在 Python 中以相反顺序读取文件
如果您正在处理一个大文件并且需要从最后一个读取其内容首先，Python 的内置函数可能不适合。这是解决此任务的有效解决方案：
反向行读取器生成器
以下代码定义了一个生成器函数，reverse_readline，它反向生成文件的行命令。它使用基于缓冲区的方法来优化性能并有效处理大文件：
import os
def reverse_readline(filename, buf_size=8192):
"""A generator that returns the lines of a file in reverse order"""
with open(filename, 'rb') as fh:
segment = None
offset = 0
fh.seek(0, os.SEEK_END)
file_size = remaining_size = fh.tell()
while remaining_size > 0:
offset = min(file_size, offset + buf_size)
fh.seek(file_size - offset)
buffer = fh.read(min(remaining_size, buf_size))
# remove file's last "\n" if it exists, only for the first buffer
if remaining_size == file_size and buffer[-1] == ord('\n'):
buffer = buffer[:-1]
remaining_size -= buf_size
lines = buffer.split('\n'.encode())
# append last chunk's segment to this chunk's last line
if segment is not None:
lines[-1] += segment
segment = lines[0]
lines = lines[1:]
# yield lines in this chunk except the segment
for line in reversed(lines):
# only decode on a parsed line, to avoid utf-8 decode error
yield line.decode()
# Don't yield None if the file was empty
if segment is not None:
yield segment.decode()用法：
要使用此生成器，您只需迭代它即可在 for 循环中：
for line in reverse_readline('myfile.txt'):
print(line)这将以相反的顺序打印文件的行。
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