从给定字符生成固定长度随机字符串的内置方法 [英] Built-in method to Generate Random Strings of Fixed Length From Given Characters

问题描述

这就是我的问题:我需要创建一个 50 个字符长的随机字符串，由 1s 和 0s 组成.

This is what my problem is: I need to make a random string 50 characters long, made up of 1s and 0s.

我知道如何解决这个问题，甚至有一个单线.我也在 SO 上寻找解决这个问题的各种解决方案，只是为了找回我已经知道的(1、2 等).但我真正想要的是最 Pythonic 的方式来做到这一点.

I know how to solve this problem, and even have a one-liner for it. I have also looked for various solutions to this problem on SO, only to get back what I already know(1, 2, etc). But what I really want is the most Pythonic way of doing this.

目前，我倾向于 ''.join(( random.choice([0,1]) for i in xrange(50) ))

有没有更pythonic的方法来做到这一点?是否有一个内置的可以做这样的事情，也许在 itertools 中?

Is there a more pythonic way of doing this? Is there a built-in that does something like this, perhaps in itertools?

推荐答案

对于 Python2.7 或更高版本:

For Python2.7 or better:

In [83]: import random

In [84]: '{:050b}'.format(random.randrange(1<<50))
Out[84]: '10011110110110000011111000011100101111101001001011'

(在 Python2.6 中，使用 '{0:050b}' 而不是 '{:050b}'.)

(In Python2.6, use '{0:050b}' instead of '{:050b}'.)

说明:

string.format 方法可以将整数转换为其二进制字符串表示形式.执行此操作的基本格式代码是 '{:b}':

The string.format method can convert integers into their binary string representations. The basic format code to do this is '{:b}':

In [91]: '{:b}'.format(10)
Out[91]: '1010'

要制作宽度为 50 的字符串，请使用格式代码 '{:50b}':

To make a string of width 50, use the format code '{:50b}':

In [92]: '{:50b}'.format(10)
Out[92]: '                                              1010'

并用零填充空格，使用 {:050b}:

and to fill in the whitespace with zeros, use {:050b}:

In [93]: '{:050b}'.format(10)
Out[93]: '00000000000000000000000000000000000000000000001010'

str.format 的语法 有点令人生畏首先.这是我的备忘单:

The syntax for str.format is a bit daunting at first. Here is my cheat sheet:

http://docs.python.org/library/string.html#format-string-syntax
replacement_field ::= "{" field_name ["!" conversion] [":" format_spec] "}"
field_name        ::= (identifier|integer)("."attribute_name|"["element_index"]")* 
attribute_name    ::= identifier
element_index     ::= integer
conversion        ::= "r" | "s"
format_spec       ::= [[fill]align][sign][#][0][width][,][.precision][type]
fill              ::= <a character other than '}'>
align             ::= "<" | ">" | "=" | "^"
                      "=" forces the padding to be placed after the sign (if any)
                          but before the digits. (for numeric types)
                      "<" left justification
                      ">" right justification 
                      "^" center justification
sign              ::= "+" | "-" | " "
                      "+" places a plus/minus sign for all numbers    
                      "-" places a sign only for negative numbers
                      " " places a leading space for positive numbers
#                     for integers with type b,o,x, tells format to prefix
                      output with 0b, 0o, or 0x.
0                     enables zero-padding. equivalent to 0= fill align.
width             ::= integer
,                     tells format to use a comma for a thousands separator
precision         ::= integer
type              ::= "b" | "c" | "d" | "e" | "E" | "f" | "F" | "g" | "G" | "n" |
                      "o" | "x" | "X" | "%"
    c convert integer to corresponding unicode character
    n uses a locale-aware separator
    % multiplies number by 100, display in 'f' format, with percent sign

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