Hi Laura, You have gotten several good suggestions. Here are two more that may be helpful if you have (or potentially could have) unruly data. In one case, the values are theoretically, but not computationally identical. In the other, missing values lead to NA being returned, which may be a problem if you are using the logical test with an if() statement.
### Two pathologic examples ### # One: the floating point problem all((x <- c(1 - .4, .4 + .2)) == x[1]) ifelse(length(unique(x))==1, "All Equal", "Not All Equal") print(x, digits = 22) ## another option tol <- .Machine$double.eps^0.5 # standard tolerance all(x < x[1] + tol | x > x[1] - tol) # Two: the missing problem x <- c(NA, NA) all(x < x[1] + tol | x > x[1] - tol) ## another option isTRUE(all(x < x[1] + tol | x > x[1] - tol)) Best Regards, Josh On Wed, Apr 6, 2011 at 3:09 PM, Laura Smith <smithlaura...@gmail.com> wrote: > Hi! > > In a function, I may have an instance in which all elements are equal. > >> x <- rep(1,5) >> >> x > [1] 1 1 1 1 1 >> identical(x) > Error in .Internal(identical(x, y, num.eq, single.NA, attrib.as.set)) : > 'y' is missing >> all.equal(x) > Error in is.expression(x) : 'x' is missing >> > > I don't care what particular value it is, I just want to know if they are > all equal. > > What am I doing wrong, please? > > Thanks, > Laura > > [[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.
