DEPR: DataFrame.resample axis parameter

doc/source/whatsnew/v2.1.0.rst

@@ -99,6 +99,7 @@ Deprecations
 - Deprecated ``axis=1`` in :meth:`DataFrame.groupby` and in :class:`Grouper` constructor, do ``frame.T.groupby(...)`` instead (:issue:`51203`)
 - Deprecated passing a :class:`DataFrame` to :meth:`DataFrame.from_records`, use :meth:`DataFrame.set_index` or :meth:`DataFrame.drop` instead (:issue:`51353`)
 - Deprecated accepting slices in :meth:`DataFrame.take`, call ``obj[slicer]`` or pass a sequence of integers instead (:issue:`51539`)
+- Deprecated ``axis=1`` in :meth:`DataFrame.resample`, do ``frame.T.resample(...)`` instead (:issue:`51778`)
 -
 
 .. ---------------------------------------------------------------------------

pandas/core/frame.py

@@ -11408,7 +11408,7 @@ def asfreq(
     def resample(
         self,
         rule,
-        axis: Axis = 0,
+        axis: Axis | lib.NoDefault = lib.no_default,
         closed: str | None = None,
         label: str | None = None,
         convention: str = "start",

pandas/core/generic.py

@@ -8531,7 +8531,7 @@ def between_time(
     def resample(
         self,
         rule,
-        axis: Axis = 0,
+        axis: Axis | lib.NoDefault = lib.no_default,
         closed: str | None = None,
         label: str | None = None,
         convention: str = "start",
@@ -8558,6 +8558,8 @@ def resample(
             Which axis to use for up- or down-sampling. For `Series` this parameter
             is unused and defaults to 0. Must be
             `DatetimeIndex`, `TimedeltaIndex` or `PeriodIndex`.
+            .. deprecated:: 2.0.0
+                Use frame.T.resample(...) instead.
         closed : {{'right', 'left'}}, default None
             Which side of bin interval is closed. The default is 'left'
             for all frequency offsets except for 'M', 'A', 'Q', 'BM',
@@ -8911,7 +8913,25 @@ def resample(
         """
         from pandas.core.resample import get_resampler
 
-        axis = self._get_axis_number(axis)
+        if axis is not lib.no_default:
+            axis = self._get_axis_number(axis)
+            if axis == 1:
+                warnings.warn(
+                    "DataFrame.resample with axis=1 is deprecated. Do "
+                    "`frame.T.resample(...)` without axis instead.",
+                    FutureWarning,
+                    stacklevel=find_stack_level(),
+                )
+            else:
+                warnings.warn(
+                    "The 'axis' keyword in DataFrame.resample is deprecated and "
+                    "will be removed in a future version.",
+                    FutureWarning,
+                    stacklevel=find_stack_level(),
+                )
+        else:
+            axis = 0
+
         return get_resampler(
             cast("Series | DataFrame", self),
             freq=rule,
@@ -11891,12 +11911,29 @@ def rolling(
         center: bool_t = False,
         win_type: str | None = None,
         on: str | None = None,
-        axis: Axis = 0,
+        axis: Axis | lib.NoDefault = lib.no_default,
         closed: str | None = None,
         step: int | None = None,
         method: str = "single",
     ) -> Window | Rolling:
-        axis = self._get_axis_number(axis)
+        if axis is not lib.no_default:
+            axis = self._get_axis_number(axis)
+            if axis == 1:
+                warnings.warn(
+                    "DataFrame.rolling with axis=1 is deprecated. Do "
+                    "`frame.T.rolling(...)` without axis instead.",
+                    FutureWarning,
+                    stacklevel=find_stack_level(),
+                )
+            else:
+                warnings.warn(
+                    "The 'axis' keyword in DataFrame.rolling is deprecated and "
+                    "will be removed in a future version.",
+                    FutureWarning,
+                    stacklevel=find_stack_level(),
+                )
+        else:
+            axis = 0
 
         if win_type is not None:
             return Window(
@@ -11930,10 +11967,28 @@ def rolling(
     def expanding(
         self,
         min_periods: int = 1,
-        axis: Axis = 0,
+        axis: Axis | lib.NoDefault = lib.no_default,
         method: str = "single",
     ) -> Expanding:
-        axis = self._get_axis_number(axis)
+        if axis is not lib.no_default:
+            axis = self._get_axis_number(axis)
+            if axis == 1:
+                warnings.warn(
+                    "DataFrame.expanding with axis=1 is deprecated. Do "
+                    "`frame.T.expanding(...)` without axis instead.",
+                    FutureWarning,
+                    stacklevel=find_stack_level(),
+                )
+            else:
+                warnings.warn(
+                    "The 'axis' keyword in DataFrame.expanding is deprecated and "
+                    "will be removed in a future version.",
+                    FutureWarning,
+                    stacklevel=find_stack_level(),
+                )
+        else:
+            axis = 0
+
         return Expanding(self, min_periods=min_periods, axis=axis, method=method)
 
     @final
@@ -11947,11 +12002,29 @@ def ewm(
         min_periods: int | None = 0,
         adjust: bool_t = True,
         ignore_na: bool_t = False,
-        axis: Axis = 0,
+        axis: Axis | lib.NoDefault = lib.no_default,
         times: np.ndarray | DataFrame | Series | None = None,
         method: str = "single",
     ) -> ExponentialMovingWindow:
-        axis = self._get_axis_number(axis)
+        if axis is not lib.no_default:
+            axis = self._get_axis_number(axis)
+            if axis == 1:
+                warnings.warn(
+                    "DataFrame.ewm with axis=1 is deprecated. Do "
+                    "`frame.T.ewm(...)` without axis instead.",
+                    FutureWarning,
+                    stacklevel=find_stack_level(),
+                )
+            else:
+                warnings.warn(
+                    "The 'axis' keyword in DataFrame.ewm is deprecated and "
+                    "will be removed in a future version.",
+                    FutureWarning,
+                    stacklevel=find_stack_level(),
+                )
+        else:
+            axis = 0
+
         return ExponentialMovingWindow(
             self,
             com=com,

pandas/core/series.py

@@ -5570,7 +5570,7 @@ def asfreq(
     def resample(
         self,
         rule,
-        axis: Axis = 0,
+        axis: Axis | lib.NoDefault = lib.no_default,
         closed: str | None = None,
         label: str | None = None,
         convention: str = "start",
@@ -5581,6 +5581,14 @@ def resample(
         offset: TimedeltaConvertibleTypes | None = None,
         group_keys: bool | lib.NoDefault = no_default,
     ) -> Resampler:
+        if axis is not lib.no_default:
+            warnings.warn(
+                "Series resample axis keyword is deprecated and will be removed in a "
+                "future version.",
+                FutureWarning,
+                stacklevel=find_stack_level(),
+            )
+
         return super().resample(
             rule=rule,
             axis=axis,

pandas/tests/resample/test_datetime_index.py

@@ -641,7 +641,10 @@ def test_resample_dup_index():
         columns=[Period(year=2000, month=i + 1, freq="M") for i in range(12)],
     )
     df.iloc[3, :] = np.nan
-    result = df.resample("Q", axis=1).mean()
+    warning_msg = "DataFrame.resample with axis=1 is deprecated."
+    with tm.assert_produces_warning(FutureWarning, match=warning_msg):
+        result = df.resample("Q", axis=1).mean()
+
     msg = "DataFrame.groupby with axis=1 is deprecated"
     with tm.assert_produces_warning(FutureWarning, match=msg):
         expected = df.groupby(lambda x: int((x.month - 1) / 3), axis=1).mean()
@@ -729,7 +732,9 @@ def test_resample_axis1(unit):
     rng = date_range("1/1/2000", "2/29/2000").as_unit(unit)
     df = DataFrame(np.random.randn(3, len(rng)), columns=rng, index=["a", "b", "c"])
 
-    result = df.resample("M", axis=1).mean()
+    warning_msg = "DataFrame.resample with axis=1 is deprecated."
+    with tm.assert_produces_warning(FutureWarning, match=warning_msg):
+        result = df.resample("M", axis=1).mean()
     expected = df.T.resample("M").mean().T
     tm.assert_frame_equal(result, expected)
 

pandas/tests/resample/test_resample_api.py

@@ -570,9 +570,13 @@ def test_multi_agg_axis_1_raises(func):
     index = date_range(datetime(2005, 1, 1), datetime(2005, 1, 10), freq="D")
     index.name = "date"
     df = DataFrame(np.random.rand(10, 2), columns=list("AB"), index=index).T
-    res = df.resample("M", axis=1)
-    with pytest.raises(NotImplementedError, match="axis other than 0 is not supported"):
-        res.agg(func)
+    warning_msg = "DataFrame.resample with axis=1 is deprecated."
+    with tm.assert_produces_warning(FutureWarning, match=warning_msg):
+        res = df.resample("M", axis=1)
+        with pytest.raises(
+            NotImplementedError, match="axis other than 0 is not supported"
+        ):
+            res.agg(func)
 
 
 def test_agg_nested_dicts():
@@ -973,3 +977,33 @@ def test_args_kwargs_depr(method, raises):
         with tm.assert_produces_warning(FutureWarning, match=warn_msg):
             with pytest.raises(TypeError, match=error_msg_type):
                 func(*args, 1, 2, 3)
+
+
+def test_df_axis_param_depr():
+    np.random.seed(1234)
+    index = date_range(datetime(2005, 1, 1), datetime(2005, 1, 10), freq="D")
+    index.name = "date"
+    df = DataFrame(np.random.rand(10, 2), columns=list("AB"), index=index).T
+
+    # Deprication error when axis=1 is explicitly passed
+    warning_msg = "DataFrame.resample with axis=1 is deprecated."
+    with tm.assert_produces_warning(FutureWarning, match=warning_msg):
+        df.resample("M", axis=1)
+
+    # Deprication error when axis=0 is explicitly passed
+    df = df.T
+    warning_msg = (
+        "The 'axis' keyword in DataFrame.resample is deprecated and "
+        "will be removed in a future version."
+    )
+    with tm.assert_produces_warning(FutureWarning, match=warning_msg):
+        df.resample("M", axis=0)
+
+
+def test_series_axis_param_depr():
+    warning_msg = (
+        "Series resample axis keyword is deprecated and will be removed in a "
+        "future version."
+    )
+    with tm.assert_produces_warning(FutureWarning, match=warning_msg):
+        test_series.resample("H", axis=0)

pandas/tests/window/test_api.py

@@ -129,7 +129,10 @@ def test_agg(step):
 def test_multi_axis_1_raises(func):
     # GH#46904
     df = DataFrame({"a": [1, 1, 2], "b": [3, 4, 5], "c": [6, 7, 8]})
-    r = df.rolling(window=3, axis=1)
+    warning_msg = "DataFrame.rolling with axis=1 is deprecated."
+
+    with tm.assert_produces_warning(FutureWarning, match=warning_msg):
+        r = df.rolling(window=3, axis=1)
     with pytest.raises(NotImplementedError, match="axis other than 0 is not supported"):
         r.agg(func)
 
@@ -344,20 +347,29 @@ def test_dont_modify_attributes_after_methods(
 
 def test_centered_axis_validation(step):
     # ok
-    Series(np.ones(10)).rolling(window=3, center=True, axis=0, step=step).mean()
+    axis_0_warning_msg =  (
+        "The 'axis' keyword in DataFrame.rolling is deprecated and "
+        "will be removed in a future version."
+    )
+    axis_1_warning_msg = "DataFrame.rolling with axis=1 is deprecated."
+
+    with tm.assert_produces_warning(FutureWarning, match=axis_0_warning_msg):
+        Series(np.ones(10)).rolling(window=3, center=True, axis=0, step=step).mean()
 
     # bad axis
     msg = "No axis named 1 for object type Series"
     with pytest.raises(ValueError, match=msg):
         Series(np.ones(10)).rolling(window=3, center=True, axis=1, step=step).mean()
 
     # ok ok
-    DataFrame(np.ones((10, 10))).rolling(
-        window=3, center=True, axis=0, step=step
-    ).mean()
-    DataFrame(np.ones((10, 10))).rolling(
-        window=3, center=True, axis=1, step=step
-    ).mean()
+    with tm.assert_produces_warning(FutureWarning, match=axis_0_warning_msg):
+        DataFrame(np.ones((10, 10))).rolling(
+            window=3, center=True, axis=0, step=step
+        ).mean()
+    with tm.assert_produces_warning(FutureWarning, match=axis_1_warning_msg):
+        DataFrame(np.ones((10, 10))).rolling(
+            window=3, center=True, axis=1, step=step
+        ).mean()
 
     # bad axis
     msg = "No axis named 2 for object type DataFrame"

pandas/tests/window/test_apply.py

@@ -321,6 +321,9 @@ def test_center_reindex_frame(raw, frame):
 def test_axis1(raw):
     # GH 45912
     df = DataFrame([1, 2])
-    result = df.rolling(window=1, axis=1).apply(np.sum, raw=raw)
+    warning_msg = "DataFrame.rolling with axis=1 is deprecated."
+
+    with tm.assert_produces_warning(FutureWarning, match=warning_msg):
+        result = df.rolling(window=1, axis=1).apply(np.sum, raw=raw)
     expected = DataFrame([1.0, 2.0])
     tm.assert_frame_equal(result, expected)

pandas/tests/window/test_ewm.py

@@ -198,7 +198,9 @@ def test_float_dtype_ewma(func, expected, float_numpy_dtype):
     df = DataFrame(
         {0: range(5), 1: range(6, 11), 2: range(10, 20, 2)}, dtype=float_numpy_dtype
     )
-    e = df.ewm(alpha=0.5, axis=1)
+    warning_msg = "DataFrame.ewm with axis=1 is deprecated."
+    with tm.assert_produces_warning(FutureWarning, match=warning_msg):
+        e = df.ewm(alpha=0.5, axis=1)
     result = getattr(e, func)()
 
     tm.assert_frame_equal(result, expected)
@@ -719,3 +721,18 @@ def test_numeric_only_corr_cov_series(kernel, use_arg, numeric_only, dtype):
         op2 = getattr(ewm2, kernel)
         expected = op2(*arg2, numeric_only=numeric_only)
         tm.assert_series_equal(result, expected)
+
+
+def test_df_ewn_axis_param_depr():
+    df = DataFrame({"a": [1], "b": 2, "c": 3})
+
+    warning_msg = (
+        "The 'axis' keyword in DataFrame.ewm is deprecated and "
+        "will be removed in a future version."
+    )
+    with tm.assert_produces_warning(FutureWarning, match=warning_msg):
+        df.ewm(span=2, axis=0)
+
+    warning_msg = "DataFrame.ewm with axis=1 is deprecated."
+    with tm.assert_produces_warning(FutureWarning, match=warning_msg):
+        df.ewm(span=2, axis=1)