如何从 Python 生成唯一的 64 位整数？

Question

I need to generate unique 64 bits integers from Python. I've checked out the UUID module . But the UUID it generates are 128 bits integers. So that wouldn't work.

Do you know of any way to generate 64 bits unique integers within Python? Thanks.

Answer 1

just mask the 128bit int

>>> import uuid
>>> uuid.uuid4().int & (1<<64)-1
9518405196747027403L
>>> uuid.uuid4().int & (1<<64)-1
12558137269921983654L

These are more or less random, so you have a tiny chance of a collision

Perhaps the first 64 bits of uuid1 is safer to use

>>> uuid.uuid1().int>>64
9392468011745350111L
>>> uuid.uuid1().int>>64
9407757923520418271L
>>> uuid.uuid1().int>>64
9418928317413528031L

These are largely based on the clock, so much less random but the uniqueness is better

Answer 2

64 bits unique

What's wrong with counting? A simple counter will create unique values. This is the simplest and it's easy to be sure you won't repeat a value.

Or, if counting isn't good enough, try this.

>>> import random
>>> random.getrandbits(64)
5316191164430650570L

Depending on how you seed and use your random number generator, that should be unique.

You can -- of course -- do this incorrectly and get a repeating sequence of random numbers. Great care must be taken with how you handle seeds for a program that starts and stops.

Answer 3

A 64-bit random number from the OS's random number generator rather than a PRNG:

>>> from struct import unpack; from os import urandom
>>> unpack("!Q", urandom(8))[0]
12494068718269657783L

Answer 4

You can use uuid4() which generates a single random 128-bit integer UUID. We have to 'binary right shift' ( >> ) each 128-bit integer generated by 64-bit (ie 128 - (128 - 64) ).

from uuid import uuid4

bit_size = 64
sized_unique_id = uuid4().int >> bit_size
print(sized_unique_id)

Answer 5

Why not try this?

import uuid
  
id = uuid.uuid1()
  
# Representations of uuid1()

print (repr(id.bytes)) # k\x10\xa1n\x02\xe7\x11\xe8\xaeY\x00\x16>\x99\x0b\xdb

print (id.int)         # 142313746482664936587190810281013480411  

print (id.hex)         # 6b10a16e02e711e8ae5900163e990bdb