package liblinear;

import static liblinear.Linear.copyOf;

/**

* C is the cost of constraints violation. (we usually use 1 to 1000)

* eps is the stopping criterion. (we usually use 0.01).

*

* nr_weight, weight_label, and weight are used to change the penalty

* for some classes (If the weight for a class is not changed, it is

* set to 1). This is useful for training classifier using unbalanced

* input data or with asymmetric misclassification cost.

*

* nr_weight is the number of elements in the array weight_label and

* weight. Each weight[i] corresponds to weight_label[i], meaning that

* the penalty of class weight_label[i] is scaled by a factor of weight[i].

*

* If you do not want to change penalty for any of the classes,

* just set nr_weight to 0.

*

* *NOTE* To avoid wrong parameters, check_parameter() should be

* called before train().

*/

public final class Parameter {

double C;

/** stopping criteria */

double eps;

SolverType solverType;

double[] weight = null;

int[] weightLabel = null;

public Parameter( SolverType solverType, double C, double eps ) {

setSolverType(solverType);

setC(C);

setEps(eps);

}

public void setWeights( double[] weights, int[] weightLabels ) {

if ( weights == null ) throw new IllegalArgumentException("'weight' must not be null");

if ( weightLabels == null || weightLabels.length != weights.length )

throw new IllegalArgumentException("'weightLabels' must have same length as 'weight'");

this.weightLabel = copyOf(weightLabels, weightLabels.length);

this.weight = copyOf(weights, weights.length);

}

public int getNumWeights() {

if ( weight == null ) return 0;

return weight.length;

}

public void setC( double C ) {

if ( C <= 0 ) throw new IllegalArgumentException("C must not be <= 0");

this.C = C;

}

public void setEps( double eps ) {

if ( eps <= 0 ) throw new IllegalArgumentException("eps must not be <= 0");

this.eps = eps;

}

public void setSolverType( SolverType solverType ) {

if ( solverType == null ) throw new IllegalArgumentException("solver type must not be null");

this.solverType = solverType;

}

}