Question :
How do I find a string between two substrings ('123STRINGabc' -> 'STRING')?
My current method is like this:
>>> start = 'asdf=5;'
>>> end = '123jasd'
>>> s = 'asdf=5;iwantthis123jasd'
>>> print((s.split(start))[1].split(end)[0])
iwantthis
However, this seems very inefficient and un-pythonic. What is a better way to do something like this?
Forgot to mention:
The string might not start and end with start and end. They may have more characters before and after.
Answer #1:
import re
s = 'asdf=5;iwantthis123jasd'
result = re.search('asdf=5;(.*)123jasd', s)
print(result.group(1))
Answer #2:
s = "123123STRINGabcabc"
def find_between( s, first, last ):
try:
start = s.index( first ) + len( first )
end = s.index( last, start )
return s[start:end]
except ValueError:
return ""
def find_between_r( s, first, last ):
try:
start = s.rindex( first ) + len( first )
end = s.rindex( last, start )
return s[start:end]
except ValueError:
return ""
print find_between( s, "123", "abc" )
print find_between_r( s, "123", "abc" )
gives:
123STRING
STRINGabc
I thought it should be noted – depending on what behavior you need, you can mix index and rindex calls or go with one of the above versions (it’s equivalent of regex (.*) and (.*?) groups).
Answer #3:
start = 'asdf=5;'
end = '123jasd'
s = 'asdf=5;iwantthis123jasd'
print s[s.find(start)+len(start):s.rfind(end)]
gives
iwantthis
Answer #4:
s[len(start):-len(end)]
Answer #5:
String formatting adds some flexibility to what Nikolaus Gradwohl suggested. start and end can now be amended as desired.
import re
s = 'asdf=5;iwantthis123jasd'
start = 'asdf=5;'
end = '123jasd'
result = re.search('%s(.*)%s' % (start, end), s).group(1)
print(result)
Answer #6:
If you don’t want to import anything, try the string method .index():
text = 'I want to find a string between two substrings'
left = 'find a '
right = 'between two'
# Output: 'string'
print(text[text.index(left)+len(left):text.index(right)])
Answer #7:
Just converting the OP’s own solution into an answer:
def find_between(s, start, end):
return (s.split(start))[1].split(end)[0]
Answer #8:
Here is one way to do it
_,_,rest = s.partition(start)
result,_,_ = rest.partition(end)
print result
Another way using regexp
import re
print re.findall(re.escape(start)+"(.*)"+re.escape(end),s)[0]
or
print re.search(re.escape(start)+"(.*)"+re.escape(end),s).group(1)
