MATLAB: Employing SOM after PCA

pcasom

Hello,
I have applied PCA on my dataset and found out my first three variables together explained 93% of the total variance. So I decided to use only first 3 variables for SOM instead of 8 variables. I have total of 2643 observations in my dataset. There are two possible classification that I expect the SOM gives me but I don't know how to force SOM to do 2 classifications instead of 4. I use GUI for this and I would appreciate if anybody could help me with this.
Regards,
Naghmeh

Best Answer

1. PCA ranks principal components, not original variables. So, did you deduce 3 variables from the 3 principal components?
2. PLSREGRESS ranks original variables. Use that instead.
3. SOM is an unsupervised clustering algorithm that ignores classes, IT IS NOT A CLASSIFIER!
4. PATTERNNET is a NEURAL NETWORK SUPERVISED CLASSIFIER. If you are familiar with NNs, use that.
5. Otherwise, search the STATISTICS TOOLBOX for classifiers.
6 Meanwhile, search both NEWSGROUP and ANSWERS using
 CLASSIFICATION
Hope this helps.
Thank you for formally accepting my answer
Greg
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