[R-sig-Geo] Problems with Kcross.inhom
David Villalobos
avi3187 at gmail.com
Tue Oct 29 01:47:56 CET 2013
Thank you Marcelino.
Regards
2013/10/22, Marcelino de la Cruz <marcelino.delacruz at upm.es>:
> It seems that you get an estimate of lambda= 0.00000 for your ficus
> point #2. Kinhom can only be estimated when lambda > 0 in all points.
>
> I would use either another sigma for bandwith estimation or set the
> argument leaveoneout=FALSE.
>
> Cheers,
>
> Marcelino
>
>
> El 22/10/2013 14:37, David Villalobos escribió:
>> Hi Rolf and Julia
>>
>>
>> Many thanks for your help, I appreciate that. I am sorry for the
>> inconvenient, I am new in these things.
>>
>>
>> Just to clarify, my window is complex because is created from a
>> "shapefile" that delimit my study area. This study area (called "W" in
>> the analysis) have the spatial locations of my data ("ficus" and
>> "tienda").
>>
>>
>> With the purpose of reproduce the analysis and try to find the problem,
>> in the attachment documents you can find the "shapefile" of my study
>> area, a "txt" document of my data and my R script (Kcrossinhom(DV)).
>>
>>
>> Again, I really appreciate your help. Thank you.
>>
>>
>> Cheers
>>
>>
>>
>> 2013/10/21 Julia Chacon Labella <juliachacon at gmail.com
>> <mailto:juliachacon at gmail.com>>
>>
>> Yes, I tried to reproduced your example, and I didn´t have any
>> problem. Have you check how are your lambdas?? Why are you using "at
>> points" instead of the default "by pixel"??
>>
>> It seems that could be the lambda values what is wrong. Try to
>> visualized them, and try with the pixel image.
>>
>> Other option is to built a new window for your pattern. How did you
>> built it?
>>
>>
>>
>> 2013/10/22 Rolf Turner <r.turner at auckland.ac.nz
>> <mailto:r.turner at auckland.ac.nz>>
>>
>>
>>
>> Again, your problem is not reproducible. We do not have the
>> objects
>> "north", "west", "W" and "tipo" which are necessary to duplicate
>> your
>> steps.
>>
>> I tried to reproduce your problem with an artificial example:
>>
>> W <- owin(c(0,3350),c(0,6150))
>> set.seed(42)
>> Z <- runifpoint(201,win=W)
>> m <- sample(rep(c("ficus","tienda")__,c(131,70)),201)
>> marks(Z) <- factor(m)
>> ff <- with(split(Z),bw.diggle(ficus)__)
>> tt <- with(split(Z),bw.diggle(__tienda))
>> lambdaf <- with(split(Z),density(ficus,__ff,at="points"))
>> lambdat <- with(split(Z),density(tienda,__tt,at="points"))
>>
>> K <- Kcross.inhom(Z,"ficus","__tienda",lambdaf,lambdat)
>>
>> No problema.
>>
>> It is possible that the error has something to do with the
>> rather intricate
>> (1716 vertices) boundary of your observation window. However
>> since I don't
>> have that window I can't tell.
>>
>> cheers,
>>
>> Rolf Turner
>>
>>
>>
>> On 10/22/13 10:16, david.villalobos wrote:
>>
>> Sure Julia,
>>
>> First:
>>
>> I have the following object called "Z"
>>
>> Z <- ppp(north, west,window=W,marks=tipo)
>> summary(Z)
>>
>> Marked planar point pattern: 201 points
>> Average intensity 4.46e-05 points per square unit
>>
>> Coordinates are integers
>> i.e. rounded to the nearest 1 unit
>>
>> Multitype:
>> frequency proportion intensity
>> ficus 131 0.652 2.90e-05
>> tienda 70 0.348 1.55e-05
>>
>> Window: polygonal boundary
>> single connected closed polygon with 1716 vertices
>> enclosing rectangle: [484546.8, 487897.4] x [1147521.3,
>> 1153682.9] units
>> Window area = 4509680 square units
>>
>> Second:
>>
>> I calculated the bandwidth sigma for the kernel estimator of
>> point process
>> intensity with a Cross Validated Bandwidth Selection for
>> Kernel Density
>> (bw.diggle)
>>
>> attach(split(Z))
>> f<-bw.diggle(ficus)
>> t<-bw.diggle(tienda)
>>
>> Third:
>>
>> I calculated with the Kernel Smoothed Intensity of Point
>> Pattern
>> (density.ppp) the values of the the estimated intensity of
>> the sub-process
>> of points of type i and j:
>>
>> lambdaf<-density.ppp(ficus,f,__at="points")
>> lambdat<-density.ppp(tienda,t,__at="points")
>>
>> and Finally:
>>
>> I ran the script for Kcross.inhom for the method (1):
>> estimate intensities
>> by nonparametric smoothing, but I had the error.
>>
>> K <- Kcross.inhom(Z, "ficus", "tienda", lambdaf, lambdat)
>>
>> Error in Kwtsum(dclose, bI, weight, b, 1/lambdaI, breaks) :
>> Weights in K-function were infinite or NA
>>
>> I tryed the method (2): leave-one-out, but I had the same
>> problems
>>
>> Any help is appreciated. A lot of thanks.
>>
>>
>>
>>
>>
>>
>> --
>> View this message in context:
>>
>> http://r-sig-geo.2731867.n2.__nabble.com/Problems-with-__Kcross-inhom-__tp7584914p7584920.html
>>
>> <http://r-sig-geo.2731867.n2.nabble.com/Problems-with-Kcross-inhom-tp7584914p7584920.html>
>> Sent from the R-sig-geo mailing list archive at Nabble.com.
>>
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>>
>>
>> --
>> Julia
>>
>>
>>
>>
>> --
>>
>> Saludos
>>
>> David Villalobos Chaves
>> Maestría Académica en Biología
>> Universidad de Costa Rica
>>
>>
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>
>
--
Saludos
David Villalobos Chaves
Maestría Académica en Biología
Universidad de Costa Rica
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