xarray.dot¶

xarray.dot(*arrays, dims=None, **kwargs)

Generalized dot product for xarray objects. Like np.einsum, but provides a simpler interface based on array dimensions.

Parameters
• arrays (DataArray (or Variable) objects) – Arrays to compute.

• dims (str or tuple of strings, optional) – Which dimensions to sum over. If not speciified, then all the common dimensions are summed over.

• **kwargs (dict) – Additional keyword arguments passed to numpy.einsum or dask.array.einsum

Returns

dot

Return type

DataArray

Examples

>>> import numpy as np
>>> import xarray as xp
>>> da_a = xr.DataArray(np.arange(3 * 2).reshape(3, 2), dims=['a', 'b'])
>>> da_b = xr.DataArray(np.arange(3 * 2 * 2).reshape(3, 2, 2),
...                     dims=['a', 'b', 'c'])
>>> da_c = xr.DataArray(np.arange(2 * 3).reshape(2, 3), dims=['c', 'd'])

>>> da_a
<xarray.DataArray (a: 3, b: 2)>
array([[0, 1],
[2, 3],
[4, 5]])
Dimensions without coordinates: a, b

>>> da_b
<xarray.DataArray (a: 3, b: 2, c: 2)>
array([[[ 0,  1],
[ 2,  3]],
[[ 4,  5],
[ 6,  7]],
[[ 8,  9],
[10, 11]]])
Dimensions without coordinates: a, b, c

>>> da_c
<xarray.DataArray (c: 2, d: 3)>
array([[0, 1, 2],
[3, 4, 5]])
Dimensions without coordinates: c, d

>>> xr.dot(da_a, da_b, dims=['a', 'b'])
<xarray.DataArray (c: 2)>
array([110, 125])
Dimensions without coordinates: c

>>> xr.dot(da_a, da_b, dims=['a'])
<xarray.DataArray (b: 2, c: 2)>
array([[40, 46],
[70, 79]])
Dimensions without coordinates: b, c

>>> xr.dot(da_a, da_b, da_c, dims=['b', 'c'])
<xarray.DataArray (a: 3, d: 3)>
array([[  9,  14,  19],
[ 93, 150, 207],
[273, 446, 619]])
Dimensions without coordinates: a, d