python - 如何在 python 中开始和结束读取特定字符串的文件？

Question

如何开始和结束读取特定字符串的文件？

例如:

start file
some data
start point
some data
end point
some data
end file

到目前为止我的情况是:

filename = 'name of file'
with open(filename) as f:
    for line in iter(lambda: f.readline().rstrip(), 'end point'):
        print(line)

Answer 1

这实际上取决于您是否正在读取 n 行，或者读取所有行直到遇到包含子字符串的特定行。

三个例子:

# Ready file until 'end point' is encountered in a line
with open('sample.txt') as f:
  for line in f:
    # ... do things with the line
    print(line)
    if 'end point' in line:
      print('---')
      break

# Read the first 5 lines
with open('sample.txt') as f:
  lines = [next(f) for x in range(5)]
  print(lines)

# Less performant, read all lines and then slice
with open('sample.txt') as f:
  all_lines = f.readlines()
  print(lines[:5])