Question: How to output a gene expression table using feature data corresponding to certain labels from an ExpressionSet?
gravatar for grokaine
6.0 years ago by
grokaine20 wrote:

Here is what I am doing:

#GDS download and processing test
gds <- getGEO('GDS756')
#Convert to ExpressionSet
eset <- GDS2eSet(gds,do.log2=TRUE)

eset is summarized like this:

ExpressionSet (storageMode: lockedEnvironment)
assayData: 22283 features, 6 samples 
  element names: exprs 
protocolData: none
  sampleNames: GSM21712 GSM21713 ... GSM21718 (6 total)
  varLabels: sample disease.state description
  varMetadata: labelDescription
  featureNames: 1007_s_at 1053_at ... AFFX-TrpnX-M_at (22283 total)
  fvarLabels: ID Gene title ... GO:Component ID (21 total)
  fvarMetadata: Column labelDescription
experimentData: use 'experimentData(object)'
  pubMedIds: 16531451 

What I want is to output a table in a text file, containing the following columns: (Affymetrix probe ID, ENTREZ Gene ID, expression for sample 1, ..., expression for sample n).

Weirdly enough, GEOQuery manual says that eset should not contain annotated genes, but it seems from my basic object inspection that the featureData contains just that. However my R knowledge is limited so I was unable to produce my table from it.

geoquery R • 9.3k views
ADD COMMENTlink modified 6.0 years ago by Sean Davis26k • written 6.0 years ago by grokaine20
gravatar for Sean Davis
6.0 years ago by
Sean Davis26k
National Institutes of Health, Bethesda, MD
Sean Davis26k wrote:
ADD COMMENTlink written 6.0 years ago by Sean Davis26k

Thanks, I modded @Sean Davis line to match my desire output:

feset <- fData(eset)
teset <- exprs(eset)
cnames <- c( c("ID", "GeneID"), colnames(teset))
write.table(data.frame(feset$ID, feset$"Gene ID",teset),file="expression.txt",row.names=FALSE, col.names=cnames, sep="\t")


ADD REPLYlink modified 6.0 years ago • written 6.0 years ago by grokaine20
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