Well, if I understand what you want to do, it's straightforward, ?"[" (pay attention to the use of column names) and ?grep would pick out the columns you want and you could then use mapply or maybe rowMeans or whatever to get your summaries.
HOWEVER ... I think what you should really should do is use a more appropriate data structure. What seems more natural to me is to convert from "wide" to "long" format so that you would end up with 3 columns: Result, ID, Rep. The Result would be the value, the ID your m1, m2, etc. and Rep your _1,_2, _3, etc. Again, this appears to be easy: ?unlist would get you the vector of Results and either ?strsplit or grep would get you all the ID's and reps, each of which just has to be repped the number of rows of your frame. Alternatively, ?reshape in base R or the reshape package can probably do it for you. Once you have a more R friendly data structure, it will be much easier for you to work with your data. Finally, you may wish to post your query on a more relevant list (e.g. geo or ecology or whatever your data are) as folks there may have better ideas for what a more "R friendly data structure" should be. Cheers, Bert On Wed, Jan 11, 2012 at 12:55 PM, Christopher G Oakley <coak...@bio.fsu.edu> wrote: > I need some help summarizing complex data frames (small example below): > > m1_1 m2_1 m3_1 m1_2 m2_2 m3_2 > i1 1 1 1 2 2 2 > i1 2 1 1 2 2 2 > i2 2 2 1 2 2 2 > > > For an arbitrary number of columns (say m1 …. m199) where the column names > have variable patterns, > > and such that each set of columns is repeated (with potentially unique data) > an arbitrary number of times (say _1 … _1000), > > I would like to summarize by row the mean values of (m1, m2, m3, … m199) over > all replicates (_1, _2, _3, … _1000). I need to do this with a large number > of dataframes of variable nrow, ncolumn, and colnames. > > I've tried various loops creating new dataframes and reassigning cell values > in loops or using rbind and bind, but run into trouble in each case. > > Any ideas? > > Thanks, > > Chris > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
