>>> dt = np.dtype('<u4,<i2,<i2,<i2,<i2,<i2,<i2,<i2,<i2,u1,u1,u1,u1')
>>> file_data = np.fromfile(os.path.join(folder,f), dtype=dt)

>>> type(file_data)
<type 'numpy.ndarray'>

>>> file_data
array([(3571121L, -54, 103, 1, 50, 48, 469, 588, -10, 0, 102, 0, 0),
   (3571122L, -78, 20, 25, 45, 44, 495, 397, -211, 0, 102, 0, 0),
   (3571123L, -69, -48, 23, 60, 19, 317, -26, -151, 0, 102, 0, 0), ...,
   (3691138L, -53, 52, -2, -11, 76, 988, 288, -101, 1, 102, 0, 0),
   (3691139L, -11, 21, -27, 25, 47, 986, 253, 176, 1, 102, 0, 0),
   (3691140L, -30, -19, -63, 59, 12, 729, 23, 302, 1, 102, 0, 0)],
  dtype=[('f0', '<u4'), ('f1', '<i2'), ('f2', '<i2'), ... , ('f12', '|u1')])

>>> file_data[0]
(3571121L, -54, 103, 1, 50, 48, 469, 588, -10, 0, 102, 0, 0)

>>> file_data[0][0]
3571121

>>> len(file_data)
120020

>>> file_data[:,0]

IndexError: invalid index.

>>> a = np.array([(1,2,3),(4,5,6)])
>>> a[:,0]
array([1, 4])

file_data[0][0]

file_data[0,0]