MinimizerOpts {EmiR}

EmiR optimization options

Description

A S4 class storing the options for the optimization algorithms in EmiR.

Slots

maximize

if TRUE the objective function is maximized instead of being minimized. Default is FALSE.

silent_mode

if TRUE no output to console is generated. Default is FALSE.

save_pop_history

if TRUE the position of all individuals in the population at each iteration is stored. This is necessary for functions like plot_population and animate_population to work. Default is FALSE.

constrained_method

method for constrained optimization. Possible values are:

• "PENALTY" - Penalty Method: the constrained problem is converted to an unconstrained one, by adding a penalty function to the objective function. The penalty function consists of a penalty parameter multiplied by a measure of violation of the constraints. The penalty parameter is multiplied by a scale factor (see penalty_scale) at every iteration;

• "BARRIER" - Barrier Method: the value of the objective function is set equal to an arbitrary large positive (or negative in case of maximization) number if any of the constraints is violated;

• "ACCREJ" - Acceptance-Rejection method: a solution violating any of the constraints is replaced by a randomly generated new one in the feasible region. Default is "PENALTY".

penalty_scale

scale factor for the penalty parameter at each iteration. It should be greater than 1. Default is 10.

start_penalty_param

initial value of the penalty parameter. It should be greater than 0. Default is 2.

max_penalty_param

maximum value for the penalty parameter. It should be greater than 0. Default is 1.e+10.

constr_init_pop

if TRUE the initial population is generated in the feasible region only. Default is TRUE.

oob_solutions

strategy to treat out-of-bound solutions. Possible values are:

• "RBC" - Reflective Boundary Condition: the solution is placed back inside the search domain at a position which is distanced from the boundary as the out-of-bound excess. Depending on the optimization algorithm, the velocity of the corresponding individual of the population could be also inverted;

• "PBC" - Periodic Boundary Condition: the solution is placed back inside the search domain at a position which is distanced from the opposite boundary as the out-of-bound excess;

• "BAB" - Back At Boundary: the solution is placed back at the boundaries for the out-of-bound dimensions;

• "DIS" - Disregard the solution: the solution is replaced by a new one, which is randomly generated in the search space. Default is "DIS".

seed

seed for the internal random number generator. Accepted values are strictly positive integers. If NULL a random seed at each execution is used. Default is NULL.

initial_population

manually specify the position of the initial population. A \(n \times d\) matrix has to be provided, where \(n\) is the population size and \(d\) is the number of parameters the objective function is minimized with respect to.