Assume that no component matrix can have repeated values. First we apply table to mat yielding a list of named counts. To each component of that we sapply the indicated function which picks out those that occur length(a) times (so they are in every column), converts the name to numeric and averages them.
sapply(apply(mat, 2, table), function(x) mean(as.numeric(names(x))[x == length(a)])) By the way, note that the a you define is slightly different from the a displayed in your post. On Jan 11, 2008 6:09 PM, dxc13 <[EMAIL PROTECTED]> wrote: > > useR's, > > I want to match the real number elements of a list that has 3 matrices as > its elements and then average those numbers. I think I am close, but I > can't get it to quite work out. For example, > > > a <- list(matrix(c(10,NA,NA,12,11, > > 10,13,NA,14,12),ncol=2),matrix(c(10,12,15,13,11, > > 13,NA,NA,12,10),ncol=2),matrix(c(10,15,NA,13,NA, 13,12,NA,NA,10),ncol=2)) > > a > [[1]] > [,1] [,2] > [1,] 10 10 > [2,] NA 13 > [3,] NA NA > [4,] 13 14 > [5,] 11 12 > > [[2]] > [,1] [,2] > [1,] 10 13 > [2,] 12 NA > [3,] 15 NA > [4,] 13 12 > [5,] 11 10 > > [[3]] > [,1] [,2] > [1,] 10 13 > [2,] 15 12 > [3,] NA NA > [4,] 13 NA > [5,] NA 10 > > I want to average the non-NA numbers that simultaneously appear in each > column of all 3 matrices. For the first column, 10 and 13 are the only > numbers that appear in all 3 matrices. Thus, I want to take the average of > 10 and 13. Then repeat the same process for the second column. The data > here is only a sample, but with the data I work with, there are many more > columns in each matrix in the list. Does anyone know a efficient way to do > this? Maybe using lapply()? Thanks in advance. > > dxc13 > -- > View this message in context: > http://www.nabble.com/matching-values-in-a-list-tp14767170p14767170.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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. > ______________________________________________ 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.
