clear R-objects inside a function?

Paul E Johnson <pauljohn at ukans.edu> writes:

Using RedHat Linux 7.0, R-1.2.2, R-hdf5-1.2 library,

I want to load a dataset, do some stuff with it, then erase its objects,
get an other, repeat.  My friend wrote a function which tried to clear
away all the objects. At the end, it uses rm() to remove objects. This
is the same way we do it interactively, from the R prompt:

testLoadSeveralHDF <- function(numFiles) {
  for (i in 0:(numFiles-1)) {
    filename <- paste("trial",i,".hdf",sep="")
    print(filename)
    hdf5load(filename)
    rm(list = ls(pat="g*"))
  }
}

However, after that program runs, the g* objects are not erased, but
typing "rm(list=ls(pat="g*")) from the command line does erase them.  I
realized there's something about the environment that I need to tell the
function, I just don't know what?

Add envir = .GlobalEnv to both the ls and the rm calls.  That is

     rm(list = ls(pat = "g*", envir = .GlobalEnv), envir = .GlobalEnv)