firestar5683
45 lines
1.1 KiB
Python
45 lines
1.1 KiB
Python
from typing import Callable, List, Optional, TypeVar, cast
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from reactivex import Observable, compose
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from reactivex import operators as ops
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from reactivex.internal.basic import identity
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from reactivex.internal.exceptions import SequenceContainsNoElementsError
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from reactivex.typing import Comparer
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_T = TypeVar("_T")
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def first_only(x: List[_T]) -> _T:
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if not x:
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raise SequenceContainsNoElementsError()
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return x[0]
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def min_(
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comparer: Optional[Comparer[_T]] = None,
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) -> Callable[[Observable[_T]], Observable[_T]]:
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"""The `min` operator.
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Returns the minimum element in an observable sequence according to
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the optional comparer else a default greater than less than check.
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Examples:
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>>> res = source.min()
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>>> res = source.min(lambda x, y: x.value - y.value)
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Args:
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comparer: [Optional] Comparer used to compare elements.
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Returns:
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An observable sequence containing a single element
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with the minimum element in the source sequence.
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"""
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return compose(
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ops.min_by(cast(Callable[[_T], _T], identity), comparer),
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ops.map(first_only),
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)
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__all__ = ["min_"]
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