python comment diviser une chaîne et rejoindrons

Question

Je fais une mission de cryptographie en python et je dois: - découper une chaîne - remplacer les lettres - rejoindrons pour qu'il soit un mot.

Ceci est le code complet, mais je suis bloqué sur la boucle for sous def encode(plain).

""" crypto.py 
Implements a simple substitution cypher 
""" 

alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" 
key = "XPMGTDHLYONZBWEARKJUFSCIQV" 

def menu(): 

    print("Secret decoder menu") 
    print("0) Quit") 
    print("1) Encode") 
    print("2) Decode") 
    print("What do you want to do?") 
    response = input() 
    return response 

def encode(plain): 

for i in range(len(plain)): 

    plain = plain.upper() 
    x = plain[i:i+1] 
    y = alpha.index(x) 
    z = key[y:y+1] 
    plain[x] = z 

return plain 

def main(): 

keepGoing = True 
    while keepGoing: 

    response = menu() 

    if response == "1": 

     plain = input("text to be encoded: ") 
     print(encode(plain)) 

    elif response == "2": 
     coded = input("code to be decyphered: ") 
     print (decode(coded)) 

    elif response == "0": 
     print ("Thanks for doing secret spy stuff with me.") 
     keepGoing = False 

    else: 
     print ("I don't know what you want to do...") 

return main 

main() 
menu() 

Answer 1

La façon la plus simple à mettre en œuvre cette substitution est d'utiliser la compréhension du dictionnaire et de la liste:

alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" 
key = "XPMGTDHLYONZBWEARKJUFSCIQV" 
converter = {a:b for a, b in zip(alpha, key)} 
def encode(s): 
    return ''.join(converter[i] for i in s) 

def decode(s): 
    reverse = {b:a for a, b in converter.items()} 
    return ''.join(reverse[i] for i in s) 

def main(): 
    response = input("Enter 1 to decode, 2 to encode: ") 
    if response == "1": 
     the_string = input("Enter the scrambled string: ") 
     print("The result is ", decode(the_string)) 
    elif response == "2": 
     the_string = input("Enter the plain string: ") 
     print("The result is ", encode(the_string)) 
main() 

Answer 2

Si vous essayez de mettre en œuvre votre propre solution ne @ comme Ajax1234 dire.

mais il est plus facile avec string translate

alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" 
key = "XPMGTDHLYONZBWEARKJUFSCIQV" 
crypto = maketrans(alpha, key) 

.... 
the_string = input("Enter the scrambled string: ") 
the_string = the_string.upper() 
encrypted = the_string.translate(crypto)