u[np.argmax(np.apply_along_axis(np.bincount, axis, indices.reshape(arr.
    shape), None, np.max(indices) + 1), axis=axis)]
array([[0, 1, 2, 3, 4], [5, 6, 7, 8, 9], [10, 11, 12, 13, 14], [15, 16, 17,
    18, 19]])
How to find most frequent values in numpy ndarray?