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minizinc

Initialize only certain elements of array in dzn file


I'm messing arround with minizinc and I want to have a static mzn file where I make the solving using only the dzn. For a better understanding of the question, here's a sample:

include "globals.mzn";
include "data.dzn";
int: time;
int: n;
int: l=n*n;
array[1..4,0..time,1..l] of var bool: X;
solve satisfy;

I now want to initialize only few elements of X using the dzn file (the other elements should be vars).

The dzn would look like this

time=1;
n=3;
X[4,1,7]=true;

Since this initialization is impossible, I also tried using X=array3d(1..4,0..time,1..l,[false,...,false] where every element other than the element in position (4,1,7) is false. However this initializes every element and I cannot obtain the result I wish since it cannot satisfy the constraints I have.

Is there a way to initialize only one or some elements of this array using the dzn file?


Solution

  • One way to do this is to use the anonymous variable (_) in the data matrix in the dzn file. Here is a simple example:

    % mzn file 
    include "data.dzn";
    int: time;
    int: n;
    array[1..time,1..n] of var bool: X;
    solve satisfy;
    

    And the data file:

    % data.dzn
    time=3;
    n=2;
    X = array2d(1..3,1..2,
       [_,_,
       _,_,
       _,false
       ]);
    

    Note that this approach requires at least one non-anonymous value, otherwise this message is thrown: array literal must contain at least one non-anonymous variable.