implicit return? [R for BE/BA]

posted by ElMaestro  – Belgium?, 2019-04-29 12:55  – Posting: # 20262
Views: 2,548

Hi Hötzi,

» Use ifelse() for vectorized conditions. See this thread.

Try this:
library(microbenchmark)

x=round(runif(100),0)
Len=100

f1=function(x, Len)
{
 ifelse ((x==0), "foo", "bar")
}

f1(x, Len)


f2=function(x, Len)
{
 rslt=rep("foo", Len)
 for (i in 1:Len)
  if (x[i]) rslt[i]="bar"
 return(rslt)
}

f2(x, Len)



res <- microbenchmark(
                      f1(round(runif(Len),0), Len),
                      f2(round(runif(Len),0), Len),
                      times=3000L)
print(res)


note I am passing Len to f1 even though it is not used there in order to give the function call the same overhead, otherwise the comparison might be called unfair.

On my system f2 is a lot faster, so the advantage of runif may be solely syntactic and not in any way a true vectorisation advantage (easier but not more efficient).

Le tits now.

Best regards,
ElMaestro

Complete thread:

Activity
 Admin contact
20,237 posts in 4,258 threads, 1,396 registered users;
online 11 (0 registered, 11 guests [including 8 identified bots]).
Forum time (Europe/Vienna): 16:17 CET

Science may set limits to knowledge,
but should not set limits to imagination.    Bertrand Russell

The Bioequivalence and Bioavailability Forum is hosted by
BEBAC Ing. Helmut Schütz
HTML5