python bijection

[MRAB]

M.-A. Lemburg wrote:
> geremy condra wrote:
>> On Thu, Dec 3, 2009 at 12:57 PM, M.-A. Lemburg <mal at egenix.com> wrote:
>>> geremy condra wrote:
>>>> On Thu, Dec 3, 2009 at 7:04 AM, M.-A. Lemburg <mal at egenix.com> wrote:
>>>>> I think the only major CS data type missing from Python is some
>>>>> form of (fast) directed graph implementation à la kjGraph:
>>>>>
>>>>>    http://gadfly.sourceforge.net/kjbuckets.html
>>>>>
>>>>> With these, you can easily build all sorts of relations between
>>>>> objects and apply fast operations on them. In fact, it should then
>>>>> be possible to build a complete relational database in Python
>>>>> (along the lines of Gadfly).
>>>> If you're in the market for a Python graph library, you may want
>>>> to check out Graphine- I'm obviously biased (I wrote most of it)
>>>> but it has a few more bells and whistles than kjbuckets, and is
>>>> pretty darned easy to use. It also supports undirected and
>>>> bridge graphs.
>>> Thanks for the hint :-)
>>>
>>> The lib looks nice and would probably serve as a good prototype
>>> for writing a new built-in type for Python.
>> I suspect that it would have a better chance at getting into
>> collections than becoming a builtin, but who knows. I'd just
>> like to have something like it in the standard library.
> 
> Integrating an easy-to-use graph library into the collections
> module (and it's C companion) is good idea.
> 
>>> This would have to be written in C, though,
>> That's currently in the works, along with database backing.
>> We'd welcome any help though... hint, hint...
>>
>>> and come under a Python compatible license.
>> I'm willing to dual license under the Python license if
>> there were a substantial interest in doing so, and I'm
>> confident that the other authors and maintainers
>> would feel the same way.
> 
> Great !
> 
>> The question in my mind is whether such an interest exists.
> 
> Since Python is being used more and more in CS classes,
> such an addition would complete the tool-set and make Python
> even more attractive for undergrad CS courses.
> 
> Finding out how much interest exists in advance is always
> a bit difficult with new data-structures. People have to
> get a feeling of how they can be put to good use first,
> so it's a chicken-and-egg problem.
> 
> We've seen the same thing happen with sets. They were first
> made available via a separate module and then became built-ins
> after people realized how useful they are in practice.
> 
I'd like to add that people (myself included) were already using dicts
for sets before the module was written, so there was already a clear
demand for them.

> With graphs, it's probably going to take a little longer
> before people realize their usefulness - graph theory is
> certainly a lot more complicated than set theory :-)
> 
>>> With the built-in feature moratorium
>>> currently in place, there's about 1.5-2 years time to get this
>>> done; perhaps a good GSoC project for next year :-)
>> I'd love to have Graphine be a GSoC project, although
>> if the target were to get it into collections the
>> moratorium wouldn't change the timeline AFAICS.
> 
> True.
>