[] works on a list and extracts multiple elements. However, that is not it seems what you want, rather, unions of elements of elements of lists. That is a pretty unusual need, and perhaps you could explain you you need it.
Andy's solution still need something like do.call("c", lapply(alist, function(x) x$vec)) but then it *is* unions of elements of elements of lists. On Thu, 15 Jan 2004, Liaw, Andy wrote: > Aren't sapply()/lapply() sufficient for this? > > > sapply(alist, function(x) x$vec) > [,1] [,2] > [1,] 1 5 > [2,] 2 6 > [3,] 3 7 > [4,] 4 8 > > lapply(alist, function(x) x$vec) > [[1]] > [1] 1 2 3 4 > > [[2]] > [1] 5 6 7 8 > > HTH, > Andy > > > From: Waichler, Scott R > > > > For a long time I've wanted a way to conveniently extract > > multiple elements > > from a list, which [[ doesn't allow. Can anyone suggest an efficient > > function to do this? Wouldn't it be a sensible addition to R? > > > > For example, > > > > alist <- list() > > alist[[1]] <- list() > > alist[[1]]$name <- "first" > > alist[[1]]$vec <- 1:4 > > alist[[2]] <- list() > > alist[[2]]$name <- "second" > > alist[[2]]$vec <- 5:8 > > both.vec <- c(alist[[1]]$vec, alist[[2]]$vec) > > > > Can I get both.vec without c() or an explicit loop? > > > > and > > > > new.names <- c("one", "two") > > alist[[1]]$name <- new.names[1] > > alist[[2]]$name <- new.names[2] > > > > Could I assign the new values in a quasi-vectorized way? > > > > Thanks, > > Scott Waichler > > Pacific Northwest National Laboratory > > Richland, WA USA > > > > > ------------------------------------------------------------------------------ > Notice: This e-mail message, together with any attachments,...{{dropped}} > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html