Question

I have a file like this:

1
2
3
TAB
1
2
3
TAB

I want to read the lines between TAB as blocks.

import itertools

def block_generator(file):
    with open(file) as lines:
        for line in lines:
            block = list(itertools.takewhile(lambda x: x.rstrip('\n') != '\t',
                                             lines))
            yield block

I want to use it as such:

blocks = block_generator(myfile)
for block in blocks:
    do_something(block)

The blocks i get all start with the second line like [2,3] [2,3], why?

Answer 1

Here is another approach using groupby

from itertools import groupby
def block_generator(filename):
    with open(filename) as lines:
        for pred,block in groupby(lines, "\t\n".__ne__):
            if pred:
                yield block