[BioC] mapping through org.Xx.eg.db packages
Iain Gallagher
iaingallagher at btopenworld.com
Thu Oct 6 13:50:41 CEST 2011
Dear List
I wonder is someone could shed some light on the following.
Given a set of gene symbols I would like to retrieve different identifiers.
Using the org.Xx.eg.db packages I can go about this by mapping through the EntrezIDs:
# mapping through eg ids as package is eg id centric
library(org.Hs.eg.db)
syms <- c('ACTB', 'TNF', 'TGFB1')
egID <- unlist(mget(syms, org.Hs.egSYMBOL2EG, ifnotfound=NA))
ensID <- unlist(mget(egID, org.Hs.egENSEMBL, ifnotfound=NA))
> ensID
60 71241 71242 71243
"ENSG00000075624" "ENSG00000204490" "ENSG00000206439" "ENSG00000223952"
71244 71245 71246 71247
"ENSG00000228321" "ENSG00000228849" "ENSG00000230108" "ENSG00000232810"
7040
"ENSG00000105329"
> egID
ACTB TNF TGFB1
"60" "7124" "7040"
Now here I assumed that the names of the ensID object were the original EntrezIDs mapped from the symbols but because R does not handle duplicate names they are not - with renumbering for those EntrezIDs that have a plurality of matches (here 7124 becomes 71241, 71242 etc etc)
This has caused me some confusion since each of these names is an actual Entrez ID - just not one I'm interested in.
The same can happen when mapping from any ID that ends in a numeric part (eg Ensembl ids).
It is useful to return a mapping showing the original identifier, the EntrezID mapped through and the required identifier so how could one reliably do this when mapping through e.g. Entrez IDs as in the method above (i.e. return the Entrez ID and Ensembl ID in one sweep)?
I have tried using the SQL approach:
dbCon <- org.Hs.eg_dbconn()
sqlQuery <- 'SELECT * FROM genes, gene_info, ensembl WHERE genes._id = gene_info._id = ensembl._id;'
result <- dbGetQuery(dbCon, sqlQuery)
where one could filter the 'result' object with the symbols of interest but this query takes a long time to run. I know little SQL so that might be an issue!
Best
iain
> sessionInfo()
R version 2.13.2 (2011-09-30)
Platform: x86_64-pc-linux-gnu (64-bit)
locale:
[1] LC_CTYPE=en_GB.utf8 LC_NUMERIC=C
[3] LC_TIME=en_GB.utf8 LC_COLLATE=en_GB.utf8
[5] LC_MONETARY=C LC_MESSAGES=en_GB.utf8
[7] LC_PAPER=en_GB.utf8 LC_NAME=C
[9] LC_ADDRESS=C LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_GB.utf8 LC_IDENTIFICATION=C
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] org.Hs.eg.db_2.4.6 RSQLite_0.9-4 DBI_0.2-5
[4] AnnotationDbi_1.14.1 Biobase_2.10.0
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