相关疑难解决方法(0)

我正在为Web应用程序编写一个日志文件查看器,为此我想通过日志文件的行分页.文件中的项目是基于行的,底部是最新项目.

所以我需要一种tail()方法,可以n从底部读取行并支持偏移量.我想出的是这样的:

def tail(f, n, offset=0):
    """Reads a n lines from f with an offset of offset lines."""
    avg_line_length = 74
    to_read = n + offset
    while 1:
        try:
            f.seek(-(avg_line_length * to_read), 2)
        except IOError:
            # woops.  apparently file is smaller than what we want
            # to step back, go to the beginning instead
            f.seek(0)
        pos = f.tell()
        lines = f.read().splitlines()
        if len(lines) >= to_read or pos == 0:
            return lines[-to_read:offset and -offset or None]
        avg_line_length …

如何使用python以相反的顺序读取文件？我想从最后一行到第一行读取一个文件.

我需要获取文件中前一行的值,并在迭代文件时将其与当前行进行比较.该文件是巨大的,所以我无法读取整个或随机访问行号,linecache因为库函数仍然将整个文件读入内存.

编辑我很抱歉我忘了提到我必须向后阅读文件.

EDIT2

我尝试过以下方法:

 f = open("filename", "r")
 for line in reversed(f.readlines()): # this doesn't work because there are too many lines to read into memory

 line = linecache.getline("filename", num_line) # this also doesn't work due to the same problem above.