system.time
CPU Time Used
Description
Return CPU (and other) times that expr
used.
Usage
system.time(expr, gcFirst = TRUE)
Arguments
expr | Valid R expression to be timed. |
gcFirst | Logical - should a garbage collection be performed immediately before the timing? Default is |
Details
system.time
calls the function proc.time
, evaluates expr
, and then calls proc.time
once more, returning the difference between the two proc.time
calls.
unix.time
has been an alias of system.time
, for compatibility with S, and has finally been deprecated in 2016.
Timings of evaluations of the same expression can vary considerably depending on whether the evaluation triggers a garbage collection. When gcFirst
is TRUE
a garbage collection (gc
) will be performed immediately before the evaluation of expr
. This will usually produce more consistent timings.
Value
A object of class "proc_time"
: see proc.time
for details.
See Also
proc.time
, time
which is for time series.
setTimeLimit
to limit the (CPU/elapsed) time R is allowed to use.
Sys.time
to get the current date & time.
Examples
require(stats) system.time(for(i in 1:100) mad(runif(1000))) ## Not run: exT <- function(n = 10000) { # Purpose: Test if system.time works ok; n: loop size system.time(for(i in 1:n) x <- mean(rt(1000, df = 4))) } #-- Try to interrupt one of the following (using Ctrl-C / Escape): exT() #- about 4 secs on a 2.5GHz Xeon system.time(exT()) #~ +/- same ## End(Not run)
Copyright (©) 1999–2012 R Foundation for Statistical Computing.
Licensed under the GNU General Public License.