arr = np.array([[1,2,3],[4,5,6],[7,8,9]])
array([[0, 1, 2],
       [3, 4, 5],
       [6, 7, 8]])

(0.5, 0.5)
(0.5, 1.5)
(0.5, 2.5)
(1.5, 0.5)
(1.5, 1.5)
(1.5, 2.5)
(2.5, 0.5)
(2.5, 1.5)
(2.5, 2.5)

for row in range(arr.shape[0]):
    for col in range(arr.shape[1]):
        print (row + 0.5, col + 0.5)

import numpy as np

arr = np.arange(3 * 3).reshape(3, 3)

grid = np.mgrid[:arr.shape[0], :arr.shape[1]] + 0.5

print(grid.reshape(2, grid.size // 2).T)