weight_model.c File Reference

Weights for PET data modelling. More...

#include "libtpcmodext.h"

Go to the source code of this file.

Functions
int	dftWeightByFreq (DFT *dft)
int	imgSetWeights (IMG *img, int wmet, int verbose)
int	dftWSampleNr (DFT *tac)

Detailed Description

Weights for PET data modelling.

Author

Vesa Oikonen

Definition in file weight_model.c.

Function Documentation

dftWeightByFreq()

int dftWeightByFreq

(

DFT *

dft

)

Add weights based on sample frequency or frame length.

Existing weights are overwritten.

Returns

Returns 0 when successful, otherwise <>0.

See also

dftRead, dftSortByFrame, sifWeight, sifWeightByFrames, dftDecayCorrection, imgSetWeights, dftWSampleNr

Parameters

dft	Samples/frames must be sorted by sample time, but duplicate samples are allowed

Definition at line 20 of file weight_model.c.

  {
  int fi, fi1, fi2;
  double f, t, t1, t2, sumw=0.0;
 
  if(dft==NULL || dft->frameNr<1) return 1;
  if(dft->frameNr==1) {
    dft->w[0]=1.0;
    dft->isweight=1;
    return 0;
  }
 
  if(dft->timetype==DFT_TIME_STARTEND) { /* weights by frame lengths */
 
    for(fi=0; fi<dft->frameNr; fi++) {
      dft->w[fi]=dft->x2[fi]-dft->x1[fi]; 
      sumw+=dft->w[fi];
    }
    /* scale weights so that sum of weights equals sample number */
    sumw/=(double)dft->frameNr;
    for(fi=0; fi<dft->frameNr; fi++) dft->w[fi]/=sumw;
 
  } else if(dft->timetype==DFT_TIME_MIDDLE) { /* weights by sample distance */
 
    for(fi=0; fi<dft->frameNr; fi++) {
      t=t1=t2=dft->x[fi]; //printf("fi=%d t=%g\n", fi, t);
      /* Find the closest sample time before this one */
      for(fi1=fi; fi1>=0; fi1--) {t1=dft->x[fi1]; if(t1<t) break;} 
      /* Find the closest sample time after this one */ 
      for(fi2=fi; fi2<dft->frameNr; fi2++) {t2=dft->x[fi2]; if(t2>t) break;} 
      //printf("  t1=%g t2=%g\n", t1, t2);
      /* Mean sample distance */
      f=0.0;
      if(t1<t) f+=t-t1; else f+=t2-t;
      if(t2>t) f+=t2-t; else f+=t-t1;
      f*=0.5; if(f<=0.0) f=1.0;
      /* Set initial weight */
      //printf("    f=%g\n", f);
      dft->w[fi]=f; sumw+=f;
    }
    /* Scale weights */
    sumw/=(double)dft->frameNr;
    for(fi=0; fi<dft->frameNr; fi++) dft->w[fi]/=sumw;
 
  } else
    return 2;
 
  dft->isweight=1;
  return(0);
}

dftWSampleNr()

int dftWSampleNr

(

DFT *

tac

)

Get the number of samples in DFT that have weight > 0. Missing (NaN) sample values are included as long as weight is not missing. If weights are not set, then nr of all samples is returned.

Returns

The number of samples with weight above zero.

See also

dftWeightByFreq, aicSS, parFreeNr

Parameters

tac	Pointer to the DFT struct.

Definition at line 147 of file weight_model.c.

  {
  if(tac==NULL || tac->voiNr<1 || tac->frameNr<1) return(0);
  if(tac->isweight==0) return(tac->frameNr);
  int n=0;
  for(int i=0; i<tac->frameNr; i++) if(tac->w[i]>0.0) n++;
  return(n);
}

imgSetWeights()

int imgSetWeights	(	IMG *	img,
		int	wmet,
		int	verbose )

Add weights based on average voxel values and frame lengths, just frame lengths, or set all weights to 1 (no weighting).

Existing weights are overwritten. Decay correction is not considered in calculation of weights.

Returns

Returns 0 when successful, otherwise <>0.

See also

dftWeightByFreq, sifWeight, sifWeightByFrames

Parameters

img	Pointer to IMG struct; image data is used to calculate relational frame weights, which are also written into IMG struct.
wmet	Weighting method: 0=based on mean voxel values times frame lengths; 1=based on frame lengths, 2=set weights to 1 (no weighting).
verbose	Verbose level; if zero, then only warnings are printed into stderr

Definition at line 85 of file weight_model.c.

  {
  if(verbose>0) printf("imgSetWeights(*img, %d, ...)\n", wmet);
  /* Check the function input */
  if(img==NULL) return(1);
  if(img->status!=IMG_STATUS_OCCUPIED) return(2);
  if(img->dimt<1 || img->dimx<1 || img->dimy<1 || img->dimz<1) return(3);
  if(wmet<0 || wmet>2) return(4);
  img->isWeight=0;
 
  /* If one time frame, then weight is 1 */
  if(img->dimt==1) {
    img->weight[0]=1.0; 
    if(wmet==0 || wmet==1) img->isWeight=1; 
    return(0);
  }
  
  int fi, ret;
  double f, fm;
 
  if(wmet==2) { /* If weights are to be set to 1 (removed) */
    for(fi=0; fi<img->dimt; fi++) img->weight[fi]=1.0;
    return(0);
  }
 
  if(wmet==0) { /* weight based on frame mean values and durations */
    SIF sif;
    sifInit(&sif);
    ret=sifAllocateWithIMG(&sif, img, 1, verbose); if(ret) return(100+ret);
    sifModerateTrues(&sif, 100.0);
    sifWeight(&sif, 0.0); if(verbose>2) sifPrint(&sif);
    for(fi=0; fi<img->dimt; fi++) img->weight[fi]=sif.weights[fi];
    sifEmpty(&sif);
  } else if(wmet==1) { /* weight based on frame durations */
    for(fi=0, fm=0.0; fi<img->dimt; fi++) {
      f=img->end[fi]-img->start[fi]; fm+=f;
      img->weight[fi]=f;
    }
    /* scale weights so that sum of weights equals sample number */
    if(fm>0.0) f=(double)img->dimt/fm; else f=1.0;
    for(fi=0; fi<img->dimt; fi++) img->weight[fi]*=f;
  }
  img->isWeight=1;
  return(0);
}