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+ | ====== Python正则表达式的用法 ====== | ||
+ | |||
+ | ===== 字符串替换 ===== | ||
+ | |||
+ | |||
+ | |||
+ | ==== 1.替换所有匹配的子串 ==== | ||
+ | |||
+ | 用newstring替换subject中所有与正则表达式regex匹配的子串 | ||
+ | <code python> | ||
+ | result, number = re.subn(regex, newstring, subject) | ||
+ | </code> | ||
+ | |||
+ | |||
+ | ==== 2.替换所有匹配的子串(使用正则表达式对象) ==== | ||
+ | <code python> | ||
+ | reobj = re.compile(regex) | ||
+ | result, number = reobj.subn(newstring, subject) | ||
+ | </code> | ||
+ | |||
+ | |||
+ | ===== 字符串拆分 ===== | ||
+ | |||
+ | ==== 1.字符串拆分 ==== | ||
+ | <code python> | ||
+ | result = re.split(regex, subject) | ||
+ | </code> | ||
+ | |||
+ | |||
+ | |||
+ | ==== 2.字符串拆分(使用正则表示式对象) ==== | ||
+ | <code python> | ||
+ | reobj = re.compile(regex) | ||
+ | result = reobj.split(subject) | ||
+ | </code> | ||
+ | |||
+ | ===== 匹配 ===== | ||
+ | |||
+ | 下面列出Python正则表达式的几种匹配用法: | ||
+ | |||
+ | ==== 1.测试正则表达式是否匹配字符串的全部或部分 ==== | ||
+ | |||
+ | <code python> | ||
+ | regex=ur"..." #正则表达式 | ||
+ | if re.search(regex, subject): | ||
+ | do_something() | ||
+ | else: | ||
+ | do_anotherthing() | ||
+ | </code> | ||
+ | |||
+ | |||
+ | ==== 2.测试正则表达式是否匹配整个字符串 ==== | ||
+ | |||
+ | <code python> | ||
+ | regex=ur"...\Z" #正则表达式末尾以\Z结束 | ||
+ | if re.match(regex, subject): | ||
+ | do_something() | ||
+ | else: | ||
+ | do_anotherthing() | ||
+ | </code> | ||
+ | |||
+ | |||
+ | ==== 3. 创建一个匹配对象,然后通过该对象获得匹配细节 ==== | ||
+ | |||
+ | <code python> | ||
+ | regex=ur"..." #正则表达式 | ||
+ | match = re.search(regex, subject) | ||
+ | if match: | ||
+ | # match start: match.start() | ||
+ | # match end (exclusive): match.end() | ||
+ | # matched text: match.group() | ||
+ | do_something() | ||
+ | else: | ||
+ | do_anotherthing() | ||
+ | </code> | ||
+ | |||
+ | ==== 4.获取正则表达式所匹配的子串 ==== | ||
+ | (Get the part of a string matched by the regex) | ||
+ | <code python> | ||
+ | regex=ur"..." #正则表达式 | ||
+ | match = re.search(regex, subject) | ||
+ | if match: | ||
+ | result = match.group() | ||
+ | else: | ||
+ | result = "" | ||
+ | </code> | ||
+ | |||
+ | ==== 5. 获取捕获组所匹配的子串 ==== | ||
+ | (Get the part of a string matched by a capturing group) | ||
+ | <code python> | ||
+ | regex=ur"..." #正则表达式 | ||
+ | match = re.search(regex, subject) | ||
+ | if match: | ||
+ | result = match.group(1) | ||
+ | else: | ||
+ | result = "" | ||
+ | </code> | ||
+ | |||
+ | ==== 6. 获取有名组所匹配的子串 ==== | ||
+ | (Get the part of a string matched by a named group) | ||
+ | <code python> | ||
+ | regex=ur"..." #正则表达式 | ||
+ | match = re.search(regex, subject) | ||
+ | if match: | ||
+ | result = match.group("groupname") | ||
+ | else: | ||
+ | result = "" | ||
+ | </code> | ||
+ | |||
+ | ==== 7. 将字符串中所有匹配的子串放入数组中 ==== | ||
+ | (Get an array of all regex matches in a string) | ||
+ | <code python> | ||
+ | result = re.findall(regex, subject) | ||
+ | </code> | ||
+ | |||
+ | ==== 8.遍历所有匹配的子串 ==== | ||
+ | (Iterate over all matches in a string) | ||
+ | <code python> | ||
+ | for match in re.finditer(r"<(.*?)\s*.*?/\1>", subject) | ||
+ | # match start: match.start() | ||
+ | # match end (exclusive): match.end() | ||
+ | # matched text: match.group() | ||
+ | </code> | ||
+ | |||
+ | ==== 9.通过正则表达式字符串创建一个正则表达式对象 ==== | ||
+ | (Create an object to use the same regex for many operations) | ||
+ | <code python> | ||
+ | reobj = re.compile(regex) | ||
+ | </code> | ||
+ | |||
+ | ==== 10.用法1的正则表达式对象版本 ==== | ||
+ | (use regex object for if/else branch whether (part of) a string can be matched) | ||
+ | <code python> | ||
+ | reobj = re.compile(regex) | ||
+ | if reobj.search(subject): | ||
+ | do_something() | ||
+ | else: | ||
+ | do_anotherthing() | ||
+ | </code> | ||
+ | |||
+ | ==== 11.用法2的正则表达式对象版本 ==== | ||
+ | (use regex object for if/else branch whether a string can be matched entirely) | ||
+ | <code python> | ||
+ | reobj = re.compile(r"\Z") #正则表达式末尾以\Z 结束 | ||
+ | if reobj.match(subject): | ||
+ | do_something() | ||
+ | else: | ||
+ | do_anotherthing() | ||
+ | </code> | ||
+ | |||
+ | |||
+ | ==== 12.创建一个正则表达式对象,然后通过该对象获得匹配细节 ==== | ||
+ | (Create an object with details about how the regex object matches (part of) a string) | ||
+ | <code python> | ||
+ | reobj = re.compile(regex) | ||
+ | match = reobj.search(subject) | ||
+ | if match: | ||
+ | # match start: match.start() | ||
+ | # match end (exclusive): match.end() | ||
+ | # matched text: match.group() | ||
+ | do_something() | ||
+ | else: | ||
+ | do_anotherthing() | ||
+ | </code> | ||
+ | |||
+ | ==== 13.用正则表达式对象获取匹配子串 ==== | ||
+ | (Use regex object to get the part of a string matched by the regex) | ||
+ | <code python> | ||
+ | reobj = re.compile(regex) | ||
+ | match = reobj.search(subject) | ||
+ | if match: | ||
+ | result = match.group() | ||
+ | else: | ||
+ | result = "" | ||
+ | </code> | ||
+ | |||
+ | ==== 14.用正则表达式对象获取捕获组所匹配的子串 ==== | ||
+ | (Use regex object to get the part of a string matched by a capturing group) | ||
+ | <code python> | ||
+ | reobj = re.compile(regex) | ||
+ | match = reobj.search(subject) | ||
+ | if match: | ||
+ | result = match.group(1) | ||
+ | else: | ||
+ | result = "" | ||
+ | </code> | ||
+ | |||
+ | ==== 15.用正则表达式对象获取有名组所匹配的子串 ==== | ||
+ | (Use regex object to get the part of a string matched by a named group) | ||
+ | <code python> | ||
+ | reobj = re.compile(regex) | ||
+ | match = reobj.search(subject) | ||
+ | if match: | ||
+ | result = match.group("groupname") | ||
+ | else: | ||
+ | result = "" | ||
+ | </code> | ||
+ | |||
+ | ==== 16.用正则表达式对象获取所有匹配子串并放入数组 ==== | ||
+ | (Use regex object to get an array of all regex matches in a string) | ||
+ | <code python> | ||
+ | reobj = re.compile(regex) | ||
+ | result = reobj.findall(subject) | ||
+ | </code> | ||
+ | |||
+ | ==== 17.通过正则表达式对象遍历所有匹配子串 ==== | ||
+ | (Use regex object to iterate over all matches in a string) | ||
+ | <code python> | ||
+ | reobj = re.compile(regex) | ||
+ | for match in reobj.finditer(subject): | ||
+ | # match start: match.start() | ||
+ | # match end (exclusive): match.end() | ||
+ | # matched text: match.group() | ||
+ | </code> | ||
+ | |||