diff options
Diffstat (limited to 'numpy/add_newdocs.py')
| -rw-r--r-- | numpy/add_newdocs.py | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/numpy/add_newdocs.py b/numpy/add_newdocs.py index 51826c5ff..f51860240 100644 --- a/numpy/add_newdocs.py +++ b/numpy/add_newdocs.py @@ -1540,13 +1540,16 @@ add_newdoc('numpy.core', 'einsum', ``np.einsum('ji', a)`` takes its transpose. The output can be controlled by specifying output subscript labels - as well. This specifies the label order, and allows summing to be - disallowed or forced when desired. The call ``np.einsum('i->', a)`` - is equivalent to ``np.sum(a, axis=-1)``, and - ``np.einsum('ii->i', a)`` is equivalent to ``np.diag(a)``. - - It is also possible to control how broadcasting occurs using - an ellipsis. To take the trace along the first and last axes, + as well. This specifies the label order, and allows summing to + be disallowed or forced when desired. The call ``np.einsum('i->', a)`` + is like ``np.sum(a, axis=-1)``, and ``np.einsum('ii->i', a)`` + is like ``np.diag(a)``. The difference is that ``einsum`` does not + allow broadcasting by default. + + To enable and control broadcasting, use an ellipsis. Default + NumPy-style broadcasting is done by adding an ellipsis + to the left of each term, like ``np.einsum('...ii->...i', a)``. + To take the trace along the first and last axes, you can do ``np.einsum('i...i', a)``, or to do a matrix-matrix product with the left-most indices instead of rightmost, you can do ``np.einsum('ij...,jk...->ik...', a, b)``. @@ -1624,7 +1627,7 @@ add_newdoc('numpy.core', 'einsum', [1, 4], [2, 5]]) - >>> np.einsum(',', 3, c) + >>> np.einsum('..., ...', 3, c) array([[ 0, 3, 6], [ 9, 12, 15]]) >>> np.multiply(3, c) @@ -1643,7 +1646,7 @@ add_newdoc('numpy.core', 'einsum', array([[0, 1, 2, 3, 4], [0, 2, 4, 6, 8]]) - >>> np.einsum('i...->', a) + >>> np.einsum('i...->...', a) array([50, 55, 60, 65, 70]) >>> np.sum(a, axis=0) array([50, 55, 60, 65, 70]) |