iminizinc 0.2

IPython extensions for the MiniZinc constraint modelling language

Author:

Guido Tack <[e-mail]>

homepage:

https://github.com/minizinc/iminizinc

This module provides a cell magic extension for IPython / Jupyter notebooks that lets you solve MiniZinc models.

The module requires an existing installation of MiniZinc.

Installation

You can install or upgrade this module via pip

pip install -U iminizinc

Make sure that the mzn2fzn binary as well as solver binaries (currently only fzn-gecode and mzn-cbc are supported) are on the PATH when you start the notebook server.

Basic usage

After installing the module, you have to load the extension using %load_ext iminizinc. This will enable the cell magic %%minizinc, which lets you solve MiniZinc models. Here is a simple example:

In[1]:  %load_ext iminizinc

In[2]:  n=8

In[3]:  %%minizinc

        include "globals.mzn";
        int: n;
        array[1..n] of var 1..n: queens;
        constraint all_different(queens);
        constraint all_different([queens[i]+i | i in 1..n]);
        constraint all_different([queens[i]-i | i in 1..n]);
        solve satisfy;

In[4]:  queens

Out[4]: [4, 2, 7, 3, 6, 8, 5, 1]

As you can see, the model binds variables in the environment (in this case, n) to MiniZinc parameters, and binds the variables in a solution (queens) back to Python variables.

Alternatively, you can bind the solution to a python object, like this:

In[1]:  %load_ext iminizinc

In[2]:  n=8

In[3]:  %%minizinc -o solution

        include "globals.mzn";
        int: n;
        array[1..n] of var 1..n: queens;
        constraint all_different(queens);
        constraint all_different([queens[i]+i | i in 1..n]);
        constraint all_different([queens[i]-i | i in 1..n]);
        solve satisfy;

In[4]:  solution

Out[4]: {u'queens': [4, 2, 7, 3, 6, 8, 5, 1]}

If you want to find all solutions of a satisfaction problem, or all intermediate solutions of an optimisation problem, you can use the -a flag:

In[1]:  %load_ext iminizinc

In[2]:  n=6

In[3]:  %%minizinc -a -o solutions

        include "globals.mzn";
        int: n;
        array[1..n] of var 1..n: queens;
        constraint all_different(queens);
        constraint all_different([queens[i]+i | i in 1..n]);
        constraint all_different([queens[i]-i | i in 1..n]);
        solve satisfy;

In[4]:  solutions

Out[4]: [{u'queens': [5, 3, 1, 6, 4, 2]},
         {u'queens': [4, 1, 5, 2, 6, 3]},
         {u'queens': [3, 6, 2, 5, 1, 4]},
         {u'queens': [2, 4, 6, 1, 3, 5]}]

The magic supports a number of additional options, take a look at the help using

In[1]:  %%minizinc?