[R 1.7.1 on Windows XP Pro] Since R allows missing values for character variables, why are NA's not propagated by character manipulation functions? For example:
> temp <- c("a", NA) > temp [1] "a" NA > is.na(temp) [1] FALSE TRUE > paste(temp[1], temp[2]) [1] "a NA" > substr(temp, 1, 1) [1] "a" "N" > sub("[aA]","b", temp) [1] "b" "Nb" It seems to me that paste(temp[1], temp[2]) should return a single character NA: it asks to concatenate "a" with some unknown string, so the result should be unknown as well. This is certainly how numeric NA's are handled. Rich Raubertas Biometrics Research, RY33-300 Merck & Co. ------------------------------------------------------------------------------ Notice: This e-mail message, together with any attachments, ...{{dropped}} ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help