pola-rs/polars · error · TypeError

cannot compare {self!r} to {value!r}

Error message

cannot compare {self!r} to {value!r}

What it means

Error "cannot compare {self!r} to {value!r}" thrown in pola-rs/polars.

Source

Thrown at py-polars/src/polars/datatype_expr/datatype_expr.py:78

    _pydatatype_expr: PyDataTypeExpr = None  # type: ignore[assignment]
    _accessors: ClassVar[set[str]] = {
        "arr",
        "enum",
        "list",
        "struct",
    }

    def __eq__(self, value: PolarsDataType | DataTypeExpr) -> pl.Expr:  # type: ignore[override]
        cmp_with: DataTypeExpr
        if isinstance(value, pl.DataType):
            cmp_with = value.to_dtype_expr()
        elif isinstance(value, pl.DataTypeClass):
            cmp_with = value.to_dtype_expr()
        elif isinstance(value, DataTypeExpr):
            cmp_with = value
        else:
            msg = f"cannot compare {self!r} to {value!r}"
            raise TypeError(msg) from None

        return pl.Expr._from_pyexpr(
            self._pydatatype_expr.equals(cmp_with._pydatatype_expr)
        )

    def __ne__(self, value: PolarsDataType | DataTypeExpr) -> pl.Expr:  # type: ignore[override]
        return (self == value).not_()

    @classmethod
    def _from_pydatatype_expr(cls, pydatatype_expr: PyDataTypeExpr) -> DataTypeExpr:
        slf = cls()
        slf._pydatatype_expr = pydatatype_expr
        return slf

    def inner_dtype(self) -> DataTypeExpr:
        """Get the inner DataType of a List or Array."""
        return DataTypeExpr._from_pydatatype_expr(self._pydatatype_expr.inner_dtype())

View on GitHub (pinned to df599052da)

When it happens

Trigger: Thrown at py-polars/src/polars/datatype_expr/datatype_expr.py:78 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of pola-rs/polars@df599052da (2026-08-16). Data as JSON: /api/errors/e212d56154072360. Report an issue: GitHub.