Re: [Scikit-learn-general] p values of exactly zero in chi2

2012-09-04 Thread Andreas Mueller
X = np.array([[0, 1], [1, 0]]) observed = X Y = np.array([[0,1], [1,0]]) expected = np.dot(np.atleast_2d(Y.mean(axis=0)).T, np.atleast_2d(X.sum(axis=0))) chisquare(observed, expected) > (array([ 1., 1.]), array([ 0., 0.])) > > It may not be pretty,

Re: [Scikit-learn-general] p values of exactly zero in chi2

2012-09-04 Thread Andreas Mueller
On 09/04/2012 04:07 PM, Olivier Grisel wrote: > 2012/9/4 Andreas Mueller : >> On 09/04/2012 03:43 PM, Olivier Grisel wrote: >>> 2012/9/4 Andreas Mueller : Hi everybody. I'm pretty new to feature selection stuff and I tried to use the chi2 selection. I got a pvalue of exactly zer

Re: [Scikit-learn-general] p values of exactly zero in chi2

2012-09-04 Thread Olivier Grisel
2012/9/4 Andreas Mueller : > On 09/04/2012 03:43 PM, Olivier Grisel wrote: >> 2012/9/4 Andreas Mueller : >>> Hi everybody. >>> I'm pretty new to feature selection stuff and I tried to use the chi2 >>> selection. >>> I got a pvalue of exactly zero on one of the features and one of e-250 >>> on anoth

Re: [Scikit-learn-general] p values of exactly zero in chi2

2012-09-04 Thread Lars Buitinck
2012/9/4 Andreas Mueller : > On 09/04/2012 03:23 PM, Lars Buitinck wrote: >> What did the input look like? chi2 expects frequencies, i.e. strictly >> non-negative feature values. >> > The inputs were non-negative, but some >1. That should be perfectly ok, it's designed for the kind of output that

Re: [Scikit-learn-general] p values of exactly zero in chi2

2012-09-04 Thread Andreas Mueller
On 09/04/2012 03:43 PM, Olivier Grisel wrote: > 2012/9/4 Andreas Mueller : >> Hi everybody. >> I'm pretty new to feature selection stuff and I tried to use the chi2 >> selection. >> I got a pvalue of exactly zero on one of the features and one of e-250 >> on another one. >> That seems a bit fishy,

Re: [Scikit-learn-general] p values of exactly zero in chi2

2012-09-04 Thread Olivier Grisel
2012/9/4 Andreas Mueller : > Hi everybody. > I'm pretty new to feature selection stuff and I tried to use the chi2 > selection. > I got a pvalue of exactly zero on one of the features and one of e-250 > on another one. > That seems a bit fishy, in particular as they don't seem to correlate > very s