mxnet.np.trace¶
-
trace
(a, offset=0, axis1=0, axis2=1, out=None)¶ Return the sum along diagonals of the array. If a is 2-D, the sum along its diagonal with the given offset is returned, i.e., the sum of elements
a[i,i+offset]
for all i. If a has more than two dimensions, then the axes specified by axis1 and axis2 are used to determine the 2-D sub-arrays whose traces are returned. The shape of the resulting array is the same as that of a with axis1 and axis2 removed.- Parameters
a (ndarray) – Input array, from which the diagonals are taken.
offset (int, optional) – Offset of the diagonal from the main diagonal. Can be both positive and negative. Defaults to 0.
axis2 (axis1,) – Axes to be used as the first and second axis of the 2-D sub-arrays from which the diagonals should be taken. Defaults are the first two axes of a.
out (ndarray, optional) – Array into which the output is placed. It must be of the right shape and right type to hold the output.
- Returns
sum_along_diagonals – If a is 2-D, the sum along the diagonal is returned. If a has larger dimensions, then an array of sums along diagonals is returned.
- Return type
ndarray
Examples
>>> a = np.array([[1, 0, 0], [0, 1, 0], [0, 0, 1]]) >>> np.trace(a) array(3.) >>> a = np.arange(8).reshape((2, 2, 2)) >>> np.trace(a) array([6., 8.]) >>> a = np.arange(24).reshape((2, 2, 2, 3)) >>> np.trace(a).shape (2, 3)