Hi, The problem is that (a == 1 | b == 1) returns some NAs. NAs are not treated as strictly TRUE or FALSE. From the documentation (see ?ifelse) "Missing values in 'test' give missing values in the result".
You need to use a construct designed to force a TRUE/FALSE value OR something that handles NAs (like is.na()). HTH, Josh On Fri, Apr 8, 2011 at 10:56 AM, wgu <w...@uab.edu> wrote: > I have used R for years but run into a seemingly simple problem involving > 'ifelse'. condensed code like this > > a=c(2,NA,NA,NA,2,2,NA,2,NA,2) > b=c(NA,1,1,NA,2,2,2,2,2,2) > > #I want to combined a and b into c so that c would be a valid number either a > or b is not missing > > c=ifelse(a==1|b==1,1,ifelse(a==2|b==2,2,NA)) > cbind(a,b,c) > > a b c > [1,] 2 NA NA > [2,] NA 1 1 > [3,] NA 1 1 > [4,] NA NA NA > [5,] 2 2 2 > [6,] 2 2 2 > [7,] NA 2 NA > [8,] 2 2 2 > [9,] NA 2 NA > [10,] 2 2 2 > > look at rows 1, 7 and 9, c supposes to be 2 but got NA instead. seemingly, > the second 'ifelse' doesn't perform as it supposes. > > my R version is 2.12.2 > > any suggestion > ______________________________________________ > 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.
