On 02/15/2013 02:10 AM, David Reed wrote:
Could you link that?

http://www.mathworks.de/products/statistics/examples.html?file=/products/demos/shipping/stats/classdemo.html#3

"The classify function can perform classification using different types of discriminant analysis. First classify the data using the default linear discriminant analysis (LDA)."

Not sure if that was the same method you are using.

I found a function in Matlab, ClassificationDiscriminant, that performs exactly the same as Python and R. So what is the real difference between calling the classify algorithm in Matlab and this ClassificationDiscriminant function?


On Thu, Feb 14, 2013 at 4:14 PM, <[email protected] <mailto:[email protected]>> wrote:

    matlab doc online says linear classifier is lda by default.



    Andrew Winterman <[email protected]
    <mailto:[email protected]>> schrieb:

        Logistic regression can be used as a linear classifier. Maybe
        that's matlab's linear classifier?

        On Thursday, February 14, 2013, David Reed wrote:

            I was mistaken,  R is providing the exact same results as
            Python.  Is there a difference between a linear classifer
            and LDA?  Matlab never uses the words
            Linear Discriminant Analysis, its just says linear
            classifier, but is giving different results than these
            other two software packages.


            On Thu, Feb 14, 2013 at 1:19 PM, David Reed
            <[email protected]> wrote:

                I don't think I can provide the data, but I'm trying
                to create some simulated data that produces a similar
                difference.

                I was just messing with R, and for LDA got a different
                result from the other 2.  I wonder if its just
                something I am doing wrong.



                On Thu, Feb 14, 2013 at 10:07 AM, Andreas Mueller
                <[email protected]> wrote:

                    On 02/14/2013 04:04 PM, Andreas Mueller wrote:
                    > On 02/14/2013 03:59 PM, David Reed wrote:
                    >> I dont think this is the problem.  My data is
                    definetly oversampled, I
                    >> have 5000 samples for the 1 feature.
                    >>
                    >> I also should say that the problem that led be
                    to LDA was seeing there
                    >> was a large bias between SVM classification
                    accuracy in sklearn and
                    >> matlab.  I am using the same parameters on
                    both, and again testing on
                    >> my training.  Using the same univariate data
                    set, I see 0.63 from
                    >> matlab and 0.58 from sklearn.
                    >>
                    > Which version of scikit-learn are you using? Are
                    you using sparse matrices?
                    > There was a weird bug in using sparse matrices
                    and SVMs in an earlier
                    > version of sklearn.
                    > If there is still a discrepancy in either of the
                    algorithms, we must
                    > investigate!
                    >
                    Would it be possible to provide your data or even
                    better, some small dataset
                    to reproduce the discrepancy?

                    
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