Python Regex使用通配符匹配字符串的开头并替换整个字符串

Question

I'm trying to match the beginning of a word and then replace the entire word with something. Below is what I'm trying to do.

add23khh234 > REMOVED
add2asdf675 > REMOVED

Below is the regex statement I'm using.

string_reg = re.sub(ur'add*', 'REMOVED', string_reg)

But this code gives me the following.

add23khh234 > REMOVED23khh234
add2asdf675 > REMOVED2asdf675  

Answer 1

add* is ad '*d' . From the document :

'*'

Causes the resulting RE to match 0 or more repetitions of the preceding RE, as many repetitions as are possible. ab* will match a , ab , or a followed by any number of b s.

So it matchs ad or add or adddddd... . But it doesn't match neither add23khh234 nor add2asdf675 (or something like these).

You should use .+? or .*? here(not .* , that's greedy). Try something like this:

string_reg = re.sub(ur'add.+? ', 'REMOVED ', string_reg)

---

Demo:

>>> import re
>>> string_reg = """\
... add23khh234 > REMOVED23khh234
... add2asdf675 > REMOVED2asdf675"""

>>> string_reg = re.sub(ur'add.+? ', 'REMOVED ', string_reg)
>>> print string_reg
REMOVED > REMOVED23khh234
REMOVED > REMOVED2asdf675
>>> 

Answer 2

尝试这个

string_reg = re.sub(ur'^add.*', 'REMOVED', string_reg)

Answer 3

如果你在一行上有多个模式

string_reg=re.sub("add[^ ]+","REMOVED",string_reg)

Answer 4

Short answer

\badd\w*

---

A quantifier such as * is applied to the previous token or subpattern. for example, the regex you're using add* matches a literal ad followed by any number of subsequent d .

Meeting your criteria

• You need to match add at the beggining of a word, so use a word boundary \\b
• Then you also need to match the rest of the word in order to replace it. \\w is a shorthand for [a-zA-Z0-9_] , which matches 1 word character, and that's what you need to repeat any number of times with * .

Code

import re

string_reg = 'add23khh234 ... add2asdf675 ... xxxadd2axxx'

string_reg = re.sub(ur'\badd\w*', 'REMOVED', string_reg)
print(string_reg)

Output

REMOVED ... REMOVED ... xxxadd2axxx

ideone demo