[R] Question about ROCR package

[Waverley]

Hi,

I have a question about ROCR package.  I got the ROC curve plotted
without any problem following the manual.  However, I don't know to
extract the values, e.g. y.values ( I think it is the area under the
curve auc measure).  The return is an object of class "performance"
which have Slots and one of the slot is "y.values".  I type the object
and I can see them in screen.  But I want to extract the value for
further programming and computation.  I did a summary of the object
and it is a "S4" mode which I don't understand.

Can someone help?

Thanks a lot in advance.

-- 
Waverley @ Palo Alto