On Jun 19, 2012, at 11:42 AM, David L Carlson wrote:
The kde2d function estimates density using the spacing of the points
in two
dimensions. The requester has gridded (x, y) data with a z value. The
function call for kde2d takes x and y and compute z values that
estimate
point density.
Kde2d is used for point data where you want to estimate the density
of the
points in 2d. Use kde2d to produce the gridded data you need to pass
on to
contour or persp, but the requester already has gridded data with a
z value
that he wants to smooth (e.g. elevation, depth to an interesting
deposit,
thickness of a stratum, rainfall, tree frog density), a standard
problem in
geostatistics.
-------
David 2
Yes. I see the point now, and your cited vignette also looks very
helpful. Thanks.
--
David, the lesser.
-----Original Message-----
From: David Winsemius [mailto:dwinsem...@comcast.net]
Sent: Tuesday, June 19, 2012 10:00 AM
To: dcarl...@tamu.edu
Cc: "'Kehl Dániel'"; r-help@r-project.org
Subject: Re: [R] Smoothing a persp graph
On Jun 19, 2012, at 10:02 AM, David L Carlson wrote:
kde2d is for two dimensional data. The persp graph is 3d.
Huh? The question asked about plotting data that was 2d. The third
dimension was to be the density. kde2d in package MASS or the
similarly named function in package KernSmooth would seem to be on
point here.
--
David.
Look at the StatDA package, particularly the Vignette for that
package,
"Tutorial to the package StatDA" which discusses smoothing
techniques
and kriging:
http://cran.r-project.org/web/packages/StatDA/vignettes/StatDA.pdf
For more options look at the Spatial Task View:
http://cran.r-project.org/web/views/Spatial.html
----------------------------------------------
David L Carlson
Associate Professor of Anthropology
Texas A&M University
College Station, TX 77843-4352
-----Original Message-----
From: r-help-boun...@r-project.org [mailto:r-help-bounces@r-
project.org] On Behalf Of Kehl Dániel
Sent: Tuesday, June 19, 2012 8:42 AM
To: r-help@r-project.org
Subject: Re: [R] Smoothing a persp graph
Take a look at the
kde2d
function in the MASS package, maybe it helps.
Best
kd
2012.06.19. 14:26 keltezissel, Guillaume Chapron mrta:
Hi,
I'm unable to find a way to smooth data for a persp() graph.
Example, suppose that I have data x,y,z like this:
x<- 1:10
y<- 1:10
k<- 20
z<- outer(x, y, "*") + matrix( k*runif(100, -1, 1), 10, 10)
persp(x, y, z, theta = 35, phi = 25)
The graph is not very nice. Is there a way to smooth the z data so
that at the end the graph would look more like something like that:
k<- 2
z<- outer(x, y, "*") + matrix( k*runif(100, -1, 1), 10, 10)
persp(x, y, z, theta = 35, phi = 25)
There seems to be many smoothing functions in R (e.g. loess) but I
have not been able to find one for a 3D graph.
Thanks!
Guillaume
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______________________________________________
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David Winsemius, MD
West Hartford, CT
David Winsemius, MD
West Hartford, CT
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
