Randomly capitalize letters in string [duplicate]

问题

I want to randomly capitalize or lowercase each letter in a string. I'm new to working with strings in python, but I think because strings are immutable that I can't do the following:

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)

And get the error: TypeError: 'str' object does not support item assignment

But then how else could I do this?

回答1:

You can use str.join with a generator expression like this:

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

Sample output:

heLlo WORLd

回答2:

Build a new string.

Here's a solution with little changes to your original code:

>>> 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!'

edit: deleted my oneliners because I like blhsing's better.

回答3:

Just change the string implementation to a list implementation. As string is immutable, you cannot change the value inside the object. But Lists can be, So I've only changed that part of your code. And make note that there are much better ways to do this, Follow 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)

回答4:

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

qUiCK TEsT

回答5:

You can do like below

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))

回答6:

One way without involving python loop would be sending it to numpy and do vectorized operation over that. For example:

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')

which outputs:

b'HELLO WoRlD jFwoJEO JAioFjOWeJfEfJAWIvJ A JofjaWOefj'

This solution should be reasonably fast especially for long string. There are two limitations of this method:

The input must be fully lower case. You can try .lower() it first but thats technically low efficient.
It need special care for non-a-to-z character. In the example above, only space is handled

You can handle a lot more special characters at the same time by replacing

t *= s != 32

with

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

For example:

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)

which outputs:

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'

来源：https://stackoverflow.com/questions/52942497/randomly-capitalize-letters-in-string

标签

python

python-3.x

uppercase

lowercase