pandas-dev/pandas · error · TypeError

Function "{res.name}" does not support keyword arguments

Error message

Function "{res.name}" does not support keyword arguments

What it means

When the resolved function is a FuncNode (the built-in math/reduction set: sin, cos, log, abs, sqrt, sum, mean, etc.), visit_Call takes the branch at expr.py:691 and explicitly rejects keyword arguments, because FuncNode.__call__ evaluates positionally against numexpr/math signatures. Any node.keywords present trigger TypeError naming the function.

Source

Thrown at pandas/core/computation/expr.py:695

                try:
                    res = FuncNode(node.func.id)
                except ValueError:
                    # Raise original error
                    raise

        if res is None:
            # error: "expr" has no attribute "id"
            raise ValueError(
                f"Invalid function call {node.func.id}"  # type: ignore[union-attr]
            )
        if hasattr(res, "value"):
            res = res.value

        if isinstance(res, FuncNode):
            new_args = [self.visit(arg) for arg in node.args]

            if node.keywords:
                raise TypeError(
                    f'Function "{res.name}" does not support keyword arguments'
                )

            return res(*new_args)

        else:
            new_args = [self.visit(arg)(self.env) for arg in node.args]

            for key in node.keywords:
                if not isinstance(key, ast.keyword):
                    # error: Item "Attribute" of "Attribute | Name" has no
                    # attribute "id"
                    raise ValueError(
                        f"keyword error in function call '{node.func.id}'"  # type: ignore[union-attr]
                    )

                if key.arg:
                    kwargs[key.arg] = self.visit(key.value)(self.env)

View on GitHub (pinned to 71959b8cb9)

Solutions

1. Pass arguments positionally: df.eval('sin(a)'), df.eval('log(a)').
2. For multi-arg functions, check supported signatures and pass positionally.
3. Compute the function call in plain Python/numpy if keyword semantics are required.

Example fix

// before
df.eval('sin(x=a)')
// after
df.eval('sin(a)')

import ast

MATH_FUNCS = {'sin', 'cos', 'tan', 'arcsin', 'arccos', 'arctan', 'arctan2',
              'sinh', 'cosh', 'tanh', 'arcsinh', 'arccosh', 'arctanh',
              'log', 'log10', 'log1p', 'exp', 'expm1', 'sqrt', 'abs',
              'sum', 'mean', 'median', 'min', 'max', 'std', 'var'}

def validate_no_kwargs_for_math_fns(expr: str) -> None:
    for node in ast.walk(ast.parse(expr, mode='eval')):
        if (isinstance(node, ast.Call)
                and isinstance(node.func, ast.Name)
                and node.func.id in MATH_FUNCS
                and node.keywords):
            raise TypeError(
                f'{node.func.id}() does not accept keyword args; pass positionally'
            )

validate_no_kwargs_for_math_fns(expr)

import ast

def math_calls_are_positional(expr: str) -> bool:
    MATH = {'sin', 'cos', 'log', 'sqrt', 'abs', 'sum', 'mean'}
    return all(
        not (isinstance(n, ast.Call) and isinstance(n.func, ast.Name)
             and n.func.id in MATH and n.keywords)
        for n in ast.walk(ast.parse(expr, mode='eval'))
    )

try:
    df.eval(expr)
except TypeError as e:
    if 'does not support keyword arguments' in str(e):
        # strip keyword names, rebuild as positional
        df.eval('sin(a)')
    raise

When it happens

Trigger: df.eval('sin(x=a)'), df.eval('log(x=a, base=10)'), df.query('abs(col=x)') — passing the argument by keyword to a built-in math function.

Common situations: Auto-generating function-call strings with keyword names. Porting sklearn/numpy-style keyword calls into eval. Copying signatures from docs that name parameters.

Related errors

• unsupported operand type(s) for {res.op}: '{lhs.type}' and '
• Only named functions are supported
• Invalid function call {node.func.id}
• keyword error in function call '{node.func.id}'
• "{name}" is not a supported function

AI-assisted analysis of pandas-dev/pandas@71959b8cb9 (2026-08-07). Data as JSON: /api/errors/0e41ec8ea6b26f24. Report an issue: GitHub.