How to open and read LZMA file in-memory

问题:

I have a giant file, let's call it one-csv-file.xz. It is an XZ-compressed CSV file.

How can I open and parse through the file without first decompressing it to disk? What if the file is, for example, 100 GB? Python cannot read all of that into memory at once, of course. Will it page or run out of memory?

回答1:

You can iterate through an LZMAFile object

import lzma  # python 3, try lzmaffi in python 2
with open('one-csv-file.xz') as compressed:
    with lzma.LZMAFile(compressed) as uncompressed:
        for line in uncompressed:
            do_stuff_with(line)

回答2:

You can decompress incrementally. See Compression using the LZMA Algorithm. You create an LZMADecompressor object, and then use the decompress method with successive chunks of the compressed data to get successive chunks of the uncompressed data.