[pymvpa] ROC

[Per B. Sederberg]

The real issue is with the argsort.  When all the predicted/values are
the same, there's nothing for it to do.  I think we may need to add in
code for how to deal with ties by grouping the labels.  Then I think
we might get more consistent results.

Though this could all be gibberish because I'm in serious need of
sleep and must head to bed now :)

Latros,
P

On Wed, Oct 1, 2008 at 10:58 PM, Yaroslav Halchenko
<debian at onerussian.com> wrote:
>
> I committed and pushed some not-finished yet code... so you could
> torture if you like, but first I want to bring your attention to the
> following misfunction imho:
>
>
> In [27]:AUCErrorFx()([0.5, 0.5], [0, 1])
> Out[27]:1.0
>
> In [28]:AUCErrorFx()([0.5, 0.5, 0.5, 0.5], [0, 1, 0, 1])
> Out[28]:0.75
>
> In [29]:AUCErrorFx()([0.5, 0.5, 0.5, 0.5, 0.5, 0.5], [0, 1, 0, 1, 0, 1])
> Out[29]:0.666666666667
>
> shouldn't in all of those cases we get 0.5?
>
> I know that it is a boundary and artificial case, but!
> So whoever is awake, he is welcome to join the coding ;)
> --
> Yaroslav Halchenko
> Research Assistant, Psychology Department, Rutgers-Newark
> Student  Ph.D. @ CS Dept. NJIT
> Office: (973) 353-5440x263 | FWD: 82823 | Fax: (973) 353-1171
>        101 Warren Str, Smith Hall, Rm 4-105, Newark NJ 07102
> WWW:     http://www.linkedin.com/in/yarik
>
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