damina::LibsvmFileLoader Class Reference

Implements a specific file loader for LibSVM structures. More...

#include <LibsvmFileLoader.h>

Collaboration diagram for damina::LibsvmFileLoader:

[legend]List of all members.

Public Member Functions
	LibsvmFileLoader (string)
	Constructor.
svm_problem *	load (bool, string)
svm_problem *	load (bool)
	Loads the data from file in LibSVM format.
virtual	~LibsvmFileLoader ()
	Destructor.
Private Attributes
string	filename
	Absolute pathname.

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Detailed Description

Implements a specific file loader for LibSVM structures.

This class loads data from file in libsvm format and returns them encapsulated in the svm_problem structure from LibSVM.

Author:

Vincenzo Russo - vincenzo.russo@neminis.org

Definition at line 20 of file LibsvmFileLoader.h.

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Constructor & Destructor Documentation

damina::LibsvmFileLoader::LibsvmFileLoader

(

string

s

)

Constructor.

Parameters:

s

The absolute pathname for the file to load

Definition at line 12 of file LibsvmFileLoader.cpp.

References filename.

                                                   {
                this->filename = s;
        }

damina::LibsvmFileLoader::~LibsvmFileLoader

(

)

[virtual]

Destructor.

Definition at line 20 of file LibsvmFileLoader.cpp.

                                            {
        }

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Member Function Documentation

struct svm_problem * damina::LibsvmFileLoader::load	(	bool	,
		string
	)			[read]

Definition at line 124 of file LibsvmFileLoader.cpp.

References filename, and load().

                                                                                   {
                this->filename = s;
                return load(precomputedKernel);
        }

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struct svm_problem * damina::LibsvmFileLoader::load

(

bool

precomputedKernel

)

[read]

Loads the data from file in LibSVM format.

Returns:

The svm_problem structure encapsulanting the loaded data

Definition at line 29 of file LibsvmFileLoader.cpp.

Referenced by load().

                                                                         {
                int elements, max_index, i, j;
                FILE *fp = fopen(this->filename.c_str(),"r");
                struct svm_problem *prob = (struct svm_problem *) malloc(sizeof(struct svm_problem));
                
                if (fp == NULL) {
                        fprintf(stderr, "can't open input file %s\n", this->filename.c_str());
                        fprintf(stderr, "reading from standard input...");
                        fp = stdin;
                        //return NULL;
                }
        
                prob->l = 0;
                elements = 0;
                while(1)
                {
                        int c = fgetc(fp);
                        switch(c)
                        {
                                case '\n':
                                        ++(prob->l);
                                        // fall through,
                                        // count the '-1' element
                                case ':':
                                        ++elements;
                                        break;
                                case EOF:
                                        goto out;
                                default:
                                        ;
                        }
                }
        out:
                rewind(fp);
        
                prob->y = (double *) malloc(sizeof(double) * prob->l);
                prob->x = (struct svm_node **) malloc(sizeof(struct svm_node*) * prob->l);
                struct svm_node *x_space = (struct svm_node *) malloc(sizeof(struct svm_node) * elements);
        
                max_index = 0;
                j=0;
                for(i=0;i<prob->l;i++)
                {
                        double label;
                        prob->x[i] = &x_space[j];
                        fscanf(fp,"%lf",&label);
                        prob->y[i] = label;
        
                        while(1)
                        {
                                int c;
                                do {
                                        c = getc(fp);
                                        if(c=='\n') goto out2;
                                } while(isspace(c));
                                ungetc(c,fp);
                                if (fscanf(fp,"%d:%lf",&(x_space[j].index),&(x_space[j].value)) < 2)
                                {
                                        fprintf(stderr,"Wrong input format at line %d\n", i+1);
                                        return NULL;
                                }
                                ++j;
                        }       
        out2:
                        if(j>=1 && x_space[j-1].index > max_index)
                                max_index = x_space[j-1].index;
                        x_space[j++].index = -1;
                }
                
                
        
//              if(param->gamma == 0)
//                      param->gamma = 1.0/max_index; //max_index is the number of attributes in the input data.
//      
                if (precomputedKernel) {
                        for (i = 0; i < prob->l; i++)
                        {
                                if (prob->x[i][0].index != 0)
                                {
                                        fprintf(stderr,"Wrong input format: first column must be 0:sample_serial_number\n");
                                        return NULL;
                                }
                                if ((int)prob->x[i][0].value <= 0 || (int)prob->x[i][0].value > max_index)
                                {
                                        fprintf(stderr,"Wrong input format: sample_serial_number out of range\n");
                                        return NULL;
                                }
                        }
                }
        
                fclose(fp);
                
                return prob;
        }

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Member Data Documentation

string damina::LibsvmFileLoader::filename [private]

Absolute pathname.

Definition at line 26 of file LibsvmFileLoader.h.

Referenced by LibsvmFileLoader(), and load().

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The documentation for this class was generated from the following files:

• LibsvmFileLoader.h
• LibsvmFileLoader.cpp

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