Community Profile

Contact

Top 1% contributor

Well, there is an answer here <http://www.mathworks.com/matlabcentral/answers/64475-does-anybody-have-expertise-with-matlab-svm...

accepted

4

Answered 2 years ago

See my comments at the bottom of this thread <http://www.mathworks.com/matlabcentral/answers/62757-how-do-i-find-slack-variables...

2

I described approaches for learning on imbalanced data here <http://www.mathworks.com/matlabcentral/answers/11549-leraning-class...

Replace temp = zeros(length(mu),1); for i = 1:length(mu) temp(i) = normrnd(mu(i),sigma(i)); end with ...

1

Answered 4 months ago

For 3 neighbors, the posterior probability has at most 4 distinct values, namely (0:3)/3. Likely less for the Fisher iris data b...

1. You can report anything you like as long as you report an estimate obtained by cross-validation or using an independent test ...

The MATLAB implementation is based on this book: Breiman, L., J. Friedman, R. Olshen, and C. Stone. Classification and Regres...

I am not an expert in image analysis, but it seems you misunderstand what you need to do. LDA uses matrix X in which rows are ob...

I described strategies for learning on imbalanced data in this post http://www.mathworks.com/matlabcentral/answers/11549-leranin...

You might want to start here http://en.wikipedia.org/wiki/One-class_classification The 1st reference (PhD thesis) gives an overv...

Answered 3 years ago

You are missing my point about the majority class. Let me try again. Suppose you generate 200 observations and assign labels ...

Combining two objects would be hard. You can work around this by growing one big ensemble and treating parts of it as separate e...

The answer depends on how you define a "fair" classifier. If the ultimate goal of your analysis is to minimize the overall class...

The error says that 1 is not found in t2. Note that your |groups| variable is logical, and so are |t1| and |t2|, but 1 is double...

0

ClassificationTree is based on Breiman, L., J. Friedman, R. Olshen, and C. Stone, Classification and Regression Trees, and uses ...

Use a loop: for n=1:30 view(t.Trees{n}); end

Answered 5 months ago

Nothing wrong with that. A classification tree optimizes the Gini index and can split a parent node in two child nodes dominated...

I can't explain in detail how the routine should be written because I don't understand how you are comparing the two populations...

Answered 7 months ago

The type of tree you need is defined by the type of output. If your output is numeric ("numeric" here means that you can do grea...

Answered 9 months ago

Plot the classification error (or whatever it is you are optimizing) against the two optimized parameters. Is the minimum well i...

Answered 11 months ago

You could start with linear regression. If you have the Statistics Toolbox, take a look at |LinearModel|. Or, if you have an old...

Answered 1 year ago

See <http://www.mathworks.com/matlabcentral/answers/68138-how-to-do-a-roc-analysis-using-matlab-build-in-svm-not-libsvm this thr...

Yes, you should be looking at the cross-validated loss.

Yes, this would be one way to accomplish this. You'd have to be careful when you convert new data to numeric for prediction. If ...

Prune the tree to the desired level using the |prune| method. Then use the |cutvar| method to see what variables are used for sp...

Classification error by definition is the fraction of misclassified observations. So if you have one misclassified point, divide...

It is not possible to access this data. However, coding is not hard. I presume you want to prune every tree to |bestlevel| retur...

<http://www.mathworks.com/help/stats/treebaggerclass.html doc TreeBagger> and take a look at the |Trees| property. For example, ...

PCA is applied to centered data. Observe that |mean(score)| is close to a vector of zeros. Rotating the scores back to the origi...

Load more