The uuid4() function of Python’s module uuid
generates a random UUID, and seems to generate a different one every time:
In [1]: import uuid In [2]: uuid.uuid4() Out[2]: UUID('f6c9ad6c-eea0-4049-a7c5-56253bc3e9c0') In [3]: uuid.uuid4() Out[3]: UUID('2fc1b6f9-9052-4564-9be0-777e790af58f')
I would like to be able to generate the same random UUID every time I run a script – that is, I’d like to seed the random generator in uuid4()
. Is there a way to do this? (Or achieve this by some other means)?
What I’ve tried so far
I’ve to generate a UUID using the uuid.UUID()
method with a random 128-bit integer (from a seeded instance of random.Random()
) as input:
import uuid import random rd = random.Random() rd.seed(0) uuid.UUID(rd.getrandbits(128))
However, UUID()
seems not to accept this as input:
Traceback (most recent call last): File "uuid_gen_seed.py", line 6, in <module> uuid.UUID(rd.getrandbits(128)) File "/usr/lib/python2.7/uuid.py", line 133, in __init__ hex = hex.replace('urn:', '').replace('uuid:', '') AttributeError: 'long' object has no attribute 'replace'
Any other suggestions?
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Answer
Almost there:
uuid.UUID(int=rd.getrandbits(128))
This was determined with the help of help
:
>>> help(uuid.UUID.__init__) Help on method __init__ in module uuid: __init__(self, hex=None, bytes=None, bytes_le=None, fields=None, int=None, version=None) unbound uuid.UUID method Create a UUID from either a string of 32 hexadecimal digits, a string of 16 bytes as the 'bytes' argument, a string of 16 bytes in little-endian order as the 'bytes_le' argument, a tuple of six integers (32-bit time_low, 16-bit time_mid, 16-bit time_hi_version, 8-bit clock_seq_hi_variant, 8-bit clock_seq_low, 48-bit node) as the 'fields' argument, or a single 128-bit integer as the 'int' argument. When a string of hex digits is given, curly braces, hyphens, and a URN prefix are all optional. For example, these expressions all yield the same UUID: UUID('{12345678-1234-5678-1234-567812345678}') UUID('12345678123456781234567812345678') UUID('urn:uuid:12345678-1234-5678-1234-567812345678') UUID(bytes='x12x34x56x78'*4) UUID(bytes_le='x78x56x34x12x34x12x78x56' + 'x12x34x56x78x12x34x56x78') UUID(fields=(0x12345678, 0x1234, 0x5678, 0x12, 0x34, 0x567812345678)) UUID(int=0x12345678123456781234567812345678) Exactly one of 'hex', 'bytes', 'bytes_le', 'fields', or 'int' must be given. The 'version' argument is optional; if given, the resulting UUID will have its variant and version set according to RFC 4122, overriding the given 'hex', 'bytes', 'bytes_le', 'fields', or 'int'.