在Python 中以相反順序讀取檔案
如果您正在處理一個大檔案並且需要從最後一個讀取其內容首先，Python 的內建函數可能不適合。這是解決此任務的有效解決方案：
反向行讀取器產生器
以下程式碼定義了一個產生器函數，reverse_readline，它反向生成文件的行命令。它使用基於緩衝區的方法來優化效能並有效處理大型檔案：
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：
要使用此產生器，您只需迭代它即可在for 循環中：
for line in reverse_readline('myfile.txt'):
print(line)這將以相反的順序列印檔案的行。
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