feat: Add numpy ufunc support to col expressions

bigframes/core/col.py

@@ -17,6 +17,7 @@
 from typing import Any, Hashable, Literal, TYPE_CHECKING
 
 import bigframes_vendored.pandas.core.col as pd_col
+import numpy
 
 from bigframes.core import agg_expressions, window_spec
 import bigframes.core.expression as bf_expression
@@ -56,14 +57,10 @@ def _apply_binary_op(
         alignment: Literal["outer", "left"] = "outer",
         reverse: bool = False,
     ):
-        if isinstance(other, Expression):
-            other_value = other._value
-        else:
-            other_value = bf_expression.const(other)
         if reverse:
-            return Expression(op.as_expr(other_value, self._value))
+            return Expression(op.as_expr(_as_bf_expr(other), self._value))
         else:
-            return Expression(op.as_expr(self._value, other_value))
+            return Expression(op.as_expr(self._value, _as_bf_expr(other)))
 
     def __add__(self, other: Any) -> Expression:
         return self._apply_binary_op(other, bf_ops.add_op)
@@ -170,6 +167,34 @@ def str(self) -> strings.StringMethods:
 
         return strings.StringMethods(self)
 
+    def __array_ufunc__(
+        self, ufunc: numpy.ufunc, method: __builtins__.str, *inputs, **kwargs
+    ) -> Expression:
+        """Used to support numpy ufuncs.
+        See: https://numpy.org/doc/stable/reference/ufuncs.html
+        """
+        # Only __call__ supported with zero arguments
+        if method != "__call__" or len(inputs) > 2 or len(kwargs) > 0:
+            return NotImplemented
+
+        if len(inputs) == 1 and ufunc in bf_ops.NUMPY_TO_OP:
+            op = bf_ops.NUMPY_TO_OP[ufunc]
+            return Expression(op.as_expr(self._value))
+        if len(inputs) == 2 and ufunc in bf_ops.NUMPY_TO_BINOP:
+            binop = bf_ops.NUMPY_TO_BINOP[ufunc]
+            if inputs[0] is self:
+                return Expression(binop.as_expr(self._value, _as_bf_expr(inputs[1])))
+            else:
+                return Expression(binop.as_expr(_as_bf_expr(inputs[0]), self._value))
+
+        return NotImplemented
+
+
+def _as_bf_expr(arg: Any) -> bf_expression.Expression:
+    if isinstance(arg, Expression):
+        return arg._value
+    return bf_expression.const(arg)
+
 
 def col(col_name: Hashable) -> Expression:
     return Expression(bf_expression.free_var(col_name))

tests/unit/test_col.py

@@ -16,6 +16,7 @@
 import pathlib
 from typing import Generator
 
+import numpy as np
 import pandas as pd
 import pytest
 
@@ -246,3 +247,26 @@ def test_col_dt_accessor(scalars_dfs):
 
     # int64[pyarrow] vs Int64
     assert_frame_equal(bf_result, pd_result, check_dtype=False)
+
+
+def test_col_numpy_ufunc(scalars_dfs):
+    scalars_df, scalars_pandas_df = scalars_dfs
+
+    bf_kwargs = {
+        "sqrt": np.sqrt(bpd.col("float64_col")),  # type: ignore
+        "add_const": np.add(bpd.col("float64_col"), 2.4),  # type: ignore
+        "radd_const": np.add(2.4, bpd.col("float64_col")),  # type: ignore
+        "add_cols": np.add(bpd.col("float64_col"), bpd.col("int64_col")),  # type: ignore
+    }
+    pd_kwargs = {
+        "sqrt": np.sqrt(pd.col("float64_col")),  # type: ignore
+        "add_const": np.add(pd.col("float64_col"), 2.4),  # type: ignore
+        "radd_const": np.add(2.4, pd.col("float64_col")),  # type: ignore
+        "add_cols": np.add(pd.col("float64_col"), pd.col("int64_col")),  # type: ignore
+    }
+
+    bf_result = scalars_df.assign(**bf_kwargs).to_pandas()
+    pd_result = scalars_pandas_df.assign(**pd_kwargs)  # type: ignore
+
+    # int64[pyarrow] vs Int64
+    assert_frame_equal(bf_result, pd_result, check_dtype=False)