Re: [R] Individual log likelihoods of nlsList objects.

From: Martin Maechler <maechler_at_stat.math.ethz.ch>
Date: Fri 02 Jul 2004 - 07:12:31 EST

>>>>> "Ken" == Ken Kelley <kkelley@nd.edu>
>>>>> on Thu, 1 Jul 2004 14:23:16 -0500 writes:

    Ken> Hello all.
    Ken> I was wondering if the logLike.nls() and logLike.nlme() functions are still
    Ken> being used. 

no, but the correctly spelled ones, logLik.nls and logLik.nlme are

    Ken> Neither function seems to be available in the most recent     Ken> release of R (1.9.1).

how do you know?

    Ken> The following is contained in the help file for
    Ken> logLik(): "classes which already have methods for this
    Ken> function include: 'glm', 'lm', 'nls' and 'gls', 'lme'
    Ken> and others in package 'nlme'." 

Hence do rather believe the documentation ....

    Ken> Thus, I was expecting
    Ken> that logLik.nls() and logLik.nlme() could be used for
    Ken> objects of the nls and nlme class, respectively. 

They *are* used whenever you (or your code indirectly) call logLik(.) on "nls" or "nlme" objects respectively.

You were never to call these directly, and you this has been discouraged a bit more as a side effect of the introduction of name spaces for all "core" and recommended (and quite a few more CRAN and bioconductor) packages.

You definitely need to learn about Classes and Methods ("S3" in this case) in R {or the S language in general}, and read the article about "Namespaces" in R-news, or (more technical), Luke Tierney's pages on this.

If you want to see them use, e.g.,

getAnywhere("logLik.nls")

    Ken> Are these functions no longer needed because logLike()
    Ken> subsumes logLike.nls() and logLike.nlme() as special
    Ken> cases? Did/does logLike.nls() and logLike.nlme() have
    Ken> any advantages above and beyond logLike() when applying
    Ken> them to nls and nlme objects?

    Ken> On a related note, is there a way to get the log likelihoods of each     Ken> individual from an nlsList object?

    Ken> On p. 349 of Pinheiro and Bates (2000) the logLik() function is said to give
    Ken> the sum of the individual nls log-likelihoods. However,
    Ken> logLike(some.nlsList.object) does not work for me (even when there are no
    Ken> NAs). Any ideas?

if you are insisting on typo-ing you will have more problems with all versions of S ;-)
or did you try logLik( <...> ) ?

In any case use, (small) reproducible examples for these. Have you read the posting guide, mentioned at the tail of this message?

Regards,
Martin



R-help@stat.math.ethz.ch mailing list
https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Jul 02 07:15:58 2004

This archive was generated by hypermail 2.1.8 : Wed 03 Nov 2004 - 22:54:39 EST