是Python 3的random.SystemRandom.randint出错了，还是我用错了？

Question

>>> import random
>>> random.SystemRandom.randint(0, 10)
Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    random.SystemRandom.randint(0, 10)
TypeError: randint() missing 1 required positional argument: 'b'

SystemRandom is supposed to give random numbers though os.urandom , randint works like normal randrange :

>>> print(random.SystemRandom.randint.__doc__)
Return random integer in range [a, b], including both end points.

In IDLE a little popup suggestion appears when I type it it saying

`random.SystemRandom.randint(self, a, b)`

I think this is the cause. I'm not very good at using classes and understanding how they work, but the first argument seems to be being passed as self , when it should be a . I never really understand why self is used when it isn't even a keyword, and how it's supposed to all just work, but it generally does.

Am I doing this wrong, or should I report this to the Python Foundation whenever one is supposed to do such things?

Answer 1

random.SystemRandom is an class. It needs to be instantiated;

In [5]: foo = random.SystemRandom()

In [6]: foo.randint(0, 10)
Out[6]: 0

The complete docstring gives a hint;

In [12]: random.SystemRandom.randint?
Signature: random.SystemRandom.randint(self, a, b)
Docstring: Return random integer in range [a, b], including both end points.
File:      /usr/local/lib/python3.4/random.py
Type:      function

The self parameter indicates that this randint is a method of SystemRandom .

Answer 2

I think you want:

import random
r = random.SystemRandom()
print(r.randint(0, 10))

instead.

This is because you need to create an instance of the random.SystemRandom class.

However you can just as easily use the following:

import random
random.randint(0, 10)

if you don't need an OS-dependent cryptographic RNG.

Answer 3

When the error is " TypeError: randint() missing 1 required positional argument: 'b' " it's because the person writing the code probably mixed up their

random.randint()

and their

random.choice()

Hope I helped :D

Answer 4

May be while using Jupyter notebook you got an error like this,Just pass the missing positional argument like randint(1,1000) it will generate a random number bw 1 to 1000.Or Re-run the random module then try to execute both will work fine