[R] lda

[Martin Maechler]

>>>>> "Pieter" == Pieter Vermeesch <pieter.vermeesch at erdw.ethz.ch>
>>>>>     on Mon, 16 Oct 2006 19:15:59 +0200 writes:

    Pieter> I'm trying to do a linear discriminant analysis on a
    Pieter> dataset of three classes ("Affinities"), using the
    Pieter> MASS library:
                 ^^^^^^^
No, no!    MASS *package*   (please!)

    >> data.frame2 <- na.omit(data.frame1)
    >> 
    >> data.ld = lda(AFFINITY ~ ., data.frame2, prior = c(1,1,1)/3)

    Pieter> Error in var(x - group.means[g, ]) : missing observations in cov/cor

    Pieter> What does this error message mean and how can I get rid of it?

You have (+ or -) 'Inf' data values which na.omit() does not
omit and  'x - group.means[g, ]' contains 'Inf - Inf' which is NaN.

Ideally, MASS:::lda.default() would check for such a case and
give a more user-friendly error message.

    Pieter> Thanks!

you're welcome.
Martin Maechler, ETH Zurich