[R] Smoothing a persp graph

[David Winsemius]

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:dwinsemius at comcast.net]
>> Sent: Tuesday, June 19, 2012 10:00 AM
>> To: dcarlson at tamu.edu
>> Cc: "'Kehl Dániel'"; r-help at 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-bounces at r-project.org [mailto:r-help-bounces at r-
>>>> project.org] On Behalf Of Kehl Dániel
>>>> Sent: Tuesday, June 19, 2012 8:42 AM
>>>> To: r-help at 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
>>>>>
>>>>> ______________________________________________
>>>>> 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.
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>> 	[[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> 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.
>>
>> David Winsemius, MD
>> West Hartford, CT
>

David Winsemius, MD
West Hartford, CT