Question about CFS

["Carlos A. García Vallejo"]

Hello (sorry for my poor English).

I have a question about CFS.

Hello. I have a question about CFS. The first thing I want to say is
that I feel like you have a question about The Godfather and write a
list in which Francis Ford Coppola answers.

Well, I am writting a new (and hope that good) Feature Selection
Algorithm. It's based on the correlation between features, so,
obviously, I use CFS (!thanks Mark!). I have modified the class
CFSSubsetEval, calling MyCFSSubsetEval, making the field m_corr_matrix
public. Then I write the following code:

    MyCfsSubsetEval cfs = new MyCfsSubsetEval();
    int numFeaturesIncludedClass = instances.numAttributes();
    numFeatures = numFeaturesIncludedClass - 1;
    BitSet bs = new BitSet(numFeatures);
    for (int i = 0; i < numFeatures; i++) {
        bs.set(i);
    }
    cfs.buildEvaluator(instances);
    cfs.evaluateSubset(bs);
    float[][] correlationMatrix = cfs.m_corr_matrix;

and I do have the correlations.

The question is: is this the best way I could do it, or there is another
more efficient way?

Many many thanks in advance

--
Carlos A. Garcma Vallejo
Departamento de Lenguajes y Sistemas Informaticos
Escuela Ticnica Superior de Ingenierma Informatica
Av. Reina Mercedes s/n 41012-Sevilla
[phone]      vallejo@...
http://www.lsi.us.es/~vallejo


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[Mark Hall-9]

On 6/7/09 9:51 AM, "Carlos A. Garcma Vallejo" wrote:
> Hello (sorry for my poor English).
>
> I have a question about CFS.
>
> Hello. I have a question about CFS. The first thing I want to say is
> that I feel like you have a question about The Godfather and write a
> list in which Francis Ford Coppola answers.

I don't feel like the Godfather - I haven't had any severed horses heads placed
in anyone's bed (at least not recently) :-)

>
> Well, I am writting a new (and hope that good) Feature Selection
> Algorithm. It's based on the correlation between features, so,
> obviously, I use CFS (!thanks Mark!). I have modified the class
> CFSSubsetEval, calling MyCFSSubsetEval, making the field m_corr_matrix
> public. Then I write the following code:
>
> MyCfsSubsetEval cfs = new MyCfsSubsetEval();
> int numFeaturesIncludedClass = instances.numAttributes();
> numFeatures = numFeaturesIncludedClass - 1;
> BitSet bs = new BitSet(numFeatures);
> for (int i = 0; i < numFeatures; i++) {
> bs.set(i);
> }
> cfs.buildEvaluator(instances);
> cfs.evaluateSubset(bs);
> float[][] correlationMatrix = cfs.m_corr_matrix;
>
> and I do have the correlations.
>
> The question is: is this the best way I could do it, or there is another
> more efficient way?

This looks OK to me. I should probably make m_corr_matrix protected and add an
accessor method for it. It didn't occur to me at the time that anyone might want
to subclass CFS.

Cheers,
Mark.

--
Mark Hall
Senior Developer/Consultant, Pentaho Open Source Business Intelligence
Citadel International, Suite 340, 5950 Hazeltine National Dr., Orlando, FL
32822, USA
[phone] office, [phone] mobile, [phone] fax,
Skype: mark.andrew.hall, Yahoo: mark_andrew_hall
Download the latest release today <http://www.sourceforge.net/projects/pentaho>


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