[BioC] intended behavior of plotPCA and AffyBatch objects?

Jenny Drnevich drnevich at uiuc.edu
Fri Apr 27 19:58:05 CEST 2007


Hi Jim,

I don't mind that plotPCA working with an AffyBatch object previously 
was an unintended behavior that now has been 'fixed'. At some point, 
someone needs to change the documentation for class AffyBatch because 
it still says it extends class exprSet (with a broken link) instead 
of class eSet.

Cheers,
Jenny

At 12:30 PM 4/27/2007, James W. MacDonald wrote:
>Hi Jenny,
>
>I never intended plotPCA() to be used with an AffyBatch, so the 
>behavior is (now) as intended. Unless your AffyBatch contains 
>normalized PM values, I am not sure how useful a PCA plot might be. 
>But maybe I am missing something?
>
>Anyway, AffyBatch now extends the eSet class instead of exprSet, 
>which as you mentioned is soon to be deprecated. Since an AffyBatch 
>is not really an extension of an ExpressionSet (or an exprSet for 
>that matter), extending eSet is a more logical choice.
>
> > extends("AffyBatch")
>[1] "AffyBatch"        "exprSet"          "annotatedDataset" 
>"VersionedBiobase" "Versioned"
> > R.version.string
>[1] "R version 2.4.1 (2006-12-18)"
>
> > extends("AffyBatch")
>[1] "AffyBatch"        "eSet"             "VersionedBiobase" "Versioned"
> > R.version.string
>[1] "R version 2.5.0 (2007-04-23)"
>
>As you mentioned, you can always extract the PM probes and call 
>plotPCA() on that. I'm not sure I want to change the behavior of 
>plotPCA() to work with AffyBatches (or the eSet class in general), 
>but I am always open to reasonable arguments.
>
>Best,
>
>Jim
>
>
>Jenny Drnevich wrote:
>>Hi Jim,
>>I just upgraded to R 2.5 and Bioconductor 2.0, and I noticed a 
>>change in the behavior of plotPCA. In R 2.4 and affycoretools 
>>1.7.5, plotPCA could take an AffyBatch object, even though the help 
>>file does say it only supports exprSet, ExpressionSet and matrices 
>>(I just noticed!). I looked through the code, and in Bioconductor 
>>1.9, if 'eset' is an AffyBatch object, a call to  ' is(eset, 
>>"exprSet")' returned true, but in R 2.5 it returns false. The 
>>newest documentation for class AffyBatch still says it extends the 
>>exprSet class, which I know is (or will be) deprecated. I guess 
>>plotPCA was never intended to be called on an AffyBatch object, and 
>>I can get around it by using pm(eset) in the call, but I did want 
>>to point out the change with the AffyBatch class. I don't know if 
>>this was intended behavior or not, or if the AffyBatch class will 
>>be updated to extend the ExpressionSet class... which makes this 
>>more of a general affy question than affycoretools, I guess!
>>Cheers,
>>Jenny
>>Jenny Drnevich, Ph.D.
>>Functional Genomics Bioinformatics Specialist
>>W.M. Keck Center for Comparative and Functional Genomics
>>Roy J. Carver Biotechnology Center
>>University of Illinois, Urbana-Champaign
>>330 ERML
>>1201 W. Gregory Dr.
>>Urbana, IL 61801
>>USA
>>ph: 217-244-7355
>>fax: 217-265-5066
>>e-mail: drnevich at uiuc.edu
>>_______________________________________________
>>Bioconductor mailing list
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>>https://stat.ethz.ch/mailman/listinfo/bioconductor
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>
>
>--
>James W. MacDonald, M.S.
>Biostatistician
>Affymetrix and cDNA Microarray Core
>University of Michigan Cancer Center
>1500 E. Medical Center Drive
>7410 CCGC
>Ann Arbor MI 48109
>734-647-5623
>
>
>**********************************************************
>Electronic Mail is not secure, may not be read every day, and should 
>not be used for urgent or sensitive issues.

Jenny Drnevich, Ph.D.

Functional Genomics Bioinformatics Specialist
W.M. Keck Center for Comparative and Functional Genomics
Roy J. Carver Biotechnology Center
University of Illinois, Urbana-Champaign

330 ERML
1201 W. Gregory Dr.
Urbana, IL 61801
USA

ph: 217-244-7355
fax: 217-265-5066
e-mail: drnevich at uiuc.edu



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