python - numpy nonzero() returns indexes sorted by row index? -

as in matlab, nonzeros return indexes ordered columns(http://www.mathworks.com/help/matlab/ref/nonzeros.html). in numpy, seems returned indexes ordered rows (for 2d matrix). not articulated in doc (http://docs.scipy.org/doc/numpy/reference/generated/numpy.nonzero.html). safe assume that?

an example:

test = np.array([[0,2], [3,0]]) test[test.nonzero()] 

gives array([2, 3]) instead of array([3, 2])

there following comment on c source code of pyarray_nonzero, c function handles calls nonzero:

/*numpy_api  * nonzero  *  * todo: in numpy 2.0, should make iteration order parameter.  */ npy_no_export pyobject * pyarray_nonzero(pyarrayobject *self) 

the iteration order is hardcoded c-order, i.e. last index varies fastest, i.e. sorted rows, columns, 2d case. given comment, safe assume that, if ever changes, providing new functionality defaults current behavior.