如何使用 Python 高效地以逆序讀取文件
以逆序讀取文件，從最後一行開始回到開頭，Python提供了一個強大的解決方案：一個反向迭代各行的生成器函數
高效的生成器解決方案：
下面的生成器函數，reverse_readline，有效率地完成了這個任務：
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()這個函數維護偏移量並從末尾開始以反向區塊讀取檔案。它以相反的順序產生行，同時處理最後一行可能有尾隨換行符的特殊情況。
要使用此生成器，只需以二進位模式開啟檔案並以相反的順序迭代各行：
for line in reverse_readline("my_file.txt"):
# Process line in reverse order以上是如何在Python中有效率地向後讀取檔案？的詳細內容。更多資訊請關注PHP中文網其他相關文章！
