Question

我有一个巨大的文本文件，其中包含来自A-Z的随机字母，我想提取一些字符。棘手的部分是给出以下输入：

response.setHeader("Content-Disposition", "attachment;filename=\"" + filename + "\";");

和模式$("#" + this.divId).append('<object id="' + this.pdfObjectId + '" data="' + yourserver + path + file+'" type="application/pdf" width="768" height="1024"></object>');，我想提取每个匹配项，直到字符串末尾。我想要以下输出：

response.setStatus(HttpServletResponse.SC_OK);
response.setHeader("pragma", "no-cache");
response.setContentType("application/pdf");

Answer 1

您可以使用str.find()查找出现模式的索引。然后，您可以相应地对字符串进行切片。一个实现可能看起来像这样：

def find(inp, what):
  matches = []
  while what in inp:
    idx = inp.find(what)
    matches.append(inp[idx:])
    # remove the previous pattern from the string
    inp = inp[idx+len(what):]

  return matches

您可以将其与find("AFVAJFLDVAJPQDVAJDSNJKVAJGHD", "VAJ")一起使用。

Answer 2

这要求具有子组匹配的正则表达式。（https://docs.python.org/3.5/library/re.html#match-objects）

我的测试文件data.txt：

QWEEEFVAJFLDVAJPQDVAJDSNJKVAJGHD
AFVAJFLDVAJPQDVAJDSNJKHFGHERQWFS
ONLY_TWO_VAJsOOVAJ123VAQQWERTY
START_VAJs_with_more_VAJ123VAJ_space_between
AAPVAJRCGVAJJKYVAJJJJJJJJVAJOOOO
AAPVAJRCGVAJJKYVAJJJJJJJJQQQOOOOO

Python代码：

import re

pattern = "VAJ"

re_str = pattern + "..." + "(" + pattern + "..." +"(" +  pattern + "(.*)))"
regex = re.compile(re_str)

regex_extra = re.compile(pattern + ".*")

for line in open("data.txt"):
    line = line.strip()
    match = regex.search(line)
    if match:
        result = list()
        result.append(match.group(0))   # entire regex match
        result.append(match.group(1))   # outer regex parenthesis'ed group
        result.append(match.group(2))   # middle regex parenthesis'ed group

        # Most inner regex parenthesis'ed group contains rest of the line.
        # Use this to find extra pattern.
        #
        the_rest = match.group(3)
        match_extra = regex_extra.search(the_rest)
        if match_extra:   # If one more <pattern> in the rest of the line
            result.append(match_extra.group(0))   # add it to the result list

        # Output         
        print(result)

输出：

['VAJFLDVAJPQDVAJDSNJKVAJGHD', 'VAJPQDVAJDSNJKVAJGHD', 'VAJDSNJKVAJGHD', 'VAJGHD']
['VAJFLDVAJPQDVAJDSNJKHFGHERQWFS', 'VAJPQDVAJDSNJKHFGHERQWFS', 'VAJDSNJKHFGHERQWFS']
['VAJRCGVAJJKYVAJJJJJJJJVAJOOOO', 'VAJJKYVAJJJJJJJJVAJOOOO', 'VAJJJJJJJJVAJOOOO', 'VAJOOOO']
['VAJRCGVAJJKYVAJJJJJJJJQQQOOOOO', 'VAJJKYVAJJJJJJJJQQQOOOOO', 'VAJJJJJJJJQQQOOOOO']

此代码的文件大小不是问题，只要最长的行在内存中适合几次，就可以了。

如何从巨大的txt文件中提取模式

2 个答案: