HardQuestions HardQuestions - 2 months ago 9
Python Question

Generate password in python

I'dl like to generate some alphanumeric passwords in python. Some possible ways are:

import string
from random import sample, choice
chars = string.letters + string.digits
length = 8
''.join(sample(chars,length)) # way 1
''.join([choice(chars) for i in range(length)]) # way 2


But I don't like both because:


  • way 1 only unique chars selected and you can't generate passwords where length > len(chars)

  • way 2 we have
    i
    variable unused and I can't find good way how to avoid that



So, any other good options?

P.S. So here we are with some testing with
timeit
for 100000 iterations:

''.join(sample(chars,length)) # way 1; 2.5 seconds
''.join([choice(chars) for i in range(length)]) # way 2; 1.8 seconds (optimizer helps?)
''.join(choice(chars) for _ in range(length)) # way 3; 1.8 seconds
''.join(choice(chars) for _ in xrange(length)) # way 4; 1.73 seconds
''.join(map(lambda x: random.choice(chars), range(length))) # way 5; 2.27 seconds


So, the winner is
''.join(choice(chars) for _ in xrange(length))
.

Answer

Option #2 seems quite reasonable except you could add a couple of improvements:

''.join(choice(chars) for _ in range(length))          # in py2k use xrange

_ is a conventional "I don't care what is in there" variable. And you don't need list comprehension there, generator expression works just fine for str.join. It is also not clear what "slow" means, if it is the only correct way.

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