Re: array current size
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- Subject: Re: array current size
- From: "Torsten K." <agonizer@...>
- Date: 2010年2月23日 11:43:03 +0100
Am Dienstag, 23. Februar 2010 11:01:45 schrieb steve donovan:
> On Tue, Feb 23, 2010 at 11:57 AM, spir <denis.spir@free.fr> wrote:
> > instead of "table.insert(array,item)" or "array[#array+1] = item".
>
> Those are often used; AFAIK the second idiom is considered pretty quick.
>
> When in doubt, do a microbenchmark!
>
> steve d.
I did it, here are the timings (i removed "sys" timing). Only one core was
used of a Q9550 @ 2.83GHz, lua 5.1.4
tk@gentoo-c2q ~ $ time lua -e "a={};for i=1,20000000 do a[#a+1]=i end"
real 0m6.863s
user 0m6.579s
tk@gentoo-c2q ~ $ time lua -e "a={};for i=1,20000000 do table.insert(a,i) end"
real 0m7.768s
user 0m7.466s
tk@gentoo-c2q ~ $ time lua -e "a={};for i=1,20000000 do a[i]=i end"
real 0m1.322s
user 0m1.050s
The same with local:
tk@gentoo-c2q ~ $ time lua -e "local a={};for i=1,20000000 do a[#a+1]=i end"
real 0m5.719s
user 0m5.427s
tk@gentoo-c2q ~ $ time lua -e "local a={};for i=1,20000000 do
table.insert(a,i) end"
real 0m7.225s
user 0m6.941s
tk@gentoo-c2q ~ $ time lua -e "local a={};for i=1,20000000 do a[i]=i end"
real 0m0.966s
user 0m0.697s
Bye,
Torsten