Question on symmetric for nb2mat
Dear all, I think the following message should work. Excuse me for the
previous message.
library(spdep)
library(rgdal)
library(Matrix)
nc_sids <- readOGR(system.file("shapes/sids.shp", package = "spData"))
adj <- poly2nb(nc_sids)
W <- as(nb2mat(adj, style = "B"), "Matrix")
Matrix::isSymmetric(W)
chol(W)
If it's still not working I added a reprex here:
https://gist.github.com/agila5/59d3a173df9b1efabe13800f748a2d48
Kind regards
Andrea
Il giorno mer 29 lug 2020 alle ore 17:19 Roger Bivand <Roger.Bivand at nhh.no>
ha scritto:
Please follow-up in this thread posting in plain text (not HTML). As you can see below, HTML garbles your message. On Wed, 29 Jul 2020, Andrea Gilardi wrote:
Dear all, probably I'm missing something obvious but I have a question on the matrix built using nb2mat with argument style = "B". More precisely,
I
don't understand why the following code says that the matrix *W* (which
should be a binary first-order adjacency matrix) is not symmetric:
*library(spdep)library(rgdal)library(Matrix)# datanc.sids <-
readOGR(system.file("shapes/sids.shp", package = "spData"))adj <-
poly2nb(nc.sids)W <- as(nb2mat(adj, style = "B"),
"Matrix")Matrix::isSymmetric(W)#> [1] FALSEchol(W)#> Error in
asMethod(object): not a symmetric matrix; consider forceSymmetric() or
symmpart()*
Kind regards
Andrea
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