On Jun 19, 2013, at 8:24 AM, Brian Perron <beper...@umich.edu> wrote:
> Greetings: > > I am looking for a way to avoid using the ifelse function for > constructing a new variable. More specifically, assume I have a set > of variables with scores ranging from 1 to 30. > > set.seed(12345) > x <- c(1:30) > x1 <- sample(x, 15, replace = TRUE) > x2 <- sample(x, 15, replace = TRUE) > x3 <- sample(x, 15, replace = TRUE) > x4 <- sample(x, 15, replace = TRUE) > > I want to construct a dichotomous variable that tests whether any of > the variables contains the value 1. > > newVar <-ifelse(x1 == 1 | x2 == 1 | x3 == 1 | x4 == 1, 1, 0) > > I want to avoid the ifelse function because I have a number of large > variable lists that will require new variables to be created. I'm > sure there is a simple way to do this, but I haven't had any luck with > my search! > > Thanks in advance. > > Brian If each of the vectors will be of the same length, create a matrix that contains each one as a column: set.seed(12345) x <- c(1:30) x1 <- sample(x, 15, replace = TRUE) x2 <- sample(x, 15, replace = TRUE) x3 <- sample(x, 15, replace = TRUE) x4 <- sample(x, 15, replace = TRUE) > cbind(x1, x2, x3, x4) x1 x2 x3 x4 [1,] 22 14 24 10 [2,] 27 12 1 2 [3,] 23 13 6 2 [4,] 27 6 21 2 [5,] 14 29 12 19 [6,] 5 14 11 29 [7,] 10 10 27 25 [8,] 16 29 28 10 [9,] 22 22 19 7 [10,] 30 20 5 22 [11,] 2 12 24 15 [12,] 5 21 13 22 [13,] 23 17 28 3 [14,] 1 7 24 14 [15,] 12 15 8 8 Then you can use: > rowSums(cbind(x1, x2, x3, x4) == 1) [1] 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 which gets you the same result as: > ifelse(x1 == 1 | x2 == 1 | x3 == 1 | x4 == 1, 1, 0) [1] 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 Regards, Marc Schwartz ______________________________________________ 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.