pandas-dev/pandas · error · ValueError

cannot subscript with

Error message

cannot subscript {value!r} with {slobj!r}

What it means

Raised in PyTablesExprVisitor.visit_Subscript when value[slobj] raises TypeError. The visitor only supports 'simple subscripts' — indexing into a Term's value (e.g. a stored constant or attribute) with an integer/Term scalar. If the slice/index type is incompatible with the value's __getitem__ (e.g. indexing a scalar, a non-subscriptable object, or using a multi-dim slice), Python raises TypeError and the visitor re-wraps it as ValueError with both operands in the message.

Solutions

1. Move the subscript out of the where clause: precompute the indexed value in Python and pass it as a @-local or store it as a data_column.
2. Use only integer scalar subscripts if subscripting is unavoidable (e.g. on a stored constant term).
3. Read the data and use pandas indexing: df = store.get('df'); df.loc[df.index[1:2], 'A'].
4. Rewrite slice conditions as range comparisons: 'A > 5' instead of indexing.

Example fix

// before
store.select('df', where='A["x"] > 0')
store.select('df', where='A[1:3] > 0')

// after
val = some_lookup['x']
store.select('df', where='A == @val')
# for ranges
store.select('df', where='A > 5 & A < 10')

import re

def where_has_complex_subscript(where: str) -> bool:
    # detect subscript with slice or non-integer index
    return bool(re.search(r'\[\s*[^\]0-9@]+', where))

assert not where_has_complex_subscript(where_clause)

def is_simple_integer_subscript(slobj) -> bool:
    return isinstance(slobj, int)

try:
    store.select('df', where='A["x"] > 0')
except ValueError as e:
    if 'cannot subscript' in str(e):
        df = store.get('df')
        df[df['A'] == 'x_value']
    else:
        raise

When it happens

Trigger: store.select('df', where='A["bad"] > 0') (string index on a numeric column), store.select('df', where='A[1:2] > 0') (slice not allowed as 'simple subscript'), or subscripting a scalar term: store.select('df', where='5[0] > 0'). Also from referencing a non-subscriptable @-local inside the where clause.

Common situations: Using list/dict-style indexing syntax in a where clause. Trying to slice a column inside an HDFStore select. Confusing query subscript support with pandas .loc/.iloc semantics.

Related errors

• arithmetic operations are not supported inside an HDFStore…
• Cannot compare of type to column
• cannot use an invert condition when passing to numexpr
• name is not defined
• passing a filterable condition to a non-table indexer

AI-assisted analysis of pandas-dev/pandas@3b7651241d (2026-08-11). Data as JSON: /api/errors/d68346af43775a97. Report an issue: GitHub.

Appendix: source

Thrown at pandas/core/computation/pytables.py:496

    def visit_Subscript(self, node, **kwargs) -> ops.Term:
        # only allow simple subscripts

        value = self.visit(node.value)
        slobj = self.visit(node.slice)
        try:
            value = value.value
        except AttributeError:
            pass

        if isinstance(slobj, Term):
            # In py39 np.ndarray lookups with Term containing int raise
            slobj = slobj.value

        try:
            return self.const_type(value[slobj], self.env)
        except TypeError as err:
            raise ValueError(f"cannot subscript {value!r} with {slobj!r}") from err

    def visit_Attribute(self, node, **kwargs):
        attr = node.attr
        value = node.value

        ctx = type(node.ctx)
        if ctx == ast.Load:
            # resolve the value
            resolved = self.visit(value)

            # try to get the value to see if we are another expression
            try:
                resolved = resolved.value
            except AttributeError:
                pass

            try:
                return self.term_type(getattr(resolved, attr), self.env)

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