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Base

base

Source contract shared by reanalyses (ERA5) and forecasts (ARPEGE, ...).

A cube is one gridded time slice of a source over a region. It is identified by its validity time and, for forecasts, the run (base time) it comes from. Sources declare their native time step; the enricher brackets every point between two consecutive valid times and asks the source which cubes (and, for forecasts, which run) to use for that interval.

CubeKey dataclass

Validity time of a cube and, for forecasts, the run it belongs to.

Source code in packages/barograph-met/src/baro/met/base.py 
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@dataclass(frozen=True, order=True)
class CubeKey:
    """Validity time of a cube and, for forecasts, the run it belongs to."""

    valid: np.datetime64
    run: np.datetime64 | None = None
    source: str | None = None  # set by composite sources to route the fetch

    @property
    def lead(self) -> np.timedelta64 | None:
        """Forecast lead time, or ``None`` for analyses and stitched forecast archives."""
        return None if self.run is None else self.valid - self.run

    def __str__(self) -> str:
        return str(self.valid) if self.run is None else f"{self.valid} (run {self.run})"
lead property

Forecast lead time, or None for analyses and stitched forecast archives.

DataUnavailableError

Bases: LookupError

The source has no data for this key (not published, expired, out of range).

Source code in packages/barograph-met/src/baro/met/base.py 
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class DataUnavailableError(LookupError):
    """The source has no data for this key (not published, expired, out of range)."""

Source

Bases: Protocol

What the enricher needs from a gridded source.

Source code in packages/barograph-met/src/baro/met/base.py 
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class Source(Protocol):
    """What the enricher needs from a gridded source."""

    source_id: str
    fields: dict[str, str]  # output name -> source-specific variable identifier
    time_step: np.timedelta64

    @property
    def stats(self) -> list[TransferStats]:
        """Transfer counters of the source's stores."""
        ...

    def cube_keys(self, t0: np.datetime64) -> tuple[CubeKey, CubeKey]:
        """Cubes bracketing the interval ``[t0, t0 + time_step)``."""
        ...

    def coverage(self) -> tuple[np.datetime64, np.datetime64] | None:
        """First and last valid times the source can serve (``None``: unknown)."""
        ...

    def tiling(self, key: CubeKey) -> Tiling | None:
        """Horizontal tiling of the cube ``key`` in storage (``None``: read as one piece)."""
        ...

    def use_cache(self, cache: RangeCache) -> None:
        """Serve the immutable bytes this source reads through ``cache`` from now on."""
        ...

    def fetch(
        self,
        key: CubeKey,
        domain: Domain,
        p_range: tuple[float, float],
        *,
        level_margin: int = 1,
        executor: Executor | None = None,
    ) -> Cube:
        """Read one cube; raise :class:`DataUnavailableError` if it does not exist."""
        ...
stats property

Transfer counters of the source's stores.

coverage()

First and last valid times the source can serve (None: unknown).

Source code in packages/barograph-met/src/baro/met/base.py 
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def coverage(self) -> tuple[np.datetime64, np.datetime64] | None:
    """First and last valid times the source can serve (``None``: unknown)."""
    ...
cube_keys(t0)

Cubes bracketing the interval [t0, t0 + time_step).

Source code in packages/barograph-met/src/baro/met/base.py 
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def cube_keys(self, t0: np.datetime64) -> tuple[CubeKey, CubeKey]:
    """Cubes bracketing the interval ``[t0, t0 + time_step)``."""
    ...
fetch(key, domain, p_range, *, level_margin=1, executor=None)

Read one cube; raise :class:DataUnavailableError if it does not exist.

Source code in packages/barograph-met/src/baro/met/base.py 
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def fetch(
    self,
    key: CubeKey,
    domain: Domain,
    p_range: tuple[float, float],
    *,
    level_margin: int = 1,
    executor: Executor | None = None,
) -> Cube:
    """Read one cube; raise :class:`DataUnavailableError` if it does not exist."""
    ...
tiling(key)

Horizontal tiling of the cube key in storage (None: read as one piece).

Source code in packages/barograph-met/src/baro/met/base.py 
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def tiling(self, key: CubeKey) -> Tiling | None:
    """Horizontal tiling of the cube ``key`` in storage (``None``: read as one piece)."""
    ...
use_cache(cache)

Serve the immutable bytes this source reads through cache from now on.

Source code in packages/barograph-met/src/baro/met/base.py 
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def use_cache(self, cache: RangeCache) -> None:
    """Serve the immutable bytes this source reads through ``cache`` from now on."""
    ...