[R] Spatial Ananlysis: zero.policy=TRUE doesn't work for no neighbour regions??

Molo kurz_m at uni-hohenheim.de
Tue Apr 16 16:51:10 CEST 2013

```Hello,

I'm new to R and to Spatial Analysis and got a problem trying to create a
Spatial Weights Matrix.

*I us the following code to create the Neighbourslist:*

>library(maptools)
>library(spdep)
>library(rgdal)

>proj4string(location_County)<- CRS("+proj=longlat ellps=WGS84")
>location_nbq<- poly2nb(location_County)
>summary(location_nbq)

*And get this Output:*

Neighbour list object:
Number of regions: 3109
Percentage nonzero weights: 0.1887671
35 689 709 881

0    1    2    3    4    5    6    7    8    9   10   11   13   14
4   29   40   94  283  616 1045  703  228   51   12    2    1    1
29 least connected regions:
45 49 587 645 844 853 1206 1286 1391 1416 1456 1478 1485 1545 1546 1548 1558
1612 1621 1663 1672 1675 1760 1794 1795 2924 2925 2952 3107 with 1 link
1 most connected region:

*As there are some regions without neighbours in my data I use the following
code to create the Weights Matrix:*

> W_Matrix<- nb2listw(location_nbq, style="W", zero.policy=TRUE)
>W_Matrix

*And get this Output:*

Fehler in print.listw(list(style = "W", neighbours = list(c(23L, 31L, 42L :
regions with no neighbours found, use zero.policy=TRUE

/("Error in print.listw(list(style = "W", neighbours = list(c(23L, 31L, 42L
:
regions with no neighbours found, use zero.policy=TRUE")/

As I use "zero.policy=TRUE" I just don't understand what I'm doing wrong...
My question would be: How could I create a Weights Matrix allowing for
no-neighbour areas?

Thanks
Michael

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```