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<html><head> <meta HTTP-EQUIV="Content-Type" CONTENT="text/html;charset=ISO-8859-1"> <title>Contents.m</title><link rel="stylesheet" type="text/css" href="../stpr.css"></head><body><table border=0 width="100%" cellpadding=0 cellspacing=0><tr valign="baseline"><td valign="baseline" class="function"><b class="function">EVALSVM</b><td valign="baseline" align="right" class="function"><a href="../svm/index.html" target="mdsdir"><img border = 0 src="../up.gif"></a></table> <p><b>Trains and evaluates Support Vector Machines classifier.</b></p> <hr><div class='code'><code><span class=help></span><br><span class=help> <span class=help_field>Synopsis:</span></span><br><span class=help> [model,Errors] = evalsvm(data,options)</span><br><span class=help> [model,Errors] = evalsvm(trn_data,val_data,options)</span><br><span class=help></span><br><span class=help> <span class=help_field>Description:</span></span><br><span class=help> [model,Errors] = evalsvm(data,options) uses cross-validation</span><br><span class=help> to assess SVM classifiers with given kernel arguments and </span><br><span class=help> regularization constants.</span><br><span class=help> </span><br><span class=help> The kernel type is given in options.ker (see 'help kernel').</span><br><span class=help> The SVM solver to be used is specified by field options.solver </span><br><span class=help> (default 'smo'). Both binary and multi-class SVM solvers are </span><br><span class=help> allowed. The input data have the following format:</span><br><span class=help> be used with regards to the number of labels of training data </span><br><span class=help> data.X [dim x num_data] ... training vectors.</span><br><span class=help> data.y [1 x num_data] ... labels.</span><br><span class=help> The set of SVM parameters to be evaluated are specified in:</span><br><span class=help> options.arg [dimarg x nargs] ... enumeration of kernel arguments; </span><br><span class=help> dimarg determins number of kernel argumens (e.g., dimarg = 1 </span><br><span class=help> for 'rbf' kernel and dimarg = 2 for 'sigmoid').</span><br><span class=help> options.C [1 x nc] ... enumeration of regularization constants.</span><br><span class=help></span><br><span class=help> Some extra parameters for the selected SVM solver can be</span><br><span class=help> specified in the field options.solver_options.</span><br><span class=help></span><br><span class=help> Each configuration of SVM paramaters is evaluated using the</span><br><span class=help> cross-validation. The number of folds is given in </span><br><span class=help> optios.num_folds (default 5). The trained SVM model with </span><br><span class=help> the smallest cross-validation error is returned. The computed</span><br><span class=help> cross-validation errors with respect to SVM parametes are </span><br><span class=help> returned in Errors [nc x nargs].</span><br><span class=help></span><br><span class=help> The progress info is displayed if options.verb is set to 1</span><br><span class=help> (default 0).</span><br><span class=help></span><br><span class=help> [model,Errors] = evalsvm(trn_data,val_data,options) each</span><br><span class=help> SVM is trained on the trn_data and evaluated on the </span><br><span class=help> validation val_data instead of using cross-validation.</span><br><span class=help> </span><br><span class=help> <span class=help_field>Example:</span></span><br><span class=help> trn = load('riply_trn');</span><br><span class=help> tst = load('riply_tst');</span><br><span class=help> options.ker = 'rbf';</span><br><span class=help> options.arg = [0.1 0.5 1 5];</span><br><span class=help> options.C = [1 10 100];</span><br><span class=help> options.solver = 'smo';</span><br><span class=help> options.num_folds = 5;</span><br><span class=help> options.verb = 1;</span><br><span class=help> [model,Errors] = evalsvm(trn,options);</span><br><span class=help> figure; mesh(options.arg,options.C,Errors);</span><br><span class=help> hold on; xlabel('arg'); ylabel('C');</span><br><span class=help> ypred = svmclass(tst.X,model);</span><br><span class=help> cerror(ypred,tst.y)</span><br><span class=help></span><br><span class=help> See also: </span><br><span class=help> SMO, SVMLIGHT, SVMCLASS.</span><br><span class=help></span><br></code></div> <hr> <b>Source:</b> <a href= "../svm/list/evalsvm.html">evalsvm.m</a> <p><b class="info_field">Modifications: </b> <br> 17-sep-2004, VF, Help improved. Info about training stage added.<br> 18-aug-2004, VF, svm_options changed to solver_options<br> 4-june-2004, VF<br> 3-jun-2004, VF<br></body></html>
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