view src/delta.c @ 214:f28f66faa016

Add "stateful" feature type with initial feature "last n"

Stateful feature extraction functions are functions that require state to be maintained between successive calls.  This is necessary, for example when an accumulation of values is required, or changes need to be measured over time.

The initial xtract_last_n() function accumulates the last N (single) values from *data and writes them to *result

/*
 * Copyright (C) 2012 Jamie Bullock
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 */

/* xtract_delta.c: defines functions that extract a feature as a single value from more than one input vector */

#include <math.h>

#include "../xtract/libxtract.h"

int xtract_flux(const double *data, const int N, const void *argv , double *result)
{

    /* FIX: don't be lazy -- take the lnorm of the difference vector! */
    return xtract_lnorm(data, N, argv, result);

}

int xtract_lnorm(const double *data, const int N, const void *argv , double *result)
{

    int n,
        type;

    double order;

    order = *(double *)argv;
    type = *((double *)argv+1);

    order = order > 0 ? order : 2.0;

    *result = 0.0;

    switch(type)
    {

    case XTRACT_POSITIVE_SLOPE:
        for(n = 0; n < N; n++)
        {
            if(data[n] > 0)
                *result += pow(data[n], order);
        }
        break;
    default:
        for(n = 0; n < N; n++)
            *result += pow(data[n], order);
        break;

    }

    *result = pow(*result, 1.0 / order);

    return XTRACT_SUCCESS;

}

int xtract_attack_time(const double *data, const int N, const void *argv , double *result)
{

    return XTRACT_FEATURE_NOT_IMPLEMENTED;

}

int xtract_decay_time(const double *data, const int N, const void *argv, double *result)
{

    return XTRACT_FEATURE_NOT_IMPLEMENTED;

}

int xtract_difference_vector(const double *data, const int N, const void *argv, double *result)
{

    const double *frame1,
          *frame2;

    int n;

    n = N >> 1;

    frame1 = data;
    frame2 = data + n;

    while(n--)
        result[n] = frame1[n] - frame2[n];

    return XTRACT_SUCCESS;

}