120 lines
2.4 KiB
C
120 lines
2.4 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "mex.h"
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#ifdef MX_API_VER
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#if MX_API_VER < 0x07030000
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typedef int mwIndex;
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#endif
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#endif
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void exit_with_help()
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{
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mexPrintf(
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"Usage: libsvmwrite('filename', label_vector, instance_matrix);\n"
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);
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}
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static void fake_answer(int nlhs, mxArray *plhs[])
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{
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int i;
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for(i=0;i<nlhs;i++)
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plhs[i] = mxCreateDoubleMatrix(0, 0, mxREAL);
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}
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void libsvmwrite(const char *filename, const mxArray *label_vec, const mxArray *instance_mat)
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{
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FILE *fp = fopen(filename,"w");
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mwIndex *ir, *jc, k, low, high;
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size_t i, l, label_vector_row_num;
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double *samples, *labels;
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mxArray *instance_mat_col; // instance sparse matrix in column format
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if(fp ==NULL)
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{
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mexPrintf("can't open output file %s\n",filename);
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return;
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}
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// transpose instance matrix
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{
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mxArray *prhs[1], *plhs[1];
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prhs[0] = mxDuplicateArray(instance_mat);
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if(mexCallMATLAB(1, plhs, 1, prhs, "transpose"))
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{
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mexPrintf("Error: cannot transpose instance matrix\n");
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return;
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}
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instance_mat_col = plhs[0];
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mxDestroyArray(prhs[0]);
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}
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// the number of instance
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l = mxGetN(instance_mat_col);
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label_vector_row_num = mxGetM(label_vec);
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if(label_vector_row_num!=l)
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{
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mexPrintf("Length of label vector does not match # of instances.\n");
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return;
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}
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// each column is one instance
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labels = mxGetPr(label_vec);
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samples = mxGetPr(instance_mat_col);
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ir = mxGetIr(instance_mat_col);
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jc = mxGetJc(instance_mat_col);
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for(i=0;i<l;i++)
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{
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fprintf(fp,"%g", labels[i]);
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low = jc[i], high = jc[i+1];
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for(k=low;k<high;k++)
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fprintf(fp," %lu:%g", (size_t)ir[k]+1, samples[k]);
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fprintf(fp,"\n");
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}
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fclose(fp);
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return;
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}
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void mexFunction( int nlhs, mxArray *plhs[],
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int nrhs, const mxArray *prhs[] )
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{
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if(nlhs > 0)
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{
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exit_with_help();
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fake_answer(nlhs, plhs);
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return;
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}
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// Transform the input Matrix to libsvm format
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if(nrhs == 3)
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{
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char filename[256];
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if(!mxIsDouble(prhs[1]) || !mxIsDouble(prhs[2]))
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{
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mexPrintf("Error: label vector and instance matrix must be double\n");
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return;
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}
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mxGetString(prhs[0], filename, mxGetN(prhs[0])+1);
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if(mxIsSparse(prhs[2]))
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libsvmwrite(filename, prhs[1], prhs[2]);
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else
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{
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mexPrintf("Instance_matrix must be sparse\n");
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return;
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}
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}
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else
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{
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exit_with_help();
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return;
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}
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}
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