[R-sig-Geo] error using predict.sarlm

[evans324 at umn.edu]

Hi Roger,

Thanks for the response. Unfortunately, I'm still getting the same error 
running predict.sarlm ("Error in if (nrow(newdata) != 
length(listw$neighbours)) stop("mismatch between newdata and spatial 
weights") : argument is of length zero"). Here's what I've done since.

>Thanks for providing the verbatim code. If this is the verbatim code, then 
>newdata = "dak_test_data" is saying that newdata is not the data.frame 
>object called dak_test_data, but a single element character vector - that 
>is, nrow("dak_test_data") is NULL. However, this does not trigger the 
>error message as such, so it could also be that you wrote newdata = 
>dak_test_data, and nrow(dak_test_data) is not equal to 

I removed quotes, but still get the same error. The dak_test_data file was 
imported using readShapePoly. I also tried importing the dataset using 
read.dbf, but still got the same error using the resulting data frame.

> However, this does not trigger the error message as such, so it could 
> also be that you wrote newdata = dak_test_data, and nrow(dak_test_data) 
> is not equal to length(dak_test.10nn.listw) - or here nrow(coords), which 
> is the test.

As you suggested, nrow(dak_test_data)is NULL and thus is not equal to 
length(dak_test.10nn.listw), which equals 3. nrow(coords) = 2255. Here's 
the sequence of code that went into creating these weights:

coords<-coordinates(dak_test_data)
rn<-sapply(slot(dak_test_data, "polygons"), function(x) slot(x, "ID"))
dak_test.10nn <- knearneigh(coords, k=10)
dak_test.10nn.nb <- knn2nb(dak_test.10nn, row.names=rn, sym=TRUE)
dak_test.10nn.listw <- nb2listw(dak_test.10nn.nb, zero.policy=TRUE)

When I ran this using the imported dbf, I used the same weights since I'm 
not aware of a way to create weights without tracing back to a shapefile. 
The data frame in this case had nrow=2255. I still received the same error 
message.

I'd appreciate any help you can offer in solving this problem.  Thanks.

Heather Sander 


-- 
Heather Sander
Ph.D. Candidate:  Conservation Biology
Office:  305 Ecology & 420 Blegen
Mail:  
University of Minnesota
Dept. of Geography
414 Social Science Bldg.
267 19th Ave. S.
Minneapolis, MN 55455
USA