[R-sig-Geo] polygon neighbor matrix

[boB Rudis]

I second the `gTouches` suggestion. There's a ref here:
http://stackoverflow.com/a/26499134/1457051 but the gist of it is
(this user needed adjacent polygons in ghana):

library(rgeos)
library(rgdal)

# using http://data.biogeo.ucdavis.edu/data/diva/adm/GHA_adm.zip
ghana <- readOGR("GHA_adm", "GHA_adm1")

gTouches(ghana, byid=TRUE)

##       0     1     2     3     4     5     6     7     8     9
## 0 FALSE  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE  TRUE
## 1  TRUE FALSE FALSE  TRUE FALSE  TRUE FALSE FALSE  TRUE  TRUE
## 2  TRUE FALSE FALSE  TRUE  TRUE FALSE FALSE FALSE FALSE  TRUE
## 3  TRUE  TRUE  TRUE FALSE  TRUE FALSE FALSE FALSE  TRUE FALSE
## 4 FALSE FALSE  TRUE  TRUE FALSE FALSE FALSE FALSE  TRUE FALSE
## 5 FALSE  TRUE FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE FALSE
## 6 FALSE FALSE FALSE FALSE FALSE  TRUE FALSE  TRUE FALSE FALSE
## 7 FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE FALSE FALSE FALSE
## 8 FALSE  TRUE FALSE  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE
## 9  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE

On Mon, Aug 31, 2015 at 2:19 PM, Roger Bivand <Roger.Bivand at nhh.no> wrote:
> On Mon, 31 Aug 2015, Paul Lantos wrote:
>
>> Hi,
>>
>> I'm trying to use the cluster analysis program Flexscan, which I gather is
>> similar to Satscan but it computes irregular clusters. This program requires
>> a polygon adjacency matrix (termed a 'matrix definition file'). The example
>> they provide has a row for every polygon, and for each row every neighboring
>> polygon is listed in successive columns. So for instance if row 1 / polygon
>> 1 has 3 neighbors there will be three polygons listed in columns 2-4.
>>
>> I have tried some techniques like the spatial weights matrix tools in
>> ArcGIS and in Spatstat, but I cannot get the output in this kind of format.
>> Was wondering if there is some obvious way to do this in R.
>>
>> The documentation for Flexscan is here:
>>
>>
>> https://sites.google.com/site/flexscansoftware/download_e/FleXScan%20User%20Guide_e31.pdf?attredirects=0&d=1
>
>
> Something like:
>
> library(spdep)
> example(nc.sids)
> out <- sapply(seq(along=ncCR85_nb), function(i) paste(attr(ncCR85_nb,
>   "region.id")[i], paste(attr(ncCR85_nb, "region.id")[ncCR85_nb[[i]]],
>   collapse=" ")))
> writeLines(out, tf)
> file.show(tf)
>
> See also:
>
> vignette("nb")
>
> Roger
>
>>
>> Thanks for any help,
>> Paul
>>
>> _______________________________________
>> Paul M. Lantos, MD, FIDSA, FAAP, FACP
>> Departments of Internal Medicine and Pediatrics
>>  Pediatric Infectious Diseases
>>  Hospital Medicine Program
>> Duke University School of Medicine
>> _______________________________________
>>
>>
>>         [[alternative HTML version deleted]]
>>
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>>
>
> --
> Roger Bivand
> Department of Economics, Norwegian School of Economics,
> Helleveien 30, N-5045 Bergen, Norway.
> voice: +47 55 95 93 55; fax +47 55 95 91 00
> e-mail: Roger.Bivand at nhh.no
>
>
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