[R-sig-Geo] kernelbb and extent

[Anna Skarin]

Hi again,

If specifying a larger grid (grid=400) giving cellsize= 187 (instead of cellsize=2000), the difference described below remain but will be much smaller and possibly negligible, so I guess my problem is solved. (I somewhat also mixed grid with cell.size when reading the instructions).

Cheers,
Anna

On Jun 7, 2012, at 21:20 , Anna Skarin wrote:

Dear All,

I'm struggling with the kernelbb in adehabitatHR. I'm calculating the Brownian Brigdes Home Range (BBHR) for reindeer using GPS-data from a number of reindeers. However when I'm using the kernelbb() I get somewhat different results depending on the number of burst included in the ltraj used in the kernelbb, even though I state the same grid size and extent. So is there a bug here or I'm doing things the wrong way, or thinking the wrong way? The function seems to fit the HR to the extent of the total data and not to the single burst, even though the same extent is defined in the function.

All the best,
Anna Skarin
(Sorry for any double posting)

Here is my script and please download example data from:

https://www.box.com/s/af1a8eeb9b33a26b09ce


ltraj4
ltraj1 <- ltraj4[c(1)]

sig2 <-10
renLiker <- liker(ltraj4, sig2, byburst=TRUE, rangesig1=c(0,20), plotit=F)
renMedian <- median(sapply(renLiker, function(x) x$sig1))


#Here I use the same sig1 in all estimations for comparison
ren1<-kernelbb(ltraj1, sig1=renMedian, sig2, byburst=TRUE, grid=50, extent=0.5)
ren4<-kernelbb(ltraj4, sig1=renMedian, sig2, byburst=TRUE, grid=50, extent=0.5)


#compare this plot with....
plot(ltraj1, spixdf=ren1)

#...this plot! shouldn't they be similar?
spren4 <- estUDm2spixdf(ren4)
plot(ltraj4[c(1)], spixdf=spren4)


#or compare these plots and data...
plot(getverticeshr(ren1, 99), lwd=2)
plot(getverticeshr(ren4$r_RG_08_079, 99),add=TRUE, lwd=2)

ren1vol <-getvolumeUD(ren1)
summary(ren1vol)
ren4vol <-getvolumeUD(ren4)
summary(ren4vol$r_RG_08_079)



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Anna Skarin,
Forskarassistent
Dr.
Sveriges lantbruksuniversitet
Swedish University of Agricultural Sciences
Institutionen för husdjurens utfodring och vård
Avdelningen för Renskötsel
Box 7024, 750 07 Uppsala
Besöksadress: Almas allé 8D
Telefon: 018/67 19 54, mobil: 070-588 28 14
Anna.Skarin at slu.se<mailto:Margareta.Norinder at slu.se>, www.slu.se<http://www.slu.se/>

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