CODEWITHSUNDEEP
pythonrandomarguments
brb
brb

Reputation: 1179

random.choice() takes two arguments?

I made a simple mistake in the following die roll function:

import random

def rollDie():
    return random.choice(1,2,3,4,5,6)

print(rollDie())

I do know that I need to pass the sequence as a list or tuple, but I was more curious about the following error message.

Traceback (most recent call last):
  File "Lecture 5.2 -- stochastic - die roll example.py", line 8, in <module>
    print(rollDie())
  File "Lecture 5.2 -- stochastic - die roll example.py", line 6, in rollDie
    return random.choice(1,2,3,4,5,6)
TypeError: choice() takes 2 positional arguments but 7 were given

The message says "choice() takes 2 positional arguments but 7 were given".

But the documentation indicates only one argument (sequence). https://docs.python.org/3/library/random.html

What is the second argument (or seventh in my case)? Is this the seed (which I have not specified so is being initialised by the clock)?

Upvotes: 2

Views: 7530

Answers (4)

PKPY
PKPY

Reputation: 1

you must give your value's in the form of a list or tuple:

List:

import random

def rollDie():
return random.choice([1,2,3,4,5,6])

print(rollDie())

Tuple:

    import random

def rollDie():
    return random.choice((1,2,3,4,5,6))

print(rollDie())

This error is because the code thinks that you give each of these numbers as an argument. the choice is an inbuilt function that randomly selects data from an iterator of data.

Upvotes: -3

user14693543
user14693543

Reputation: 7

To fix the code do this:

import random
options=[1,2,3,4,5,6]
def rollDie():
      return random.choice(options)


#whenever you use choice you must put the options in a list since choice only takes one argument.

print(rollDie())

Upvotes: -1

Shalini Baranwal
Shalini Baranwal

Reputation: 2998

As per my experience : random.sample is better solution than random.choice.

Upvotes: -1

Martijn Pieters
Martijn Pieters

Reputation: 1121744

choice() is a method on the hidden Random() instance the random module maintains. Because it is a method, it has 2 arguments: self and the iterable from which to make a choice.

From the module documentation:

The functions supplied by this module are actually bound methods of a hidden instance of the random.Random class.

and the random module source code:

def choice(self, seq):
    """Choose a random element from a non-empty sequence."""
    try:
        i = self._randbelow(len(seq))
    except ValueError:
        raise IndexError('Cannot choose from an empty sequence') from None
    return seq[i]

Upvotes: 8

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