Jan Holstein
2014-Mar-20 12:47 UTC
dnearneigh::spdep: undesired behaviour with SpatialPoints object: bug or feature? Please confirm.
I noticed that dnearneigh::spdep shows diverging behaviour with matrix and
SpatialPoints objects respectively:
reproducible example:
library(spdep)
set.seed(5)
spdf<-SpatialPointsDataFrame(cbind(lon=runif(1000,2,8),lat=runif(1000,53,56)),
data=data.frame(par=runif(1000,0,1)),coords.nrs
numeric(0),proj4string=CRS("+init=epsg:4326"))
dnearneigh(x=coordinates(spdf), d1=0, d2=20,longlat = TRUE)
#Neighbour list object:
#Number of regions: 1000
#Number of nonzero links: 9504
#Percentage nonzero weights: 0.9504
#Average number of links: 9.504
#2 regions with no links:
#449 619
but ...
dnearneigh(as(spdf,"SpatialPoints"), 0, 20,longlat = TRUE)
#Neighbour list object:
#Number of regions: 1000
#Number of nonzero links: 999000
#Percentage nonzero weights: 99.9
#Average number of links: 999
it seems that 'dnearneigh' ignores longlat=TRUE if
class(x)==SpatialPoints,
since
dnearneigh(x=coordinates(spdf), d1=0, d2=20,longlat = FALSE)
#Neighbour list object:
#Number of regions: 1000
#Number of nonzero links: 999000
#Percentage nonzero weights: 99.9
#Average number of links: 999
gives the same 'undesired' result.
- can you confirm this behavior?
- is this a bug (to it feels like on) or did I overlook the greater picture
and this is a feature??
R version 2.15.3 (2013-03-01)
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)
other attached packages:
[1] spdep_0.5-56 coda_0.16-1 deldir_0.0-21 maptools_0.8-23
foreign_0.8-53 nlme_3.1-108
[7] MASS_7.3-23 Matrix_1.0-12 lattice_0.20-15 boot_1.3-7
sp_1.0-8
-----
Jan M. Holstein, Dept. Functional Ecology, Alfred Wegener Institut for Polar and
Marine Research (AWI)
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