hi,

from what I remember we fixed the random label ordering problem
at least for the 2 classes case.

can you check that things behave fine and the same way with  Y = [0,
1] and Y = [1, 0]?

Alex

On Mon, Mar 26, 2012 at 5:00 AM, xinfan meng <[email protected]> wrote:
> I use the following codes to obtain decision values for SVC classifier clf.
>
> -----------------------------------------------------------------------------------------------
>
> In [5]: >>> clf = svm.SVC()
>
> In [23]: >>> X = [[0], [1], [2]]
>
> In [24]: >>> Y = [0, 1, 2]
>
> In [25]: clf.fit(X, Y)
> Out[25]:
> SVC(C=1.0, cache_size=200, coef0=0.0, degree=3, gamma=1.0, kernel='rbf',
>   probability=False, scale_C=False, shrinking=True, tol=0.001)
>
> In [26]: clf.predict([[0]])
> Out[26]: array([ 0.])
>
> In [27]: clf.predict(X)
> Out[27]: array([ 0.,  1.,  2.])
>
> In [28]: clf.decision_function(X)
> Out[28]:
> array([[-0.63212056, -0.98168436, -0.3495638 ],
>        [ 0.63212056, -0.        , -0.63212056],
>        [ 0.3495638 ,  0.98168436,  0.63212056]])
>
> -----------------------------------------------------------------------------------------------
>
>
>
> The decision_function return confusing results.  Why [-0.63212056,
> -0.98168436, -0.3495638 ] corresponds to label 0 ?
> The encoding of labels seems to be different from the natural orders of (0,
> 1, 2 ...) .
> After reading the README file of LibSVM, I found the label encoding can be
> obtained by calling svm_get_labels().
> Where can I find this function wrapper in sklearn? Without that, the return
> results of decision_function() are difficult to interpret.
> Thanks!
>
> --
> Best Wishes
> --------------------------------------------
> Meng Xinfan(蒙新泛)
> Institute of Computational Linguistics
> Department of Computer Science & Technology
> School of Electronic Engineering & Computer Science
> Peking University
> Beijing, 100871
> China
>
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