Python|与给定的字符替换的多个字符第N次出现在字符串

给定一个字符串S 、一个字符数组ch[] 、一个数字N和一个替换字符，任务是用给定的替换字符替换字符串字符数组ch[]中每个字符的第 N 次出现。

Input: S = “GeeksforGeeks”, ch[] = {‘G’, ‘e’, ‘k’}, N = 2, replacing_character = ‘#’ 
Output: Ge#ksfor#ee#s 
Explanation: 
In the given string S, the second occurrence of the ‘G’, ‘e’, ‘K’ is replaced with ‘#’ 
 

Input: S = abcdeahu, ch[] = {‘a’, ‘d’, ‘u’}, N = 1, replacing_character = ‘#’ 
Output: #bc#eah# 
Explanation: 
In the given string S, the first occurrence of the ‘a’, ‘d’, ‘u’ is replaced with ‘#’ 
 

方法 1：天真的方法
在这种方法中，一般的想法是将每个字符的第 N 个出现索引存储在另一个数组中，并用给定的另一个字符替换它们。

下面是上述方法的实现。

Python

# Python implementation to replace nth
# occurrence of the every character
# in a string
 
# Function to replace the Nth occurrence
# of the character of string
def replacer(initial_string, ch,
         replacing_character, occurrence):
     
    # breaking a string into it's
    # every single character in list
    lst1 = list(initial_string)
    lst2 = list(ch)
     
    # List to store the indexes in which
    # it is replaced with the
    # replacing_character
    lst3 = []
     
    # Loop to find the Nth occurrence of
    # given characters in the string
    for i in lst2:
        if(lst1.count(i)>= occurrence):
            count = 0
            for j in range(0, len(initial_string)):
                if(i == lst1[j]):
                    count+= 1
                    if(count == occurrence):
                        lst3.append(j)
     
    for i in lst3:
        # Replacing that particular index
        # with the requested character
        lst1[i] = replacing_character
     
         
    print(''.join(lst1))
     
# Driver Code:
if __name__ == '__main__':
    initial_string = 'GeeksforGeeks'
    ch = ['G', 'e', 'k']
    occurrence = 2
    replacing_character = '#'
    replacer(initial_string, ch,
    replacing_character, occurrence)

输出：

Ge#ksfor#ee#s

方法二：使用 find() 方法
在这种方法中，想法是使用 find()函数查找给定字符串S 中出现的第 N 个字符，并将其替换为另一个给定字符。

下面是上述方法的实现。

Python

# Python implementation to replace nth
# occurrence of the every character
# in a string using find() function
 
# Function to replace the Nth occurrence
# of the character of string
def replacer(initial_string, ch,
         replacing_character, occurrence):
     
    # breaking a string into
    # it's every single character
    lst1 = list(initial_string)
    lst2 = list(ch)
 
    # Loop to find the occurrence
    # of the character in the string
    # and replace it with the given
    # replacing_character
    for i in lst2:
        sub_string = i
        val = -1
        for i in range(0, occurrence):
            val = initial_string.find(sub_string,
                                      val + 1)
        lst1[val] = replacing_character
 
    print(''.join(lst1))
 
# Driver Code:
if __name__ == '__main__':
    initial_string = 'GeeksforGeeks'
    ch = ['G', 'e', 'k']
    occurrence = 2
    replacing_character = '#'
    replacer(initial_string, ch,
    replacing_character, occurrence)

输出：

Ge#ksfor#ee#s

方法三：使用startswith()方法
在这种方法中，这个想法是使用Python的startswith()函数来找到字符的索引，其中的字符的发生是等于给定第N次出现，然后用给定的替换字符替换。

下面是上述方法的实现。

Python

# Python implementation to replace nth
# occurrence of the every character
# in a string
 
# Function to replace the Nth occurrence
# of the character of string
def replacer(initial_string, ch,
         replacing_character, occurrence):
     
    # breaking a string into
    # it's every single character
    lst1 = list(initial_string)
    lst2 = list(ch)
     
    # Loop to find the occurrence
    # of the character in the string
    # and replace it with the given
    # replacing_character   
    for j in lst2:
        sub_string = j
        checklist = [i for i in range(0, len(initial_string))
              if initial_string[i:].startswith(sub_string)]
        if len(checklist)>= occurrence:
            lst1[checklist[occurrence-1]] = replacing_character
 
    print(''.join(lst1))
 
# Driver Code:
if __name__ == '__main__':
    initial_string = 'GeeksforGeeks'
    ch = ['G', 'e', 'k']
    occurrence = 2
    replacing_character = '#'
    replacer(initial_string, ch,
    replacing_character, occurrence)

输出：

Ge#ksfor#ee#s

如果您想与行业专家一起参加直播课程，请参阅Geeks Classes Live