在python中写入文件时如何跳过文本块 - python

从另一个文件写入文件时，是否可以使用python跳过文本块？

例如，假设输入文件为:

This is the file I would like to write this line
I would like to skip this line
and this one...
and this one...
and this one...
but I want to write this one
and this one...

如何编写一个脚本，使我可以跳过内容和大小不同的某些行，一旦识别出某一行，就可以继续将行写到另一个文件中？

编辑

我的代码读取这些行，不编写重复的行，并使用字典和正则表达式对该行执行一些操作。

python大神给出的解决方案

def is_wanted(line):
    #
    # You have to define this!
    #
    # return True to keep the line, or False to discard it

def copy_some_lines(infname, outfname, wanted_fn=is_wanted):
    with open(infname) as inf, open(outfname, "w") as outf:
        outf.writelines(line for line in inf if wanted_fn(line))

copy_some_lines("file_a.txt", "some_of_a.txt")

为了将其扩展到多行块，您可以实现一个有限状态机，例如

会变成类似

class BlockState:
    GOOD_BLOCK = True
    BAD_BLOCK = False

    def __init__(self):
        self.state = self.GOOD_BLOCK

    def is_bad(self, line):
        # *** Implement this! ***
        # return True if line is bad

    def is_good(self, line):
        # *** Implement this! ***
        # return True if line is good

    def __call__(self, line):
        if self.state == self.GOOD_BLOCK:
            if self.is_bad(line):
                self.state = self.BAD_BLOCK
        else:
            if self.is_good(line):
                self.state = self.GOOD_BLOCK
        return self.state

然后

copy_some_lines("file_a.txt", "some_of_a.txt", BlockState())