[pymvpa] RFE confusion_state

[Kimberly Zhou]

Hi all,

I'm still trying to get recursive feature selection to work with the example
from http://dev.pymvpa.org/featsel.html#recursive-feature-elimination,
however I can't get past an error from the line with confusion_state=
"confusion".

Here's the code:
rfesvm_split = SplitClassifier(LinearCSVMC())
rfeclf = \
    FeatureSelectionClassifier(
    clf = LinearCSVMC(),
    feature_selection = RFE(
        sensitivity_analyzer = rfesvm_split.get_sensitivity_analyzer(),
        transfer_error = ConfusionBasedError(
            rfesvm_split,
            confusion_state="confusion"),
        feature_selector = FractionTailSelector(
            0.2, mode='discard', tail='lower'),
        update_sensitivity=True),
    enable_states=['feature_ids'],
    descr='LinSVM+RFE(splits_avg)')

The error:
Traceback (most recent call last):
  File "<stdin>", line 8, in <module>
  File "/usr/lib/pymodules/python2.6/mvpa/clfs/transerror.py", line 1500, in
__init__
    (confusion_state, clf)
ValueError: Conditional attribute confusion is not defined for classifier
SplitClassifier(combiner=None, space='targets')

"confusion" is the ID of the conditional attribute that stores
ConfusionMatrix, but since confusion matrix isn't computed until data is
acquired (as stated from
http://pymvpa.org/generated/mvpa.clfs.transerror.ConfusionMatrix.html#mvpa-clfs-transerror-confusionmatrix),
am I missing something before this code that I should have and that is why
it gives that error?

Or must I enable the conditional attribute confusion in some way before
this?

I would really appreciate any Ideas or input as we are pretty stuck at this
point...
and of course, thanks in advance for any replies!

Kimberly
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