f <- function (x) { lengths <- vapply(x, FUN = length, FUN.VALUE = 0L) split(rep(seq_along(x), lengths), unlist(x, use.names = FALSE)) } f(A1) # gives about what you want (has, e.g., name 23, not position 23, in output) Bill Dunlap TIBCO Software wdunlap tibco.com
On Tue, Jul 8, 2014 at 9:39 AM, Lorenzo Alfieri <alfio...@hotmail.com> wrote: > Hi, > I'm trying to find a way to reorder the elements of a list. > Let's say I have a list like this: > A1<-list(c(1:4),c(2,4,5),23,c(4,5,13)) > >> A1 > [[1]] > [1] 1 2 3 4 > > [[2]] > [1] 2 4 5 > > [[3]] > [1] 23 > > [[4]] > [1] 4 5 13 > > All the elements included in it are values, while each sublist is a time index > Now, I'd like to reorder the list (without looping) so to obtain one sublist > for each value, which include all the time indices where each value appears. > In other words, the result should look like this: >>A2 > [[1]] > [1] 1 > > [[2]] > [1] 1 2 #because value "2" appears in the time index [[1]] and [[2]] of A1 > > [[3]] > [1] 1 > > [[4]] > [1] 1 2 4 > > [[5]] > [1] 2 4 > > [[13]] > [1] 4 > > [[23]] > [1] 3 > > Any suggestion? > Thanks > Alfio > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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.