I can not use libsvm!!!

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Atieh
Atieh on 3 Jun 2011
Commented: Najiyah Valappil on 16 Mar 2020
Hi,
can anybody help me in using libsvm?
but it can not be recognized by my matlab, I got the following error:
??? Undefined function or method 'libsvmtrain' for input arguments of type 'double'.
Error in ==> svmtrts at 139 D.net.svm=libsvmtrain(otY,stX,'-t 0');
Error in ==> main at 148 [D,Dtest]=svmtrts(trndataSVM,tstdataSVM,'libsvm');
can anybody help me.
Regards, Atieh

Accepted Answer

Friedrich
Friedrich on 3 Jun 2011
I think your are talking about:
The function libsvmtrain does not exist in that package. The training function is called svmtrain.

More Answers (1)

Jonas Reber
Jonas Reber on 3 Jun 2011
I used libsvm myself in matlab.
then let me provide you my sample code - note: I use precompiled kernel data.
Here, I would like to find the optimal parameter c for my SVM.
clear all; close all;
%%load datasets
[lvtest, test] = libsvmread('test.krnl');
[lvtrain, train] = libsvmread('train.krnl');
[lvvalid, valid] = libsvmread('valid.krnl');
%%optimize parameter c on validation set
n = -17:17;
accuracy = nan(size(n));
for i=1:numel(n); % n = {-17,...,17}
c=2^n(i);
% create model
model = svmtrain(lvtrain, train,['-q -t 4 -c ' num2str(c)]);
% option: -t 4 -> precomputed kernel
[lbl, acc, dec] = svmpredict(lvvalid, valid, model);
accuracy(i) = acc(1);
end
% output the accuracy vs the chosen parameter c
plot(accuracy);
xlabel('c'), ylabel('Accuracy'); title('Accuracy vs. c');
%%test optimal c on the test set
[~, i] = max(accuracy); % find the best value
c = 2^n(i); % this is the optimal c
% create model
model = svmtrain(lvtrain, train,['-q -t 4 -c ' num2str(c)]);
% test on the testset
[lbl, acc, dec] = svmpredict(lvtest, test, model, []);
% show accuracy
disp(['Accuracy with optimized c (' ...
num2str(c) ') on Testset: ' num2str(acc(1)) '%']);
hope this helps...?
  2 Comments
judy  frost
judy frost on 23 Sep 2013
Can you please explain the example further by showing how to find optimal cost and gamma values from validation data that are used for k-fold cross validation. Furthermore is it possible to plot the graph of classified data at the end of validation,training and test stages. I will appreciate any further explanation regarding the topic. Thank you.
Najiyah Valappil
Najiyah Valappil on 16 Mar 2020
Can you plaese explain how this data was prepared?

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