[R] index to select rows of a large matrix

tsunhin wong thjwong at gmail.com
Thu May 21 16:10:28 CEST 2009

Dear R Users,

I have created a 1500 x 20000 data frame - DataSeq. Each of the 1500
rows represents a data sequence.
I have another data frame iData that stores the information of these
1500 data sequences in the same order, for example, condition, gender,

If I use "subset" to select certain groups within iData according to
some criteria that I have set, e.g. condition, gender
Then how can I used the retrieved subset of iData to point to and
retrieve corresponding rows in the DataSeq data.frame for
manipulations and analysis?

I hope some of you can give me some idea!
Thank you very much!!!

- John

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