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Progress bar when copying one large file in Python?(在Python中复制一个大文件时出现进度条吗？)

转载 作者：bug小助手 更新时间：2023-10-24 22:37:47 29 4
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I want to use tqdm to display a progress bar when copying a single large file from one filepath to another.

我想使用tqdm在将单个大文件从一个文件路径复制到另一个文件路径时显示进度条。


This is not the same as showing a progress bar when copying multiple small files.

这与复制多个小文件时显示进度条不同。


更多回答
优秀答案推荐

Strategy:

战略：



  1. Determine the length of the file first so that you can tell tqdm what it is.



  2. Normally then you'd use shutil.copyfile (or shutil.copyfileobj) to actually copy the file but neither of those functions provide a way to receive updates during the copy, which we need to forward to tqdm:



    • So I created a slightly modified version of copyfileobj which supports passing an update function which is called regularly during copying.

    • Then I passed the tqdm's update method as the update function to the new copyfileobj so that it gets called regularly during the copy.




Code:

代码：


import os
from tqdm import tqdm

def copy_with_progress(source_filepath, target_filepath):
    with open(source_filepath, 'rb') as source_file:
        with open(target_filepath, 'wb') as target_file:
            source_file.seek(0, os.SEEK_END)
            file_length = source_file.tell()
            
            print(f'Copying: {source_filepath} ({file_length:n} bytes)')
            source_file.seek(0, os.SEEK_SET)
            with tqdm(total=file_length, unit='B', unit_scale=True) as progress_bar:
                copyfileobj_with_progress(
                    source_file, target_file,
                    progress_func=progress_bar.update)

# Based on shutil.copyfileobj 
_WINDOWS = os.name == 'nt'
COPY_BUFSIZE = 1024 * 1024 if _WINDOWS else 64 * 1024
def copyfileobj_with_progress(fsrc, fdst, length=0, progress_func=None):
    if not length:
        length = COPY_BUFSIZE
    if progress_func is None:
        progress_func = lambda offset: None
    
    # Localize variable access to minimize overhead.
    fsrc_read = fsrc.read
    fdst_write = fdst.write
    
    while True:
        buf = fsrc_read(length)
        if not buf:
            break
        fdst_write(buf)
        progress_func(len(buf))  # delta offset

更多回答

You could also directly retrieve the size with os.stat(), without needing to seek back and forth.

您还可以使用os.stat()直接检索大小，而不需要来回查找。

BTW, you might think about trying to correctly handle file-like objects that aren't seekable (which will be pretty much identical to the set for which stat won't give you a useful size -- FIFOs, many kinds of character devices, files in procfs, etc). Even if that just means falling back to a normal copy without a progress bar, it's better to gracefully degrade than fail outright.

顺便说一句，您可能会考虑尝试正确地处理不可查找的类似文件的对象(这将与stat不会为您提供有用大小的集合基本相同--FIFO、多种字符设备、prof中的文件等)。即使这只是意味着退回到没有进度条的正常副本，但优雅地降级也比彻底失败要好。

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