Find a conda-only solution for eidl

[haasad]

Currently a manual installation of 7zip is required to use eidl. It would be way more convenient to have an 7z-capable unarchive program installed via conda. This would also make it possible to include eidl as a dependency to bw2io to use eidl directly via brightway.

Options:

• libarchive:
  • since around two months libarchive is available for all three major OS on the official anaconda channel (windows was missing before)
  • the only python wrapper for libarchive that I could get to work is python-libarchive-c
  • libarchive-c works fine on linux, but fails to extract a 7z archive on windows, I get the error message described here
• 7zip conda package:
  • while there is no conda channel that provides 7zip/p7zip for all OSs, there appears to be at least one example for every OS
  • would need to package these myself and test on all OS, otherwise the channel requirements for brightway get out of hand

ping @cmutel, picking up from our email conversation from some weeks ago

[cmutel]

I have also been looking at this, and have played around a bit with libarchive, but without any progress. Unfortunately, 7zip seems to compress ecoinvent particularly well - I tried different compression levels with zip, bz2, and gz. I don't have the exact numbers, but think that 7zip for 3.4 cutoff is around 70 MB, and the best alternative, bz2 was around 110 MB. Still might be worth asking if ecoinvent would post .tar.bz2, this would allow the use of the standard lib.

Maybe you already do this, but I would save the compressed archive in a system directory (using appdirs) to avoid downloading more than once.

[haasad]

I created https://github.com/haasad/eidl7zip to solve this issue. I provides a command-line version of the 7zip program for all three OSs. I'll make a PR for bw2io when I find the time, @cmutel.