On Wed, Dec 15, 2010 at 2:22 PM, Jim Maas <jimmaa...@gmail.com> wrote: > I get a list object from an iterative function. I'm trying to figure out > the most efficient way to calculate the mean of one element, across all > components of the overall list. > > I've tried > > output <- mean (listobject[[1:5]]$element) > > to get the mean of "element" in the first five components? > > It doesn't like the $. I'm suspect one of the "apply" functions will work, > but again I've not had success > Are you looking for this?
> x <- list() > x[[1]] <- list() > x[[1]][['element']] <- rnorm(100) > x[[2]] <- list() > x[[2]][['element']] <- rnorm(100) > x[[3]] <- list() > x[[3]][['element']] <- rnorm(100) > str(x) List of 3 $ :List of 1 ..$ element: num [1:100] 1.822 1.818 -2.305 -0.307 0.268 ... $ :List of 1 ..$ element: num [1:100] 0.0167 0.3834 1.2947 -0.4583 -0.2165 ... $ :List of 1 ..$ element: num [1:100] -1.244 -0.369 0.772 -2.368 2.136 ... > mean(x[[1]][['element']]) [1] 0.1446610 > mean(x[[2]][['element']]) [1] -0.1471191 > mapply(function(y) mean(y$element), x) [1] 0.14466105 -0.14711910 0.05024247 Liviu ______________________________________________ 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.
