从字母中提取Python文本 - 索引

Question

我想用 Python 从一个 txt 文件中提取一个字母的某个部分。开头和结尾由清晰的开头/结尾表达式（letter_begin / letter_end）标记。我的问题是文本的“记录”需要从 letter_begin 列表中任何项目的第一次出现开始，并在 letter_end 列表中的最后一项（+3 行缓冲区）结束。我想将输出文本写入文件。到目前为止，这是我的示例文本和代码：

sample_text = """Some random text right here 
.........
Dear Shareholders: We are pleased to provide this report to our shareholders and fellow shareholders. we thank you for your continued support.
Best regards, 
Douglas - Director


Other random text in this lines """

letter_begin = ["dear", "to our shareholders", "fellow shareholders"]
letter_end = ["best regards", "respectfully submitted", "thank you for your continued support"]

with open(filename, 'r', encoding="utf-8") as infile, open(xyz.txt, mode = 'w', encoding="utf-8") as f: 
        text = infile.read()
        lines = text.strip().split("\n")
        target_start_idx = None
        target_end_idx = None
        for index, line in enumerate(lines):
            line = line.lower()
            if any(beg in line for beg in letter_begin):
                target_start_idx = index
                continue
            if any(end in line for end in letter_end):
                target_end_idx = index + 3
                break


        if target_start_idx is not None:
            target = "\n".join(lines[target_start_idx : target_end_idx])
            f.write(str(target))

我想要的输出应该是：

output = "Dear Shareholders: We are pleased to provide this report to our shareholders and fellow shareholders. we thank you for your continued support.
    Best regards, 
    Douglas - Director

    "

Answer 1

您的循环为您提供了最后次出现的开始序列。

您应该将读取部分分成两个循环，如下所示：

with open(filename, 'r', encoding="utf-8") as infile:

    text = infile.read()
    lines = text.strip().split("\n")
    target_start_idx = None
    target_end_idx = None
    for index, line in enumerate(lines):
        line = line.lower()
        if any(beg in line for beg in letter_begin):
            target_start_idx = index
            break
    for index, line in enumerate(lines):
        if any(end in line for end in letter_end):
            target_end_idx = index + 3
            continue

这样，当出现第一次开始序列时，您退出循环。