On Fri, 16 Jul 2010, elaine kuo wrote:
Dear List,
I encountered an error message when trying to use Chebyshev as method for
SAR.
Please kindly help and thanks.
Beyond what Danlin said, I am very unsure where to start. Please provide
adequate information about your input data, specifically the number of
observations, and the number of links in the neighbour list
length(nb10)
sum(card(nb10))
In addition, the implicit discription of nb10 looks confusing (is the
distance threshold 1.5, 9, or 10?). The ordering of lat and lon looks
wrong. You are not using Great Circle distances (and probably should?). So
memory issues in errorsarlm are the least of your problems. My guess is
that with dnearneigh() and a threshold of 9 degrees, you are including
most of a large data set in the neighbour list, and if n is large, this
will give a very large almost dense set of spatial weights, which was not
what you intended.
Get the weights correct first, and the rest will likely follow.
Roger
package spdep was updated on 07162010
system: windows vista home 32-bit
R version 2.10.0 (20091026)
Elaine
Code
library(ncf)
library(spdep)
# Define coordinates, neighbours, and spatial weights
coords<-cbind(datam$lat,datam$lon)
coords<-as.matrix(coords)
#Define neighbourhood (here distance 1.5)
nb10<-dnearneigh(coords,0,9)
nb10.w<-nb2listw(nb10, glist=NULL, style="W", zero.policy=FALSE)
sem.nb10.w <-
errorsarlm(datam$WinterM_ratio~datam$topo_mean+datam$coast+datam$prec_max
+datam$temp_min+datam$evi_min, listw=nb10.w,
method="Chebyshev",tol.solve=1.0e-17)
error: cannot allocate vector of size 121.8 Mb
sem.nb10.w <-
errorsarlm(datam$WinterM_ratio~datam$topo_mean+datam$coast+datam$prec_max
+datam$temp_min+datam$evi_min, listw=nb10.w,
method="Chebyshev",zero.policy=TRUE,tol.solve=1.0e-17)
error in switch(Generic, `+` = , `-` = { :
Cholmod error 'out of memory' at file:../Core/cholmod_memory.c, line 148
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--
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: roger.biv...@nhh.no
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