Thank you for the response, I'm always lazy to improve problem description (and my english doesn't help me!!!)
Theoretically for every fold I have to select important features, so I perform ANOVA, the algorithm ranks my feature, but I want to drop the first 1% and use the 5% (or X%) of the new rank after 1% dropping. I found on my analysis that most important feature are, in the 90% of cases, on the brain edge (probably motion artefacts voxels that still affect the dataset also after preprocessing). For this reason I would like to extract ANOVA ranking stack or to find a method to use voxels from 1.01% to 5.01%! So I want to perform ANOVA on data, drop the first 1%, select the new ranking stack (5% of residual voxels) and train the classifier! Thank you RG On 3 October 2011 18:14, Yaroslav Halchenko <[email protected]> wrote: > I might be missing the problem since you seem to have to know the blocks > you need ;) so following the example from the clfs warehouse: > > FeatureSelectionClassifier( > kNN(), > SensitivityBasedFeatureSelection( > OneWayAnova(), > FractionTailSelector(0.05, mode='select', tail='upper')), > descr="kNN on 5%(ANOVA)") > > logical change would be to use 0.99 instead of 0.05 to select 99% top > voxels > (or in other words to dump 1%)... or just change mode to 'discard' and > specify > 0.01 as the fraction > > On Mon, 03 Oct 2011, Roberto Guidotti wrote: > > > Hi all, > > > I would like to know if there is a method to extract the feature > > ranking from ANOVA feature selection or if there is a method to drop > > first 1% of voxel included in the ranking and select other voxel as > > usual (with FractionTailSelection()). > > > Thank you > > > Roberto > > > _______________________________________________ > > Pkg-ExpPsy-PyMVPA mailing list > > [email protected] > > > http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/pkg-exppsy-pymvpa > > > -- > =------------------------------------------------------------------= > Keep in touch www.onerussian.com > Yaroslav Halchenko www.ohloh.net/accounts/yarikoptic > > _______________________________________________ > Pkg-ExpPsy-PyMVPA mailing list > [email protected] > http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/pkg-exppsy-pymvpa >
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