SNOW-1669082: Add support for Resampler.asfreq (#2310)

SNOW-1669082 This PR implements `Resampler.asfreq` which follows the same underlying code path as `Series.asfreq` and `DataFrame.asfreq` which was implemented in a previous PR. --------- Signed-off-by: Naren Krishna <[email protected]> Co-authored-by: Jonathan Shi <[email protected]>
snowflakedb · Sep 18, 2024 · f7b9c67 · f7b9c67
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -15,6 +15,7 @@
 - Added support for `by`, `left_by`, `right_by`, `left_index`, and `right_index` for `pd.merge_asof`.
 - Added support for passing parameter `include_describe` to `Session.query_history`.
 - Added support for `DatetimeIndex.mean` and `DatetimeIndex.std` methods.
+- Added support for `Resampler.asfreq`.
 
 #### Bug Fixes
 

diff --git a/docs/source/modin/supported/resampling_supported.rst b/docs/source/modin/supported/resampling_supported.rst
@@ -44,7 +44,7 @@ Upsampling
 +-----------------------------+---------------------------------+----------------------------------+----------------------------------------------------+
 | Resampler method            | Snowpark implemented? (Y/N/P/D) | Missing parameters               | Notes for current implementation                   |
 +-----------------------------+---------------------------------+----------------------------------+----------------------------------------------------+
-| ``asfreq``                  | N                               |                                  |                                                    |
+| ``asfreq``                  | P                               | ``fill_value``                   |                                                    |
 +-----------------------------+---------------------------------+----------------------------------+----------------------------------------------------+
 | ``bfill``                   | P                               | ``limit``                        |                                                    |
 +-----------------------------+---------------------------------+----------------------------------+----------------------------------------------------+

diff --git a/src/snowflake/snowpark/modin/pandas/resample.py b/src/snowflake/snowpark/modin/pandas/resample.py
@@ -280,8 +280,24 @@ def fillna(self, method: str, limit: Optional[int] = None):
             )
         return getattr(self, method)(limit=limit)
 
-    def asfreq(self, fill_value: Optional[Any] = None):  # pragma: no cover
-        self._method_not_implemented("asfreq")
+    def asfreq(self, fill_value: Optional[Any] = None):
+        is_series = not self._dataframe._is_dataframe
+
+        if fill_value is not None:
+            # TODO: SNOW-1660802: Implement `fill_value` parameter once `GroupBy.fillna` is supported
+            ErrorMessage.parameter_not_implemented_error(
+                "fill_value", "Resampler.asfreq"
+            )
+
+        return self._dataframe.__constructor__(
+            query_compiler=self._query_compiler.resample(
+                self.resample_kwargs,
+                "first",
+                (),
+                {},
+                is_series,
+            )
+        )
 
     def interpolate(
         self,

diff --git a/src/snowflake/snowpark/modin/plugin/docstrings/resample.py b/src/snowflake/snowpark/modin/plugin/docstrings/resample.py
@@ -406,7 +406,44 @@ def fillna():
         """
 
     def asfreq():
-        pass
+        """
+        Return the values at the new freq, essentially a reindex.
+
+        Parameters
+        ----------
+        fill_value : scalar, optional
+            This parameter is not supported and will raise NotImplementedError.
+
+        Returns
+        -------
+        :class:`~modin.pandas.Series` or :class:`~modin.pandas.DataFrame`
+            Values at the specified freq.
+
+        See Also
+        --------
+        Series.asfreq: Convert TimeSeries to specified frequency.
+        DataFrame.asfreq: Convert TimeSeries to specified frequency.
+
+        Examples
+        --------
+        >>> s = pd.Series([1, 2, 3], index=pd.date_range('20180101', periods=3, freq='h'))
+        >>> s
+        2018-01-01 00:00:00    1
+        2018-01-01 01:00:00    2
+        2018-01-01 02:00:00    3
+        Freq: None, dtype: int64
+        >>> s.resample("30min").asfreq()
+        2018-01-01 00:00:00    1.0
+        2018-01-01 00:30:00    NaN
+        2018-01-01 01:00:00    2.0
+        2018-01-01 01:30:00    NaN
+        2018-01-01 02:00:00    3.0
+        Freq: None, dtype: float64
+        >>> s.resample("2h").asfreq()
+        2018-01-01 00:00:00    1
+        2018-01-01 02:00:00    3
+        Freq: None, dtype: int64
+        """
 
     def interpolate():
         pass

diff --git a/tests/integ/modin/resample/test_resample_asfreq.py b/tests/integ/modin/resample/test_resample_asfreq.py
@@ -44,6 +44,19 @@ def test_asfreq_ffill():
     )
 
 
+@sql_count_checker(query_count=3, join_count=1)
+@pytest.mark.parametrize("freq", ["3min", "30S"])
+def test_resampler_asfreq(freq):
+    eval_snowpark_pandas_result(
+        *create_test_dfs(
+            {"A": np.random.randn(15)},
+            index=native_pd.date_range("2020-01-01", periods=15, freq="1min"),
+        ),
+        lambda df: df.resample(freq).asfreq(),
+        check_freq=False,
+    )
+
+
 @sql_count_checker(query_count=0)
 def test_asfreq_negative():
     snow_df = pd.DataFrame(
@@ -56,3 +69,5 @@ def test_asfreq_negative():
         snow_df.asfreq(freq="5s", method="ffill", normalize=True)
     with pytest.raises(NotImplementedError):
         snow_df.asfreq(freq="5s", method="ffill", fill_value=2)
+    with pytest.raises(NotImplementedError):
+        snow_df.resample("5s").asfreq(fill_value=2)