如何在string.replace中input正则expression式？
我需要一些关于声明正则expression式的帮助。 我的input如下所示：
this is a paragraph with<[1> in between</[1> and then there are cases ... where the<[99> number ranges from 1-100</[99>. and there are many other lines in the txt files with<[3> such tags </[3> 所需的输出是：
this is a paragraph with in between and then there are cases ... where the number ranges from 1-100. and there are many other lines in the txt files with such tags
我试过这个：
#!/usr/bin/python import os, sys, re, glob for infile in glob.glob(os.path.join(os.getcwd(), '*.txt')): for line in reader: line2 = line.replace('<[1> ', '') line = line2.replace('</[1> ', '') line2 = line.replace('<[1>', '') line = line2.replace('</[1>', '') print line
我也试过这个（但似乎我使用错误的正则expression式语法）：
line2 = line.replace('<[*> ', '') line = line2.replace('</[*> ', '') line2 = line.replace('<[*>', '') line = line2.replace('</[*>', '')
我不想硬编码replace从1到99。 。 。
这个testing片段应该这样做：
import re line = re.sub(r"</?\[\d+>", "", line)
编辑：这是一个注释版本，解释它是如何工作的：
line = re.sub(r""" (?x) # Use free-spacing mode. < # Match a literal '<' /? # Optionally match a '/' \[ # Match a literal '[' \d+ # Match one or more digits > # Match a literal '>' """, "", line)
正则expression式很有趣！ 但我强烈build议花一两个小时来学习基础知识。 对于初学者来说，你需要知道哪些字符是特殊的：需要转义的“元字符” （即在前面放置一个反斜杠 – 规则在字符类内部和外部是不同的）。有一个很好的在线教程： www .regular-expressions.info 。 你花在那里的时间会多次为自己付出。 快乐的regexing！
str.replace()做了固定的replace。 使用re.sub()来代替。
我会这样去（正则expression式在评论中解释）：
import re # If you need to use the regex more than once it is suggested to compile it. pattern = re.compile(r"</{0,}\[\d+>") # <\/{0,}\[\d+> # # Match the character “<” literally «<» # Match the character “/” literally «\/{0,}» # Between zero and unlimited times, as many times as possible, giving back as needed (greedy) «{0,}» # Match the character “[” literally «\[» # Match a single digit 0..9 «\d+» # Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+» # Match the character “>” literally «>» subject = """this is a paragraph with<[1> in between</[1> and then there are cases ... where the<[99> number ranges from 1-100</[99>. and there are many other lines in the txt files with<[3> such tags </[3>""" result = pattern.sub("", subject) print(result)
如果你想了解更多关于正则expression式，我build议阅读Jan Goyvaerts和Steven Levithan的正则expression式食谱 。
最简单的方法
import re txt='this is a paragraph with<[1> in between</[1> and then there are cases ... where the<[99> number ranges from 1-100</[99>. and there are many other lines in the txt files with<[3> such tags </[3>' out = re.sub("(<[^>]+>)", '', txt) print out
string对象的replace方法不接受正则expression式，只接受固定string（参见文档： http : //docs.python.org/2/library/stdtypes.html#str.replace ）。
你必须使用re模块：
import re newline= re.sub("<\/?\[[0-9]+>", "", line)
不必使用正则expression式（对于您的示例string）
>>> s 'this is a paragraph with<[1> in between</[1> and then there are cases ... where the<[99> number ranges from 1-100</[99>. \nand there are many other lines in the txt files\nwith<[3> such tags </[3>\n' >>> for w in s.split(">"): ... if "<" in w: ... print w.split("<")[0] ... this is a paragraph with in between and then there are cases ... where the number ranges from 1-100 . and there are many other lines in the txt files with such tags
