npy文件格式记录在numpy的

https://github.com/numpy/numpy/blob/master/doc/neps/npy-format.rst中.

例如,代码

>>> dt=numpy.dtype([('outer','(3,)

... ('outer2',[('inner','(10,)

>>> a=numpy.array([((1,2,3),((10,11,12,13,14,15,16,17,18,19),3.14)),

... ((4,5,6),((-1,-2,-3,-4,-5,-6,-7,-8,-9,-20),6.28))],dt)

>>> numpy.save('1.npy', a)

导致文件：

93 4E 55 4D 50 59 magic ("\x93NUMPY")

01 major version (1)

00 minor version (0)

96 00 HEADER_LEN (0x0096 = 150)

7B 27 64 65 73 63 72 27

3A 20 5B 28 27 6F 75 74

65 72 27 2C 20 27 3C 69

34 27 2C 20 28 33 2C 29

29 2C 20 28 27 6F 75 74

65 72 32 27 2C 20 5B 28

27 69 6E 6E 65 72 27 2C

20 27 3C 69 34 27 2C 20

28 31 30 2C 29 29 2C 20

28 27 69 6E 6E 65 72 32 Header, describing the data structure

27 2C 20 27 3C 66 38 27 "{'descr': [('outer', '

29 5D 29 5D 2C 20 27 66 ('outer2', [

6F 72 74 72 61 6E 5F 6F ('inner', '

72 64 65 72 27 3A 20 46 ('inner2', '

61 6C 73 65 2C 20 27 73 )],

68 61 70 65 27 3A 20 28 'fortran_order': False,

32 2C 29 2C 20 7D 20 20 'shape': (2,), }"

20 20 20 20 20 20 20 20

20 20 20 20 20 0A

01 00 00 00 02 00 00 00 03 00 00 00 (1,2,3)

0A 00 00 00 0B 00 00 00 0C 00 00 00

0D 00 00 00 0E 00 00 00 0F 00 00 00

10 00 00 00 11 00 00 00 12 00 00 00

13 00 00 00 (10,11,12,13,14,15,16,17,18,19)

1F 85 EB 51 B8 1E 09 40 3.14

04 00 00 00 05 00 00 00 06 00 00 00 (4,5,6)

FF FF FF FF FE FF FF FF FD FF FF FF

FC FF FF FF FB FF FF FF FA FF FF FF

F9 FF FF FF F8 FF FF FF F7 FF FF FF

EC FF FF FF (-1,-2,-3,-4,-5,-6,-7,-8,-9,-20)

1F 85 EB 51 B8 1E 19 40 6.28