[R] Coalesce function in BBmisc, emoa, and microbenchmark packages
pjmiller_57 at yahoo.com
Sat Mar 17 14:24:54 CET 2012
Need to coalesce some columns using R. Looked online to see how this is done. One approach appears to be to use ifelse. Also uncovered a coalesce function in the BBmisc, emoa, and microbenchmark packages.
Trouble is I can't seem to get it to work in any of these packages. Or perhaps I misunderstand what it's intended to do. The documentation is generally pretty scant.
Working with two columns: Date of Death (DOD) and Last Known Date Alive (LKDA). One or the other column is populated for each of the patients in my dataframe and the other column is blank.
When I run code like "with(Demographics, coalesce(DOD, LKDA))", the function generates a value whenever DOD is not missing and generates NA otherwise (even though the value for LKDA is not missing). So, for example, I get an NA for the 8th element below, even though I have a value of "2008-03-25" for LKDA.
> with(Demographics, coalesce(DOD, LKDA))
 "2006-07-23" "2008-07-09" "2007-12-16" "2008-01-19" "2009-05-05" "2006-04-29" "2006-06-18" NA
At least that's what happens in the BBmisc and emoa packages. The microbenchmark package appears not to have a coalesce function though the documentation says it does. I think I've seen instances where a function gets removed from a package. So maybe that's what happened here.
Thought maybe there is a difference between blank and NA as far as R or the function is concerned. The is.na() function seems to indicate that a blank is an NA. I also tried making the blanks into NA but that didn't help.
Does anyone have experience with the coalesce function in any of the three packages? If so, can they help me understand what I might be doing wrong?
More information about the R-help