[REBOL] Who is that grouch? -or- Fun with functions! Re:(2)
From: joel:neely:fedex at: 5-Oct-2000 8:56
Hi, Allen,
Thanks for the help! (Any suggestions for speeding up map?)
[allen--rebolforces--com] wrote:
> >
> > >> iota: function [n [integer!]] [r i] [
> > [ r: copy []
> > [ i: 0
> > [ while [i < n] [append r i: i + 1]
> > [ r
> > [ ]
>
> iota: function [n [integer!]][r i][
> r: copy []
> repeat i n [append r i]
> ]
>
> Using the 'repeat native is quicker. (by about 1 sec per 1000
> iterations on my machine).
>
Motivated by your comment, I ran a quick benchmark test:
>> bloop/run 50000
repeat: 8 1
loop: 25 3.125
while: 26 3.25
for: 30 3.75
where the second column is raw times (on a slow box) and the
third column is times relative to the repeat version. I'd
guess that the performance hit for loop and while is in
the high-level handling of the counter; a quick look at the
source for for explains its 4th place showing -- he's a
busy little beaver!
-jn-
PS: The QAD benchmark code is below, if anyone's interested:
REBOL []
bloop: make object! [
t0: t1: t2: t3: t4: now/time
dsec: func [b [time!] e [time!]] [
e: e - b
e/hour * 60 + e/minute * 60 + e/second
]
run: func [n [integer!] /local b i] [
t0: now/time
b: copy []
repeat i n [append b i: i + 1]
t1: now/time
b: copy []
i: 0
loop n [append b i: i + 1]
t2: now/time
b: copy []
i: 0
while [i < n] [append b i: i + 1]
t3: now/time
b: copy []
for i 1 n 1 [append b i]
t4: now/time
print [
"repeat: " t0: dsec t0 t1 tab t0 / t0 newline
" loop: " t1: dsec t1 t2 tab t1 / t0 newline
" while: " t2: dsec t2 t3 tab t2 / t0 newline
" for: " t3: dsec t3 t4 tab t3 / t0
]
]
]
