跟踪读取的字节数 [英] Keep Track of Number of Bytes Read

问题描述

我想为我的一个程序IN PYTHON实现一个命令行进度条，该程序逐行从文件中读取文本。

I would like to implement a command line progress bar for one of my programs IN PYTHON which reads text from a file line by line.

我可以采用以下两种方式之一来实现进度表：

I can implement the progress scale in one of two ways:

1. （行数/总行数）或


2. （已完成的字节数/总字节数）

我不在乎，但是行数 似乎需要我遍历整个文档（可能很大）才能获取值总行数 。

I don't care which, but "number of lines" would seem to require me to loop through the entire document (which could be VERY large) just to get the value for "total lines".

这似乎效率很低。我在盒子外面思考，也许想想如果我考虑文件的大小（更容易获取？）并跟踪已读取的字节数，那么它可能会成为良好的进度条指标。

This seems extremely inefficient. I was thinking outside the box and thought perhaps if I took the size of the file (easier to get?) and kept track of the number of bytes that have been read, it might make for a good progress bar metric.

我可以使用 os.path.getsize（file）或 os.stat（ file）.st_size 来检索文件的大小，但是我还没有找到一种方法来跟踪 readline（）。我正在使用的文件应该以ASCII甚至是Unicode编码，所以...我应该确定使用的编码，然后记录读取的字符数或使用 os.getsizeof（）或某些 len（）函数用于读取的每一行？

I can use os.path.getsize(file) or os.stat(file).st_size to retrieve the size of the file, but I have not yet found a way to keep track of the number of bytes read by readline(). The files I am working with should be encoded in ASCII, or maybe even Unicode, so... should I just determine the encoding used and then record the number of characters read or use os.getsizeof() or some len() function for each line read?

我确信这里会出现问题。有什么建议吗？

I am sure there will be problems here. Any suggestions?

（PS-我认为手动输入一次读取的字节数不会起作用，因为我需要单独处理每一行；否则，我以后需要将其拆分为 n。）

(P.S. - I don't think manually inputting the number of bytes to read at a time will work, because I need to work with each line individually; or else I will need to split it up afterwards by "\n"'s.)

推荐答案

bytesread = 0
while True:
  line = fh.readline()
  if line == '':
    break
  bytesread += len(line)

或者，短一点：$ b​​ $ b

Or, a little shorter:

bytesread = 0
for line in fh:
  bytesread += len(line)

使用 os.path.getsize（）（或 os.stat ）是确定文件大小的有效方法。

Using os.path.getsize() (or os.stat) is an efficient way of determining the file size.

这篇关于跟踪读取的字节数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！