First commit

libsvm-3.36/matlab/libsvmwrite.c

@@ -0,0 +1,119 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "mex.h"
+
+#ifdef MX_API_VER
+#if MX_API_VER < 0x07030000
+typedef int mwIndex;
+#endif
+#endif
+
+void exit_with_help()
+{
+	mexPrintf(
+	"Usage: libsvmwrite('filename', label_vector, instance_matrix);\n"
+	);
+}
+
+static void fake_answer(int nlhs, mxArray *plhs[])
+{
+	int i;
+	for(i=0;i<nlhs;i++)
+		plhs[i] = mxCreateDoubleMatrix(0, 0, mxREAL);
+}
+
+void libsvmwrite(const char *filename, const mxArray *label_vec, const mxArray *instance_mat)
+{
+	FILE *fp = fopen(filename,"w");
+	mwIndex *ir, *jc, k, low, high;
+	size_t i, l, label_vector_row_num;
+	double *samples, *labels;
+	mxArray *instance_mat_col; // instance sparse matrix in column format
+
+	if(fp ==NULL)
+	{
+		mexPrintf("can't open output file %s\n",filename);
+		return;
+	}
+
+	// transpose instance matrix
+	{
+		mxArray *prhs[1], *plhs[1];
+		prhs[0] = mxDuplicateArray(instance_mat);
+		if(mexCallMATLAB(1, plhs, 1, prhs, "transpose"))
+		{
+			mexPrintf("Error: cannot transpose instance matrix\n");
+			return;
+		}
+		instance_mat_col = plhs[0];
+		mxDestroyArray(prhs[0]);
+	}
+
+	// the number of instance
+	l = mxGetN(instance_mat_col);
+	label_vector_row_num = mxGetM(label_vec);
+
+	if(label_vector_row_num!=l)
+	{
+		mexPrintf("Length of label vector does not match # of instances.\n");
+		return;
+	}
+
+	// each column is one instance
+	labels = mxGetPr(label_vec);
+	samples = mxGetPr(instance_mat_col);
+	ir = mxGetIr(instance_mat_col);
+	jc = mxGetJc(instance_mat_col);
+
+	for(i=0;i<l;i++)
+	{
+		fprintf(fp,"%.17g", labels[i]);
+
+		low = jc[i], high = jc[i+1];
+		for(k=low;k<high;k++)
+			fprintf(fp," %lu:%g", (size_t)ir[k]+1, samples[k]);
+
+		fprintf(fp,"\n");
+	}
+
+	fclose(fp);
+	return;
+}
+
+void mexFunction( int nlhs, mxArray *plhs[],
+		int nrhs, const mxArray *prhs[] )
+{
+	if(nlhs > 0)
+	{
+		exit_with_help();
+		fake_answer(nlhs, plhs);
+		return;
+	}
+
+	// Transform the input Matrix to libsvm format
+	if(nrhs == 3)
+	{
+		char filename[256];
+		if(!mxIsDouble(prhs[1]) || !mxIsDouble(prhs[2]))
+		{
+			mexPrintf("Error: label vector and instance matrix must be double\n");
+			return;
+		}
+
+		mxGetString(prhs[0], filename, mxGetN(prhs[0])+1);
+
+		if(mxIsSparse(prhs[2]))
+			libsvmwrite(filename, prhs[1], prhs[2]);
+		else
+		{
+			mexPrintf("Instance_matrix must be sparse\n");
+			return;
+		}
+	}
+	else
+	{
+		exit_with_help();
+		return;
+	}
+}