Dear R Help, I am trying to create a boolean vector that is TRUE whenever a particular value occurs in a numeric vector, and FALSE otherwise. For example, suppose that
> y <- c(5, 2, 4, 3, 1) > y [1] 5 2 4 3 1 and suppose that I want to find where 3 occurs in y. Then, the following yields the solution: > y == 3 [1] FALSE FALSE FALSE TRUE FALSE My problem arises when the numeric vector has missing values. For example, suppose that x is the vector > x <- c( 2, NA, 1, 5, 3) > x [1] 2 NA 1 5 3 Now x == 5 yields > x == 5 [1] FALSE NA FALSE TRUE FALSE whereas what I want is FALSE FALSE FALSE TRUE FALSE I can solve this problem with a for loop: > flag <- NULL > for (i in 1:length(x)) flag <- c(flag, identical(x[i], 5)) > flag [1] FALSE FALSE FALSE TRUE FALSE Is there a way to avoid the for loop? I'm also curious why the following does not work, because it seems to me it should: > test <- function(x) identical(x[1], x[2]) > apply(cbind(x, 5), 1, test) [1] FALSE FALSE FALSE FALSE FALSE I was expecting to see FALSE FALSE FALSE TRUE FALSE. John Miyamoto -------------------------------------------------------------------- John Miyamoto, Dept. of Psychology, Box 351525 University of Washington, Seattle, WA 98195-1525 Phone 206-543-0805, Fax 206-685-3157, Email [EMAIL PROTECTED] Homepage http://faculty.washington.edu/jmiyamot/ -------------------------------------------------------------------- ______________________________________________ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help
