#include <stdio.h>#include <string.h>#include <stdlib.h>#include <ctype.h>#include <errno.h>#include "mex.h"#if MX_API_VER < 0x07030000typedef int mwIndex;#endif #define max(x,y) (((x)>(y))?(x):(y))#define min(x,y) (((x)<(y))?(x):(y))void exit_with_help(){	mexPrintf(	"Usage: [label_vector, instance_matrix] = read_sparse(fname);\n"	);}static void fake_answer(mxArray *plhs[]){	plhs[0] = mxCreateDoubleMatrix(0, 0, mxREAL);	plhs[1] = mxCreateDoubleMatrix(0, 0, mxREAL);}static char *line;static int max_line_len;static char* readline(FILE *input){	int len;		if(fgets(line,max_line_len,input) == NULL)		return NULL;	while(strrchr(line,'\n') == NULL)	{		max_line_len *= 2;		line = (char *) realloc(line, max_line_len);		len = (int) strlen(line);		if(fgets(line+len,max_line_len-len,input) == NULL)			break;	}	return line;}// read in a problem (in svmlight format)void read_problem(const char *filename, mxArray *plhs[]){	int max_index, min_index, inst_max_index, i;	long elements, k;	FILE *fp = fopen(filename,"r");	int l = 0;	char *endptr;	mwIndex *ir, *jc;	double *labels, *samples;		if(fp == NULL)	{		mexPrintf("can't open input file %s\n",filename);		fake_answer(plhs);		return;	}	max_line_len = 1024;	line = (char *) malloc(max_line_len*sizeof(char));	max_index = 0;	min_index = 1; // our index starts from 1	elements = 0;	while(readline(fp) != NULL)	{		char *idx, *val;		// features		int index = 0;		inst_max_index = -1; // strtol gives 0 if wrong format, and precomputed kernel has <index> start from 0		strtok(line," \t"); // label		while (1)		{			idx = strtok(NULL,":"); // index:value			val = strtok(NULL," \t");			if(val == NULL)				break;			errno = 0;			index = (int) strtol(idx,&endptr,10);			if(endptr == idx || errno != 0 || *endptr != '\0' || index <= inst_max_index)			{				mexPrintf("Wrong input format at line %d\n",l+1);				fake_answer(plhs);				return;			}			else				inst_max_index = index;			min_index = min(min_index, index);			elements++;		}		max_index = max(max_index, inst_max_index);		l++;	}	rewind(fp);	// y	plhs[0] = mxCreateDoubleMatrix(l, 1, mxREAL);	// x^T	if (min_index <= 0)		plhs[1] = mxCreateSparse(max_index-min_index+1, l, elements, mxREAL);	else		plhs[1] = mxCreateSparse(max_index, l, elements, mxREAL);	labels = mxGetPr(plhs[0]);	samples = mxGetPr(plhs[1]);	ir = mxGetIr(plhs[1]);	jc = mxGetJc(plhs[1]);	k=0;	for(i=0;i<l;i++)	{		char *idx, *val, *label;		jc[i] = k;		readline(fp);		label = strtok(line," \t");		labels[i] = (int)strtol(label,&endptr,10);		if(endptr == label)		{			mexPrintf("Wrong input format at line %d\n",i+1);			fake_answer(plhs);			return;		}		// features		while(1)		{			idx = strtok(NULL,":");			val = strtok(NULL," \t");			if(val == NULL)				break;			ir[k] = (mwIndex) (strtol(idx,&endptr,10) - min_index); // precomputed kernel has <index> start from 0			errno = 0;			samples[k] = strtod(val,&endptr);			if (endptr == val || errno != 0 || (*endptr != '\0' && !isspace(*endptr)))			{				mexPrintf("Wrong input format at line %d\n",i+1);				fake_answer(plhs);				return;			}			++k;		}	}	jc[l] = k;	fclose(fp);	free(line);	{		mxArray *rhs[1], *lhs[1];		rhs[0] = plhs[1];		if(mexCallMATLAB(1, lhs, 1, rhs, "transpose"))		{			mexPrintf("Error: cannot transpose problem\n");			fake_answer(plhs);			return;		}		plhs[1] = lhs[0];	}}void mexFunction( int nlhs, mxArray *plhs[],		int nrhs, const mxArray *prhs[] ){	if(nrhs == 1)	{		char filename[256];		mxGetString(prhs[0], filename, mxGetN(prhs[0]) + 1);		if(filename == NULL)		{			mexPrintf("Error: filename is NULL\n");			return;		}		read_problem(filename, plhs);	}	else	{		exit_with_help();		fake_answer(plhs);		return;	}}