Python 3.5.2如何缩短这段代码？

Question

我做了一些代码，基本上用一个字母替换另一个字母，但问题是它需要很多代码。

请告诉我如何缩短它。有没有办法我可以使用变量而不需要写这么多行？

def begin():
    lock = input("Enter the passcode")
    if lock == 'password':
        start()
    else:
        print("Wrong passcode")
        begin()

def start():
    print("Put in each letter one by one")
    print("Your message should be a 5 letter word") 
    letter1 = input("")
    letter2 = input("")
    letter3 = input("")
    letter4 = input("")
    letter5 = input("")
#letter 1 
    if letter1 == 'f':
        letter1 = 'a'
    elif letter1 == 'g':
        letter1 = 'b'
    elif letter1 == 'h':
        letter1 = 'c'
    elif letter1 == 'i':
        letter1 = 'd'
    elif letter1 == 'j':
        letter1 = 'e'
    elif letter1 == 'k':
        letter1 = 'f'
    elif letter1 == 'l':
        letter1 = 'g'
    elif letter1 == 'm':
        letter1 = 'h'
    elif letter1 == 'n':
        letter1 = 'i'
    elif letter1 == 'o':
        letter1 = 'j' 
    elif letter1 == 'p':
        letter1 = 'k'
    elif letter1 == 'q':
        letter1 = 'l'
    elif letter1 == 'r':
        letter1 = 'm'
    elif letter1 == 's':
        letter1 = 'n'
    elif letter1 == 't':
        letter1 = 'o'
    elif letter1 == 'u':
        letter1 = 'p'
    elif letter1 == 'v':
        letter1 = 'q'
    elif letter1 == 'w':
        letter1 = 'r'
    elif letter1 == 'x':
        letter1 = 's'
    elif letter1 == 'y':
        letter1 = 't'
    elif letter1 == 'z':
        letter1 = 'u'
    elif letter1 == 'a':
        letter1 = 'v' 
    elif letter1 == 'b':
        letter1 = 'w'
    elif letter1 == 'c':
        letter1 = 'x'
    elif letter1 == 'd':
        letter1 = 'y'
    elif letter1 == 'e':
        letter1 = 'z'
#letter 2
    if letter2 == 'f':
        letter2 = 'a'
    elif letter2 == 'g':
        letter2 = 'b'
    elif letter2 == 'h':
        letter2 = 'c'
    elif letter2 == 'i':
        letter2 = 'd'
    elif letter2 == 'j':
        letter2 = 'e'
    elif letter2 == 'k':
        letter2 = 'f'
    elif letter2 == 'l':
        letter2 = 'g'
    elif letter2 == 'm':
        letter2 = 'h'
    elif letter2 == 'n':
        letter2 = 'i'
    elif letter2 == 'o':
        letter2 = 'j' 
    elif letter2 == 'p':
        letter2 = 'k'
    elif letter2 == 'q':
        letter2 = 'l'
    elif letter2 == 'r':
        letter2 = 'm'
    elif letter2 == 's':
        letter2 = 'n'
    elif letter2 == 't':
        letter2 = 'o'
    elif letter2 == 'u':
        letter2 = 'p'
    elif letter2 == 'v':
        letter2 = 'q'
    elif letter2 == 'w':
        letter2 = 'r'
    elif letter2 == 'x':
        letter2 = 's'
    elif letter2 == 'y':
        letter2 = 't'
    elif letter2 == 'z':
        letter2 = 'u'
    elif letter2 == 'a':
        letter2 = 'v' 
    elif letter2 == 'b':
        letter2 = 'w'
    elif letter2 == 'c':
        letter2 = 'x'
    elif letter2 == 'd':
        letter2 = 'y'
    elif letter2 == 'e':
        letter2 = 'z'
#letter 3
    if letter3 == 'f':
        letter3 = 'a'
    elif letter3 == 'g':
        letter3 = 'b'
    elif letter3 == 'h':
        letter3 = 'c'
    elif letter3 == 'i':
        letter3 = 'd'
    elif letter3 == 'j':
        letter3 = 'e'
    elif letter3 == 'k':
        letter3 = 'f'
    elif letter3 == 'l':
        letter3 = 'g'
    elif letter3 == 'm':
        letter3 = 'h'
    elif letter3 == 'n':
        letter3 = 'i'
    elif letter3 == 'o':
        letter3 = 'j' 
    elif letter3 == 'p':
        letter3 = 'k'
    elif letter3 == 'q':
        letter3 = 'l'
    elif letter3 == 'r':
        letter3 = 'm'
    elif letter3 == 's':
        letter3 = 'n'
    elif letter3 == 't':
        letter3 = 'o'
    elif letter3 == 'u':
        letter3 = 'p'
    elif letter3 == 'v':
        letter3 = 'q'
    elif letter3 == 'w':
        letter3 = 'r'
    elif letter3 == 'x':
        letter3 = 's'
    elif letter3 == 'y':
        letter3 = 't'
    elif letter3 == 'z':
        letter3 = 'u'
    elif letter3 == 'a':
        letter3 = 'v' 
    elif letter3 == 'b':
        letter3 = 'w'
    elif letter3 == 'c':
        letter3 = 'x'
    elif letter3 == 'd':
        letter3 = 'y'
    elif letter3 == 'e':
        letter3 = 'z'
#letter 4
    if letter4 == 'f':
        letter4 = 'a'
    elif letter4 == 'g':
        letter4 = 'b'
    elif letter4 == 'h':
        letter4 = 'c'
    elif letter4 == 'i':
        letter4 = 'd'
    elif letter4 == 'j':
        letter4 = 'e'
    elif letter4 == 'k':
        letter4 = 'f'
    elif letter4 == 'l':
        letter4 = 'g'
    elif letter4 == 'm':
        letter4 = 'h'
    elif letter4 == 'n':
        letter4 = 'i'
    elif letter4 == 'o':
        letter4 = 'j' 
    elif letter4 == 'p':
        letter4 = 'k'
    elif letter4 == 'q':
        letter4 = 'l'
    elif letter4 == 'r':
        letter4 = 'm'
    elif letter4 == 's':
        letter4 = 'n'
    elif letter4 == 't':
        letter4 = 'o'
    elif letter4 == 'u':
        letter4 = 'p'
    elif letter4 == 'v':
        letter4 = 'q'
    elif letter4 == 'w':
        letter4 = 'r'
    elif letter4 == 'x':
        letter4 = 's'
    elif letter4 == 'y':
        letter4 = 't'
    elif letter4 == 'z':
        letter4 = 'u'
    elif letter4 == 'a':
        letter4 = 'v' 
    elif letter4 == 'b':
        letter4 = 'w'
    elif letter4 == 'c':
        letter4 = 'x'
    elif letter4 == 'd':
        letter4 = 'y'
    elif letter4 == 'e':
        letter4 = 'z'
#letter 5
    if letter5 == 'f':
        letter5 = 'a'
    elif letter5 == 'g':
        letter5 = 'b'
    elif letter5 == 'h':
        letter5 = 'c'
    elif letter5 == 'i':
        letter5 = 'd'
    elif letter5 == 'j':
        letter5 = 'e'
    elif letter5 == 'k':
        letter5 = 'f'
    elif letter5 == 'l':
        letter5 = 'g'
    elif letter5 == 'm':
        letter5 = 'h'
    elif letter5 == 'n':
        letter5 = 'i'
    elif letter5 == 'o':
        letter5 = 'j' 
    elif letter5 == 'p':
        letter5 = 'k'
    elif letter5 == 'q':
        letter5 = 'l'
    elif letter5 == 'r':
        letter5 = 'm'
    elif letter5 == 's':
        letter5 = 'n'
    elif letter5 == 't':
        letter5 = 'o'
    elif letter5 == 'u':
        letter5 = 'p'
    elif letter5 == 'v':
        letter5 = 'q'
    elif letter5 == 'w':
        letter5 = 'r'
    elif letter5 == 'x':
        letter5 = 's'
    elif letter5 == 'y':
        letter5 = 't'
    elif letter5 == 'z':
        letter5 = 'u'
    elif letter5 == 'a':
        letter5 = 'v' 
    elif letter5 == 'b':
        letter5 = 'w'
    elif letter5 == 'c':
        letter5 = 'x'
    elif letter5 == 'd':
        letter5 = 'y'
    elif letter5 == 'e':
        letter5 = 'z'



    print("Your encypted message is:")
    print(letter1 + letter2 + letter3 + letter4 + letter5)
    QUIT = input("Press enter to quit")
    quit 

begin() 

Answer 1

使用str.maketrans()创建翻译表，str.translate()使用翻译。使用string.ascii_lowercase而不是拼写您的信件。使用string.ascii_letters来处理大写和小写字母，这可能是一个很好的改进。

>>> import string
>>> letters = string.ascii_lowercase
>>> table = str.maketrans(letters[5:]+letters[:5], letters)
>>> str.translate('crown', table)
'xmjri'

或者将字典用作转换表。如果没有指定的映射，请使用dict.get()和默认值来允许字符无法翻译。

>>> import string
>>> letters = string.ascii_lowercase
>>> d = dict(zip(letters[5:]+letters[:5], letters))
>>> ''.join(d.get(c, c) for c in 'crown')
'xmjri'

Answer 2

我建议使用if语句创建一个包含从letter1到letter2的映射的字典。

letterMapping = {'f':'a','g':'b'}等等，当您收到输入时，请执行以下操作：

letter1 = input("")
letterMapping[letter1] 

因此如果letter1为f，则会返回a。

Answer 3

您好，为什么不尝试使用while循环和数组。

不确定代码是否有效，但您会明白

def start():
letters = array();
x = 0;
while(x != 5):
    print("Enter 1 letter");
    letters[x] = input("");
    x = x +1;
while(x != 5):
    if (letters[x] == 'f'):
        letters[x] = 'a'
    elif(letters[x] == 'g'):
        letters[x] = 'b'
    elif ((letters[x] == 'h'):
        letters[x]= 'c'
    elif (letters[x] == 'i'):
        letters[x] = 'd'
    elif (letters[x] == 'j'):
        letters[x] = 'e'
    elif (letters[x] == 'k'):
        letters[x] = 'f'
    elif (letters[x] == 'l'):
        letters[x] = 'g'
    elif (letters[x] == 'm'):
        letters[x] = 'h'
    elif (letters[x] == 'n'):
        letters[x] = 'i'
    elif (letters[x] == 'o'):
        letters[x] = 'j' ;
    elif (letters[x] == 'p'):
        letters[x] = 'k'
    elif (letters[x] == 'q'):
        letters[x] = 'l'
    elif (letters[x] == 'r'):
        letters[x] = 'm'
    elif (letters[x] == 's'):
        letters[x] = 'n'
    elif (letters[x] == 't'):
        letters[x] = 'o'
    elif (letters[x] == 'u'):
        letters[x] = 'p'
    elif (letters[x] == 'v'):
        letters[x] = 'q'
    elif (letters[x] == 'w'):
        letters[x] = 'r'
    elif (letters[x] == 'x'):
        letters[x] = 's'
    elif (letters[x] == 'y'):
        letters[x] = 't'
    elif (letters[x] == 'z'):
        letters[x] = 'u'
    elif (letters[x] == 'a'):
        letters[x] = 'v' }
    elif (letters[x] == 'b'):
        letters[x] = 'w'
    elif (letters[x] == 'c'):
        letters[x] = 'x'
    elif (letters[x] == 'd'):
        letters[x] = 'y'
    elif (letters[x] == 'e'):
        letters[x] = 'z'

    x = x + 1;


print("Your encypted message is:")
print(letters[0] + letters[1] + letters[2] + letters[3] + letters[4])
QUIT = input("Press enter to quit")
quit