Hi all, I have a table (t) of the following format (first row is the header): A x1 x2 c 1 NA c 2 1002 c 3 NA a 4 1004 b 5 NA c 6 1006 c 7 1007 c 8 1008 b 9 1009 a 10 1010 a 11 1011 c 12 1012 c 13 1013 a 14 1014 c NA 1015 I want to find the mean of all the values corresponding to the row names "a", "b", "c" (which are duplicated). I tried the following which works: U <- unique(t$A) tt <- t(sapply(U, FUN=function(u) {mean(na.omit(t[t$A==u, ]))})) However, in reality the table t is real huge ( almost 44K rows and 100 columns). The above approach takes too long. Is there another alternative that anyone can think of. Thanks a lot for any help/suggestions. Sincerely, Hari [[alternative HTML version deleted]]

On Thu, Sep 24, 2009 at 2:49 PM, Hari Easwaran <hariharan.pe at="" gmail.com=""> wrote: > Hi all, > I have a table (t) of the following format (first row is the header): > A ? ? ? x1 ? ? ? ?x2 > c ? ? ? 1 ? ? ? ? ?NA > c ? ? ? 2 ? ? ? ? ?1002 > c ? ? ? 3 ? ? ? ? ? NA > a ? ? ? 4 ? ? ? ? ?1004 > b ? ? ? 5 ? ? ? ? ? NA > c ? ? ? ?6 ? ? ? ? ?1006 > c ? ? ? ?7 ? ? ? ? ?1007 > c ? ? ? ?8 ? ? ? ? ?1008 > b ? ? ? ?9 ? ? ? ? ?1009 > a ? ? ? 10 ? ? ? ? 1010 > a ? ? ? 11 ? ? ? ? 1011 > c ? ? ? 12 ? ? ? ? 1012 > c ? ? ? 13 ? ? ? ? 1013 > a ? ? ? 14 ? ? ? ? 1014 > c ? ? ? ?NA ? ? ? ?1015 > > > I want to find the mean of all the values corresponding to the row names > "a", "b", "c" (which are duplicated). > I tried the following which works: > U <- unique(t$A) > tt <- t(sapply(U, FUN=function(u) {mean(na.omit(t[t$A==u, ]))})) Take a look at the aggregate() function. Sean > However, in reality the table t is real huge ( almost 44K rows and 100 > columns). The above approach takes too long. Is there another alternative > that anyone can think of. > > Thanks a lot for any help/suggestions. > > Sincerely, > Hari > > ? ? ? ?[[alternative HTML version deleted]] > > _______________________________________________ > Bioconductor mailing list > Bioconductor at stat.math.ethz.ch > https://stat.ethz.ch/mailman/listinfo/bioconductor > Search the archives: http://news.gmane.org/gmane.science.biology.informatics.conductor >