Reset R instance

Question

Is it possible to reset an instance of R?

Eg. if I have used the commands

x <- 1:10
plot(x, -x)

And thus polluted the system with the x variable. In this state can I then revert back to a clean state without shutting R down and launching it again?

Answer 1

You can remove all variables from your workspace using

rm(list = ls())

You can 'unload' packages with

detach(package:packagename)

---

EDIT:

You can close all graphics devices with

graphics.off()

You can clear the command editor history with CTRL+L.

If you use Tinn-R as your editor, there is a 'Clear all' button, which clears your workspace and command editor history, and closes graphics devices. (It does not detach packages.)

---

ANOTHER EDIT:

One other thing that you would have to do to reset R is to close all open connections. It is incredibly bad form to leave open connections lying about, so this is more belt and braces than a necessity. (You can probably fool close_all_connections by opening connections in obscure environments, but in that case you have only yourself to blame.)

is.connection <- function(x) inherits(x, "connection")

get_connections <- function(envir = parent.frame()) 
{
  Filter(is.connection, mget(ls(envir = envir), envir = envir))
}

close_all_connections <- function() 
{
   lapply(c(sys.frames(), globalenv(), baseenv()), 
      function(e) lapply(get_connections(e), close))
}

close_all_connections()

As Marek suggests, use closeAllConnections to do this.

ANOTHER EDIT:

In response to Ben's comment about resetting options, that's actually a little bit tricky. the best way to do it would be to store a copy of your options when you load R, and then reset them at this point.

#on R load
assign(".Options2", options(), baseenv())

#on reset
options(baseenv()$.Options2)

If you aren't foresighted enough to set this up when you load R, then you need something like this function.

reset_options <- function()
{
  is_win <- .Platform$OS.type == "windows"
  options(
    add.smooth            = TRUE,
    browserNLdisabled     = FALSE,
    CBoundsCheck          = FALSE,
    check.bounds          = FALSE,
    continue              = "+ ",
    contrasts             = c(
      unordered = "contr.treatment", 
      ordered   = "contr.poly"
    ), 
    defaultPackages       = c(
      "datasets", 
      "utils", 
      "grDevices", 
      "graphics", 
      "stats",
      "methods"
    ),  
    demo.ask              = "default",
    device                = if(is_win) windows else x11,
    device.ask.default    = FALSE,
    digits                = 7,
    echo                  = TRUE,
    editor                = "internal",
    encoding              = "native.enc",
    example.ask           = "default",
    expressions           = 5000,
    help.search.types     = c("vignette", "demo", "help"),    
    help.try.all.packages = FALSE,
    help_type             = "text",
    HTTPUserAgent         = with(
      R.version, 
      paste0(
        "R (", 
        paste(major, minor, sep = "."), 
        " ", 
        platform, 
        " ", 
        arch, 
        " ", 
        os, 
        ")"
      )
    ),
    internet.info         = 2,
    keep.source           = TRUE,
    keep.source.pkgs      = FALSE,
    locatorBell           = TRUE,
    mailer                = "mailto",
    max.print             = 99999,
    menu.graphics         = TRUE,
    na.action             = "na.omit",
    nwarnings             = 50,
    OutDec                = ".",
    pager                 = "internal",
    papersize             = "a4",
    pdfviewer             = file.path(R.home("bin"), "open.exe"),
    pkgType               = if(is_win) "win.binary" else "source",
    prompt                = "> ",
    repos                 = c(
      CRAN      = "@CRAN@", 
      CRANextra = "http://www.stats.ox.ac.uk/pub/RWin"
    ), 
    scipen                = 0,
    show.coef.Pvalues     = TRUE,
    show.error.messages   = TRUE,
    show.signif.stars     = TRUE,
    str                   = list(
      strict.width = "no",
      digits.d     = 3,
      vec.len      = 4
    ),
    str.dendrogram.last   = "`",
    stringsAsFactors      = TRUE,
    timeout               = 60,
    ts.eps                = 1e-05,
    ts.S.compat           = FALSE,
    unzip                 = "internal",
    useFancyQuotes        = TRUE,
    verbose               = FALSE,
    warn                  = 0,
    warning.length        = 1000,
    width                 = 80,
    windowsTimeouts       = c(100, 500)
  )
)

The options in that function provide a vanilla R session so you might wish to source your Rprofile.site file afterwards to customise R how you like it.

source(file.path(R.home("etc"), "Rprofile.site"))