Function blockwise

dask/array/_array_expr/_collection.py:694–875

Tensor operation: Generalized inner and outer products A broad class of blocked algorithms and patterns can be specified with a concise multi-index notation. The ``blockwise`` function applies an in-memory function across multiple blocks of multiple inputs in a variety of ways. Man

(
    func,
    out_ind,
    *args,
    name=None,
    token=None,
    dtype=None,
    adjust_chunks=None,
    new_axes=None,
    align_arrays=True,
    concatenate=None,
    meta=None,
    **kwargs,
)

def blockwise(
    func,
    out_ind,
    *args,
    name=None,
    token=None,
    dtype=None,
    adjust_chunks=None,
    new_axes=None,
    align_arrays=True,
    concatenate=None,
    meta=None,
    **kwargs,
):
    """Tensor operation: Generalized inner and outer products

    A broad class of blocked algorithms and patterns can be specified with a
    concise multi-index notation.  The ``blockwise`` function applies an in-memory
    function across multiple blocks of multiple inputs in a variety of ways.
    Many dask.array operations are special cases of blockwise including
    elementwise, broadcasting, reductions, tensordot, and transpose.

    Parameters
    ----------
    func : callable
        Function to apply to individual tuples of blocks
    out_ind : iterable
        Block pattern of the output, something like 'ijk' or (1, 2, 3)
    *args : sequence of Array, index pairs
        You may also pass literal arguments, accompanied by None index
        e.g. (x, 'ij', y, 'jk', z, 'i', some_literal, None)
    **kwargs : dict
        Extra keyword arguments to pass to function
    dtype : np.dtype
        Datatype of resulting array.
    concatenate : bool, keyword only
        If true concatenate arrays along dummy indices, else provide lists
    adjust_chunks : dict
        Dictionary mapping index to function to be applied to chunk sizes
    new_axes : dict, keyword only
        New indexes and their dimension lengths
    align_arrays: bool
        Whether or not to align chunks along equally sized dimensions when
        multiple arrays are provided.  This allows for larger chunks in some
        arrays to be broken into smaller ones that match chunk sizes in other
        arrays such that they are compatible for block function mapping. If
        this is false, then an error will be thrown if arrays do not already
        have the same number of blocks in each dimension.

    Examples
    --------
    2D embarrassingly parallel operation from two arrays, x, and y.

    >>> import operator, numpy as np, dask.array as da
    >>> x = da.from_array([[1, 2],
    ...                    [3, 4]], chunks=(1, 2))
    >>> y = da.from_array([[10, 20],
    ...                    [0, 0]])