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IPython extensions for the MiniZinc constraint modelling language

Project description

Author: Guido Tack <guido.tack@monash.edu>
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;
Out[3]: {u'queens': [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 returns an object with fields for all declared decision variables.

Alternatively, you can bind the decision variables to Python variables:

In[1]:  %load_ext iminizinc

In[2]:  n=8

In[3]:  %%minizinc -m bind

        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]

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

        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;

Out[3]: [{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?

Project details


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Filename, size & hash SHA256 hash help File type Python version Upload date
iminizinc-0.3.tar.gz (11.5 kB) Copy SHA256 hash SHA256 Source None Mar 12, 2018

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