system.time {base} | 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, has been deprecated in 2016 and finally became
defunct in 2022.
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)