python正则匹配字符串_python re正则匹配过滤指定字符串

python re.sub 正则表达式过滤指定字符

实例代码

re.sub(pattern, repl, string, count=0, flags=0)

Return the string obtained by replacing the leftmost non-overlapping occurrences of pattern in string by the replacement repl. If the pattern isn’t found, string is returned unchanged. repl can be a string or a function; if it is a string, any backslash escapes in it are processed. That is, \n is converted to a single newline character, \r is converted to a carriage return, and so forth. Unknown escapes such as \j are left alone. Backreferences, such as \6, are replaced with the substring matched by group 6 in the pattern. For example:

>>> re.sub(r'def\s+([a-zA-Z_][a-zA-Z_0-9]*)\s*\(\s*\):',

... r'static PyObject*\npy_\1(void)\n{',

... 'def myfunc():')

'static PyObject*\npy_myfunc(void)\n{'

If repl is a function, it is called for every non-overlapping occurrence of pattern. The function takes a single match object argument, and returns the replacement string. For example:

>>> def dashrepl(matchobj):

... if matchobj.group(0) == '-': return ' '

... else: return '-'

>>> re.sub('-{1,2}', dashrepl, 'pro----gram-files')

'pro--gram files'

>>> re.sub(r'\sAND\s', ' & ', 'Baked Beans And Spam', flags=re.IGNORECASE)

'Baked Beans & Spam'

The pattern may be a string or an RE object.

The optional argument count is the maximum number of pattern occurrences to be replaced; countmust be a non-negative integer. If omitted or zero, all occurrences will be replaced. Empty matches for the pattern are replaced only when not adjacent to a previous match, so sub('x*', '-', 'abc') returns '-a-b-c-'.

In addition to character escapes and backreferences as described above, \g will use the substring matched by the group named name, as defined by the (?P...) syntax. \guses the corresponding group number; \g<2> is therefore equivalent to \2, but isn’t ambiguous in a replacement such as \g<2>0. \20 would be interpreted as a reference to group 20, not a reference to group 2 followed by the literal character '0'. The backreference \g<0> substitutes in the entire substring matched by the RE.

Changed in version 2.7: Added the optional flags argument.

简单来说，pattern 就是一个需要被替换的正则表达式，当其匹配成功后，就会用 repl 进行替换，而 string 就是需要被替换的字符串。

比如，我们需要对一个字符串进行处理，首先需要删除括号内所有内容，包括括号