[R-sig-Geo] Accessing the ids of neighbours in spdep

[Roger Bivand]

On Mon, 29 Sep 2014, Frede Aakmann Tøgersen wrote:

> Hi
>
> I'm not really sure I understand you but perhaps something like this:
>
> lapply(xx, paste, collapse = ", ")

Yes, this is the closest we can get without more input from Kenny.

This gives the 1-base integer indices in a list of single element 
character vectors. If the output should be a character vector with the 
same number of elements as the input:

lapply(xx, as.character)

will do it. But the IDs of the underlying entities (could be FIPS, NUTS3, 
whatever) are in attr(xx, "region.id"), so to get those:

lapply(xx, function(x) attr(xx, "region.id")[x])

is needed, or if a list of single element character vectors is required:

lapply(xx, function(x) paste(attr(xx, "region.id")[x], collapse = ", "))

Here the IDs are 0-based rather than 1-based, but the attr(xx, 
"region.id") values are arbitrary - they are taken from row.names() of the 
spatial object unless given as an argument to functions creating the "nb" 
object.

Hope this clarifies,

Roger

>
> Yours sincerely / Med venlig hilsen
>
>
> Frede Aakmann Tøgersen
> Specialist, M.Sc., Ph.D.
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>
>> -----Original Message-----
>> From: r-sig-geo-bounces at r-project.org [mailto:r-sig-geo-bounces at r-
>> project.org] On Behalf Of Kenny Bell
>> Sent: 29. september 2014 00:10
>> To: r-sig-geo at r-project.org
>> Subject: [R-sig-Geo] Accessing the ids of neighbours in spdep
>>
>> Hi,
>>
>> I am trying to get an actual list of neighbour ids out of an nb object. For
>> example, I have
>>
>> library(spdep)
>> example(columbus)
>> xx <- poly2nb(columbus)
>>
>> What would be my command to get the list of neighbours as a list of
>> character vectors?
>>
>> Thanks so much for any help,
>> Kenny
>>
>> 	[[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