Python – 反转字符串，除了标点符号

给定一个带有标点符号的字符串，执行字符串反转，将标点符号留在原处。

Input : test_str = ‘geeks@#for&%%gee)ks’ 
Output : skeeg@#rof&%%ske)eg 
Explanation : Whole string is reversed, except the punctuations.

Input : test_str = ‘geeks@#for&%%gee)ks’ [ only substring reversal ] 
Output : skeeg@#rof&%%eeg)sk 
Explanation : Only substrings are reversed. 
 

方法 #1：使用循环 + 堆栈 + 标点符号 + split()

在此，我们使用堆栈来执行字符串反转，检查标点符号，如果当前字符是一个，我们追加它。 split 方法用于处理空格的情况，在反向时需要忽略。

Python3

# Python3 code to demonstrate working of
# Reverse String except punctuations
# Using loop + stack + punctuation + split()
from string import punctuation
 
# initializing string
test_str = 'geeks# for&%% gee)ks'
 
# printing original string
print("The original string is : " + str(test_str))
 
# getting punctuations
punc_set = set(punctuation)
res = []
for sub in test_str.split(' '):
     
    # getting all alphabets
    alphas = [chr for chr in sub if chr not in punc_set]
    for chr in sub:
         
        # checking for punctuations
        if chr not in punc_set:
            res.append(alphas.pop())
            continue
        else:
            res.append(chr)
             
    # handling spaces
    res.append(' ')
res = "".join(res)
 
# printing result
print("The Reversed String ignoring punctuation : " + str(res))

输出

The original string is : geeks#for&%%gee)ks
The Reversed String ignoring punctuation : skeeg#rof&%%ske)eg 

方法#2：使用 groupby() + isalnum() [ 用于子串特定的反转]

在此，我们在标点符号之间形成每个子串的分组，并在它们之间反转它们，而不是整体。 isalnum() 用于检查所有字母。

Python3

# Python3 code to demonstrate working of
# Reverse String except punctuations
# Using groupby() + isalnum() [ for substring specific reversal ]
from itertools import groupby
 
# initializing string
test_str = 'geeks# for&%% gee)ks'
 
# printing original string
print("The original string is : " + str(test_str))
 
res = ''
 
# grouping all sections
for ele, sub in groupby(test_str, str.isalnum):
    sub = list(sub)
     
    # reversal on alphanumeric occurrence
    if ele:
        sub = sub[::-1]
         
    # joining all subparts
    res += ''.join(sub)
 
 
# printing result
print("The Reversed String ignoring punctuation [substring] : " + str(res))

输出

The original string is : geeks#for&%%gee)ks
The Reversed String ignoring punctuation [substring] : skeeg#rof&%%eeg)sk