具有大写字母和数字的随机字符串生成 [英] Random string generation with upper case letters and digits

问题描述

我想生成一个大小为N的字符串.

I want to generate a string of size N.

它应该由数字和大写英文字母组成，例如:

It should be made up of numbers and uppercase English letters such as:

• 6U1S75
• 4Z4UKK
• U911K4

如何以 pythonic 的方式实现这一目标?

How can I achieve this in a pythonic way?

推荐答案

答案在一行:

''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(N))

甚至更短，使用 random.choices() :

or even shorter starting with Python 3.6 using random.choices():

''.join(random.choices(string.ascii_uppercase + string.digits, k=N))

加密方式更安全的版本；参见 https://stackoverflow.com/a/23728630/2213647 :

A cryptographically more secure version; see https://stackoverflow.com/a/23728630/2213647:

''.join(random.SystemRandom().choice(string.ascii_uppercase + string.digits) for _ in range(N))

详细信息，具有清除函数以供进一步重用:

>>> import string
>>> import random
>>> def id_generator(size=6, chars=string.ascii_uppercase + string.digits):
...    return ''.join(random.choice(chars) for _ in range(size))
...
>>> id_generator()
'G5G74W'
>>> id_generator(3, "6793YUIO")
'Y3U'

它如何工作?

我们导入string(一个包含常见ASCII字符序列的模块)和random(一个用于处理随机生成的模块).

We import string, a module that contains sequences of common ASCII characters, and random, a module that deals with random generation.

string.ascii_uppercase + string.digits只是连接表示大写ASCII字符和数字的字符列表:

string.ascii_uppercase + string.digits just concatenates the list of characters representing uppercase ASCII chars and digits:

>>> string.ascii_uppercase
'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
>>> string.digits
'0123456789'
>>> string.ascii_uppercase + string.digits
'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'

然后，我们使用列表推导来创建"n"个元素的列表:

Then we use a list comprehension to create a list of 'n' elements:

>>> range(4) # range create a list of 'n' numbers
[0, 1, 2, 3]
>>> ['elem' for _ in range(4)] # we use range to create 4 times 'elem'
['elem', 'elem', 'elem', 'elem']

在上面的示例中，我们使用[创建列表，但是我们不在id_generator函数中，因此Python不会在内存中创建列表，而是通过以下方式即时生成元素:一个(有关更多信息，请此处).

In the example above, we use [ to create the list, but we don't in the id_generator function so Python doesn't create the list in memory, but generates the elements on the fly, one by one (more about this here).

我们将要求Python从字符串序列中选择一个随机字符，而不是创建字符串n乘以elem:

Instead of asking to create 'n' times the string elem, we will ask Python to create 'n' times a random character, picked from a sequence of characters:

>>> random.choice("abcde")
'a'
>>> random.choice("abcde")
'd'
>>> random.choice("abcde")
'b'

因此，random.choice(chars) for _ in range(size)实际上是在创建size字符序列.从chars:

Therefore random.choice(chars) for _ in range(size) really is creating a sequence of size characters. Characters that are randomly picked from chars:

>>> [random.choice('abcde') for _ in range(3)]
['a', 'b', 'b']
>>> [random.choice('abcde') for _ in range(3)]
['e', 'b', 'e']
>>> [random.choice('abcde') for _ in range(3)]
['d', 'a', 'c']

然后我们将它们与一个空字符串连接起来，以便该序列成为一个字符串:

Then we just join them with an empty string so the sequence becomes a string:

>>> ''.join(['a', 'b', 'b'])
'abb'
>>> [random.choice('abcde') for _ in range(3)]
['d', 'c', 'b']
>>> ''.join(random.choice('abcde') for _ in range(3))
'dac'

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