pandas-dev/pandas · error · TypeError

'{type(self).__name__}' object is not iterable

Error message

'{type(self).__name__}' object is not iterable

What it means

ListAccessor explicitly defines __iter__ to raise TypeError, so you cannot iterate the accessor object itself. This prevents 'for x in s.list' from silently doing nothing meaningful; to iterate list elements you must first materialize them via .flatten() or .explode().

Source

Thrown at pandas/core/arrays/arrow/accessors.py:198

            if start is None:
                # TODO: When adding negative step support
                #  this should be set to last element of array
                # when step is negative.
                start = 0
            if step is None:
                step = 1
            sliced = pc.list_slice(self._pa_array, start, stop, step)
            return Series(
                sliced,
                dtype=ArrowDtype(sliced.type),
                index=self._data.index,
                name=self._data.name,
            )
        else:
            raise ValueError(f"key must be an int or slice, got {type(key).__name__}")

    def __iter__(self) -> Iterator:
        raise TypeError(f"'{type(self).__name__}' object is not iterable")

    def flatten(self) -> Series:
        """
        Flatten list values.

        Each list element is expanded into separate rows, preserving the
        original index. The resulting Series may have a longer length than
        the original if lists contain more than one element.

        Returns
        -------
        pandas.Series
            The data from all lists in the series flattened.

        See Also
        --------
        ListAccessor.__getitem__ : Index or slice values in the Series.

View on GitHub (pinned to 71959b8cb9)

Solutions

1. Use s.list.flatten() (or s.explode()) to get elements, then iterate the resulting Series.
2. Use s.tolist() / s.apply(list) when you need plain Python lists.

Example fix

// before
for x in s.list:
    ...
// after
for x in s.list.flatten():
    ...

def iter_list_elements(s):
    return iter(s.list.flatten())

When it happens

Trigger: for x in s.list:, list(s.list), or *s.list unpacking on a list[pyarrow] Series.

Common situations: Expecting the accessor to yield list elements directly; writing a comprehension over the accessor instead of the data.

Related errors

• Can only use the '.list' accessor with 'list[pyarrow]' dtype
• key must be an int or slice, got {type(key).__name__}
• __invert__ is not supported for string dtypes
• unary '-' not supported for dtype '{self.dtype}'
• operation '{op.__name__}' not supported for dtype '{self.dty

AI-assisted analysis of pandas-dev/pandas@71959b8cb9 (2026-08-07). Data as JSON: /api/errors/e91b2ea7298862ac. Report an issue: GitHub.