random.choice() 需要两个参数? [英] random.choice() takes two arguments?

问题描述

我在以下掷骰函数中犯了一个简单的错误:

随机导入def rollDie():返回 random.choice(1,2,3,4,5,6)打印(rollDie())

我知道我需要将序列作为列表或元组传递，但我对以下错误消息更好奇.

回溯(最近一次调用最后一次):文件Lecture 5.2 -- stochastic - die roll example.py"，第 8 行，在 <module> 中.打印(rollDie())文件Lecture 5.2 -- stochastic - die roll example.py"，第 6 行，在 rollDie返回 random.choice(1,2,3,4,5,6)类型错误:choice() 需要 2 个位置参数，但给出了 7 个

消息说choice() 需要 2 个位置参数，但给出了 7 个".

但是文档只说明了一个参数(序列).https://docs.python.org/3/library/random.html

第二个参数是什么(在我的例子中是第七个参数)?这是种子吗(我没有指定，所以正在由时钟初始化)?

解决方案

choice() 是隐藏的 Random() 实例 random 模块维护.因为它是一个方法，所以它有 2 个参数:self 和可从中做出选择的迭代.

来自模块文档:

<块引用>

该模块提供的函数实际上是 random.Random 类的隐藏实例的绑定方法.

和 random模块源代码:

<块引用>

def 选择(自我，序列):"""从非空序列中随机选择一个元素."""尝试:i = self._randbelow(len(seq))除了值错误:从无引发 IndexError('不能从空序列中选择')返回序列[i]

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)?

解决方案

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]

这篇关于random.choice() 需要两个参数?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！