Suppose I'm messing about with some data by binding vectors together, as I'm wont to do on a lazy sunday afternoon.

    x <- rnorm(25, mean = 65, sd = 10)
    y <- rnorm(25, mean = 75, sd = 7)
    z <- 1:25

    dd <- data.frame(mscore = x, vscore = y, caseid = z)

I've now got my new dataframe dd, which is wonderful. But there's also still the detritus from my prior slicings and dicings:

    > ls()
    [1] "dd"        "x"          "y"          "z"         

What's a simple way to clean up my workspace if I no longer need my "source" columns, but I want to keep the dataframe? That is, now that I'm done manipulating data I'd like to just have dd and none of the smaller variables that might inadvertently mask further analysis:

    > ls()
    [1] "dd"

I feel like the solution must be of the form rm(ls[ -(dd) ]) or something, but I can't quite figure out how to say "please clean up everything BUT the following objects."