>Date: Fri, 7 Apr 2006 16:22:23 -0700 (PDT) >From: Srinivas Iyyer <srini_iyyer_bio at="" yahoo.com=""> >Subject: [BioC] Limma: How to read gene list , coordinates of sport > when NO GAL file available >To: bioconductor at stat.math.ethz.ch > >Dera group, >limma is an excellent module for gene expression data >preprocessing and analysis. >however, I looked into many places i did not find a >good tutorial when the .gpr file is not what I it >should look like. Also, when GAL file is not the same >what it should be. > >I have a dataset downloaded from ArrayExpress and has >the following column names: > >[B635+1SD B635+2SD Autoflag B >Pixels B635 B635 CV B635 >Mean B635 Median B635 SD Circularity Dia. F Pixels >F635 % Sat. F635 CV F635 Mean F635 Mean - B635 F635 >Median F635 Median - B635 F635 SD F635 Total Intensity >Flags Normalize SNR 635] > > >The chip definition file obtained from "Array design >used" section of ArrayExpress has the following >columns: > >[MetaColumn MetaRow Column Row Reporter Identifier >Reporter Name Reporter Biosequence Type Reporter >actual Sequence Reporter Comment Reporter Group Role >Reporter Control Type CompositeSequence Identifier >CompositeSequence Name Composite Sequence Comment] > >when i did: >dat <- read.maimages('filename',source >='genepix.custom') > >I get "Error in readGPRHeader(fullname) : File is not >in Axon Text File (ATF) format" > > >my questions are: > >what should I tell read.maimages to accept my file and >process further. > >what should I do when I do not have GAL file. how can >the other file help me get genelist etc. > >Please help me. > >Thanks >sri Dear Sri, I am a bit puzzled why you would try to tell read.maimages() that you have GenePix data. Is this because the data files were originally GenePix according the description? Anyway, it is apparent that ArrayExpression changes the data format, so that using the GenePix setup will not work. To read the intensity data into limma, you should proceed as per the section of the User's Guide starting from "What should you do if your image analysis program is not currently supported by limma?" in the middle of page 14. As for reading the chip definition file, I assume that this file is of the same length and order as the intensity data files. If that is so, just read the file into R yourself using something like anndata <- read.delim(chipdeffile, as.is = TRUE, quote = "\"", fill = TRUE) and then RG$genes <- anndata That's all. You do not need to create your own GAL file. Best wishes Gordon