SNOW-1748281: Add support for Series.str.center (#2731)

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   Fixes SNOW-1748281

2. Fill out the following pre-review checklist:

- [x] I am adding a new automated test(s) to verify correctness of my
new code
- [ ] If this test skips Local Testing mode, I'm requesting review from
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   - [ ] I am adding new logging messages
   - [ ] I am adding a new telemetry message
   - [ ] I am adding new credentials
   - [ ] I am adding a new dependency
- [ ] If this is a new feature/behavior, I'm adding the Local Testing
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- [ ] I acknowledge that I have ensured my changes to be thread-safe.
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3. Please describe how your code solves the related issue.

   Add support for Series.str.center.

CHANGELOG.md

@@ -7,6 +7,7 @@
 #### New Features
 
 - Added support for `Series.str.ljust` and `Series.str.rjust`.
+- Added support for `Series.str.center`.
 
 
 ## 1.26.0 (2024-12-05)

docs/source/modin/supported/series_str_supported.rst

@@ -23,7 +23,7 @@ the method in the left column.
 +-----------------------------+---------------------------------+----------------------------------------------------+
 | ``cat``                     | N                               |                                                    |
 +-----------------------------+---------------------------------+----------------------------------------------------+
-| ``center``                  | N                               |                                                    |
+| ``center``                  | Y                               |                                                    |
 +-----------------------------+---------------------------------+----------------------------------------------------+
 | ``contains``                | P                               |  ``N`` if the `na` parameter is set to a non-bool  |
 |                             |                                 |  value.                                            |

src/snowflake/snowpark/modin/plugin/compiler/snowflake_query_compiler.py

@@ -16253,8 +16253,39 @@ def str___getitem__(self, key: Union[Scalar, slice]) -> "SnowflakeQueryCompiler"
                 raise ValueError("slice step cannot be zero")
             return self.str_slice(key.start, key.stop, key.step)
 
-    def str_center(self, width: int, fillchar: str = " ") -> None:
-        ErrorMessage.method_not_implemented_error("center", "Series.str")
+    def str_center(self, width: int, fillchar: str = " ") -> "SnowflakeQueryCompiler":
+        if not isinstance(width, int):
+            raise TypeError(
+                f"width must be of integer type, not {type(width).__name__}"
+            )
+        if not isinstance(fillchar, str):
+            raise TypeError(
+                f"fillchar must be of integer type, not {type(fillchar).__name__}"
+            )
+        if len(fillchar) != 1:
+            raise TypeError("fillchar must be a character, not str")
+
+        def output_col(column: SnowparkColumn) -> SnowparkColumn:
+            new_col = rpad(
+                lpad(
+                    column,
+                    greatest(
+                        length(column),
+                        length(column)
+                        + (pandas_lit(width) - length(column) - pandas_lit(1))
+                        / pandas_lit(2),
+                    ),
+                    pandas_lit(fillchar),
+                ),
+                greatest(length(column), pandas_lit(width)),
+                pandas_lit(fillchar),
+            )
+            return self._replace_non_str(column, new_col)
+
+        new_internal_frame = self._modin_frame.apply_snowpark_function_to_columns(
+            output_col
+        )
+        return SnowflakeQueryCompiler(new_internal_frame)
 
     def str_contains(
         self,
@@ -16473,6 +16504,12 @@ def str_ljust(self, width: int, fillchar: str = " ") -> "SnowflakeQueryCompiler"
             raise TypeError(
                 f"width must be of integer type, not {type(width).__name__}"
             )
+        if not isinstance(fillchar, str):
+            raise TypeError(
+                f"fillchar must be of integer type, not {type(fillchar).__name__}"
+            )
+        if len(fillchar) != 1:
+            raise TypeError("fillchar must be a character, not str")
 
         def output_col(column: SnowparkColumn) -> SnowparkColumn:
             new_col = rpad(
@@ -16507,6 +16544,12 @@ def str_rjust(self, width: int, fillchar: str = " ") -> "SnowflakeQueryCompiler"
             raise TypeError(
                 f"width must be of integer type, not {type(width).__name__}"
             )
+        if not isinstance(fillchar, str):
+            raise TypeError(
+                f"fillchar must be of integer type, not {type(fillchar).__name__}"
+            )
+        if len(fillchar) != 1:
+            raise TypeError("fillchar must be a character, not str")
 
         def output_col(column: SnowparkColumn) -> SnowparkColumn:
             new_col = lpad(

src/snowflake/snowpark/modin/plugin/docstrings/series_utils.py

@@ -337,7 +337,51 @@ def pad():
         pass
 
     def center():
-        pass
+        """
+        Pad left and right side of strings in the Series/Index.
+
+        Equivalent to str.center().
+
+        Parameters
+        ----------
+        width : int
+            Minimum width of resulting string; additional characters will be filled with fillchar.
+        fillchar : str
+            Additional character for filling, default is whitespace.
+
+        Returns
+        -------
+        Series/Index of objects.
+
+        Examples
+        --------
+        For Series.str.center:
+
+        >>> ser = pd.Series(['dog', 'bird', 'mouse'])
+        >>> ser.str.center(8, fillchar='.')
+        0    ..dog...
+        1    ..bird..
+        2    .mouse..
+        dtype: object
+
+        For Series.str.ljust:
+
+        >>> ser = pd.Series(['dog', 'bird', 'mouse'])
+        >>> ser.str.ljust(8, fillchar='.')
+        0    dog.....
+        1    bird....
+        2    mouse...
+        dtype: object
+
+        For Series.str.rjust:
+
+        >>> ser = pd.Series(['dog', 'bird', 'mouse'])
+        >>> ser.str.rjust(8, fillchar='.')
+        0    .....dog
+        1    ....bird
+        2    ...mouse
+        dtype: object
+        """
 
     def ljust():
         """

tests/integ/modin/series/test_str_accessor.py

@@ -422,11 +422,11 @@ def test_str_no_params(func):
     )
 
 
-@pytest.mark.parametrize("func", ["ljust", "rjust"])
+@pytest.mark.parametrize("func", ["center", "ljust", "rjust"])
 @pytest.mark.parametrize("width", [-1, 0, 1, 10, 100])
 @pytest.mark.parametrize("fillchar", [" ", "#"])
 @sql_count_checker(query_count=1)
-def test_str_ljust_rjust(func, width, fillchar):
+def test_str_center_ljust_rjust(func, width, fillchar):
     native_ser = native_pd.Series(TEST_DATA)
     snow_ser = pd.Series(native_ser)
     eval_snowpark_pandas_result(
@@ -436,18 +436,20 @@ def test_str_ljust_rjust(func, width, fillchar):
     )
 
 
-@pytest.mark.parametrize("func", ["ljust", "rjust"])
+@pytest.mark.parametrize("func", ["center", "ljust", "rjust"])
 @pytest.mark.parametrize(
     "width, fillchar",
     [
         (None, " "),
+        ("ten", " "),
         (10, ""),
         (10, "ab"),
         (10, None),
+        (10, 10),
     ],
 )
 @sql_count_checker(query_count=0)
-def test_str_ljust_rjust_neg(func, width, fillchar):
+def test_str_center_ljust_rjust_neg(func, width, fillchar):
     native_ser = native_pd.Series(TEST_DATA)
     snow_ser = pd.Series(native_ser)
     with pytest.raises(TypeError):

tests/unit/modin/test_series_strings.py

@@ -37,7 +37,6 @@ def test_str_cat_no_others(mock_str_register, mock_series):
         (lambda s: s.str.rsplit("_", n=1), "rsplit"),
         (lambda s: s.str.join("_"), "join"),
         (lambda s: s.str.pad(10), "pad"),
-        (lambda s: s.str.center(10), "center"),
         (lambda s: s.str.zfill(8), "zfill"),
         (lambda s: s.str.wrap(3), "wrap"),
         (lambda s: s.str.slice_replace(start=3, stop=5, repl="abc"), "slice_replace"),
@@ -105,11 +104,6 @@ def test_str_methods_with_dataframe_return(func, func_name, mock_series):
             TypeError,
             "fillchar must be a character, not str",
         ),
-        (
-            lambda s: s.str.center(8, fillchar="abc"),
-            TypeError,
-            "fillchar must be a character, not str",
-        ),
         (lambda s: s.str.wrap(-1), ValueError, r"invalid width -1 \(must be > 0\)"),
         (
             lambda s: s.str.count(12),