numpy.trace(a, offset=0, axis1=0, axis2=1, dtype=None, out=None)
[source]
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 : array_like 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. axis1, axis2 : int, optional 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 dtype : dtype, optional Determines the data-type of the returned array and of the accumulator where the elements are summed. If dtype has the value None and out : ndarray, optional Array into which the output is placed. Its type is preserved and it must be of the right shape to hold the output. |
---|---|
Returns: |
sum_along_diagonals : ndarray If |
>>> np.trace(np.eye(3)) 3.0 >>> 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)
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https://docs.scipy.org/doc/numpy-1.13.0/reference/generated/numpy.trace.html