Dear Hadly, dear list,
On Wed, Feb 16, 2011 at 9:53 PM, Hadley Wickham <had...@rice.edu> wrote:
> I wondered about this statement too but:
>
>> system.time(replicate(1e4, base::print))
> user system elapsed
> 0.539 0.001 0.541
>> system.time(replicate(1e4, print))
> user system elapsed
> 0.013 0.000 0.012
These timings are skewed. Because I too have wondered about this in
the past, I recently published the microbenchmark package which tries
hard to accurately time it takes to evaluate some expression(s). Using
this package I get:
> library("microbenchmark")
> res <- microbenchmark(print, base::print, times=10000)
> res
Unit: nanoeconds ## I've fixed the typo, but not pushed to CRAN
min lq median uq max
print 57 65 68.0 69 48389
base::print 41763 43357 44278.5 48403 4749851
A better way to look at this is by converting to evaluations per second:
> print(res, unit="eps")
Unit: evaluations per second
min lq median uq max
print 17543859.65 15384615.38 14705882.35 14492753.62 20665.8538
base::print 23944.64 23064.33 22584.32 20659.88 210.5329
Resolving 23000 names per second or ~15M ist quite a dramatic
difference in my world. The timings obtained by
> system.time(replicate(1e4, base::print))
User System verstrichen
0.475 0.006 0.483
> system.time(replicate(1e4, print))
User System verstrichen
0.011 0.001 0.014
are skewed by the overhead of replicate() in this case because the
execution time of the expression under test is so short.
Cheers,
Olaf Mersmann
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