OpenMDAO: discrete optimization problems; how to define the set of discrete variables?

Question

I am trying to learn how to use OpenMDAO in order to solve discrete optimization problems. I saw that it was possible to define discrete variables (https://openmdao.org/newdocs/versions/latest/features/core_features/working_with_components/discrete_variables.html) but I cannot find where I can define the set of possible values that the optimizer is allowed to select.

Can you help me?

Answer 1

OpenMDAO supports using discrete variables as optimizer variables for certain optimizers that support them, but that support is limited to integer variables. You can only specify a lower and upper bound, just as you would with a continuous variable.

A relevant example can be found here, where 'xI' is a discrete variable:

https://openmdao.org/newdocs/versions/latest/features/building_blocks/drivers/genetic_algorithm.html

Note that the SimpleGADriver will also encode any continuous OpenMDAO variable as if it were an integer, if you don't set a 'bits' value for it in the driver's options.