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

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Linear Discriminant analysis WITH variable selection
Here is an example in the doc: <http://www.mathworks.com/help/stats/discriminant-analysis.html#btaf5dv> It shows how to use the ...

plus de 12 ans il y a | 0

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Leave-One-Out with ROC
Here is an example for cross-validating a discriminant model: <http://www.mathworks.com/help/stats/discriminant-analysis.html#bs...

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SVM - SVMTRAIN method SMO (error: No convergence achieved within maximum number of iterations)
You can increase the maximal number of iterations. See 'options' in the doc or help for |svmtrain|.

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Perfcurve with multiple negative classes
By default, the Y criterion is TPR computed for all possible score thresholds. The score thresholds are distinct values in the 2...

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What decision tree learning algorithm does MATLAB use to create decision trees?
|classregtree| uses the CART algorithm described in the Classification and Regression Trees book by Breiman et al.

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How to use option "stream" of Kmeans
Does this help? help parallelstats

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How to build a correct spline kernel for svm
Check out this thread and let us know if it helps: <http://www.mathworks.com/matlabcentral/answers/57232-how-to-use-svmtrain-wit...

presque 13 ans il y a | 0

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Selecting important features from a very large pool
You may find these two posts useful: <http://www.mathworks.com/matlabcentral/answers/48633-how-to-find-the-important-features...

presque 13 ans il y a | 0

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Error in kmeans of Matlab R2013 ?
Type which kmeans which randsample to verify that you are using the functions from the official MATLAB installation. ...

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problem when performing PCA on large dataset
If you can load the dataset into memory, the rest should be easy. Here is how you compute coefficients and scores for wide data ...

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How can I define the cost matrix using Classify function for discriminant analysis classification in MATLAB R2009a?
One option is to upgrade. In 11b, we introduced ClassificationDiscriminant which accepts the cost option. Otherwise take a lo...

presque 13 ans il y a | 0

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Create an 'other' category for classregtree?
It is not entirely clear from your post if you are talking about a categorical predictor (one of the variables in X) or the cate...

environ 13 ans il y a | 0

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ClassificationDiscriminant - How to exclude a predictor for only one group level?
Delete the corresponding column in the matrix of predictors you pass to ClassificationDiscriminant.fit: X(:,1) = [];

environ 13 ans il y a | 1

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How to do a ROC analysis using Matlab build-in SVM (Not LibSVM)
Well, there is an answer here <http://www.mathworks.com/matlabcentral/answers/64475-does-anybody-have-expertise-with-matlab-svm...

environ 13 ans il y a | 7

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

environ 13 ans il y a | 1

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What exactly the ROC curve can tell us or can be inferred?
1. You can report anything you like as long as you report an estimate obtained by cross-validation or using an independent test ...

environ 13 ans il y a | 2

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What exactly the ROC curve can tell us or can be inferred?
1-2. You can use either accuracy. The accuracy obtained by LDA is for assigning every observation into the class with the larges...

environ 13 ans il y a | 1

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How to do a classification using Matlab?
If you are using a relatively recent release, I suggest switching to |ClassificationDiscriminant|. It has more functionality and...

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SVM TRAIN - WARNING ABOUT SINGULAR MATRIX
This warning is thrown by the backslash operator \ when it solves the linear system based on the kernel matrix. You don't need t...

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How can I find the confusion matrix for a three class problem and thenfind specificity, sensitivity and accuracy from them.
If you have Statistics Toolbox, take a look at the |confusionmat| function. The accuracy is simply the sum of the diagonal eleme...

environ 13 ans il y a | 0

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Euclidean Distance Classifier implementation for classifying 6 expressions
If by "Euclidean distance classifier" you mean nearest neighbor rules, take a look at |ClassificationKNN| in Statistics Toolbox....

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Supervised Learning, how to examine the model produced
The answer varies per model. For linear types of |ClassificationDiscriminant|, you can use the |DeltaPredictor| property. Thi...

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SVMTRAIN - LEAST SQUARE METHOD OR QUADRATIC PROGRAMMING METHOD
LS minimizes mean squared error to solve the SVM regression problem. In SVM classification, coefficients alpha are bounded betwe...

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SVM - SVMTRAIN method SMO (error: No convergence achieved within maximum number of iterations)
You can do 3 things: # Lower the box constraint. # Increase |tolkkt|. # Set |kktviolationlevel| to a positive value. Any...

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does anybody have expertise with matlab SVM classifier?
See my comments at the bottom of this thread <http://www.mathworks.com/matlabcentral/answers/62757-how-do-i-find-slack-variables...

environ 13 ans il y a | 2

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PCA output: coefficients vs loadings
The |princomp| and |pca| functions center the data but do *not* scale. (In addition, |pca| allows not to center.) The easiest...

environ 13 ans il y a | 0

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How do I find slack variables in SVM?/ Distance to the boundary?
By definition, a slack variable for observation x with label y (-1 or +1) is max(0,1-y*f), where f is the SVM prediction (soft s...

environ 13 ans il y a | 0

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How does RegressionTree.fit works?
The MATLAB implementation is based on this book: Breiman, L., J. Friedman, R. Olshen, and C. Stone. Classification and Regres...

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Cross validation in matlab
The Statistics Toolbox provides utilities for cross-validation. If you are using R2011a or later, take a look at |Classification...

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