[BioC] how can I use the limma result as input in topGo
Caroline Reiff
C.Reiff at rri.sari.ac.uk
Thu Nov 8 15:41:04 CET 2007
I wonder if somebody can tell me how I can use my P values from the limma
test as input into topGo. This is what I tried:
In topGo I usually do the following using the standard t-test:
> geneList <- getPvalues(exprs(esetSub), classlabel = y, alternative =
"two.sided", correction = "BH")
> geneList[1:10]
1415670_at 1415671_at 1415672_at 1415673_at 1415674_a_at
1415675_at
0.15021513 0.07711458 0.38562825 0.78996178 0.64844312
0.16257882
1415676_a_at 1415677_at 1415678_at 1415679_at
0.92404052 0.01690829 0.30654309 0.55264382
> length(geneList)
[1] 9103
> topDiffGenes <- function(allScore) {
+ return(allScore < 0.01)
+ }
> GOdata <- new("topGOdata",
+ ontology = "BP",
+ allGenes = geneList,
+ geneSel = topDiffGenes,
+ description = "GO analysis of data. Diff. Expre. between WT and IL10",
+ annot = annFUN.hgu,
+ affyLib = affyLib)
Building most specific GOs ..... ( 2088 GO terms found. )
Build GO DAG topology .......... ( 3286 GO terms and 5438 relations.
)
Annotating nodes ............... ( 6088 genes annotated to the GO
terms. )
I tried to replace geneList with the results from limma in the following
way:
> geneList<-as.array(mytable$P.Value)
> dimnames(geneList) <- list(mytable$ID)
This gives me a genelist just as the one before except that the results are
ordered by P-value as they come from the limma table
> geneList[1:10]
1423677_at NuGO_emt025263_at 1421628_at 1436576_at
4.335431e-10 2.530289e-09 4.326564e-09 4.470340e-09
1450034_at 1422632_at 1453080_at 1438037_at
5.625014e-09 5.931422e-09 6.114187e-09 6.872450e-09
1422953_at 1446280_at
1.078998e-08 1.143128e-08
> length(geneList)
[1] 9103
but when I use this as input in topGo I get an error message:
> topDiffGenes <- function(allScore) {
+ return(allScore < 0.01)
+ }
> GOdata <- new("topGOdata",
+ ontology = "BP",
+ allGenes = geneList,
+ geneSel = topDiffGenes,
+ description = "WT versus Il10 ko",
+ annot = annFUN.hgu,
+ affyLib = affyLib)
Error in checkSlotAssignment(object, name, value) :
assignment of an object of class "AsIs" is not valid for slot
"allGenes" in an object of class "topGOdata"; is(value, "character") is not
TRUE
>
Hope somebody can help, Many thanks Caroline
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