Try this: aggregate(x ~ lc1 + id, DF, FUN = mean)
Where DF is your data.frame On Fri, Mar 25, 2011 at 2:36 PM, Steven Ranney <steven.ran...@gmail.com> wrote: > All – > > I have an example data frame > > x lc1 id > 43.38812035 85 ga1 > 47.55710661 85 ga1 > 47.55710661 85 ga2 > 47.55710661 85 ga2 > 51.99211429 85 ga3 > 51.99211429 85 ga3 > 51.99211429 95 ga1 > 54.78449958 95 ga1 > 54.78449958 95 ga2 > 54.78449958 95 ga2 > 56.70201864 95 ga3 > 56.70201864 95 ga3 > 56.70201864 105 ga1 > 59.66361903 105 ga1 > 59.66361903 105 ga2 > 61.69573564 105 ga2 > 61.69573564 105 ga3 > 61.69573564 105 ga3 > 63.77469479 115 ga1 > 63.77469479 115 ga1 > 64.83191994 115 ga2 > 64.83191994 115 ga2 > 64.83191994 115 ga3 > 66.98222118 115 ga3 > 66.98222118 125 ga1 > 66.98222118 125 ga1 > 66.98222118 125 ga2 > 66.98222118 125 ga2 > 66.98222118 125 ga3 > 66.98222118 125 ga3 > > and I’m trying to extract means for every lc1 and id level so that I > would have a data frame that looks like > > x.m lc1 id > x.1 085 ga1 > x.2 085 ga2 > x.3 085 ga3 > x.4 095 ga1 > x.5 095 ga2 > x.6 095 ga3 > x.7 105 ga1 > x.8 105 ga2 > x.9 105 ga3 > x.10 115 ga1 > x.11 115 ga2 > x.12 115 ga3 > x.13 125 ga1 > x.14 125 ga2 > x.15 125 ga3 > > Now, I can use brute force to get the second data frame by > > write.table(tapply(x[lc1=="085"], id[lc1=="085"], mean), "file.xls", sep=",") > write.table(tapply(x[lc1=="095"], id[lc1=="095"], mean), “file.xls", > sep=",", append=T) > write.table(tapply(x[lc1=="105"], id[lc1=="105"], mean), “file.xls", > sep=",", append=T) > etc… > > and add the values for the lc1 column in the .xls file until I’ve > worked my way through every level for lc1 then read the file back into > R, but this would require a great deal of my time. (I have 72 levels > for lc1 and 346 levels for id totalling over 20,000 lines.) > > I am confident that there is a simple, more elegant solution available > to me that I am overlooking. I am sure that I could use a “for” loop, > but as someone that is new to R programming, I am unsure of how to go > about creating the for loop to build the second data frame. I've > tried to modify existing for loops that I already have but have been > unsuccessful. > > Do you have any suggestions? > > Thank you – > > Steven Ranney > > ______________________________________________ > 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. > -- Henrique Dallazuanna Curitiba-Paraná-Brasil 25° 25' 40" S 49° 16' 22" O ______________________________________________ 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.
