Python Regex子-使用Match作为替换中的Dict键

Python Regex子-使用Match作为替换中的Dict键

您可以传递一个callable来

re.sub

告诉它如何处理match对象。

s = re.sub(r'<(w+)>', lambda m: replacement_dict.get(m.group()), s)

dict.get

如果说的字词不在替换字典中，则使用允许您提供“备用”，即

lambda m: replacement_dict.get(m.group(), m.group()) # fallback to just leaving the word there if we don't have a replacement

我会注意到，在使用

re.sub

（和系列，即

re.split

）时，指定所需替换 周围
存在的内容时，使用环顾四周表达式通常会更干净，以免匹配周围的内容被淡化。所以在这种情况下，我会像这样写你的正则表达式

r'(?<=<)(w+)(?=>)'

否则，您必须在的括号中进行一些拼接/切入

lambda

。为了弄清楚我在说什么，举一个例子：

s = "<sometag>this is stuff<othertag>this is other stuff<closetag>"d = {'othertag': 'blah'}#this doesn't work because `group` returns the whole match, including non-groupsre.sub(r'<(w+)>', lambda m: d.get(m.group(), m.group()), s)Out[23]: '<sometag>this is stuff<othertag>this is other stuff<closetag>'#this output isn't exactly ideal...re.sub(r'<(w+)>', lambda m: d.get(m.group(1), m.group(1)), s)Out[24]: 'sometagthis is stuffblahthis is other stuffclosetag'#this works, but is ugly and hard to maintainre.sub(r'<(w+)>', lambda m: '<{}>'.format(d.get(m.group(1), m.group(1))), s)Out[26]: '<sometag>this is stuff<blah>this is other stuff<closetag>'#lookbehind/lookahead makes this nicer.re.sub(r'(?<=<)(w+)(?=>)', lambda m: d.get(m.group(), m.group()), s)Out[27]: '<sometag>this is stuff<blah>this is other stuff<closetag>'