[Rd] There is pmin and pmax each taking na.rm, how about psum?

[Matthew Dowle]

Hi,

Please consider the following :

x = c(1,3,NA,5)
y = c(2,NA,4,1)

min(x,y,na.rm=TRUE)    # ok
[1] 1
max(x,y,na.rm=TRUE)    # ok
[1] 5
sum(x,y,na.rm=TRUE)    # ok
[1] 16

pmin(x,y,na.rm=TRUE)   # ok
[1] 1 3 4 1
pmax(x,y,na.rm=TRUE)   # ok
[1] 2 3 4 5
psum(x,y,na.rm=TRUE)
[1] 3 3 4 6                             # expected result
Error: could not find function "psum"   # actual result

I realise that + is already like psum, but what about NA?

x+y
[1]  3 NA NA  6        # can't supply `na.rm=TRUE` to `+`

Is there a case to add psum? Or have I missed something.

This question survived when I asked on Stack Overflow :
http://stackoverflow.com/questions/13123638/there-is-pmin-and-pmax-each-taking-na-rm-why-no-psum

And a search of the archives found that has Gabor has suggested it too as
an aside :
http://r.789695.n4.nabble.com/How-to-do-it-without-for-loops-tp794745p794750.html

If someone from R core is willing to sponsor the idea, I am willing to
write, test and submit the code for psum. Implemented in a very similar
fashion to pmin and pmax.  Or perhaps it exists already in a package
somewhere (I searched but didn't find it).

Matthew