Sort Matrices by Mean Value Obtained (OpenCV, Python and Numpy)

[scidam]

You can use numpy.argsort to sort by mean values,
look at the following example (for red channel):

r_inds = np.argsort(np.array(r_submatrices).reshape(-1, len(r_submatrices)).mean(axis=0))[::-1]
np.array(r_submatrices)[r_inds]  # sorted array