seek() a file within a zip file in Python without passing it to memory

问题

is there anyway to make a file inside a zip file seekable in Python without reading it to memory?

I tried the obvious procedure but I get an error since the file is not seekable:

In [74]: inputZipFile = zipfile.ZipFile("linear_g_LAN2A_F_3keV_1MeV_30_small.zip", 'r')

In [76]: inputCSVFile = inputZipFile.open(inputZipFile.namelist()[0], 'r')   

In [77]: inputCSVFile
Out[77]: <zipfile.ZipExtFile at 0x102f5fad0>

In [78]: inputCSVFile.se
inputCSVFile.seek      inputCSVFile.seekable  

In [78]: inputCSVFile.seek(0)
---------------------------------------------------------------------------
UnsupportedOperation                      Traceback (most recent call last)
<ipython-input-78-f1f9795b3d55> in <module>()
----> 1 inputCSVFile.seek(0)

UnsupportedOperation: seek

回答1:

There is no way to do so for all zip files. DEFLATE is a stream compression algorithm, which means that there is no way to decompress arbitrary parts of the file without having decompressed everything before it. It could possibly be implemented for files that have been stored, but then you get in the unfavorable position where some entries are seekable and others aren't.