Limitations on tuples

When using tuples in your models, you should be aware of various limitations.

Data types in tuples

Not all data types are allowed inside tuples. The limitations are given here.

Data types allowed in tuples

  • Primitives (int, float, string)

  • Tuples (also known as subtuples)

  • Arrays with primitive items (not string), that is: integer or float arrays

  • Sets with primitive items, that is: integer, float or string sets

Note:

Arrays and sets in tuples are not compared by content. If collections inside a tuple are modified, duplicates are not detected.

Data types not allowed in tuples

  • Sets of tuples (instances of IloTupleSet)

  • Arrays of strings, tuples, and tuple sets

  • Multidimensional arrays

Tuple indices and tuple patterns

You cannot mix tuple indexes and patterns within the declaration and the use of decision expressions. For example, these code lines raise the following error message Data not consistent for "xxx": can not mix pattern and index between declaration of dexpr and instantiation.

Do not mix tuple indices and tuple patterns in dexpr


dexpr float y[i in t] = ...;
subject to {
   forall(<a,b,c> in t) y[<a,b,c>]==...; };

dexpr float y[<a,b,c> in t] = ...;
subject to {
   forall(i in t) y[i]==...;
};

Performance and memory consumption

If you choose to label constraints in large models, use tuple indices instead of tuple patterns to avoid increasing the performance and memory cost. See Constraint labels.