I'd like to evaluate a function at each point on a 2 or 3-D grid. Is there some function that already does this, or generates the grid of points? My search has led me to the grid and lattice packages, and I found a reference to the sp package (e.g., SpatialGrid) for this. There are things in there that might be relevant, but at first blush many of them are embedded in other concepts (grobs, shingles, rugs) and don't obviously solve the problem. I know this is not a hard thing to program, but I suspect someone has already done it. Any pointers? Thanks. -- Ross Boylan wk: (415) 514-8146 185 Berry St #5700 ross at biostat.ucsf.edu Dept of Epidemiology and Biostatistics fax: (415) 514-8150 University of California, San Francisco San Francisco, CA 94107-1739 hm: (415) 550-1062
Ross
I think you want
?expand.grid
BTW, help.search('grid') finds this.
Cheers ......
Peter Alspach
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Ross Boylan
> Sent: Friday, 8 December 2006 8:03 a.m.
> To: r-help
> Subject: [R] making a grid of points
>
> I'd like to evaluate a function at each point on a 2 or 3-D
> grid. Is there some function that already does this, or
> generates the grid of points?
>
> My search has led me to the grid and lattice packages, and I
> found a reference to the sp package (e.g., SpatialGrid) for
> this. There are things in there that might be relevant, but
> at first blush many of them are embedded in other concepts
> (grobs, shingles, rugs) and don't obviously solve the problem.
>
> I know this is not a hard thing to program, but I suspect
> someone has already done it. Any pointers?
>
> Thanks.
> --
> Ross Boylan wk: (415) 514-8146
> 185 Berry St #5700 ross at biostat.ucsf.edu
> Dept of Epidemiology and Biostatistics fax: (415) 514-8150
> University of California, San Francisco
> San Francisco, CA 94107-1739 hm: (415) 550-1062
>
> ______________________________________________
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> 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.
>
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On Thu, 7 Dec 2006, Ross Boylan wrote:> I'd like to evaluate a function at each point on a 2 or 3-D grid. Is > there some function that already does this, or generates the grid of > points? > > My search has led me to the grid and lattice packages, and I found a > reference to the sp package (e.g., SpatialGrid) for this. There are > things in there that might be relevant, but at first blush many of them > are embedded in other concepts (grobs, shingles, rugs) and don't > obviously solve the problem. > > I know this is not a hard thing to program, but I suspect someone has > already done it. Any pointers?Which "space" are your points in? The sp package might help if the data are spatial/geographical, but I think that expand.grid() is your friend, followed by one of the apply() family to run your function on each row of the data frame output by expand.grid(). Roger> > Thanks. >-- Roger Bivand Economic Geography Section, Department of Economics, Norwegian School of Economics and Business Administration, Helleveien 30, N-5045 Bergen, Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43 e-mail: Roger.Bivand at nhh.no