Shogun Structured Output Toolbox Interface

Sketch.cpp

class CVanillaStructuredOutputMachine : public CMachine {
    // Constructor, Destructor
    CStructuredOutputMachine(
        CStructuredData* trainset,CLoss* loss,CModel* model)
    virtual ~CStructuredOutputMachine
    
    // heritable data
    CStructuredData* trainset
    CLoss* loss
    CModel* model
              
    // nice to have \dots
    // simple solution: deliver zeros or rand
    virtual vector presolver() {
        return zeros(trainset->get_dimensionality(),1)
    }

    // application specific methods
    virtual void init_op()
    virtual CResultSet compute_argmax(int index,vector w);

    // vanilla SO-SVM training
    void train() {
        init_op
        // assume diagonal regularization matrix with just one value
        lambda = C(1,1)
        w = presolver
        List results = empty
        repeat
            // amount of constraints generated so far
            lens = length(results)

            for (i=0;i<trainset->get_size);i++) {
                res = compute_argmax(i,w)
                if (res->delta+ w*res->phi_pred > 
                    max_j(results_i(j)->delta+w*results_i(j)->phi_pred) {
                    results_i->add(res)
                }
            }
            // Solve QP
        until lens&=&length(results)
    }
};


struct CResultSet {
    vector phi_example
    vector phi_pred
    double delta
}



class CStructuredData {
    // class containing the structured data, e.g. sequences,
    // trees, \dots

    int get_size()
    int get_dimensionality()
    virtual generic get_example(int i)
    virtual generic get_label(int i)
}



class CModel {
  // Containing the application specific model.
  // e.g. State model for HMM-SVM.
  
  CDeltaLoss* get_delta_func();
}


class CLoss {
    bool is_smooth
    bool is_convex
    // loss: Re -> Re^+ ?
    bool is_positive
    double calc(double x)

    // derivatives missing
}


class CDeltaLoss {
   // Application specific loss.
   double calc(generic y_sol,y_pred) 
}