我正在尝试仅在python中打印文件的前5行

Posted 2021-04-28

我只想打印文件的前5行，但是当行数大于5时，它会打印多次。这是我的代码：

numLines = 0
with open("points_sorted", "r") as f:
  for line in f:
    pointsList = line.split()
    numLines += 1
    if numLines >= 5:
      from itertools import islice
      with open("points_sorted") as myfile:
        head = list(islice(myfile, 5))
        print(head)

这是我的文件：

101 
87 M
71 Ko
55 Ko
15 Ko
15 M
0 M Ko

有人可以帮助我完成我的程序吗？

答案

您可以在满足条件后使用break语句退出循环：

numLines = 0
with open("points_sorted", "r") as f:
  for line in f:
    pointsList = line.split()
    numLines += 1
    if numLines >= 5:
      break

您也可以使用enumerate()，因此您不必手动计算行数：

with open("points_sorted", "r") as f:
  for numLines, line in enumerate(f):
    pointsList = line.split()
    if numLines >= 4: # counting now starts at 0 instead of 1
      break

另一答案

您可以通过这种方式尝试

with open("points_sorted", "r") as f:
 cnt = 5
 while(cnt > 0):
   pointsList = f.readline().split()
   cnt = cnt -1