microsoft/qlib · error · NotImplementedError

Please implement the `__gt__` method

Error message

Please implement the `__gt__` method

What it means

BaseSingleMetric.__gt__ is the abstract greater-than operator, intended to return an element-wise boolean metric (return type BaseSingleMetric), not a bool. The base class raises NotImplementedError; SingleMetric provides the implementation. Applying > to a bare BaseSingleMetric raises this error.

Source

Thrown at qlib/backtest/high_performance_ds.py:252

        return self + other

    def __sub__(self, other: Union[BaseSingleMetric, int, float]) -> BaseSingleMetric:
        raise NotImplementedError(f"Please implement the `__sub__` method")

    def __rsub__(self, other: Union[BaseSingleMetric, int, float]) -> BaseSingleMetric:
        raise NotImplementedError(f"Please implement the `__rsub__` method")

    def __mul__(self, other: Union[BaseSingleMetric, int, float]) -> BaseSingleMetric:
        raise NotImplementedError(f"Please implement the `__mul__` method")

    def __truediv__(self, other: Union[BaseSingleMetric, int, float]) -> BaseSingleMetric:
        raise NotImplementedError(f"Please implement the `__truediv__` method")

    def __eq__(self, other: object) -> BaseSingleMetric:
        raise NotImplementedError(f"Please implement the `__eq__` method")

    def __gt__(self, other: Union[BaseSingleMetric, int, float]) -> BaseSingleMetric:
        raise NotImplementedError(f"Please implement the `__gt__` method")

    def __lt__(self, other: Union[BaseSingleMetric, int, float]) -> BaseSingleMetric:
        raise NotImplementedError(f"Please implement the `__lt__` method")

    def __len__(self) -> int:
        raise NotImplementedError(f"Please implement the `__len__` method")

    def sum(self) -> float:
        raise NotImplementedError(f"Please implement the `sum` method")

    def mean(self) -> float:
        raise NotImplementedError(f"Please implement the `mean` method")

    def count(self) -> int:
        """Return the count of the single metric, NaN is not included."""

        raise NotImplementedError(f"Please implement the `count` method")

View on GitHub (pinned to 79633dd950)

Solutions

1. Use SingleMetric for comparisons; convert the result with .astype or use its storage when a pandas boolean Series is needed
2. Implement __gt__ in your subclass returning type(self)(self.storage > other)
3. Sort/compare the underlying .storage Series rather than metric objects

Example fix

# before
buy = BaseSingleMetric(score) > 0.0
# after
from qlib.backtest.high_performance_ds import SingleMetric
buy = SingleMetric(score) > 0.0  # SingleMetric of booleans

from qlib.backtest.high_performance_ds import BaseSingleMetric
assert type(m).__gt__ is not BaseSingleMetric.__gt__, "object does not implement __gt__"

def supports_gt(m) -> bool:
    from qlib.backtest.high_performance_ds import BaseSingleMetric
    return isinstance(m, BaseSingleMetric) and type(m).__gt__ is not BaseSingleMetric.__gt__

When it happens

Trigger: m > threshold or m1 > m2 on a raw BaseSingleMetric; strategy filter code like (momentum > 0) to build tradable universes; sorted()/max() calls that invoke __gt__ on metric objects; subclasses implementing __lt__ but not __gt__.

Common situations: Thresholding factor scores into buy/sell masks; ranking code that accidentally sorts metric objects instead of their underlying Series; partial operator coverage in user subclasses.

Related errors

• Please implement the `__lt__` method
• Please implement the `__add__` method
• Please implement the `__sub__` method
• Please implement the `__rsub__` method
• Please implement the `__mul__` method

AI-assisted analysis of microsoft/qlib@79633dd950 (2026-08-15). Data as JSON: /api/errors/3afbeb43023befe5. Report an issue: GitHub.