Hi Chris, Does this do what you're after? It just compares each element of a (i.e., a[[1]] and a[[2]]) to c(1, 2) and determines if they are identical or not.
which(sapply(a, identical, y = c(1, 2))) There were too many 1s floating around for me to figure out if you wanted to find elements of a that matched the entire vector or subelements of a that matched elements of the vector (if that makes any sense). HTH, Josh On Mon, Nov 15, 2010 at 1:24 PM, Chris Carleton <w_chris_carle...@hotmail.com> wrote: > Hi List, > > I'm trying to work out how to use which(), or another function, to find the > top-level index of a list item based on a condition. An example will clarify > my question. > > a <- list(c(1,2),c(3,4)) > a > [[1]] > [1] 1 2 > > [[2]] > [1] 3 4 > > I want to find the top level index of c(1,2), which should return 1 since; > > a[[1]] > [1] 1 2 > > I can't seem to work out the syntax. I've tried; > > which(a == c(1,2)) > > and an error about coercing to double is returned. I can find the index of > elements of a particular item by > > which(a[[1]]==c(1,2)) or which(a[[1]]==1) etc that return [1] 1 2 and [1] 1 > respectively as they should. Any thoughts? > > C > > [[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. > -- Joshua Wiley Ph.D. Student, Health Psychology University of California, Los Angeles http://www.joshuawiley.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.
