随机将字符串中的字母大写

Question

我想随机将字符串中的每个字母大写或小写。我刚开始使用 python 中的字符串，但我认为因为字符串是不可变的，所以我不能执行以下操作：

i =0             
for c in sentence:
    case = random.randint(0,1)
    print("case = ", case)
    if case == 0:
        print("here0")
        sentence[i] = sentence[i].lower()
    else:
        print("here1")
        sentence[i] = sentence[i].upper()
    i += 1
print ("new sentence = ", sentence)

并得到错误：TypeError: 'str' object does not support item assignment

但是我还能怎么做呢？

Answer 1

import random
sentence='quick test'
print(''.join([char.lower() if random.randint(0,1) else char.upper() \
                   for char in sentence]))

qUiCK TEsT

Answer 2

你可以像下面那样做

char_list = []            
for c in sentence:
    ucase = random.randint(0,1)
    print("case = ", case)
    if ucase:
        print("here1")
        char_list.append(c.upper())
    else:
        print("here0")
        char_list.append(c.lower())
print ("new sentence = ", ''.join(char_list))

Answer 3

您可以将 str.join 与生成器表达式一起使用，如下所示：

from random import choice
sentence = 'Hello World'
print(''.join(choice((str.upper, str.lower))(c) for c in sentence))

示例输出：

heLlo WORLd

Answer 4

建立一个新的字符串。

这是一个对您的原始代码稍作改动的解决方案：

>>> import random
>>> 
>>> def randomcase(s):
...:    result = ''
...:    for c in s:
...:        case = random.randint(0, 1)
...:        if case == 0:
...:            result += c.upper()
...:        else:
...:            result += c.lower()
...:    return result
...:
...:
>>> randomcase('Hello Whosebug!')
>>> 'hElLo Whosebug!'

编辑：删除了我的 oneliner，因为我更喜欢 blhsing。

Answer 5

只需将字符串实现更改为列表实现即可。由于字符串是不可变的，因此您无法更改对象内部的值。但是 Lists 可以，所以我只更改了您的那部分代码。请注意，有更好的方法可以做到这一点，请关注 here

import random
sentence = "This is a test sentence" # Strings are immutable
i =0
new_sentence = [] # Lists are mutable sequences
for c in sentence:
    case = random.randint(0,1)
    print("case = ", case)
    if case == 0:
        print("here0")
        new_sentence += sentence[i].lower() # append to the list
    else:
        print("here1")
        new_sentence += sentence[i].upper() # append to the list
    i += 1
print ("new sentence = ", new_sentence)

# to print as string
new_sent = ''.join(new_sentence)
print(new_sent)

Answer 6

一种不涉及 python 循环的方法是将其发送到 numpy 并对其进行矢量化操作。例如：

import numpy as np
def randomCapitalize(s):
    s  = np.array(s, 'c').view('u1')
    t  = np.random.randint(0, 2, len(s), 'u1') # Temporary array
    t *= s != 32 # ASCII 32 (i.e. space) should not be lowercased
    t *= 32 # Decrease ASCII by 32 to lowercase
    s -= t
    return s.view('S' + str(len(s)))[0]
randomCapitalize('hello world jfwojeo jaiofjowejfefjawivj a jofjawoefj')

输出：

b'HELLO WoRlD jFwoJEO JAioFjOWeJfEfJAWIvJ A JofjaWOefj'

这个解决方案应该相当快，尤其是对于长字符串。这种方法有两个限制：

输入必须完全小写。您可以先尝试 .lower()，但从技术上讲效率很低。
非a-to-z字符需要特别注意。在上面的例子中，只处理了space

你可以通过替换

同时处理更多的特殊字符

t *= s != 32

和

# using space, enter, comma, period as example
t *= np.isin(s, list(map(ord, ' \n,.')), invert=True)

例如：

s = 'ascii table and description. ascii stands for american standard code for information interchange. computers can only understand numbers, so an ascii code is the numerical representation of a character such as'
randomCapitalize(s)

输出：

b'ascII tABLe AnD descRiptIOn. ascii sTaNds for AmEricAN stanDaRD codE FOr InForMAtION iNTeRCHaNge. ComPUtERS can onLY UNdersTand nUMBers, So An asCIi COdE IS tHE nuMERIcaL rEPrEsEnTATion Of a CHaractEr such as'

随机将字符串中的字母大写

Randomly capitalize letters in string

python

lowercase

python-3.x

uppercase