遍历 txt 文件中的行时，如何在正则表达式触发后捕获多个后续行？

Question

I have a txt file:

This is the first line of block 1. It is always identifiable
Random
Stuff

This is the first line of block 2. It is always identifiable
Is
Always

This is the first line of block 3. It is always identifiable
In
Here!

I want to iterate through each line and look for the following code to trigger and capture a fixed amount of lines following:

for line in lines:
    match = re.compile(r'(.*)block 2.(.*)'.search(line)
    if match:
        #capture current line and the following 2 lines

After parsing the txt file, I want to return:

This is the first line of block 2
Is
Always

In my particular example, the first line of my block is always identifiable. There is a consistent row count per block. The contents of lines >= 2 will always change and cannot reliably be returned when using regex.

Answer 1

You can call the next() function to get the next element in the iterator.

def get_block2(lines):
    for line in lines:
        match = re.compile(r'(.*)block 2\n').search(line)
        if match:
            line2 = next(lines)
            line3 = next(lines)
            return line, line2, line3

Answer 2

assuming lines is an iterator, so you can just grab them from it.

block2 = re.compile(r'(.*)block 2\n')

for l in lines:
    if block2.search(l):
        res = [l, next(lines), next(lines)]
        break

print(res)

if not lines isn't an iterator, you just have to add lines = iter(lines) to the code.