@dataclass class WindowFrame: start: tuple[int, FrameBound] # (offset, bound_type) end: tuple[int, FrameBound] frame_type: str = "rows" # rows, range, groups
class WindowellEngine: """Dynamic window function processor""" windowell expressions
def _apply_frame(self, df: pd.DataFrame, window: WindowellExpression) -> pd.DataFrame: """Apply frame boundaries (simplified implementation)""" # Real implementation would handle ROWS BETWEEN X PRECEDING AND Y FOLLOWING frame = window.frame if frame.frame_type == "rows" and frame.start[1] == FrameBound.PRECEDING: # Rolling window logic return df.assign( _row_num=np.arange(len(df)), _window_start=lambda x: x._row_num - frame.start[0] ) return df class WindowellBuilder: """Fluent API for building window expressions""" @dataclass class WindowFrame: start: tuple[int
def define_window(self, name: str, expression: WindowellExpression): """Register a named window template""" self.window_registry[name] = expression return self FrameBound] # (offset
def setUp(self): self.engine = WindowellEngine() self.df = pd.DataFrame( 'product': ['A', 'A', 'A', 'B', 'B'], 'date': pd.date_range('2024-01-01', periods=5), 'sales': [100, 150, 200, 50, 75] )
def evaluate(self, df: pd.DataFrame) -> int: return self.expression(df) dynamic_window = WindowellBuilder() .partition("category") .order("timestamp") .rows_between( DynamicBoundary(lambda df: df['lag'].max()), "preceding", 0, "current_row" ).build() 4. Testing Suite import unittest class TestWindowellExpressions(unittest.TestCase):