bagof.hints.dask

Hints for [dask.array][] arrays.

dask reuses numpy's data types, so this module only defines the array type itself; dtype, DTypeLike and the protocols are re-exported from bagof.hints.numpy and bagof.hints.array.

Note

This module is not imported by bagof.hints, so that importing the package never imports dask. It stays importable when dask is absent, in which case Array degrades to an empty generic stub.

Attributes

DTypeLike `module-attribute`

DTypeLike = npt.DTypeLike

See numpy.typing.DTypeLike.

NDArray `module-attribute`

NDArray = Array[tx.Tuple[int, ...], dtype[DTYPE]]

A dask array of arbitrary shape, parametrised by its data type.

Classes

ArrayNamespace

Bases: Protocol

An object that implements the Python array API standard.

This is the modern, portable alternative to ArrayProtocol: rather than converting to a numpy array, it exposes the namespace of the library that owns the object, so that library-agnostic code can call xp.mean(x) without knowing which library x came from.

See https://data-apis.org/array-api/latest/.

Tip

Prefer this over ArrayProtocol when the goal is to stay in the originating library (and off the host, for GPU arrays), since __array__ forces a conversion to numpy.

ArrayProtocol

Bases: Protocol

An object that can be converted to an array.

This is the oldest and most widely implemented array hook: numpy, cupy, dask, torch and pandas objects all provide it, so a single structural check covers them all. See numpy.ndarray.__array__.

Example

>>> import numpy as np
>>> from bagof.hints.array import ArrayProtocol
>>> isinstance(np.array([1, 2, 3]), ArrayProtocol)
True
>>> isinstance([1, 2, 3], ArrayProtocol)
False

DTypeProtocol

Bases: Protocol[DTYPE]

An object that carries a data type.

Any array, and any numpy.dtype-like object, satisfies this. The parameter is the type of the dtype attribute itself; it is invariant, because the protocol declares a mutable attribute rather than a read-only property.

dtype

Bases: Generic[DTYPE]

A generic stub for numpy.dtype.

Array

Bases: Generic[SHAPE, DTYPE]

A generic stub for dask.array.Array.