我如何找到两个子字符串('123STRINGabc' -> '字符串')之间的字符串?
我现在的方法是这样的:
>>> start = 'asdf=5;'
>>> end = '123jasd'
>>> s = 'asdf=5;iwantthis123jasd'
>>> print((s.split(start))[1].split(end)[0])
iwantthis
然而，这似乎非常低效且不符合python规则。有什么更好的方法来做这样的事情吗?
忘了说: 字符串可能不是以start和end开始和结束的。他们可能会有更多的字符之前和之后。
当前回答
如果你不想导入任何东西，试试字符串方法.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)])
其他回答
这是我之前在Daniweb中发布的代码片段:
# picking up piece of string between separators
# function using partition, like partition, but drops the separators
def between(left,right,s):
before,_,a = s.partition(left)
a,_,after = a.partition(right)
return before,a,after
s = "bla bla blaa <a>data</a> lsdjfasdjöf (important notice) 'Daniweb forum' tcha tcha tchaa"
print between('<a>','</a>',s)
print between('(',')',s)
print between("'","'",s)
""" Output:
('bla bla blaa ', 'data', " lsdjfasdj\xc3\xb6f (important notice) 'Daniweb forum' tcha tcha tchaa")
('bla bla blaa <a>data</a> lsdjfasdj\xc3\xb6f ', 'important notice', " 'Daniweb forum' tcha tcha tchaa")
('bla bla blaa <a>data</a> lsdjfasdj\xc3\xb6f (important notice) ', 'Daniweb forum', ' tcha tcha tchaa')
"""
如果你不想导入任何东西，试试字符串方法.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)])
这本质上是cji的答案——7月30日10日5:58。 我更改了try except结构，以便更清楚地说明导致异常的原因。
def find_between( inputStr, firstSubstr, lastSubstr ):
'''
find between firstSubstr and lastSubstr in inputStr STARTING FROM THE LEFT
http://stackoverflow.com/questions/3368969/find-string-between-two-substrings
above also has a func that does this FROM THE RIGHT
'''
start, end = (-1,-1)
try:
start = inputStr.index( firstSubstr ) + len( firstSubstr )
except ValueError:
print ' ValueError: ',
print "firstSubstr=%s - "%( firstSubstr ),
print sys.exc_info()[1]
try:
end = inputStr.index( lastSubstr, start )
except ValueError:
print ' ValueError: ',
print "lastSubstr=%s - "%( lastSubstr ),
print sys.exc_info()[1]
return inputStr[start:end]
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" )
给:
123STRING
STRINGabc
我认为应该注意的是-根据需要的行为，您可以混合使用index和rindex调用，或者使用上述版本之一(它相当于regex(.*)和(.*?)组)。
这对我来说似乎更直接:
import re
s = 'asdf=5;iwantthis123jasd'
x= re.search('iwantthis',s)
print(s[x.start():x.end()])
