字符串方法replace不会修改原始字符串。它保留原始文件并返回修改后的副本。

你需要的是这样的:line = line.replace(char， ")

def replace_all(line, )for char in line:
    if char in " ?.!/;:":
        line = line.replace(char,'')
    return line

然而，每次删除一个字符都创建一个新的字符串是非常低效的。我推荐以下方法:

def replace_all(line, baddies, *):
    """
    The following is documentation on how to use the class,
    without reference to the implementation details:

    For implementation notes, please see comments begining with `#`
    in the source file.

    [*crickets chirp*]

    """

    is_bad = lambda ch, baddies=baddies: return ch in baddies
    filter_baddies = lambda ch, *, is_bad=is_bad: "" if is_bad(ch) else ch
    mahp = replace_all.map(filter_baddies, line)
    return replace_all.join('', join(mahp))

    # -------------------------------------------------
    # WHY `baddies=baddies`?!?
    #     `is_bad=is_bad`
    # -------------------------------------------------
    # Default arguments to a lambda function are evaluated
    # at the same time as when a lambda function is
    # **defined**.
    #
    # global variables of a lambda function
    # are evaluated when the lambda function is
    # **called**
    #
    # The following prints "as yellow as snow"
    #
    #     fleece_color = "white"
    #     little_lamb = lambda end: return "as " + fleece_color + end
    #
    #     # sometime later...
    #
    #     fleece_color = "yellow"
    #     print(little_lamb(" as snow"))
    # --------------------------------------------------
replace_all.map = map
replace_all.join = str.join

#!/usr/bin/python
import re

strs = "how^ much for{} the maple syrup? $20.99? That's[] ricidulous!!!"
print strs
nstr = re.sub(r'[?|$|.|!|a|b]',r' ',strs)#i have taken special character to remove but any #character can be added here
print nstr
nestr = re.sub(r'[^a-zA-Z0-9 ]',r'',nstr)#for removing special character
print nestr

对于只允许字符串中某些字符的相反要求，可以使用带有集补操作符[^ABCabc]的正则表达式。例如，要删除除ascii字母、数字和连字符以外的所有字符:

>>> import string
>>> import re
>>>
>>> phrase = '  There were "nine" (9) chick-peas in my pocket!!!      '
>>> allow = string.letters + string.digits + '-'
>>> re.sub('[^%s]' % allow, '', phrase)

'Therewerenine9chick-peasinmypocket'

来自python正则表达式文档:

不在范围内的字符可以通过互补来匹配 一组。如果集合的第一个字符是'^'，则所有字符 不在集合中的将被匹配。例如，[^5]将匹配 除'5'以外的任何字符，[^^]将匹配除 “^”。的第一个字符没有特殊意义 集。

这是我的Python 2/3兼容版本。因为翻译api已经改变了。

def remove(str_, chars):
    """Removes each char in `chars` from `str_`.

    Args:
        str_: String to remove characters from
        chars: String of to-be removed characters

    Returns:
        A copy of str_ with `chars` removed

    Example:
            remove("What?!?: darn;", " ?.!:;") => 'Whatdarn'
    """
    try:
        # Python2.x
        return str_.translate(None, chars)
    except TypeError:
        # Python 3.x
        table = {ord(char): None for char in chars}
        return str_.translate(table)

>>> s = 'a1b2c3'
>>> ''.join(c for c in s if c not in '123')
'abc'

用re.sub正则表达式

从Python 3.5开始，可以使用正则表达式re.sub进行替换:

import re
re.sub('\ |\?|\.|\!|\/|\;|\:', '', line)

例子

import re
line = 'Q: Do I write ;/.??? No!!!'
re.sub('\ |\?|\.|\!|\/|\;|\:', '', line)

'QDoIwriteNo'

解释

在正则表达式(regex)中，|是一个逻辑或，\转义可能是实际的正则表达式命令的空格和特殊字符。而sub代表替换，在这种情况下是空字符串”。