在python中按一定顺序查找子字符串

Question

我有一长串字符串，它们按给出的顺序包含感兴趣的子字符串，但这里有一个在文本文件中使用句子的小示例：

This is a long drawn out sentence needed to emphasize a topic I am trying to learn.
It is new idea for me and I need your help with it please!
Thank you so much in advance, I really appreciate it.

从这个文本文件中，我想找到任何同时包含“I”和“need”的句子，但它们必须按该顺序出现。

所以在这个例子中，'I'和'需要'都出现在句子1和句子2中，但是在句子1中它们的顺序不对，所以我不想返回。我只想返回第二句，因为它的顺序是'我需要'。

我用这个例子来识别子字符串，但是我不知道如何按顺序找到它们:

id1 = "I"
id2 = "need"

with open('fun.txt') as f:
    for line in f:
        if id1 and id2 in line:
            print(line[:-1])

这将返回：

This is a long drawn out sentence needed to emphasize a topic I am trying to learn.
It is new idea for me and I need your help with it please!

但我只想要:

It is new idea for me and I need your help with it please!

谢谢你！

Answer 1

就这样吧

  import re
  match = re.match('pattern','yourString' )

https://developers.google.com/edu/python/regular-expressions

所以你正在寻找的模式是'I（.*）需要' 正则表达式 匹配两个字符串之间的所有字符 您可能必须以不同的方式构建模式，因为我不知道是否有例外。如果是这样，您可以运行正则表达式两次以获取原始字符串的子集，然后再次运行以获得所需的完全匹配项

Answer 2

您可以使用正则表达式来检查这一点。一种可能的解决方案是这样的：

id1 = "I"
id2 = "need"
regex = re.compile(r'^.*{}.*{}.*$'.format(id1, id2))

with open('fun.txt') as f:
    for line in f:
        if re.search(regex, line):
            print(line[:-1])

Answer 3

您需要在 id1 之后的行部分中标识 id2：

infile = [
    "This is a long drawn out sentence needed to emphasize a topic I am trying to learn.",
    "It is new idea for me and I need your help with it please!",
    "Thank you so much in advance, I really appreciate it.",
]

id1 = "I"
id2 = "need"

for line in infile:
    if id1 in line:
        pos1 = line.index(id1)
        if id2 in line[pos1+len(id1) :] :
            print(line)

输出：

It is new idea for me and I need your help with it please!