/* Functions for normalizing weights in a bow_barrel *//* Copyright (C) 1997 Andrew McCallum   Written by:  Andrew Kachites McCallum <mccallum@cs.cmu.edu>   This file is part of the Bag-Of-Words Library, `libbow'.   This library is free software; you can redistribute it and/or   modify it under the terms of the GNU Library General Public License   as published by the Free Software Foundation, version 2.      This library 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   Library General Public License for more details.   You should have received a copy of the GNU Library General Public   License along with this library; if not, write to the Free Software   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA */#include <bow/libbow.h>#if !HAVE_SQRTF#define sqrtf sqrt#endifstatic float_accumulate_for_vector_length (float total_so_far, float increment){  return (total_so_far + (increment * increment));}static float_finalize_for_vector_length (float total){  return (1.0 / sqrtf (total));}static float_accumulate_for_summing (float total_so_far, float increment){  return (total_so_far + increment);}static float_finalize_for_summing (float total){  return (1.0 / total);}/* Calculate the normalizing factor by which each weight should be    multiplied.  Store it in each cdoc->normalizer. */static void_bow_barrel_normalize_weights (bow_barrel *barrel,			       float (*accumulator)(float, float),			       float (*finalizer)(float))				    {  int current_di;		/* the index of the document for which				   we are currently normalizing the				   "word vector". */  float norm_total;		/* the length of the word vector */  float weight;			/* the weight of a single wi/di entry */  bow_dv_heap *heap;		/* a heap of "document vectors" */  bow_cdoc *cdoc;		/* The document we're working on */  heap = bow_make_dv_heap_from_wi2dvf (barrel->wi2dvf);  bow_verbosify (bow_progress, "Normalizing weights:          ");  /* Keep going until the heap is empty */  while (heap->length > 0)    {      /* Set the current document we're working on */      current_di = heap->entry[0].current_di;      assert (heap->entry[0].dv->idf == heap->entry[0].dv->idf);  /* NaN */      if (current_di % 10 == 0)	bow_verbosify (bow_progress, "\b\b\b\b\b\b%6d", current_di);      /* Here we should check if this di is part of some training set and	 move on if it isn't. */          /* Get the document */      cdoc = bow_cdocs_di2doc (barrel->cdocs, current_di);      /* If it's not a model document, then move on to next one */      if (cdoc->type != model)	{	  do 	    {	      bow_dv_heap_update (heap);	    }	  while ((current_di == heap->entry[0].current_di)		 && (heap->length > 0));	  	  /* Try again */	  continue;	}          /* Reset the length */      norm_total = 0.0;      /* Loop over all words in this document, summing up the score */      do 	{	  weight = heap->entry[0].dv->entry[heap->entry[0].index].weight;	  norm_total = (*accumulator)(norm_total, weight);	  /* Update the heap, we are done with this di, move it to its	     new position */	  bow_dv_heap_update (heap);	}       while ((current_di == heap->entry[0].current_di)	     && (heap->length > 0));      /* xxx Why isn't this always true? -am */      /* assert (norm_total != 0); */      /* Do final processing of, and store the result. */      cdoc->normalizer = (*finalizer)(norm_total);    }  /* xxx We could actually re-set the weights using the normalizer now     and avoid storing the normalizer.  This would be easier than     figuring out the normalizer, because we don't have to use the heap     again, we can just loop through all the WI's and DVI's. */  bow_free (heap);  bow_verbosify (bow_progress, "\n"); }/* Normalize the weight-vector for each class (or document) such that   all vectors have Euclidean length 1. */voidbow_barrel_normalize_weights_by_vector_length (bow_barrel *barrel){  _bow_barrel_normalize_weights (barrel, 				 _accumulate_for_vector_length,				 _finalize_for_vector_length);}/* Normalize the weight-vector for each class (or document) such that   in all vectors, the elements of the vector sum to 1. */voidbow_barrel_normalize_weights_by_summing (bow_barrel *barrel){  _bow_barrel_normalize_weights (barrel, 				 _accumulate_for_summing,				 _finalize_for_summing);}/* Assign a value to the "word vector's" NORMALIZER field, such that   when all the weights in the vector are multiplied by the   NORMALIZER, the Euclidian length of the vector will be one. */voidbow_wv_normalize_weights_by_vector_length (bow_wv *wv){  float total = 0.0f;  int wvi;  for (wvi = 0; wvi < wv->num_entries; wvi++)    total += wv->entry[wvi].weight * wv->entry[wvi].weight;  if (total == 0)    bow_error ("You forgot to set the weights before normalizing the WV.");  wv->normalizer = 1.0 / sqrtf (total);}/* Assign a value to the "word vector's" NORMALIZER field, such that   when all the weights in the vector are multiplied by the   NORMALIZER, all the vector entries will to one. */voidbow_wv_normalize_weights_by_summing (bow_wv *wv){  float total = 0.0f;  int wvi;  for (wvi = 0; wvi < wv->num_entries; wvi++)    total += wv->entry[wvi].weight;  if (total == 0)    bow_error ("You forgot to set the weights before normalizing the WV.");  wv->normalizer = 1.0 / total;}