system.time | R Documentation |
Return CPU (and other) times that expr
used.
system.time(expr, gcFirst = TRUE)
expr |
Valid R expression to be timed. |
gcFirst |
Logical - should a garbage collection be performed
immediately before the timing? Default is |
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.
A object of class "proc_time"
: see
proc.time
for details.
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.
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)
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