Lib svm how to convert MyModel.mat to MyModel.model

Question

I have a .mat file that can be read easily with matlab, but I need to convert it to a file readable in C ++. is there any way to do this (by hand or perhaps programmatically)?

Answer 1

You can load the data matrix into MATLAB like any regular MAT file:

load data.mat 

then use the MEX function libsvmwrite , which comes with the libsvm MATLAB interface, to write it to the so-called "sparse" format:

 libsvmwrite('data.txt', label_vector, instance_matrix) 

If you are talking about trained models, not about data, a quick search showed this page (I have not personally tested it).

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EDIT:

Well, it looks like the code I mentioned needs some tweaking. Below is my modified version. I tested it using the latest libSVM-3.12, with VS2010 as the compiler:

svm_savemodel.c

 #include "../svm.h" #include "mex.h" #include "svm_model_matlab.h" static void fake_answer(mxArray *plhs[]) { plhs[0] = mxCreateDoubleMatrix(0, 0, mxREAL); } void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) { struct svm_model *model; char *filename; const char *error_msg; int status; // check input if(nrhs != 2) { mexPrintf("Usage: svm_savemodel(model, 'filename');\n"); fake_answer(plhs); return; } if(!mxIsStruct(prhs[0])) { mexPrintf("model file should be a struct array\n"); fake_answer(plhs); return; } if(!mxIsChar(prhs[1]) || mxGetM(prhs[1])!=1) { mexPrintf("filename should be given as char(s)\n"); fake_answer(plhs); return; } // convert MATLAB struct to C struct model = matlab_matrix_to_model(prhs[0], &error_msg); if(model == NULL) { mexPrintf("Error: can't read model: %s\n", error_msg); fake_answer(plhs); return; } // get filename filename = mxArrayToString(prhs[1]); // save model to file status = svm_save_model(filename,model); if (status != 0) { mexWarnMsgTxt("Error occured while writing to file."); } // destroy model svm_free_and_destroy_model(&model); mxFree(filename); // return status value (0: success, -1: failure) plhs[0] = mxCreateDoubleScalar(status); return; } 

Assuming you compiled the above MEX file, here is a usage example:

 [labels, data] = libsvmread('./heart_scale'); model = svmtrain(labels, data, '-c 1 -g 0.07'); svm_savemodel(model, 'mymodel.model'); 

The created text file looks like this:

mymodel.model

 svm_type c_svc kernel_type rbf gamma 0.07 nr_class 2 total_sv 130 rho 0.426412 label 1 -1 nr_sv 63 67 SV 1 1:0.166667 2:1 3:-0.333333 4:-0.433962 5:-0.383562 6:-1 7:-1 8:0.0687023 9:-1 10:-0.903226 11:-1 12:-1 13:1 0.6646947579781318 1:0.125 2:1 3:0.333333 4:-0.320755 5:-0.406393 6:1 7:1 8:0.0839695 9:1 10:-0.806452 12:-0.333333 13:0.5 . .