.replace语法在python中遇到麻烦

Question

尝试导入此代码行时出现语法错误（第8行rw.replace）。 它应该工作正常吗？

---

def mirror(word):
    mirrorletters = str([[p,q],[q,p],[d,b][b,d]])
    rw == reverse(word)
    while True:
        if item in word:
            for mirrorletters in rw:
                for p in rw:
                    print rw.replace('p','q')
                for q in rw:
                    print rw.replace('q','p')
                for d in rw:
                    print rw.replace('d','b')
                for b in rw:
                    print rw.replace('b','d')
        elif item not in word:
            print(rw)

Answer 1

我假设您要执行的操作是反转传入的字符串，并用“ q”替换“ p”，反之亦然，用“ d”和“ b”替换相同的字符串？

mirrorletters = str([[p,q],[q,p],[d,b][b,d]])引发错误，因为您尝试引用p ， q ， d和b ，都不是存在。 您需要这些字母的字符串表示形式。

rw == reverse(word)不会将rw设置为与==进行比较的reverse(word)的内容。

另外，据我所知， reverse()不在Python 2或3的标准库中。

您可以通过说出反向字符串

word = 'hello' r = word[::-1] print(r) # prints "olleh"

这就是我相信您正在尝试做的事情：

def mirror(word):

        # Make a list of characters to be swapped.
        # "d" will be swapped with "b" and vice versa.
        # The same goes for "q" and "p"
        mirror_letters = [('d', 'b'), ('q', 'p')]

        # Start with a new string
        new_word = ''

        # Go through each letter in the word and keep up with the index
        for letter in word:

            # Go through each "character set" in mirror_letters
            for char_set in mirror_letters:

                # enumerate the char_set and get an index and character of each item in the list
                for index, char in enumerate(char_set):

                    # If the letter is equal to the character, set letter to character
                    if letter == char:

                        # Doing a little bit of "reverse indexing" here to determine which character to set letter to
                        letter = char_set[::-1][index]

                        # If we set the letter, break so we don't possibly change back.
                        break

            # Add the letter to the new word
            new_word += letter

        return new_word[::-1]

输出：

print(mirror('abcd')) # prints "bcda"

print(mirror('pqrs')) # prints "srpq"

Answer 2

如果要ro镜像一个字符串然后交换一些字母，则可以使用以下函数：

def mirrorString(string, swap=[]):
    mirroed = string[::-1]
    i = 0
    while chr(i) in mirroed:
        i += 1
    for a, b in swap:
        mirroed = mirroed.replace(a, chr(i)).replace(b, a).replace(chr(i), b)
    return mirroed

print(mirrorString("abcd", [('b', 'd'), ('p', 'q')])) # bcda

我首先镜像字符串，然后选择字符串中不存在的字符用作临时占位符，然后遍历交换对，并用占位符替换对中的第一个字母，第二个替换为占位符。第一个，占位符第二个。