[R] Efficiency of for-loop in R
Tong Wang
wangtong at usc.edu
Fri Dec 28 02:39:56 CET 2007
HI,
The question is meant to be a general one, I am trying to find out if there is new development in R that I might have missed.
but here's a trivial example,
To compute y=sin(x) , x = 1,2,... 100000
x=1:100000,
1. y =sin(x)
2. for(i in 1:100000) y=sin(x[i])
1 is much faster than 2.
Old Matlab also had this problem, but in new versions, 1 and 2 are mostly the same.
I am just wondering if the same improvement has happened or will happen to R.
Thanks .
----- Original Message -----
From: jim holtman <jholtman at gmail.com>
Date: Thursday, December 27, 2007 4:39 pm
Subject: Re: [R] Efficiency of for-loop in R
To: Tong Wang <wangtong at usc.edu>
Cc: R help <r-help at stat.math.ethz.ch>
> Exactly "what is the problem you are trying to solve"? Could you
> "provide commented, minimal, self-contained, reproducible code"?
>
> A lot depends on what you are trying to do, There might be other
> ways, in R, than a 'for' loop to solve your problems.
>
> On Dec 27, 2007 6:44 PM, Tong Wang <wangtong at usc.edu> wrote:
> > Hi,
> > I just realized that in Matlab, as long as memory is pre-
> allocated, doing for-loop doesn't cost more time than doing things
> in vector form.
> > But it seems in R, it still cost a lot to do for-loop. Is
> there any improvement in R that I missed. Thanks a lot.
> >
> > Merry Xmas Everyone !
> >
> > ______________________________________________
> > R-help at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html> and provide commented, minimal, self-contained,
> reproducible code.
> >
>
>
>
> --
> Jim Holtman
> Cincinnati, OH
> +1 513 646 9390
>
> What is the problem you are trying to solve?
>
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