#include <float.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
void exit_with_help()
{
printf(
"Usage: svm-scale [options] data_filename/n"
"options:/n"
"-l lower : x scaling lower limit (default -1)/n"
"-u upper : x scaling upper limit (default +1)/n"
"-y y_lower y_upper : y scaling limits (default: no y scaling)/n"
"-s save_filename : save scaling parameters to save_filename/n"
"-r restore_filename : restore scaling parameters from restore_filename/n"
);
exit(1);
}
char *line = NULL; //用于读入每一个训练样本的数据
int max_line_len = 1024;//存储数据文件的每一行最大为1024个字节
double lower=-1.0,upper=1.0,y_lower,y_upper;//lower,upper要缩放到目标范围。y_lower,y_upper未知？？？
int y_scaling = 0;//????
double *feature_max;
double *feature_min;
double y_max = -DBL_MAX;//和y_scaling有关
double y_min = DBL_MAX;
int max_index;//遍历所有样本，最大的属性个数
long int num_nonzeros = 0;
long int new_num_nonzeros = 0;
#define max(x,y) (((x)>(y))?(x):(y))
#define min(x,y) (((x)<(y))?(x):(y))
void output_target(double value);//和y_scaling有关？？？
void output(int index, double value);//对一个样本的一个属性数据（index:value）进行缩放，并且对空白数据（index:0值的数据）
char* readline(FILE *input);
int main(int argc,char **argv)
{
int i,index;
FILE *fp, *fp_restore = NULL;
char *save_filename = NULL;
char *restore_filename = NULL;
for(i=1;i<argc;i++)
{
if(argv[i][0] != '-') break;//用户没有指定-l, -u, -y, -s, -r的值
++i;
switch(argv[i-1][1])
{
case 'l': lower = atof(argv[i]); break;
case 'u': upper = atof(argv[i]); break;
case 'y':
y_lower = atof(argv[i]);
++i;
y_upper = atof(argv[i]);
y_scaling = 1;
break;
case 's': save_filename = argv[i]; break;
case 'r': restore_filename = argv[i]; break;
default:
fprintf(stderr,"unknown option/n");
exit_with_help();
}
}
if(!(upper > lower) || (y_scaling && !(y_upper > y_lower)))
{
fprintf(stderr,"inconsistent lower/upper specification/n");
exit(1);
}
if(restore_filename && save_filename)
{
fprintf(stderr,"cannot use -r and -s simultaneously/n");
exit(1);
}
if(argc != i+1)
exit_with_help();
fp=fopen(argv[i],"r");//读入待缩放文件
if(fp==NULL)
{
fprintf(stderr,"can't open file %s/n", argv[i]);
exit(1);
}
line = (char *) malloc(max_line_len*sizeof(char));//开辟1024的空间
#define SKIP_TARGET/
while(isspace(*p)) ++p;/
while(!isspace(*p)) ++p;
#define SKIP_ELEMENT/
while(*p!=':') ++p;/
++p;/
while(isspace(*p)) ++p;/
while(*p && !isspace(*p)) ++p;
/* assumption: min index of attributes is 1 */ //注意：这里默认最小index为1，不是0！！！
/* pass 1: find out max index of attributes */
max_index = 0;
if(restore_filename) //如果指定-r参数，则从其后面指定的文件中找到最大的属性个数
{
int idx, c;
fp_restore = fopen(restore_filename,"r");
if(fp_restore==NULL)
{
fprintf(stderr,"can't open file %s/n", restore_filename);
exit(1);
}
c = fgetc(fp_restore);
if(c == 'y')
{
readline(fp_restore);
readline(fp_restore);
readline(fp_restore);
}
readline(fp_restore);
readline(fp_restore);
while(fscanf(fp_restore,"%d %*f %*f/n",&idx) == 1)
max_index = max(idx,max_index); //和现有值比较
rewind(fp_restore);
}
while(readline(fp)!=NULL) //待缩放文件中读入一个样本数据
{
char *p=line;
SKIP_TARGET
while(sscanf(p,"%d:%*f",&index)==1) //此行数据中不断读入index值（注意有可能出现跳跃现象，如： 1:value1 3:value3 ）
{
max_index = max(max_index, index); //求出最大的index值，存于max_index，主要为了feature_max,feature_min开辟空间
SKIP_ELEMENT
num_nonzeros++;
}
}
rewind(fp);//重新指向文件流的开头
feature_max = (double *)malloc((max_index+1)* sizeof(double));
feature_min = (double *)malloc((max_index+1)* sizeof(double));
if(feature_max == NULL || feature_min == NULL)
{
fprintf(stderr,"can't allocate enough memory/n");
exit(1);
}
for(i=0;i<=max_index;i++)
{
feature_max[i]=-DBL_MAX;
feature_min[i]=DBL_MAX;
}
/* pass 2: find out min/max value */
while(readline(fp)!=NULL)//读入一个样本数据
{
char *p=line;
int next_index=1;
double target;
double value;
sscanf(p,"%lf",&target);//y_scaling 有关？？？？？？
y_max = max(y_max,target);
y_min = min(y_min,target);
SKIP_TARGET
while(sscanf(p,"%d:%lf",&index,&value)==2) //从一个样本中读入每一个index和对应的value
{
for(i=next_index;i<index;i++)
{
feature_max[i]=max(feature_max[i],0); //这两句是为了出现index0:value0 index2:value2的时候，将中间省略的0项
feature_min[i]=min(feature_min[i],0);//index1:value1也考虑进内
}
feature_max[index]=max(feature_max[index],value);//取最大值
feature_min[index]=min(feature_min[index],value);//取最小值
SKIP_ELEMENT
next_index=index+1;
}
for(i=next_index;i<=max_index;i++) //对于读入此样本数据，可能总属性个数不能达到最大个数max_index，此处需要考虑此样本
//后面省略的那些0值
{
feature_max[i]=max(feature_max[i],0);
feature_min[i]=min(feature_min[i],0);
}
}
rewind(fp);
/* pass 2.5: save/restore feature_min/feature_max */
if(restore_filename)
{
/* fp_restore rewinded in finding max_index */
int idx, c;
double fmin, fmax;
if((c = fgetc(fp_restore)) == 'y')
{
fscanf(fp_restore, "%lf %lf/n", &y_lower, &y_upper);
fscanf(fp_restore, "%lf %lf/n", &y_min, &y_max);
y_scaling = 1;
}
else
ungetc(c, fp_restore);
if (fgetc(fp_restore) == 'x') {
fscanf(fp_restore, "%lf %lf/n", &lower, &upper);
while(fscanf(fp_restore,"%d %lf %lf/n",&idx,&fmin,&fmax)==3)//如果指定-r，则feature_max,feature_min的值以 //fp_restore中存的每一个列的最大最小值为准，前面从待缩放文件中求出的每列最大最小值就没用了。此时缩放之后的值有可能不在
//[lower,upper]之内。很明显这是合理的，因为待测试的样本（即需要-r来缩放的，都是不可靠的数据，所以不能将他们的最值作为缩
//放的标准，而用-s参数时，因为样本数据都是训练样本都是经过标记的，所以可以作为缩放的标准
{
if(idx<=max_index)
{
feature_min[idx] = fmin;
feature_max[idx] = fmax;
}
}
}
fclose(fp_restore);
}
if(save_filename)//将feature_max,feature_min存成文件
{
FILE *fp_save = fopen(save_filename,"w");
if(fp_save==NULL)
{
fprintf(stderr,"can't open file %s/n", save_filename);
exit(1);
}
if(y_scaling)
{
fprintf(fp_save, "y/n");
fprintf(fp_save, "%.16g %.16g/n", y_lower, y_upper);
fprintf(fp_save, "%.16g %.16g/n", y_min, y_max);
}
fprintf(fp_save, "x/n");
fprintf(fp_save, "%.16g %.16g/n", lower, upper);
for(i=1;i<=max_index;i++)
{
if(feature_min[i]!=feature_max[i])
fprintf(fp_save,"%d %.16g %.16g/n",i,feature_min[i],feature_max[i]);
}
fclose(fp_save);
}
/* pass 3: scale */
while(readline(fp)!=NULL)//对样本数据进行缩放
{
char *p=line;
int next_index=1;
double target;
double value;
sscanf(p,"%lf",&target);
output_target(target);
SKIP_TARGET
while(sscanf(p,"%d:%lf",&index,&value)==2)
{
for(i=next_index;i<index;i++)//对样本数据中那些空的属性进行以0值缩放
output(i,0);
output(index,value);//对非0值进行缩放
SKIP_ELEMENT
next_index=index+1;
}
for(i=next_index;i<=max_index;i++)//对剩下的空值也以0值进行缩放
output(i,0);
printf("/n");
}
if (new_num_nonzeros > num_nonzeros)
fprintf(stderr,
"Warning: original #nonzeros %ld/n"
" new #nonzeros %ld/n"
"Use -l 0 if many original feature values are zeros/n",
num_nonzeros, new_num_nonzeros);
free(line);
free(feature_max);
free(feature_min);
fclose(fp);
return 0;
}
char* readline(FILE *input)//读入一个样本，注意是一个样本，不是一个行数据
{
int len;
if(fgets(line,max_line_len,input) == NULL)//读入一行
return NULL;
while(strrchr(line,'/n') == NULL)//判断是不是到了一个样本的末尾‘/n'
{
max_line_len *= 2;
line = (char *) realloc(line, max_line_len);//将空间加2倍
len = (int) strlen(line);
if(fgets(line+len,max_line_len-len,input) == NULL)//读入一行的新的数据，并加到line的后面
break;
}
return line;
}
void output_target(double value)
{
if(y_scaling)
{
if(value == y_min)
value = y_lower;
else if(value == y_max)
value = y_upper;
else value = y_lower + (y_upper-y_lower) *
(value - y_min)/(y_max-y_min);
}
printf("%g ",value);
}
void output(int index, double value)
{
/* skip single-valued attribute */
if(feature_max[index] == feature_min[index])//一列的最大值和最小值相等，不用处理
return;
if(value == feature_min[index])
value = lower;
else if(value == feature_max[index])
value = upper;
else
value = lower + (upper-lower) *
(value-feature_min[index])/
(feature_max[index]-feature_min[index]);
if(value != 0)
{
printf("%d:%g ",index, value);
new_num_nonzeros++;
}
}
注意这里代码没有提到将缩放后的数据存放到哪，这是由命令行提供的“> out.scale "决定的,指将原本要输出到控制台中的数据存储到一个指定的文件out.scale中；如果不加"> out.scale”，则直接输出到控制台中！
