I'm a little puzzled by the assertion that the result is 0.0 when all the elements are NA:
> sum(NA) [1] NA > sum(c(NA,NA)) [1] NA > sum(rep(NA, 10)) [1] NA > sum(as.numeric(letters[1:4])) [1] NA Warning message: NAs introduced by coercion Considering that the example snippet of code has several other aspects besides using sum(), among them subsetting rows of a data frame when there are apparently NAs in some its variables ... I wonder if the reason for the failure of that snippet has been misunderstood? -- Don MacQueen Lawrence Livermore National Laboratory 7000 East Ave., L-627 Livermore, CA 94550 925-423-1062 On 1/25/15, 3:21 PM, "Allen Bingham" <aebingh...@gmail.com> wrote: >I understand that in order to get the sum function to ignore missing >values >I need to supply the argument na.rm=TRUE. However, when summing numeric >values in which ALL components are "NA" ... the result is 0.0 ... instead >of >(what I would get from SAS) of NA (or in the case of SAS "."). > >Accordingly, I've had to go to 'extreme' measures to get the sum function >to >result in NA if all arguments are missing (otherwise give me a sum of all >non-NA elements). > >So for example here's a snippet of code that ALMOST does what I want: > > >SumValue<-apply(subset(InputDataFrame,!is.na(Variable.1)|!is.na(Variable.2 >), >select=c(Variable.1,Variable.2)),1,sum,na.rm=TRUE) > >In reality this does NOT give me records with NA for SumValue ... but it >doesn't give me values for any records in which both Variable.1 and >Variable.2 are NA --- which is "good enough" for my purposes. > >I'm guessing with a little more work I could come up with a way to adapt >the >code above so that I could get it to work like SAS's sum function ... > >... but before I go that extra mile I thought I'd ask others if they know >of >functions in either base R ... or in a package that will better mimic the >SAS sum function. > >Any suggestions? > >Thanks. >______________________________________ >Allen Bingham >aebingh...@gmail.com > >______________________________________________ >R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >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. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
