Pulp + SCIP?

[kretch]

Hi There

Thanks for the great library- I've been using it successfully with
GLPK. Since I have a lot of mixed-integer problems and cannot afford
Gurobi, I'm interested in finding out whether there's a PULP-SCIP
connector?
If not, how difficult is it to put one together?

Thanks
Kretch

[Stuart Mitchell]

On Wed, Dec 21, 2011 at 9:05 PM, kretch <yaronkr...@gmail.com> wrote:
> Hi There
>
> Thanks for the great library- I've been using it successfully with
> GLPK.

Thanks the default PULP_CBC_CMD solver will be faster though.

> Since I have a lot of mixed-integer problems and cannot afford
> Gurobi, I'm interested in finding out whether there's a PULP-SCIP
> connector?

There is not one though it should be easy to put one together based on
the CPLEX_CMD solver (both use an interactive shell)

However, SCIP is free only for academic use so you might as well get
an academic version of Gurobi and solve with that.

Stu

--
Stuart Mitchell
PhD Engineering Science
Freelance Programmer and Optimisation Expert
www.stuartmitchell.com

[Christophe-Marie Duquesne]

Hi,

No, there is no pulp-scip connector.

Writing a pulp-scip connector should not be very hard, provided there
is a good python binding available. I see at least one binding here (I
don't know if there are more):
https://code.google.com/p/python-zibopt/

Should you write a patch to add support for scip, here are some
instructions to quickly get started:

Connectors are in the file src/pulp/solvers.py:
https://code.google.com/p/pulp-or/source/browse/src/pulp/solvers.py.
If you want to write your own connector, you should have a look at the
class GUROBI, which is the inspiration for connecting pulp to
bindings. If scip has a command line solver that can read mps files,
it could be a good idea to also write a class to use it as a fall back
(then I would advise to get inspiration from GLPK_CMD, but maybe
Stuart has a comment for that). For testing, just add your new solver
in the function pulpTestAll of the file src/pulp/pulp.py and run the
file pulp.py.

I hope that helps,

Cheers,
Christophe-Marie

[Shawn Helm]

Hi

Just to add to what Christophe-Marie said, besides Zibopt here are two other python projects that connect to SCIP.  Maybe they would be useful examples for using SCIP with Pulp OR.

Sage Math : http://trac.sagemath.org/sage_trac/ticket/10879
Numberjack: http://4c110.ucc.ie/numberjack/node/38

Shawn

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