python - 如何仅在特定字符串之后读取文本文件中的行？

Question

我想将文本文件中特定字符串之后的所有行读入字典。我想对数千个文本文件执行此操作。

我能够使用以下代码(来自 this answer )识别并打印出特定字符串('Abstract'):

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的行？

Answer 1

当你到达你想开始的行时，开始另一个循环:

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

文件对象是它自己的迭代器，所以当我们到达其中包含 'Abstract' 的行时，我们从该行继续迭代，直到我们使用了迭代器。

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消耗线到你想要的点:

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)