feat: get first cell with value other than None

src/safeds/data/tabular/containers/_cell.py

@@ -21,6 +21,19 @@ class Cell(ABC, Generic[T_co]):
     This class cannot be instantiated directly. It is only used for arguments of callbacks.
     """
 
+    # ------------------------------------------------------------------------------------------------------------------
+    # Static methods
+    # ------------------------------------------------------------------------------------------------------------------
+
+    @staticmethod
+    def first_not_none(cells: list[Cell]) -> Cell:
+        """Return the first cell from the given list that is not None."""
+        import polars as pl
+
+        from ._lazy_cell import _LazyCell  # circular import
+
+        return _LazyCell(pl.coalesce([cell._polars_expression for cell in cells]))
+
     # ------------------------------------------------------------------------------------------------------------------
     # Dunder methods
     # ------------------------------------------------------------------------------------------------------------------

tests/safeds/data/tabular/containers/_cell/test_first_not_none.py

@@ -0,0 +1,54 @@
+from datetime import date, time
+
+import pytest
+from safeds.data.tabular.containers._cell import Cell
+from safeds.data.tabular.containers._lazy_cell import _LazyCell
+
+
+class TestFirstNotNone:
+    def test_should_return_none(self) -> None:
+        to_eval: list[Cell] = [_LazyCell(None) for i in range(5)]
+        res = Cell.first_not_none(to_eval)
+        assert res.eq(_LazyCell(None))
+
+    @pytest.mark.parametrize(
+        ("list_of_cells", "expected"),
+        [
+            ([_LazyCell(None), _LazyCell(1), _LazyCell(None), _LazyCell(4)], _LazyCell(1)),
+            ([_LazyCell(i) for i in range(5)], _LazyCell(1)),
+            (
+                [_LazyCell(None), _LazyCell(None), _LazyCell("Hello, World!"), _LazyCell("Not returned")],
+                _LazyCell("Hello, World!"),
+            ),
+            ([_LazyCell(i) for i in ["a", "b", "c", "d"]], _LazyCell("a")),
+            ([_LazyCell(i) for i in [None, time(0, 0, 0, 0), None, time(1, 1, 1, 1)]], _LazyCell(time(0, 0, 0, 0))),
+            (
+                [_LazyCell(i) for i in [time(0, 0, 0, 0), time(1, 1, 1, 1), time(2, 2, 2, 2), time(3, 3, 3, 3)]],
+                _LazyCell(time(0, 0, 0, 0)),
+            ),
+            ([_LazyCell(i) for i in [None, date(2000, 1, 1), date(1098, 3, 4), None]], _LazyCell(date(2000, 1, 1))),
+            ([_LazyCell(date(2000, 3, i)) for i in range(1, 5)], _LazyCell(date(2000, 3, 1))),
+            ([_LazyCell(i) for i in [None, "a", 1, time(0, 0, 0, 0)]], _LazyCell("a")),
+            ([_LazyCell(i) for i in [time(1, 1, 1, 1), 0, "c", date(2020, 1, 7)]], _LazyCell(time(1, 1, 1, 1))),
+        ],
+        ids=[
+            "numeric_with_null",
+            "numeric_no_null",
+            "strings_with_null",
+            "strings_no_null",
+            "times_with_null",
+            "times_no_null",
+            "dates_with_null",
+            "dates_no_null",
+            "mixed_with_null",
+            "mixed_no_null",
+        ],
+    )
+    def test_should_not_return_none(self, list_of_cells: list[Cell], expected: Cell) -> None:
+        res = Cell.first_not_none(list_of_cells)
+        assert res.eq(expected)
+
+    def test_given_empty_list(self) -> None:
+        to_eval: list[Cell] = []
+        res = Cell.first_not_none(to_eval)
+        assert res.eq(_LazyCell(None))