dlibs/dlib/data_io/libsvm_io.h

// Copyright (C) 2010  Davis E. King ([email protected])
// License: Boost Software License   See LICENSE.txt for the full license.
#ifndef DLIB_LIBSVM_iO_Hh_
#define DLIB_LIBSVM_iO_Hh_

#include "libsvm_io_abstract.h"

#include <fstream>
#include <string>
#include <utility>
#include "../algs.h"
#include "../matrix.h"
#include "../string.h"
#include "../svm/sparse_vector.h"
#include <vector>

namespace dlib
{
    struct sample_data_io_error : public error
    {
        sample_data_io_error(const std::string& message): error(message) {}
    };

// ----------------------------------------------------------------------------------------

    template <typename sample_type, typename label_type, typename alloc1, typename alloc2>
    void load_libsvm_formatted_data (
        const std::string& file_name,
        std::vector<sample_type, alloc1>& samples,
        std::vector<label_type, alloc2>& labels
    )
    {
        using namespace std;
        typedef typename sample_type::value_type pair_type;
        typedef typename basic_type<typename pair_type::first_type>::type key_type;
        typedef typename pair_type::second_type value_type;

        // You must use unsigned integral key types in your sparse vectors
        COMPILE_TIME_ASSERT(is_unsigned_type<key_type>::value);

        samples.clear();
        labels.clear();

        ifstream fin(file_name.c_str());

        if (!fin)
            throw sample_data_io_error("Unable to open file " + file_name);

        string line;
        istringstream sin;
        key_type key;
        value_type value;
        label_type label;
        sample_type sample;
        long line_num = 0;
        while (fin.peek() != EOF)
        {
            ++line_num;
            getline(fin, line);

            string::size_type pos = line.find_first_not_of(" \t\r\n");

            // ignore empty lines or comment lines
            if (pos == string::npos || line[pos] == '#')
                continue;

            sin.clear();
            sin.str(line);
            sample.clear();

            sin >> label;

            if (!sin)
                throw sample_data_io_error("On line: " + cast_to_string(line_num) + ", error while reading file " + file_name );

            // eat whitespace
            sin >> ws;

            while (sin.peek() != EOF && sin.peek() != '#')
            {

                sin >> key >> ws;

                // ignore what should be a : character
                if (sin.get() != ':')
                    throw sample_data_io_error("On line: " + cast_to_string(line_num) + ", error while reading file " + file_name);

                sin >> value;

                if (sin && value != 0)
                {
                    sample.insert(sample.end(), make_pair(key, value));
                }

                sin >> ws;
            }

            samples.push_back(sample);
            labels.push_back(label);
        }

    }

// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------

    template <typename sample_type, typename alloc>
    typename enable_if<is_const_type<typename sample_type::value_type::first_type> >::type 
    fix_nonzero_indexing (
        std::vector<sample_type,alloc>& samples
    )
    {
        typedef typename sample_type::value_type pair_type;
        typedef typename basic_type<typename pair_type::first_type>::type key_type;

        if (samples.size() == 0)
            return;

        // figure out the min index value
        key_type min_idx = samples[0].begin()->first;
        for (unsigned long i = 0; i < samples.size(); ++i)
            min_idx = std::min(min_idx, samples[i].begin()->first);

        // Now adjust all the samples so that their min index value is zero.
        if (min_idx != 0)
        {
            sample_type temp;
            for (unsigned long i = 0; i < samples.size(); ++i)
            {
                // copy samples[i] into temp but make sure it has a min index of zero.
                temp.clear();
                typename sample_type::iterator j;
                for (j = samples[i].begin(); j != samples[i].end(); ++j)
                {
                    temp.insert(temp.end(), std::make_pair(j->first-min_idx, j->second));
                }

                // replace the current sample with temp.
                samples[i].swap(temp);
            }
        }
    }

// ----------------------------------------------------------------------------------------

// If the "first" values in the std::pair objects are not const then we can modify them 
// directly and that is what this version of fix_nonzero_indexing() does.
    template <typename sample_type, typename alloc>
    typename disable_if<is_const_type<typename sample_type::value_type::first_type> >::type 
    fix_nonzero_indexing (
        std::vector<sample_type,alloc>& samples
    )
    {
        typedef typename sample_type::value_type pair_type;
        typedef typename basic_type<typename pair_type::first_type>::type key_type;

        if (samples.size() == 0)
            return;

        // figure out the min index value
        key_type min_idx = samples[0].begin()->first;
        for (unsigned long i = 0; i < samples.size(); ++i)
            min_idx = std::min(min_idx, samples[i].begin()->first);

        // Now adjust all the samples so that their min index value is zero.
        if (min_idx != 0)
        {
            for (unsigned long i = 0; i < samples.size(); ++i)
            {
                typename sample_type::iterator j;
                for (j = samples[i].begin(); j != samples[i].end(); ++j)
                {
                    j->first -= min_idx;
                }
            }
        }
    }

// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------

// This is an overload for sparse vectors
    template <typename sample_type, typename label_type, typename alloc1, typename alloc2>
    typename disable_if<is_matrix<sample_type>,void>::type save_libsvm_formatted_data (
        const std::string& file_name,
        const std::vector<sample_type, alloc1>& samples,
        const std::vector<label_type, alloc2>& labels
    )
    {
        typedef typename sample_type::value_type pair_type;
        typedef typename basic_type<typename pair_type::first_type>::type key_type;

        // You must use unsigned integral key types in your sparse vectors
        COMPILE_TIME_ASSERT(is_unsigned_type<key_type>::value);

        // make sure requires clause is not broken
        DLIB_ASSERT(samples.size() == labels.size(),
            "\t void save_libsvm_formatted_data()"
            << "\n\t You have to have labels for each sample and vice versa"
            << "\n\t samples.size(): " << samples.size()
            << "\n\t labels.size():  " << labels.size()
            );


        using namespace std;
        ofstream fout(file_name.c_str());
        fout.precision(14);

        if (!fout)
            throw sample_data_io_error("Unable to open file " + file_name);

        for (unsigned long i = 0; i < samples.size(); ++i)
        {
            fout << labels[i];

            for (typename sample_type::const_iterator j = samples[i].begin(); j != samples[i].end(); ++j)
            {
                if (j->second != 0)
                    fout << " " << j->first << ":" << j->second;
            }
            fout << "\n";

            if (!fout)
                throw sample_data_io_error("Error while writing to file " + file_name);
        }

    }

// ----------------------------------------------------------------------------------------

// This is an overload for dense vectors
    template <typename sample_type, typename label_type, typename alloc1, typename alloc2>
    typename enable_if<is_matrix<sample_type>,void>::type save_libsvm_formatted_data (
        const std::string& file_name,
        const std::vector<sample_type, alloc1>& samples,
        const std::vector<label_type, alloc2>& labels
    )
    {
        // make sure requires clause is not broken
        DLIB_ASSERT(samples.size() == labels.size(),
            "\t void save_libsvm_formatted_data()"
            << "\n\t You have to have labels for each sample and vice versa"
            << "\n\t samples.size(): " << samples.size()
            << "\n\t labels.size():  " << labels.size()
            );

        using namespace std;
        ofstream fout(file_name.c_str());
        fout.precision(14);

        if (!fout)
            throw sample_data_io_error("Unable to open file " + file_name);

        for (unsigned long i = 0; i < samples.size(); ++i)
        {
            fout << labels[i];

            for (long j = 0; j < samples[i].size(); ++j)
            {
                if (samples[i](j) != 0)
                    fout << " " << j << ":" << samples[i](j);
            }
            fout << "\n";

            if (!fout)
                throw sample_data_io_error("Error while writing to file " + file_name);
        }

    }

// ----------------------------------------------------------------------------------------

}

#endif // DLIB_LIBSVM_iO_Hh_