Add to_ibis() method to DataFrame and Series

This commit adds a `to_ibis()` method to both `DataFrame` and `Series` classes. This method allows users to access the underlying Ibis expression (`_data`) for more advanced operations or interoperability with Ibis directly.

Tests were added in `tests/test_to_ibis.py` to verify the functionality.

Author: google-labs-jules[bot]

leanframe/core/frame.py

@@ -91,6 +91,10 @@ def to_pandas(self) -> pd.DataFrame:
             types_mapper=lambda type_: pd.ArrowDtype(type_)
         )
 
+    def to_ibis(self) -> ibis_types.Table:
+        """Return the underlying Ibis expression."""
+        return self._data
+
 
 """
 Dynamic Nested Data Handler for leanframe

leanframe/core/series.py

@@ -234,6 +234,10 @@ def to_pandas(self) -> pd.Series:
             types_mapper=lambda type_: pd.ArrowDtype(type_)
         )
 
+    def to_ibis(self) -> ibis_types.Column:
+        """Return the underlying Ibis expression."""
+        return self._data
+
     def to_numpy(self) -> np.ndarray:
         """Return a numpy representation of the Series."""
         return self.values

tests/test_to_ibis.py

@@ -0,0 +1,34 @@
+
+import pytest
+import pandas as pd
+import leanframe as lf
+import ibis
+import ibis.expr.types as ibis_types
+from leanframe.core.frame import DataFrame
+from leanframe.core.series import Series
+
+def test_dataframe_to_ibis():
+    # Setup
+    con = ibis.sqlite.connect()
+    t = con.create_table('test_df_ibis', schema=ibis.schema({'a': 'int64', 'b': 'string'}))
+    df = DataFrame(t)
+
+    # Execute
+    expr = df.to_ibis()
+
+    # Assert
+    assert isinstance(expr, ibis_types.Table)
+    assert expr.equals(t)
+
+def test_series_to_ibis():
+    # Setup
+    con = ibis.sqlite.connect()
+    t = con.create_table('test_series_ibis', schema=ibis.schema({'a': 'int64'}))
+    s = Series(t['a'])
+
+    # Execute
+    expr = s.to_ibis()
+
+    # Assert
+    assert isinstance(expr, ibis_types.Column)
+    assert expr.equals(t['a'])