Method map_blocks

xarray/core/dataarray.py:5668–5774

Apply a function to each block of this DataArray. .. warning:: This method is experimental and its signature may change. Parameters ---------- func : callable User-provided function that accepts a DataArray as its first p

(
        self,
        func: Callable[..., T_Xarray],
        args: Sequence[Any] = (),
        kwargs: Mapping[str, Any] | None = None,
        template: DataArray | Dataset | None = None,
    )

        return unify_chunks(self)[0]

    def map_blocks(
        self,
        func: Callable[..., T_Xarray],
        args: Sequence[Any] = (),
        kwargs: Mapping[str, Any] | None = None,
        template: DataArray | Dataset | None = None,
    ) -> T_Xarray:
        """
        Apply a function to each block of this DataArray.

        .. warning::
            This method is experimental and its signature may change.

        Parameters
        ----------
        func : callable
            User-provided function that accepts a DataArray as its first
            parameter. The function will receive a subset or 'block' of this DataArray (see below),
            corresponding to one chunk along each chunked dimension. ``func`` will be
            executed as ``func(subset_dataarray, *subset_args, **kwargs)``.

            This function must return either a single DataArray or a single Dataset.

            This function cannot add a new chunked dimension.
        args : sequence
            Passed to func after unpacking and subsetting any xarray objects by blocks.
            xarray objects in args must be aligned with this object, otherwise an error is raised.
        kwargs : mapping
            Passed verbatim to func after unpacking. xarray objects, if any, will not be
            subset to blocks. Passing dask collections in kwargs is not allowed.
        template : DataArray or Dataset, optional
            xarray object representing the final result after compute is called. If not provided,
            the function will be first run on mocked-up data, that looks like this object but
            has sizes 0, to determine properties of the returned object such as dtype,
            variable names, attributes, new dimensions and new indexes (if any).
            ``template`` must be provided if the function changes the size of existing dimensions.
            When provided, ``attrs`` on variables in `template` are copied over to the result. Any
            ``attrs`` set by ``func`` will be ignored.

        Returns
        -------
        A single DataArray or Dataset with dask backend, reassembled from the outputs of the
        function.

        Notes
        -----
        This function is designed for when ``func`` needs to manipulate a whole xarray object
        subset to each block. Each block is loaded into memory. In the more common case where
        ``func`` can work on numpy arrays, it is recommended to use ``apply_ufunc``.

        If none of the variables in this object is backed by dask arrays, calling this function is
        equivalent to calling ``func(obj, *args, **kwargs)``.

        See Also
        --------
        :func:`dask.array.map_blocks <dask.array.map_blocks>`
        :func:`xarray.apply_ufunc <xarray.apply_ufunc>`
        :func:`xarray.Dataset.map_blocks <xarray.Dataset.map_blocks>`