python - 如何在 Python 中廉价地获取大文件的行数？

Question

如何以最节省内存和时间的方式获取大文件的行数？

def file_len(filename):
    with open(filename) as f:
        for i, _ in enumerate(f):
            pass
    return i + 1

Answer 1

一行，可能很快:

num_lines = sum(1 for line in open('myfile.txt'))