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
字符串格式为Nikolaus Gradwohl的建议增加了一些灵活性。开始和结束现在可以根据需要进行修改。
import re
s = 'asdf=5;iwantthis123jasd'
start = 'asdf=5;'
end = '123jasd'
result = re.search('%s(.*)%s' % (start, end), s).group(1)
print(result)
其他回答
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()])
from timeit import timeit
from re import search, DOTALL
def partition_find(string, start, end):
return string.partition(start)[2].rpartition(end)[0]
def re_find(string, start, end):
# applying re.escape to start and end would be safer
return search(start + '(.*)' + end, string, DOTALL).group(1)
def index_find(string, start, end):
return string[string.find(start) + len(start):string.rfind(end)]
# The wikitext of "Alan Turing law" article form English Wikipeida
# https://en.wikipedia.org/w/index.php?title=Alan_Turing_law&action=edit&oldid=763725886
string = """..."""
start = '==Proposals=='
end = '==Rival bills=='
assert index_find(string, start, end) \
== partition_find(string, start, end) \
== re_find(string, start, end)
print('index_find', timeit(
'index_find(string, start, end)',
globals=globals(),
number=100_000,
))
print('partition_find', timeit(
'partition_find(string, start, end)',
globals=globals(),
number=100_000,
))
print('re_find', timeit(
're_find(string, start, end)',
globals=globals(),
number=100_000,
))
结果:
index_find 0.35047444528454114
partition_find 0.5327825636197754
re_find 7.552149639286381
在这个例子中，Re_find几乎比index_find慢20倍。
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')
"""
字符串格式为Nikolaus Gradwohl的建议增加了一些灵活性。开始和结束现在可以根据需要进行修改。
import re
s = 'asdf=5;iwantthis123jasd'
start = 'asdf=5;'
end = '123jasd'
result = re.search('%s(.*)%s' % (start, end), s).group(1)
print(result)
要提取STRING，请尝试:
myString = '123STRINGabc'
startString = '123'
endString = 'abc'
mySubString=myString[myString.find(startString)+len(startString):myString.find(endString)]
