data
-        arg = arg.reindex_like(data, method=None).to_numpy(**dtype)
+        arg = arg.reindex_like(data).to_numpy(**dtype)
     else:
         arg = np.asarray(arg, **dtype)
         assert isinstance(arg, np.ndarray)  # mypy requirement

pandas/tests/frame/methods/test_reindex_like.py

@@ -22,9 +22,11 @@ def test_reindex_like(self, float_frame):
     def test_reindex_like_methods(self, method, expected_values):
         df = DataFrame({"x": list(range(5))})
 
-        result = df.reindex_like(df, method=method, tolerance=0)
+        with tm.assert_produces_warning(FutureWarning):
+            result = df.reindex_like(df, method=method, tolerance=0)
         tm.assert_frame_equal(df, result)
-        result = df.reindex_like(df, method=method, tolerance=[0, 0, 0, 0])
+        with tm.assert_produces_warning(FutureWarning):
+            result = df.reindex_like(df, method=method, tolerance=[0, 0, 0, 0])
         tm.assert_frame_equal(df, result)
 
     def test_reindex_like_subclass(self):

pandas/tests/resample/test_datetime_index.py

@@ -1300,7 +1300,8 @@ def test_resample_consistency(unit):
 
     s10 = s.reindex(index=i10, method="bfill")
     s10_2 = s.reindex(index=i10, method="bfill", limit=2)
-    rl = s.reindex_like(s10, method="bfill", limit=2)
+    with tm.assert_produces_warning(FutureWarning):
+        rl = s.reindex_like(s10, method="bfill", limit=2)
     r10_2 = s.resample("10Min").bfill(limit=2)
     r10 = s.resample("10Min").bfill()
 

pandas/tests/series/methods/test_reindex_like.py

@@ -20,7 +20,8 @@ def test_reindex_like(datetime_series):
     series1 = Series([5, None, None], [day1, day2, day3])
     series2 = Series([None, None], [day1, day3])
 
-    result = series1.reindex_like(series2, method="pad")
+    with tm.assert_produces_warning(FutureWarning):
+        result = series1.reindex_like(series2, method="pad")
     expected = Series([5, np.nan], index=[day1, day3])
     tm.assert_series_equal(result, expected)
 
@@ -32,10 +33,13 @@ def test_reindex_like_nearest():
     other = ser.reindex(target, method="nearest")
     expected = Series(np.around(target).astype("int64"), target)
 
-    result = ser.reindex_like(other, method="nearest")
+    with tm.assert_produces_warning(FutureWarning):
+        result = ser.reindex_like(other, method="nearest")
     tm.assert_series_equal(expected, result)
 
-    result = ser.reindex_like(other, method="nearest", tolerance=1)
+    with tm.assert_produces_warning(FutureWarning):
+        result = ser.reindex_like(other, method="nearest", tolerance=1)
     tm.assert_series_equal(expected, result)
-    result = ser.reindex_like(other, method="nearest", tolerance=[1, 2, 3, 4])
+    with tm.assert_produces_warning(FutureWarning):
+        result = ser.reindex_like(other, method="nearest", tolerance=[1, 2, 3, 4])
     tm.assert_series_equal(expected, result)