How can I generate a unique ID in Python

Question

I need to generate a unique ID based on a random value

User · Answer

Maybe the uuid module

User · Answer

Maybe this work for u  str uuid uuid4   fields -1    5

User · Answer

This will work very quickly but will not generate random values but monotonously increasing ones  for a given thread       import threading   uid   threading local   def genuid        if getattr  uid   uid   None  is None           uid tid   threading current thread   ident          uid uid   0      uid uid    1     return   uid tid   uid uid    It is thread safe and working with tuples may have benefit as opposed to strings  shorter if anything   If you do not need thread safety feel free remove the threading bits  in stead of threading local  use object   and remove tid altogether     Hope that helps

User · Answer

Perhaps uuid uuid4   might do the job  See uuid for more information

User · Answer

here you can find an implementation    def   uniqueid                    generate unique id with length 17 to 21        ensure uniqueness even with daylight savings events  clocks adjusted one-hour backward          if you generate 1 million ids per second during 100 years  you will generate        2 25  approx sec per year    10  6  1 million id per sec    100  years    5   10  9 unique ids         with 17 digits  radix 16  id  you can represent 16  17   295147905179352825856 ids  around 2 9   10  20         In fact  as we need far less than that  we agree that the format used to represent id  seed   timestamp reversed        do not cover all numbers that could be represented with 35 digits  radix 16          if you generate 1 million id per second with this algorithm  it will increase the seed by less than 2  12 per hour       so if a DST occurs and backward one hour  we need to ensure to generate unique id for twice times for the same period        the seed must be at least 1 to 2  13 range  if we want to ensure uniqueness for two hours  100  contingency   we need        a seed for 1 to 2  14 range  that s what we have with this algorithm  You have to increment seed range bits if you       move your machine by airplane to another time zone or if you have a glucky wallet and use a computer that can generate       more than 1 million ids per second         one word about predictability   This algorithm is absolutely NOT designed to generate unpredictable unique id        you can add a sha-1 or sha-256 digest step at the end of this algorithm but you will loose uniqueness and enter to collision probability world        hash algorithms ensure that for same id generated here  you will have the same hash but for two differents id  a pair of ids   it is       possible to have the same hash with a very little probability  You would certainly take an option on a bijective function that maps       35 digits  or more  number to 35 digits  or more  number based on cipher block and secret key  read paper on breaking PRNG algorithms        in order to be convinced that problems could occur as soon as you use random library           1 million id per second      on a Intel R  Core TM 2 CPU 6400   2 13GHz  you get           gt  gt  gt  timeit timeit uniqueid number 40000        1 0114529132843018        an average of 40000 id second             mynow datetime now     sft datetime strftime       store old datetime each time in order to check if we generate during same microsecond  glucky wallet          or if daylight savings event occurs  when clocks are adjusted backward   rarely detected at this level      old time mynow     fake init - on very speed machine it could increase your seed to seed   1    but we have our contingency          manage seed     seed range bits 14   max range for seed     seed max value 2  seed range bits - 1   seed could not exceed 2  nbbits - 1       get random seed     seed random getrandbits seed range bits      current seed str seed        producing new ids     while True            get current time          current time mynow           if current time  lt   old time                previous id generated in the same microsecond or Daylight saving time event occurs  when clocks are adjusted backward              seed   max 1  seed   1    seed max value              current seed str seed            generate new id  concatenate seed and timestamp as numbers           newid hex int    join  sft current time   f S M H d m Y   current seed     2 -1          newid int    join  sft current time   f S M H d m Y   current seed              save current time         old time current time           return a new id         yield newid      you get a new id for each call of uniqueid       uniqueid   uniqueid     next  import unittest class UniqueIdTest unittest TestCase       def testGen self           for   in range 3               m  uniqueid   for   in range 10               self assertEqual len m  len set m    duplicates found       hope it helps

User · Answer

unique and random are mutually exclusive   perhaps you want this   import random def uniqueid        seed   random getrandbits 32      while True         yield seed        seed    1   Usage   unique sequence   uniqueid   id1   next unique sequence  id2   next unique sequence  id3   next unique sequence  ids   list itertools islice unique sequence  1000     no two returned id is the same  Unique  and this is based on a randomized seed value

User · Answer

import time import random import socket import hashlib  def guid   args                Generates a universally unique ID      Any arguments only create more randomness              t   long  time time     1000       r   long  random random   100000000000000000L       try          a   socket gethostbyname  socket gethostname         except            if we can t get a network address  just imagine one         a   random random   100000000000000000L     data   str t      str r      str a      str args      data   hashlib md5 data  hexdigest        return data

User · Answer

You might want Python s UUID functions   21 15  uuid     UUID objects according to RFC 4122  eg   import uuid print uuid uuid4        7d529dd4-548b-4258-aa8e-23e34dc8d43d

[python] How can I generate a unique ID in Python?

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