scipy's spilu doesn't accept some string args

[renefritze]

spilu errors out with Type Error in

        return _superlu.gstrf(N, A.nnz, A.data, A.indices, A.indptr,
>                             ilu=True, options=_options)
E       TypeError: 'str' does not support the buffer interface

passing only matrix, drop_tol=options['spilu_drop_tol'], fill_factor=options['spilu_fill_factor'] works around that issue

[sdrave]

LGTM. Has scipy an open issue for this?

[renefritze]

Nope, not even a closed one. And their tests pass for python 3.{3,4,5}.

[sdrave]

Have you tried encoding the strings to bytes before passing them to scipy?

[renefritze]

Yeah, I did. Threw a different error that I understood even less, which is why this ticket exists 😉

[sdrave]

I just checked with current scipy master: Passing permc_spec to work, only drop_rule fails. Can you confirm that with your scipy installation?

[renefritze]

Confirmed (python 3.5)

[sdrave]

Yeah, I did. Threw a different error that I understood even less, which is why this ticket exists 😉

What error message did you get? I get the following:

In [4]: scipy.sparse.linalg.spilu(A, drop_rule='basic,area'.encode('UTF-8'))
/home/stephan/.virtualenvs/pymor34/lib/python3.4/site-packages/scipy/sparse/linalg/dsolve/linsolve.py:305: SparseEfficiencyWarning: splu requires CSC matrix format
  warn('splu requires CSC matrix format', SparseEfficiencyWarning)
Writing out traceback for vim ...
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-4-98147bd99f5d> in <module>()
----> 1 scipy.sparse.linalg.spilu(A, drop_rule='basic,area'.encode('UTF-8'))

/home/stephan/.virtualenvs/pymor34/lib/python3.4/site-packages/scipy/sparse/linalg/dsolve/linsolve.py in spilu(A, drop_tol, fill_factor, drop_rule, permc_spec, diag_pivot_thresh, relax, panel_size, options)
    319         _options.update(options)
    320     return _superlu.gstrf(N, A.nnz, A.data, A.indices, A.indptr,
--> 321                           ilu=True, options=_options)
    322 
    323 

TypeError: 'str' does not support the buffer interface

so it seems the bytes are converted back to str in scipy.

[renefritze]

RIght. But then we cannot win atm, or can we?

[sdrave]

Ok, so I guess we should file a bug report ...

[renefritze]

Still happening on current scipy master and 0.18.1. Reported: scipy/scipy#6917

[renefritze]

The scipy bug has supposedly been fixed. I haven't tried yet, but I propose we wait till the next scipy release to revert the workaround and then pin >= that release in requirements.

[sdrave]

I do not think that support for theses arguments is a reason to require a newer scipy (I have never used them). What about changing the try-except to a dispatch on the scipy and Python version?

Is this already in the latest scipy release?

[renefritze]

Is this already in the latest scipy release?

The latest release is 0.18.1 from September 2016, so no.

Btw I get lots of test failures with scipy master because someone tried to parse the scipy version with this:

>               if list(map(int, scipy.version.version.split('.'))) >= [0, 14, 0]:
E               ValueError: invalid literal for int() with base 10: 'dev0+9e87f45'

Otherwise dispatching on version would be ok with me.

[sdrave]

The error should be gone due to #405 ...

[sdrave]

Has landed in SciPy 0.19. See 34daa3d.