import numpy as np

ridership = np.array([
    [   0,    0,    2,    5,    0],
    [1478, 3877, 3674, 2328, 2539],
    [1613, 4088, 3991, 6461, 2691],
    [1560, 3392, 3826, 4787, 2613],
    [1608, 4802, 3932, 4477, 2705],
    [1576, 3933, 3909, 4979, 2685],
    [  95,  229,  255,  496,  201],
    [   2,    0,    1,   27,    0],
    [1438, 3785, 3589, 4174, 2215],
    [1342, 4043, 4009, 4665, 3033]
])
 

    print ridership[1, 3]

2328

  print ridership[1:3, 3:5]

[[2328 2539]
 [6461 2691]]

 print ridership[1, :]

[1478 3877 3674 2328 2539]

 print ridership[0, :] + ridership[1, :]

[1478 3877 3676 2333 2539]

  print ridership[:, 0] + ridership[:, 1]

[   0 5355 5701 4952 6410 5509  324    2 5223 5385]

    a = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
    b = np.array([[1, 1, 1], [2, 2, 2], [3, 3, 3]])
    print a + b
 

[[ 2  3  4]
 [ 6  7  8]
 [10 11 12]]

    a = np.array([
        [1, 2, 3],
        [4, 5, 6],
        [7, 8, 9]
    ])
    
    print a.sum()
    print a.sum(axis=0)
    print a.sum(axis=1)

45
[12 15 18]
[ 6 15 24]