Entering edit mode
I have been until now downloading GEO data directly to my computer and
using basic R functions to load tables and process them.
It works, but I figured I would probably save time if I learn to use
the GEOquery package, which looks promising.
However, I'm failing tremendously at my first attempt. I can get a lot
of good information, except the actual experiment data... and it seems
to be there, but can't get to it!
Example. I'm trying to get GSE19044, which contains 42 samples and
uses the Illumina WG6 platform, which is great as I'm familiar with
it.
so I do:
library(GEOquery)
u = getGEO('GSE19044')
show(u)
> show(u)
$GSE19044_series_matrix.txt.gz
ExpressionSet (storageMode: lockedEnvironment)
assayData: 45281 features, 42 samples
element names: exprs
protocolData: none
phenoData
sampleNames: GSM471318, GSM471319, ..., GSM471359 (42 total)
varLabels and varMetadata description:
title: NA
geo_accession: NA
...: ...
data_row_count: NA
(39 total)
featureData
featureNames: ILMN_1212602, ILMN_1212603, ..., ILMN_3163582 (45281
total)
fvarLabels and fvarMetadata description:
ID: NA
Species: NA
...: ...
SPOT_ID: NA
(31 total)
additional fvarMetadata: Column, Description
experimentData: use 'experimentData(object)'
Annotation: GPL6887
It looks good. It looks like what I want is the 'assayData'. But I
can't get to it.
'u' is a list, containing one element...
> class(u)
[1] "list"
> length(u)
[1] 1
> class(u[[1]])
[1] "ExpressionSet"
attr(,"package")
[1] "Biobase"
ok, so I rename that, and look at its structure:
eset<-u[[1]]
str(eset)
> str(eset)
Formal class 'ExpressionSet' [package "Biobase"] with 7 slots
..@ assayData :<environment: 0x0645ec5c="">
..@ phenoData :Formal class 'AnnotatedDataFrame' [package
"Biobase"] [...] (omitted for brevity)
I can extract the sample names, the basic annotation/probe identity
etc easily:
eset at phenoData@data #samples
eset at featureData@data #annotation
but how do I get into 'assayData'?
from the 'show(u)' it looks like it contains what I am after: 45281
features, 42 samples ... but it's class 'environment' and that's
throwing me off.
I was looking into the GEOquery user guide, but I'm still none the
wiser.
How do I get in there?
thanks for any help.
Jose
--
Dr. Jose I. de las Heras Email: J.delasHeras at
ed.ac.uk
The Wellcome Trust Centre for Cell Biology Phone: +44 (0)131
6507090
Institute for Cell & Molecular Biology Fax: +44 (0)131
6507360
Swann Building, Mayfield Road
University of Edinburgh
Edinburgh EH9 3JR
UK
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