如何仅读取特定字符串后的文本文件中的行? [英] How to only read lines in a text file after a certain string?

问题描述

我想将字典中所有在特定字符串之后的所有行都读到字典中.我想对数千个文本文件执行此操作.

I'd like to read to a dictionary all of the lines in a text file that come after a particular string. I'd like to do this over thousands of text files.

我能够使用以下代码(从此答案中获得)识别并打印出特定字符串('Abstract')):

I'm able to identify and print out the particular string ('Abstract') using the following code (gotten from this answer):

for files in filepath:
    with open(files, 'r') as f:
        for line in f:
            if 'Abstract' in line:
                print line;

但是我如何告诉Python开始读取仅在字符串之后出现的行?

But how do I tell Python to start reading the lines that only come after the string?

推荐答案

当您到达要从其开始的行时，只需开始另一个循环即可:

Just start another loop when you reach the line you want to start from:

for files in filepath:
    with open(files, 'r') as f:
        for line in f:
            if 'Abstract' in line:                
                for line in f: # now you are at the lines you want
                    # do work

文件对象是其自己的迭代器，因此当我们到达其中带有'Abstract'的行时，我们将从该行继续进行迭代，直到消耗完迭代器为止.

A file object is its own iterator, so when we reach the line with 'Abstract' in it we continue our iteration from that line until we have consumed the iterator.

一个简单的例子:

gen = (n for n in xrange(8))

for x in gen:
    if x == 3:
        print('Starting second loop')
        for x in gen:
            print('In second loop', x)
    else:
        print('In first loop', x)

产生:

In first loop 0
In first loop 1
In first loop 2
Starting second loop
In second loop 4
In second loop 5
In second loop 6
In second loop 7

您还可以使用 itertools.dropwhile 进行消费所需的线条:

You can also use itertools.dropwhile to consume the lines up to the point you want:

from itertools import dropwhile

for files in filepath:
    with open(files, 'r') as f:
        dropped = dropwhile(lambda _line: 'Abstract' not in _line, f)
        next(dropped, '')
        for line in dropped:
                print(line)

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