Python | Reemplazo de la enésima aparición de varios caracteres en una string con el carácter dado

Dado un String S , una array de caracteres ch[] , un número N y un carácter de reemplazo, la tarea es reemplazar cada enésima aparición de cada carácter de la array de caracteres ch[] en la string con el carácter de reemplazo dado.
 

Entrada: S = «GeeksforGeeks», ch[] = {‘G’, ‘e’, ​​’k’}, N = 2, replace_character = ‘#’ Salida: Ge#ksfor#ee#s Explicación: 
en la 
string 
dada S, la segunda aparición de ‘G’, ‘e’, ​​’K’ se reemplaza con ‘#’ 
 

Entrada: S = abcdeahu, ch[] = {‘a’, ‘d’, ‘u’}, N = 1, replace_character = ‘#’ Salida: #bc# 
eah # 
Explicación: 
En la string dada S, la primera la ocurrencia de ‘a’, ‘d’, ‘u’ se reemplaza con ‘#’ 
 

Método 1: Enfoque ingenuo 
En este enfoque, la idea general es almacenar cada N-ésimo índice de ocurrencia de cada carácter en otra array y reemplazarlos con el otro carácter dado.

A continuación se muestra la implementación del enfoque anterior. 

# 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)

Ge#ksfor#ee#s

Método 2: usar el método find() 
En este enfoque, la idea es usar la función find() para encontrar la enésima ocurrencia del carácter en la string S dada y reemplazarla con otro carácter dador.

A continuación se muestra la implementación del enfoque anterior.

# 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)

Ge#ksfor#ee#s

Método 3: Usando el método beginwith() 
En este enfoque, la idea es usar la función beginwith() de python para encontrar el índice del carácter donde la ocurrencia del carácter es igual a la enésima ocurrencia dada y luego reemplazarla con la dado el carácter de reemplazo.

A continuación se muestra la implementación del enfoque anterior. 

# 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)

Ge#ksfor#ee#s