[WIP] Fix to ppm chemical shift wrapper, better tests, CI integration.

What he said.

I did do some testing with Python3 and it seemed to be Py3 incompatible.
We can possibly change this to something less restrictive later if people
have the need.


On Sun, Jul 6, 2014 at 8:01 PM, Jason Swails <notifications@github.com>
wrote:

> In MDTraj/nmr/shift_wrappers.py:
>
> > @@ -131,6 +131,9 @@ def chemical_shifts_shiftx2(trj):
> >      if binary is None:
> >          raise OSError('External command not found. Looked for %s in PATH. `chemical_shifts_shiftx2` requires the external program SHIFTX2, available at http://www.shiftx2.ca/' % ', '.join(SHIFTX2))
> >
> > +    if six.PY3:
> > +        raise(OSError("Cannot run shiftx2.py on Python 3.X"))
>
> shiftx2 is written in Python, and presumably does not work in Python 3
> (I've never tried).
>
> If mdtraj is being invoked with Python 3, it's safest to assume that's the
> default (and potentially *only*) interpreter available, even if in some
> cases it can be coerced to work.
>
> An alternative would be to change the shiftx2 command to: "python2 %s -b
> 'trj*.pdb'" % binary rather than the current version.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/rmcgibbo/mdtraj/pull/501/files#r14578583>.
>