Question

我想随机将字符串中的每个字母大写或小写。我是在python中处理字符串的新手，但是我认为由于字符串是不可变的，因此我无法执行以下操作：

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)

并收到错误消息：TypeError：'str'对象不支持项目分配

但是我还能怎么做呢？

Answer 1

您可以将str.join与这样的生成器表达式一起使用：

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 2

建立一个新的字符串。

这是一个对原始代码几乎没有更改的解决方案：

>>> 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 Stackoverflow!')
>>> 'hElLo StaCkoVERFLow!'

编辑：删除了我的oneliners，因为我喜欢blhsing更好。

Answer 3

只需将字符串实现更改为列表实现。由于字符串是不可变的，因此无法更改对象内部的值。但是Lists可以，所以我只更改了部分代码。并请注意，有更好的方法可以执行此操作，请按照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 4

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

qUiCK TEsT

Answer 5

您可以像下面这样

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 6

不涉及python循环的一种方法是将其发送到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'

此解决方案应该相当快，尤其是对于长字符串。此方法有两个局限性：

输入必须完全小写。您可以先尝试.lower()，但这在技术上效率很低。
对于非a到z字符，需要特别注意。在上面的示例中，仅处理了空间

通过替换，您可以同时处理更多特殊字符

t *= s != 32

使用

# 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'

将字符串中的字母随机大写

6 个答案: