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--></style></head><body bgcolor=white lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt'>Is there a way to use PLR with a multiclass problem? When I try to use the MulticlassClassifier, that produces binary labels with -1 and 1. But PLR expects 0 and 1.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>The classifier is created like so:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>from mvpa2.clfs.plr import PLR<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>from mvpa2.clfs.meta import MulticlassClassifier<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>clf = MulticlassClassifier(PLR(lm=10))<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>When I try to train the classifier on an fMRI dataset with four classes, I get:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Traceback (most recent call last):<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> File "/home1/03206/mortonne/analysis/bender/mvpa/loc_xval_diag.py", line 98, in <module><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> clf.train(ds1)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> File "/work/IRC/ls5/lib/python2.7/site-packages/mvpa2/base/learner.py", line 137, in train<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> self._train(ds)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> File "/work/IRC/ls5/lib/python2.7/site-packages/mvpa2/clfs/meta.py", line 1165, in _train<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> CombinedClassifier._train(self, dataset)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> File "/work/IRC/ls5/lib/python2.7/site-packages/mvpa2/clfs/meta.py", line 628, in _train<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> BoostedClassifier._train(self, dataset)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> File "/work/IRC/ls5/lib/python2.7/site-packages/mvpa2/clfs/meta.py", line 118, in _train<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> clf.train(dataset)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> File "/work/IRC/ls5/lib/python2.7/site-packages/mvpa2/base/learner.py", line 137, in train<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> self._train(ds)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> File "/work/IRC/ls5/lib/python2.7/site-packages/mvpa2/clfs/meta.py", line 1053, in _train<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> self.clf.train(datasetselected)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> File "/work/IRC/ls5/lib/python2.7/site-packages/mvpa2/base/learner.py", line 137, in train<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> self._train(ds)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> File "/work/IRC/ls5/lib/python2.7/site-packages/mvpa2/clfs/plr.py", line 76, in _train<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> %(set(d),)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>ValueError: Regressors for logistic regression should be [0,1]. Got set([1, -1])<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>I have the latest versions of meta.py and plr.py. There was a <a href="https://github.com/PyMVPA/PyMVPA/issues/37">change</a> in PLRWeights to support different values of labels, but that change doesn’t seem to have affected the PLR classifier.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Thanks,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Neal<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p></div></body></html>