How to specify the criterion for sequentialfs?

Question

maria 2015-5-26

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https://ww2.mathworks.cn/matlabcentral/answers/218798-how-to-specify-the-criterion-for-sequentialfs

回答： Tsinghua THU 2017-11-28

Hi everyone,

i need some help for the use of the function sequential, i've 28 features and i want to select the subset that minimizes the classification error. I follow the example in the guide of the function

%Applying Sequential Feature Selection
%First we generate a stratified 10-fold partition for the training set:
 tenfoldCVP = cvpartition(Y,'kfold',10);
 opts = statset('display','iter');
 fun = @(XT,yT,Xt,yt)...
      (sum(~strcmp(yt,classify(Xt,XT,yT,'quadratic'))));
%We apply forward sequential feature selection on the selected features
inmodel = sequentialfs(fun,Xfea,Y,'cv',tenfoldCVP, 'options',opts);

but the subset that i obtain is of only one feature and the error i obtain is worst of the whole subset features..where am i wrong? i can't find the mistake? i think is the criterion but maybe not..can someone please help me? is very important

Thank you in advance

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Answer 1

Tsinghua THU 2017-11-28

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/218798-how-to-specify-the-criterion-for-sequentialfs#answer_293504

Do you kown what meaning the sentence starting from fun is.I also meet this question.Strcmp is used to compare two character data.But,my data is data type.Then, I modify strcmp to eq and successfully solve this problem.I hope my example can give you inspiration.