There may be better solutions, but find("functionname") seems to work reasonably well? However, it only works for loaded packages.
> find("strwidth")
[1] "package:graphics"
> find("qplot")
character(0)
> library(ggplot2)
> find("qplot")
[1] "package:ggplot2"
>
(If you need the raw name of the package you can use gsub("^package:","",results))
(The answers to the previous question linked by Andrie include this answer; they don't give the bit about gsub, and they all seem to share the issue of not finding non-loaded packages.)
Here's a quick hack to find functions even in non-loaded packages:
findAllFun <- function(f) {
h <- help.search(paste0("^",f,"$"),agrep=FALSE)
h$matches[,"Package"]
}
findAllFun("qplot")
## "ggplot2"
findAllFun("lambertW")
## "emdbook" "VGAM"
> findAllFun("xYplot")
## "Hmisc" "lattice"
If you need to find functions in non-installed packages (i.e. searching CRAN), then findFn from the sos package will be your friend.
