feat(python): Improve Expr.is_between API (#5981)

py-polars/polars/internals/expr/expr.py

@@ -3327,7 +3327,8 @@ def is_between(
         self,
         start: Expr | datetime | date | int | float,
         end: Expr | datetime | date | int | float,
-        include_bounds: bool | tuple[bool, bool] = False,
+        include_bounds: bool | tuple[bool, bool] | None = None,
+        closed: ClosedWindow | None = None,
     ) -> Expr:
         """
         Check if this expression is between start and end.
@@ -3339,12 +3340,16 @@ def is_between(
         end
             Upper bound as primitive type or datetime.
         include_bounds
-           False:           Exclude both start and end (default).
-           True:            Include both start and end.
-           (False, False):  Exclude start and exclude end.
-           (True, True):    Include start and include end.
-           (False, True):   Exclude start and include end.
-           (True, False):   Include start and exclude end.
+            This argument is deprecated. Use ``closed`` instead!
+
+            - False:           Exclude both start and end (default).
+            - True:            Include both start and end.
+            - (False, False):  Exclude start and exclude end.
+            - (True, True):    Include start and include end.
+            - (False, True):   Exclude start and include end.
+            - (True, False):   Include start and exclude end.
+        closed : {'none', 'left', 'right', 'both'}
+            Define whether the interval is closed or not. Defaults to 'none'.
 
         Returns
         -------
@@ -3367,25 +3372,67 @@ def is_between(
         │ 5   ┆ false      │
         └─────┴────────────┘
 
+        Use the ``closed`` argument to include or exclude the values at the bounds.
+
+        >>> df.with_column(pl.col("num").is_between(2, 4, closed="left"))
+        shape: (5, 2)
+        ┌─────┬────────────┐
+        │ num ┆ is_between │
+        │ --- ┆ ---        │
+        │ i64 ┆ bool       │
+        ╞═════╪════════════╡
+        │ 1   ┆ false      │
+        │ 2   ┆ true       │
+        │ 3   ┆ true       │
+        │ 4   ┆ false      │
+        │ 5   ┆ false      │
+        └─────┴────────────┘
+
         """
-        if isinstance(include_bounds, list):
+        if include_bounds is not None:
             warnings.warn(
-                "include_bounds: list[bool] will not be supported in a future "
-                "version; pass include_bounds: tuple[bool, bool] instead",
+                "The `include_bounds` argument will be replaced in a future version."
+                " Use the `closed` argument to silence this warning.",
                 category=DeprecationWarning,
             )
-            include_bounds = tuple(include_bounds)
+            if isinstance(include_bounds, list):
+                include_bounds = tuple(include_bounds)
+
+            if include_bounds is False or include_bounds == (False, False):
+                closed = "none"
+            elif include_bounds is True or include_bounds == (True, True):
+                closed = "both"
+            elif include_bounds == (False, True):
+                closed = "right"
+            elif include_bounds == (True, False):
+                closed = "left"
+            else:
+                raise ValueError(
+                    "include_bounds should be a bool or tuple[bool, bool]."
+                )
+
+        if closed is None:
+            warnings.warn(
+                "Default behaviour will change from excluding both bounds to including"
+                " both bounds. Provide a value for the `closed` argument to silence"
+                " this warning.",
+                category=FutureWarning,
+            )
+            closed = "none"
 
-        if include_bounds is False or include_bounds == (False, False):
+        if closed == "none":
             return ((self > start) & (self < end)).alias("is_between")
-        elif include_bounds is True or include_bounds == (True, True):
+        elif closed == "both":
             return ((self >= start) & (self <= end)).alias("is_between")
-        elif include_bounds == (False, True):
+        elif closed == "right":
             return ((self > start) & (self <= end)).alias("is_between")
-        elif include_bounds == (True, False):
+        elif closed == "left":
             return ((self >= start) & (self < end)).alias("is_between")
         else:
-            raise ValueError("include_bounds should be a bool or tuple[bool, bool].")
+            raise ValueError(
+                "closed must be one of {'left', 'right', 'both', 'none'},"
+                f" got {closed}"
+            )
 
     def hash(
         self,

py-polars/tests/unit/test_lazy.py

@@ -1168,51 +1168,43 @@ def test_quantile(fruits_cars: pl.DataFrame) -> None:
     assert fruits_cars.select(pl.col("A").quantile(0.24, "linear"))["A"][0] == 1.96
 
 
+@pytest.mark.filterwarnings("ignore::FutureWarning")
 def test_is_between(fruits_cars: pl.DataFrame) -> None:
     result = fruits_cars.select(pl.col("A").is_between(2, 4))["is_between"]
     assert result.series_equal(
         pl.Series("is_between", [False, False, True, False, False])
     )
 
-    result = fruits_cars.select(pl.col("A").is_between(2, 4, False))["is_between"]
-    assert result.series_equal(
-        pl.Series("is_between", [False, False, True, False, False])
-    )
-
-    result = fruits_cars.select(pl.col("A").is_between(2, 4, (False, False)))[
+    result = fruits_cars.select(pl.col("A").is_between(2, 4, closed="none"))[
         "is_between"
     ]
     assert result.series_equal(
         pl.Series("is_between", [False, False, True, False, False])
     )
 
-    result = fruits_cars.select(pl.col("A").is_between(2, 4, True))["is_between"]
-    assert result.series_equal(
-        pl.Series("is_between", [False, True, True, True, False])
-    )
-
-    result = fruits_cars.select(pl.col("A").is_between(2, 4, (True, True)))[
+    result = fruits_cars.select(pl.col("A").is_between(2, 4, closed="both"))[
         "is_between"
     ]
     assert result.series_equal(
         pl.Series("is_between", [False, True, True, True, False])
     )
 
-    result = fruits_cars.select(pl.col("A").is_between(2, 4, (False, True)))[
+    result = fruits_cars.select(pl.col("A").is_between(2, 4, closed="right"))[
         "is_between"
     ]
     assert result.series_equal(
         pl.Series("is_between", [False, False, True, True, False])
     )
 
-    result = fruits_cars.select(pl.col("A").is_between(2, 4, (True, False)))[
+    result = fruits_cars.select(pl.col("A").is_between(2, 4, closed="left"))[
         "is_between"
     ]
     assert result.series_equal(
         pl.Series("is_between", [False, True, True, False, False])
     )
 
 
+@pytest.mark.filterwarnings("ignore::FutureWarning")
 def test_is_between_data_types() -> None:
     df = pl.DataFrame(
         {

py-polars/tests/unit/test_series.py

@@ -2050,6 +2050,7 @@ def test_to_physical() -> None:
     verify_series_and_expr_api(a, expected, "to_physical")
 
 
+@pytest.mark.filterwarnings("ignore::FutureWarning")
 def test_is_between_datetime() -> None:
     s = pl.Series("a", [datetime(2020, 1, 1, 10, 0, 0), datetime(2020, 1, 1, 20, 0, 0)])
     start = datetime(2020, 1, 1, 12, 0, 0)