How to compute the progress of a download given the chunk number, its size and the total size of the download?

Python's urllib.request.urlretrieve() accepts a function that will be called when each chunk is fetched from the network.

The function is called with three arguments: a progressive identifier of the chunk, its size and the total size of the download.

Given those three information can I compute the number of bytes already fetched? This will be used to compute the progress of the download.

I'm tempted to do chunk_number * chunk_size / download_size, but I'm not sure the chunk size is constant for all the chunks.

Solution

You can keep a running total of all the sizes you've seen so far.

Try this:

import urllib.request


def my_downloader(url, filename = None):
    running_total = 0
    def my_reporthook(count, size, total):
        nonlocal running_total
        running_total += size
        print ("{}%".format(100*running_total//total))
    return urllib.request.urlretrieve(url, filename, my_reporthook)

print (my_downloader('https://www.gutenberg.org/files/55146/55146-h.zip'))