<div dir="ltr"><span style="font-family:arial,sans-serif;font-size:13px">Roberto,</span><br><div><span style="font-family:arial,sans-serif;font-size:13px"><br></span></div><div style><span style="font-family:arial,sans-serif;font-size:13px">Thanks very much, this answered my question perfectly! Also, thanks for the links on the interpretation, that was also very helpful.</span></div>
<div style><span style="font-family:arial,sans-serif;font-size:13px"><br></span></div><div style><span style="font-family:arial,sans-serif;font-size:13px">-Ricky</span></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">
On Wed, Apr 3, 2013 at 7:00 AM, <span dir="ltr"><<a href="mailto:pkg-exppsy-pymvpa-request@lists.alioth.debian.org" target="_blank">pkg-exppsy-pymvpa-request@lists.alioth.debian.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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1. Re: SVM weights - positive and negative values (Roberto Guidotti)<br>
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Message: 1<br>
Date: Tue, 2 Apr 2013 16:24:19 +0200<br>
From: Roberto Guidotti <<a href="mailto:robbenson18@gmail.com">robbenson18@gmail.com</a>><br>
To: Development and support of PyMVPA<br>
<<a href="mailto:pkg-exppsy-pymvpa@lists.alioth.debian.org">pkg-exppsy-pymvpa@lists.alioth.debian.org</a>><br>
Subject: Re: [pymvpa] SVM weights - positive and negative values<br>
Message-ID:<br>
<CAGj93cHSb3xuLsqa9B8=7kX179d8d1xHfgeEEYewg=_<a href="mailto:jkwCrNQ@mail.gmail.com">jkwCrNQ@mail.gmail.com</a>><br>
Content-Type: text/plain; charset="iso-8859-1"<br>
<br>
Dear Ricky,<br>
<br>
basically I look at classifier estimates attribute (clf.ca.estimates) and<br>
at predictions (clf.ca.predictions), since the prediction is based on svm<br>
decision function sign, you could derive the class label (predictions) from<br>
the decision function sign (estimates).<br>
<br>
For the interpretation you can look at a discussion on this forum, in which<br>
I asked about weights signifiance:<br>
<a href="http://lists.alioth.debian.org/pipermail/pkg-exppsy-pymvpa/2011q2/001752.html" target="_blank">http://lists.alioth.debian.org/pipermail/pkg-exppsy-pymvpa/2011q2/001752.html</a><br>
<br>
R<br>
<br>
<br>
On 31 March 2013 22:11, Ricky Savjani <<a href="mailto:rsavjani@gmail.com">rsavjani@gmail.com</a>> wrote:<br>
<br>
> Hi PyMVPA team,<br>
><br>
> I had a quick question (or perhaps just pt of confusion) on the output of<br>
> SVM weights using a sensitivity_analyzer. In particular, I think that the<br>
> sign (positive vs negative) of the svm weights reflects the weighting for<br>
> the particular target (say 'class1' vs "class2"). I think positive values<br>
> would be associated with class1 and negative values to be associated with<br>
> class2. But how can you be sure which target corresponds to positive values<br>
> in the SVM weights? Is it simply alphabetically, meaning class1 would take<br>
> on positive values and class2 negative values? Or is this entirely the<br>
> incorrect interpretation of the SVM weights that are output by the<br>
> sensitivity analyzer?<br>
><br>
> Thanks very much for the help.<br>
><br>
> -Ricky<br>
><br>
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</blockquote></div><br></div>