一行，可能很快:

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

我发现你可以。

f = open("data.txt")
linecout = len(f.readlines())

会给你答案吗

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')))

这是我用的，看起来很干净:

import subprocess

def count_file_lines(file_path):
    """
    Counts the number of lines in a file using wc utility.
    :param file_path: path to file
    :return: int, no of lines
    """
    num = subprocess.check_output(['wc', '-l', file_path])
    num = num.split(' ')
    return int(num[0])

更新:这比使用纯python略快，但以内存使用为代价。子进程在执行您的命令时将派生一个与父进程具有相同内存占用的新进程。

def file_len(full_path):
  """ Count number of lines in a file."""
  f = open(full_path)
  nr_of_lines = sum(1 for line in f)
  f.close()
  return nr_of_lines

类似的:

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