Python - 在多个子字符串之间捕获多个子字符串

Question

我拥有的数据格式非常糟糕 .txt 。我试图捕捉这些开始和结束字符串之间的完整单词/句子。现在，我在一个文本中发现了大约 4 种类型的子字符串模式。我正在尝试捕获这些多个开始和结束子字符串之间的字符串。我能够正确捕获第一个字符串出现，但不能正确捕获第二个、第三个、...等。

开始和结束字符串： FOO，酒吧，酒吧，酒吧2

text = 'I do not want this FOO string1 BARS I do not want this FOO string 2 BAR I do not want this FOO string3 BAR2 I do not want this FOO string4 BARS '


snippet1 = text[text.index('FOO')+len('FOO'):text.index('BARS')] \
            if text[text.index('FOO')+len('FOO'):text.index('BARS')] else ''

snippet2 = text[text.index('FOO')+len('FOO'):text.index('BAR')] \
            if text[text.index('FOO')+len('FOO'):text.index('BAR')] else ''

snippet3 = text[text.index('FOO')+len('FOO'):text.index('BAR2')] \
            if text[text.index('FOO')+len('FOO'):text.index('BAR2')] else ''

# print(type(snippet1))
print('')
print('snippet1:',snippet1) #Output: snippet1:  string1
print('')
print('snippet2',snippet2) # Output: snippet2  string1
print('')
print('snippet3',snippet3) # Output: snippet3  string1 BARS I do not want this FOO string2 BAR I do not want this FOO string3

# How do I get this output? Is it possible to code this?
snippet1:  string1
snippet2:  string2
snippet3:  string3

Answer 1

IIUC：您可以使用regex：

import re
txt='I do not want this FOO string1 BARS I do not want this FOO string 2 BAR I do not want this FOO string3 BAR2 I do not want this FOO string4 BARS '
re.findall('FOO(.*?)BAR', txt)

会产生这样的匹配字符串列表：

[' string1 ', ' string 2 ', ' string3 ', ' string4 ']

更新匹配多个关键字：

import re
txt='I do not want this FOO string1 BARS I do not want this FOO string 2 SECTION I do not want this FOO string3 BAR2 I do not want this FOO string4 BARS'
re.findall('FOO(.*?)[BAR|SECTION]', txt)

将导致：

[' string1 ', ' string 2 ', ' string3 ', ' string4 ']

Answer 2

这样的东西就是你想要的。

def find_substrings(text, start_marker, end_marker):
    index = 0
    results = []

    while True:
        index = text.find(start_marker, index)
        if index == -1: # If the start string wasn't found then there are no more instances left in the string
            break
        index2 = text.find(end_marker, index+len(start_marker))
        if index2 == -1: # Sub string was not terminated. 
            break
        results.append(text[index+len(start_marker):index2])
        index = index2 + len(end_marker)

    return results

目前您正在使用索引（类似于 find，但如果找不到任何内容则会抛出错误），但它每次都会开始查看字符串的开头。

text = 'I do not want this FOO string1 BARS I do not want this FOO string 2 BAR I do not want this FOO string3 BAR2 I do not want this FOO string4 BARS '
find_substrings(text, "FOO ", " BAR")

将返回

['string1', 'string 2', 'string3', 'string4']