R 中测量函数执行时间的方法

Is there a standardized way in R of measuring execution time of function?

Obviously I can take system.time before and after execution and then take the difference of those, but I would like to know if there is some standardized way or function (would like to not invent the wheel).

I seem to remember that I have once used something like below:

somesysfunction("myfunction(with,arguments)")
> Start time : 2001-01-01 00:00:00  # output of somesysfunction
> "Result" "of" "myfunction"        # output of myfunction
> End time : 2001-01-01 00:00:10    # output of somesysfunction
> Total Execution time : 10 seconds # output of somesysfunction

The built-in function system.time() will do it.

Use like: system.time(result <- myfunction(with, arguments))

A slightly nicer way of measuring execution time, is to use the rbenchmark package. This package (easily) allows you to specify how many times to replicate your test and would the relative benchmark should be.

See also a related question at stats.stackexchange

You can use MATLAB-style tic-toc functions, if you prefer. See this other SO question

Stopwatch function in R

As Andrie said, system.time() works fine. For short function I prefer to put replicate() in it:

system.time( replicate(10000, myfunction(with,arguments) ) )

Another possible way of doing this would be to use Sys.time():

start.time <- Sys.time()
...Relevent codes...
end.time <- Sys.time()
time.taken <- end.time - start.time
time.taken

Not the most elegant way to do it, compared to the answere above , but definitely a way to do it.

There is also proc.time()

You can use in the same way as Sys.time but it gives you a similar result to system.time.

ptm <- proc.time()
#your function here
proc.time() - ptm

the main difference between using

system.time({ #your function here })

is that the proc.time() method still does execute your function instead of just measuring the time... and by the way, I like to use system.time with {} inside so you can put a set of things...

The package "tictoc" gives you a very simple way of measuring execution time. The documentation is in: https://cran.fhcrc.org/web/packages/tictoc/tictoc.pdf.

install.packages("tictoc")
require(tictoc)
tic()
rnorm(1000,0,1)
toc()

To save the elapsed time into a variable you can do:

install.packages("tictoc")
require(tictoc)
tic()
rnorm(1000,0,1)
exectime <- toc()
exectime <- exectime$toc - exectime$tic

Although other solutions are useful for a single function, I recommend the following piece of code where is more general and effective:

Rprof ( tf <- "log.log",  memory.profiling = TRUE )
your code must be in between
Rprof ( NULL ) ; print ( summaryRprof ( tf )  )

microbenchmark is a lightweight (~50kB) package and more-or-less a standard way in R for benchmarking multiple expressions and functions:

microbenchmark(myfunction(with,arguments))

For example:

> microbenchmark::microbenchmark(log10(5), log(5)/log(10), times = 10000)
Unit: nanoseconds
           expr min lq    mean median uq   max neval cld
       log10(5)   0  0 25.5738      0  1 10265 10000   a
 log(5)/log(10)   0  0 28.1838      0  1 10265 10000

Here both the expressions were evaluated 10000 times, with mean execution time being around 25-30 ns.

Another simple but very powerful way to do this is by using the package profvis. It doesn't just measure the execution time of your code but gives you a drill down for each function you execute. It can be used for Shiny as well.

library(profvis)

profvis({
  #your code here
})

Click here for some examples.