VwConditionalProbabilityTree.h

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/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * Written (W) 2012 Chiyuan Zhang
 * Copyright (C) 2012 Chiyuan Zhang
 */

#ifndef CONDITIONALPROBABILITYTREE_H__
#define CONDITIONALPROBABILITYTREE_H__

#include <map>

#include <shogun/multiclass/tree/TreeMachine.h>
#include <shogun/classifier/vw/VowpalWabbit.h>

namespace shogun
{

struct VwConditionalProbabilityTreeNodeData
{
    int32_t label;
    float64_t p_right; 

    VwConditionalProbabilityTreeNodeData():label(-1), p_right(0) {}
};

class CVwConditionalProbabilityTree: public CTreeMachine<VwConditionalProbabilityTreeNodeData>
{
public:
    typedef CTreeMachineNode<VwConditionalProbabilityTreeNodeData> node_t;

    CVwConditionalProbabilityTree(int32_t num_passes=1)
        :m_num_passes(num_passes), m_feats(NULL)
    {
    }

    virtual ~CVwConditionalProbabilityTree() {}

    virtual const char* get_name() const { return "VwConditionalProbabilityTree"; }

    void set_num_passes(int32_t num_passes)
    {
        m_num_passes = num_passes;
    }

    int32_t get_num_passes() const
    {
        return m_num_passes;
    }

    void set_features(CStreamingVwFeatures *feats)
    {
        SG_REF(feats);
        SG_UNREF(m_feats);
        m_feats = feats;
    }

    virtual CMulticlassLabels* apply_multiclass(CFeatures* data=NULL);

    virtual int32_t apply_multiclass_example(VwExample* ex);
protected:
    virtual bool train_require_labels() const { return false; }

    virtual bool train_machine(CFeatures* data);

    void train_example(VwExample *ex);

    void train_path(VwExample *ex, node_t *node);

    float64_t train_node(VwExample *ex, node_t *node);

    int32_t create_machine(VwExample *ex);

    virtual bool which_subtree(node_t *node, VwExample *ex)=0;

    void compute_conditional_probabilities(VwExample *ex);

    float64_t accumulate_conditional_probability(node_t *leaf);

    int32_t m_num_passes; 
    std::map<int32_t, node_t*> m_leaves; 
    CStreamingVwFeatures *m_feats; 
};

} /* shogun */ 

#endif /* end of include guard: CONDITIONALPROBABILITYTREE_H__ */