Error with read.GWT2nb in making KNN weights symmetrical
On Thu, 17 Mar 2011, Kevin Wolff wrote:
Hi all,
I have worked with R before, but admittedly not in some time. What I am
trying to do is take my Geoda?Nearest Neighbors Spatial weights files
and make them symmetrical in order to use the Spatial Lag and Spatial
Error functions in Geoda. Roger has been kind enough to help with this
in the past and I have the code to do it. The issue I am facing
currently is getting R to run the code specified. I run the first line
knngwt?<- read.GWT2nb("1503_NN.GWT", region.id=NULL ) and get the
following error: "Error: could not find function "read.GWT2nb"
Well, R is case sensitive, and the function is named read.gwt2nb(), so the error does seem plausible. Try using the right name. Tip - try ?<name> to see if a function exists and is user-visible. Roger
I have installed the newest version of R (2.12) as well as installed the maptools and spdep packages which seem to run okay.
install.packages("maptools",dependencies=TRUE)
install.packages("spdep",dependencies=TRUE)
But when I put the syntax in I get that error message. This may be due to an error on my part in installing the required packages, but I have tried everything I have come across to no avail. I appreciate any guidance in this matter. The full code, that I am attempting to run is below. Thank you again. Kevin
knngwt <- read.GWT2nb("1503_NN.GWT", region.id=NULL )
class(knngwt) # "nb"
summary(knngwt)
print(is.symmetric.nb(knngwt))
knngwtsym <- make.sym.nb(knngwt)
class(knngwtsym) # "nb"
print(is.symmetric.nb(knngwtsym))
listw1 <- nb2listw(knngwtsym, style="B")
class(listw1) # "listw"
knngwtsymsn <- listw2sn(listw1)
class(knngwtsymsn) # "spatial.neighbour"
write.sn2gwt(knngwtsymsn, "1503_NN_SYM.GWT"
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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.Bivand at nhh.no