Sven and John, Thanks for your suggested code ... hits the mark! The code by John is what I need to be able to use in an apply function, but I really like the simplicity of Sven's suggestion.
Also thanks to all who replied --- really helped broaden my knowledge of R. Allen -----Original Message----- From: Sven E. Templer [mailto:sven.temp...@gmail.com] Sent: Monday, January 26, 2015 6:56 AM To: Martin Maechler Cc: Jim Lemon; r-help mailing list; Allen Bingham Subject: Re: [R] Sum function and missing values --- need to mimic SAS sum function you can also define 'na.rm' in sum() by 'NA state' of x (where x is your vector holding the data): sum(x, na.rm=!all(is.na(x))) On 26 January 2015 at 13:45, Martin Maechler <maech...@lynne.stat.math.ethz.ch> wrote: >>>>>> Jim Lemon <drjimle...@gmail.com> >>>>>> on Mon, 26 Jan 2015 11:21:03 +1100 writes: > > > Hi Allen, How about this: > > > sum_w_NA<-function(x) ifelse(all(is.na(x)),NA,sum(x,na.rm=TRUE)) > > Excuse, Jim, but that's yet another "horrible misuse of ifelse()" > > John Fox's reply *did* contain the "proper" solution > > if (all(is.na(x))) NA else sum(x, na.rm=TRUE) > > The ifelse() function should never be used in such cases. > Read more after googling > > "Do NOT use ifelse()" > > -- include the quotes in your search -- > > or directly at > http://stat.ethz.ch/pipermail/r-help/2014-December/424367.html > > Yes, this has been on R-help a month ago.. > Martin > > > On Mon, Jan 26, 2015 at 10:21 AM, 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. > > ______________________________________________ > 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.