If I want to replace a pattern in the following statement structure:
cat&345;
bat &#hut;
I want to replace elements starting from & and ending before (not including ;). What is the best way to do so?
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are both of those one stringaaronman– aaronman2013-06-28 02:07:52 +00:00Commented Jun 28, 2013 at 2:07
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No, 2 separate stringsJames Hallen– James Hallen2013-06-28 02:08:48 +00:00Commented Jun 28, 2013 at 2:08
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Good question, but please show also what you have been trying :)icedwater– icedwater2013-06-28 02:09:51 +00:00Commented Jun 28, 2013 at 2:09
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4 Answers
Including or not including the & in the replacement?
>>> re.sub(r'&.*?(?=;)','REPL','cat&345;') # including
'catREPL;'
>>> re.sub(r'(?<=&).*?(?=;)','REPL','bat &#hut;') # not including
'bat &REPL;'
Explanation:
- Although not required here, use a
r'raw string'to prevent having to escape backslashes which often occur in regular expressions. .*?is a "non-greedy" match of anything, which makes the match stop at the first semicolon.(?=;)the match must be followed by a semicolon, but it is not included in the match.(?<=&)the match must be preceded by an ampersand, but it is not included in the match.
Comments
Here is a good regex
import re
result = re.sub("(?<=\\&).*(?=;)", replacementstr, searchText)
Basically this will put the replacement in between the & and the ;
Comments
Maybe go a different direction all together and use HTMLParser.unescape(). The unescape() method is undocumented, but it doesn't appear to be "internal" because it doesn't have a leading underscore.
Comments
You can use negated character classes to do this:
import re
st='''\
cat&345;
bat &#hut;'''
for line in st.splitlines():
print line
print re.sub(r'([^&]*)&[^;]*;',r'\1;',line)
