IPython extensions for the MiniZinc constraint modelling language
Project description
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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?
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