[SciPy-Dev] removing pure python KDTree implementation

[Ralf Gommers]

On Sun, Feb 21, 2016 at 2:41 PM, Sturla Molden <sturla.molden at gmail.com>
wrote:

> Ralf Gommers <ralf.gommers at gmail.com> wrote:
> > Hi all,
> >
> > For a long time we've had both a Python (KDTree) and a Cython/C++
> (cKDTree)
> > version of a k-d tree structure in scipy.spatial. The cKDTree version
> > reached feature-parity with KDTree in 0.12.0, and new features are being
> > added regularly now. So keeping the orders of magnitude slower pure
> Python
> > version seems to be a bit pointless - only adds to a maintenance burden
> and
> > to giving users an unnecessary choice to make.
> >
> > So proposal: remove the pure Python code and make KDTree an alias for
> > cKDTree. This can be done straight away.
> >
> > For the future it may also be desirable to get rid of the duplicate name.
> > The issue then is which one to keep. KDTree is nicer, but it would
> require
> > users who have picked the fast version now to change their code. So maybe
> > just deprecate one in documentation, but keep both names working?
>
>
> What about this?
>
> 1. make KDTree an alias for cKDTree
> 2. make KDTreeNode an alias for cKDTreeNode
> 3. keep all names working
> 4. only have KDTree and KDTreeNode in the documentation
> 5. keep kdtree.py for the test suite, but do not export its contents
>

That sounds good to me. Keeping the Python version as a fancy test class
may be useful.

The only thing that we should probably provide is a robust version
comparator (anyway a good idea), so users can write this in a robust way:

     if scipy_version >= (0, 18, 0):
         KDTree()
     else:
         cKDTree()

 Ralf
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