[R] paste and NAs

[Benjamin.STABLER@odot.state.or.us]

I understand how R treats NAs but in the situation below it would be nice to
have a na.skip argument to paste so it does not convert the NAs to "NA"s and
simply skips those elements of the vector for pasting.  

> x
[1] "2.13" "2.3"  NA     NA     "2.83" NA    

> paste(x, "0", sep="")
[1] "2.130" "2.30"  "NA0"   "NA0"   "2.830" "NA0"  

With na.skip argument:

paste(x, "0", sep="", na.skip=T)
[1] "2.130" "2.30"  NA   NA   "2.830" NA  

Otherwise I will use:

y <- paste(x, "0", sep="")
gsub(paste("NA","0",sep=""),"", y)

"" is not the same as NA, but for my purposes "" is close enough.  Why can't
I use NA as a replacement in gsub, even though c("a", NA) works?

Benjamin Stabler
Transportation Planning Analysis Unit
Oregon Department of Transportation
555 13th Street NE, Suite 2
Salem, OR 97301  Ph: 503-986-4104