Clarify dependencies and Python version required

[astrofrog]

I have a couple of questions regarding dependencies (in the context of package managers). First, in the SunPy docs, there are some dependencies listed (see http://www.sunpy.org/download/), but the list is not exactly the same as that in requirements.txt which is used for a pip-based install, also it is different that the one in tox.ini used by jenkins and setup.py

Could you clarify which dependencies are absolutely necessary for building and using Sunpy, as opposed to which ones are optional?

In addition, is SunPy compatible with Python 3? I noticed that configobj is in requirements.txt but I'm not sure if there is a Python 3 version available, so does this make SunPy Python 3 incompatible for now, or can it function without configobj?

[Cadair]

I think that the main block on Sunpy's python 3 compatibility is matplotlib?

[ayshih]

Okay, I've spent a lot of time this week investigating dependencies. From the current installation procedure and code inspection, packages can be divided into 3 classes:

Essential

• Binaries/scripts
  • Python
  • Git
  • Both the "quick" and "developer" installation methods require Git
  • Pip
  • Distribute
  • Not technically "essential", because pip can get by with just setuptools, but SunPy's setup.py will end up installing distribute regardless so it's unavoidable
• Modules (imported throughout SunPy)
  • NumPy
  • SciPy
  • Matplotlib
  • PyFITS
  • pandas (just sunpy.lightcurve)
  • Although pandas is not used outside of sunpy.lightcurve, SunPy will not currently import successfully without it

Recommended

• Binaries/scripts
  • OpenJPEG
• Modules (imported from localized parts of SunPy)
  • PyQt (just sunpy.gui)
  • suds (just sunpy.net.vso)
  • beautifulsoup4 (just sunpy.spectra.sources.callisto)
  • PIL (not actually directly imported)

Optional

• paver
  • Although paver develop is being used by many developers, pip install -e <sunpy path> should accomplish the same goal, so very few people really need to have paver installed
• virtualenv
• pytest
• pylint
• tox
• sphinx
• numpydoc
• ipython

Conclusion

My suggestions:

• setup.py should require only numpy, scipy, matplotlib, pyfits, and pandas. (Incidentally, pip does not currently support "extras_require".)
• tox.ini should install both "essential" and "recommended" modules, plus pytest, for proper testing by jenkins.
• requirements.txt, which I believe is only used by an explicit call such as pip install -r requirements.txt, can match either setup.py or tox.ini or even tack on the "optional" modules.

[astrofrog]

@ayshih - thanks for clarifying this. I will update the MacPorts portfile to reflect this.

[ayshih]

I have updated the list: pandas is now "essential" (rather than "recommended"). Even though it is localized to sunpy.lightcurve, it is probably too fundamental to SunPy to not be required.

I am going to go ahead and edit setup.py to remove suds and beautifulsoup4 from the requirements.

[Cadair]

Albert, has this now been wrapped up???

[Cadair]

Closed by #504