如何在字符串中获得前后匹配？

Question

I want to get an after and before match in a string.

For example, using the following string:

"Hello I am Jim!"

with the search string being: "I am" , the match before the search string should be: "Hello" and the match after should be: "Jim!" .

How can I achieve this?

Answer 1

Use str.partition which does exactly this:

S.rpartition(sep) -> (head, sep, tail)

Search for the separator sep in S , starting at the end of S , and return the part before it, the separator itself, and the part after it.

So, using your example string:

before, search_str, after = "Hello I am Jim!".partition("I am ")

Now before , search_str and after are:

>>> print(before)
Hello 
>>> print(search_str)
I am
>>> print(after)
Jim!

str.partition also grabs the separator for you as the middle element in the returned tuple. If you don't require that, str.split(separator) suffices.

Answer 2

You can also use split()

>>> before, after = "Hello I am Jim!".split("I am")
>>> before
'Hello '
>>> after
' Jim!'

Answer 3

Answer is a good way to appeal, but you can also use the python string operation find the most basic operation to get the same point.

s = "Hello I am Jim!"
print s.find('I am')
for i in range(s.find('I am')):
    print s[i],
for i in range(s.find('I am')+len('I am'),len(s)):
    print s[i],

---

python team.py 
6
H e l l o     J i m !

In a variety of ways to achieve, then choose the most simple approach

Answer 4

Here is the another way:

>>> import re
>>> str1 = "Hello I am Jim!"
>>> before, after = re.split(" I am ", str1)
>>> before
'Hello'
>>> after
'Jim!'