Count the number of line in a file. Useful for large file that cannot fit in memory.

count_line_file.py

from itertools import takewhile, repeat

def rawincount(filepath:str) -> int:
    f = open(filepath, 'rb')
    bufgen = takewhile(lambda x: x, (f.raw.read(1024*1024) for _ in repeat(None)))
    return sum(buf.count(b'\n') for buf in bufgen)