凯尔的回答

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

最好的替代方案是什么

num_lines =  len(open('my_file.txt').read().splitlines())

这里是两者的性能比较

In [20]: timeit sum(1 for line in open('Charts.ipynb'))
100000 loops, best of 3: 9.79 µs per loop

In [21]: timeit len(open('Charts.ipynb').read().splitlines())
100000 loops, best of 3: 12 µs per loop

这段代码更短、更清晰。这可能是最好的方法:

num_lines = open('yourfile.ext').read().count('\n')

计数= max(开放(文件))[0]

def line_count(path):
    count = 0
    with open(path) as lines:
        for count, l in enumerate(lines, start=1):
            pass
    return count

类似的:

lines = 0
with open(path) as f:
    for line in f:
        lines += 1

简单的方法:

1)

>>> f = len(open("myfile.txt").readlines())
>>> f

430

>>> f = open("myfile.txt").read().count('\n')
>>> f
430
>>>

num_lines = len(list(open('myfile.txt')))