source: src/spectral/statistics.c @ 6bbdcff

/*
  Copyright (C) 2007-2009 Paul Brossier <piem@aubio.org>

  This file is part of aubio.

  aubio 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.

  aubio is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with aubio.  If not, see <http://www.gnu.org/licenses/>.

*/

#include "aubio_priv.h"
#include "cvec.h"
#include "spectral/specdesc.h"

smpl_t
cvec_sum (cvec_t * s)
{
  uint_t j;
  smpl_t tmp = 0.0;
  for (j = 0; j < s->length; j++) {
    tmp += s->norm[j];
  }
  return tmp;
}

smpl_t
cvec_mean (cvec_t * s)
{
  return cvec_sum (s) / (smpl_t) (s->length);
}

smpl_t
cvec_centroid (cvec_t * spec)
{
  smpl_t sum = 0., sc = 0.;
  uint_t j;
  sum = cvec_sum (spec); 
  if (sum == 0.) {
    return 0.;
  } else {
    for (j = 0; j < spec->length; j++) {
      sc += (smpl_t) j *spec->norm[j];
    }
    return sc / sum;
  }
}

smpl_t
cvec_moment (cvec_t * spec, uint_t order)
{
  smpl_t sum = 0., centroid = 0., sc = 0.;
  uint_t j;
  sum = cvec_sum (spec); 
  if (sum == 0.) {
    return 0.;
  } else {
    centroid = cvec_centroid (spec);
    for (j = 0; j < spec->length; j++) {
      sc += (smpl_t) POW(j - centroid, order) * spec->norm[j];
    }
    return sc / sum;
  }
}

void
aubio_specdesc_centroid (aubio_specdesc_t * o UNUSED, cvec_t * spec,
    fvec_t * desc)
{
  desc->data[0] = cvec_centroid (spec); 
}

void
aubio_specdesc_spread (aubio_specdesc_t * o UNUSED, cvec_t * spec,
    fvec_t * desc)
{
  desc->data[0] = cvec_moment (spec, 2);
}

void
aubio_specdesc_skewness (aubio_specdesc_t * o UNUSED, cvec_t * spec,
    fvec_t * desc)
{
  smpl_t spread;
  spread = cvec_moment (spec, 2);
  if (spread == 0) {
    desc->data[0] = 0.;
  } else {
    desc->data[0] = cvec_moment (spec, 3);
    desc->data[0] /= POW ( SQRT (spread), 3);
  }
}

void
aubio_specdesc_kurtosis (aubio_specdesc_t * o UNUSED, cvec_t * spec,
    fvec_t * desc)
{
  smpl_t spread;
  spread = cvec_moment (spec, 2);
  if (spread == 0) {
    desc->data[0] = 0.;
  } else {
    desc->data[0] = cvec_moment (spec, 4);
    desc->data[0] /= SQR (spread);
  }
}

void
aubio_specdesc_slope (aubio_specdesc_t * o UNUSED, cvec_t * spec,
    fvec_t * desc)
{
  uint_t j;
  smpl_t norm = 0, sum = 0.; 
  // compute N * sum(j**2) - sum(j)**2
  for (j = 0; j < spec->length; j++) {
    norm += j*j;
  }
  norm *= spec->length;
  // sum_0^N(j) = length * (length + 1) / 2
  norm -= SQR( (spec->length) * (spec->length - 1.) / 2. );
  sum = cvec_sum (spec); 
  desc->data[0] = 0.;
  if (sum == 0.) {
    return; 
  } else {
    for (j = 0; j < spec->length; j++) {
      desc->data[0] += j * spec->norm[j]; 
    }
    desc->data[0] *= spec->length;
    desc->data[0] -= sum * spec->length * (spec->length - 1) / 2.;
    desc->data[0] /= norm;
    desc->data[0] /= sum;
  }
}

void
aubio_specdesc_decrease (aubio_specdesc_t *o UNUSED, cvec_t * spec,
    fvec_t * desc)
{
  uint_t j; smpl_t sum;
  sum = cvec_sum (spec); 
  desc->data[0] = 0;
  if (sum == 0.) {
    return;
  } else {
    sum -= spec->norm[0];
    for (j = 1; j < spec->length; j++) {
      desc->data[0] += (spec->norm[j] - spec->norm[0]) / j;
    }
    desc->data[0] /= sum;
  }
}

void
aubio_specdesc_rolloff (aubio_specdesc_t *o UNUSED, cvec_t * spec,
    fvec_t *desc)
{
  uint_t j; smpl_t cumsum, rollsum;
  cumsum = 0.; rollsum = 0.;
  for (j = 0; j < spec->length; j++) {
    cumsum += SQR (spec->norm[j]);
  }
  if (cumsum == 0) {
    desc->data[0] = 0.;
  } else {
    cumsum *= 0.95;
    j = 0;
    while (rollsum < cumsum) { 
      rollsum += SQR (spec->norm[j]);
      j++;
    }
    desc->data[0] = j;
  }
}